EPA/&30/2-3G/045
Anril 1906
TOXIC SUBSTANCE REMOVAL IN
ACTIVATED SLUDGE AND PAC TREATMENT SYSTEMS
by
Walt°r J. Weber, Jr. ar.d Bruce E. Jones
The University of Michigan
Ann Arbor, Michigan 48109
Grant No. CK 806030
Project Officer
Sidney A. Hannah
Mastewater ?cse?rch Division
Water Engineering Research Laboratory
Cincinnati, Ohio 45268
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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TECHNICAL REPORT DATA
(Please reod lnr:njcitcns on the ,evene be/Ore corn ple:tn )
1 REPORT NO 13 RECIP
EWN N0
EPA/600/2—86/OLe S I r c6ccrl 242 5
4 TITLE ANO SUOTITLE 15 REPORT DATE
Toxic Substance Removal in Activated Sludge I April 1986
6 PERFORMING ORGANIZATION C OE
and PAC Treatment Systems
AUTHOR(S)
Walter J. Weber, Jr. and Bruce E. Jones
8 PERFORMING ORGANIZATION REPORT NO
PERFORMING ORGANIZATION NAME AND ADDRESS
The University of Michigan
Environmental Engineering Laboratory
Department of Civil Engineering
s.r , , rhr ,r MT
O PROGRAM ELEMENT NO
12 CONTRACT/GRANT NO
CR 806030
12 SPONSORING AGENCY NAME ANO ADDRESS
Water Engineering Resear:h Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45263
13 TYPE OF REPORT AND PERIO.3 COVERED
Final 9/1/80 — 2/28/83
14 SPONSORING AGENCY CODE
EPA/6 00/14
15 SUPPLEMENTARY NOTES
Project Officer: Sidney A. Hannah 513-684-2621 FTS: 634-2621
16. A8STHACT
The effectiveness of addir.g powdered act vated carbon to activated sludge systems
was evaluated for enhanced removal of specific toxic organic compounds. Nine organic
compounds encompassing a rarge of solubility, volatility, biodegradability, and
adsorptive properties were studied along with selected commercial powdered activated
carbons. The studies showed that the addition of less than 100 mg/i powdered activatec
carbon did not enhdnce the removal of the biodegradable compounds benzene, toluene,
ethylbenzene, o—xylene, chlorobenzene, and nitrobenzene. Significantly improved
removals of the poorly degradable and non—biodegradable compounds l,2—dichloro—
benzene, l,2,4—trichlorobenzene, and lindane, occurred at influent powdered carbon
concentrations in the 12.5— to 25—mg/i ran ,e. Influent powdered carbon concentrations
of 100 mg/i effected overall removals of greater than 90Z. The addition of powdered
activated carbon not only reduced effluent concentrations but also reduced the
amounts of the volatile compounds stripped to the atmosphere. -
ii. KEY WORDS ANO DOCUMENT ANAL .SIS
OESCRIP TORS
b IOENTIFIERS/OPEN ENDED TERMS
C COSATI F cId/Croup
adsorption, activated carbon,
activated sludge, biological treatment
priority pollutants, tocic compounds
21 AGES
rj’
18. BISTRIOUTJON STATEMENT
Release unlimited
29 SECURITY CLASS iT7 i Reporr
none
20 SECURITY CLASS IT7IIZP9ICJ
none
22 PRICE
EPA Fo. 2220—I (R.,. 4_7 ) PR VIOU$ LOITION 1$ OUIOI.C1(
i
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D1SCLAIME
The information in this document ‘tas been funded wholly or in part
by the United States Enviroririefltal Protection Agency under assistance
agreement number C 8ObO3O to the University of Michigan. It has been
subject to the Agency’s peer and administrative review, and it has been
approved for publication as an EPA locument. Mention of trade names or
comcierc1a products does not constitute endorsement or recommendation for
use.
Ii
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FORFI ORD
The U.S. Enviromoeiital Prot tion Agency is charged by Congress
with protecting the Nation’s land, air, and nter systems. Under a
mandate of national envirormental laws, the agency strives to formulate
and implement actions leading to a compatible balance bet en human
activities and the ability of natural systrms to support and nurture
life. The Clean Water Act, the Safe Drinking Water Act, and the Toxics
Substances Control Act are three of the major congressional laws that
provide the framework for restoring and ma3ntalning the integrity of
our Nation’a water, for preserving and enhancing the water we drink,
and for protecting the environment from toxic substances. These laws
direct the EPA to perform research to define our enviromnental
problems, measure the impacts, and search for solutions.
The Water Engineering Research Laboratory is that component of
EPA’s Research and Development progran concerned with preventing,
treating, and managing municipal and industrial wastewater discharges;
establishing practices to control and remove contaminants from drinking
water and to prevent its deterioration during storage and distribution;
and assessing the nature and controllability of releases of toxic
substances to the air, water, and land from manufacturing processes and
subsequent product uses. This publication is one of the products of
that research and provides a vital conounication link between the
researcher and the use community.
The project described in this report examines the fate of toxic
substances in conventional wastecnter treatmen systems, and evaluates
methods for enhancing the removal of toxic compounds in such systems.
As such, it addresses toe issues of treatment of municipal and
industrial vastewater discharges as well as the control of releases of
toxic substances to the environment.
Francis 1. Mayo, Director
Water Engineering Research Laboratory
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ABSTRACT
The effectiveness of adding nowdered activated carbon to
activated sludge systems was evaluated fcr enhanced removal of
specific toxic organic compounds. Little prior information existed
on the behavior of toxic organics during activated sludge
trpatneflt. Thus a considerable effort was dir ted toward
identifying and quantifying the fate of specific compounds in
conventional activated sludge systems as well as in those to which
carbon was added. Nine organic compounds encompassing a range of
solubility, volatility, biodegradability, and adsorptive properties
wre studied along with se]ected cont rcial powdered activated
carbons recommended for use in IntEgrated activated sludge/carbon
treatment systems. Compli te1y—1BixedfiOv bioreactors equipped with
internal clarifiers and ‘ir—L’ght lids were used to study the
removal of each compounc ’ . Completely—mixed batch rate and
equilibriun studies were conducted to quantify the removal
mechanisms — — volatilization, biodegradation, biosorptiofl, and
carbon adsorption.
Results from steady—state bioreator studies showed that the
addition of less than 100 mg/i pcwdered activated carbon did not
enhance the removal of the biodegradable ta ics benzene, toluene,
ethylbenzetle, o—xylene , chiorobenzene, and nitrobeniene.
Significantly improved removals of the poorly degradable and
nonbiodegradable compounds 1 ,2—dichlorobenzeue, 1,2,4—
trichlorobenzene, and lindane occurred at influent powdered carbon
concentrations in the 12.5— to 25—mg/I range. Influent powdered
carbon concentrations of 100 mg/I effected ov rail removals of
greater than 90%. The addition of powdered activated carbon not
only reduced effluent concentrations but also raduced the amounts
of the volatile compounds stripped to the atemephere.
This report was submitted in fulfiilnmnt of Contract No.
CR 806030 by The University of Michigan under the sponsorship of
the U.S. Environmental Prot tion Agency. This report covers the
period 9/1/80 to 2/28/83, and work was completed as of 2/28/83.
iv
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CO NT EN S
Foreword . j•
ADs r8ct . iv
Figures
Tables
Abbreviations and Symbols xlv
1. Introduction 1
2. Conclusions
3. Recommendations 5
4. Background 6
Occurrence of Toxic Organic Compour4s
in Waste.,ater 6
Int rate i ActivatEd Sludge/Carbon
Treatment 8
5. Experimental Design 13
Selection of Toxic O-ga ic Compounds 13
Selection of PowderEd ActivatEd Carbons ... 13
Bioreactor Design 16
Rate Studies 20
Equilibrium Studies 23
6. Analytical Methodologies 26
Aqueous Samples ... 26
Off—Gas Samples 29
7. Resu1 s: Vo .ati1ization Studies 33
Effect of ALr—Str3pping on the Fate of
Toxic Organics in Bioreactors without
Actii ateI Sludge 33
Determination of Volatilization Rate
Coef f ic ients .. . . . . . . . . . . . . 33
Effect of Aeration Rate on Volati1izat cn
RateCoeff ientS 37
Air Stripping Model for CMF Bioreactor ....
Effect of Using Sealed Bioreactors on
Volatilization Rate Coefficients ......... 50
Oxygen ReaeraLou 63
8. Results: Biosorption Studies . 67
Rate Studies 67
Equ ili.briumRe sults 67
CorreiationofKgv1 bKo w 69
V
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9. Development of Tr e Organics Removai Model
for Activated Sludge 75
Introduction 75
General STORN Developtrent 76
Application of STORI to Nonbiooegraiable
Compounds 77
Applicatton of STOIM to Biodegradable
Compounds 85
10. Results: Control Activat Sludge Bioreactor
Studies 92
Activatal Sludge Bioreacto Operating
Conditions 94
Systmo Performance with Rc pect to T
Removal 96
Fate of Nonbiodegralable and Poorly
Biodegradable Organic Compounds 103
Fate of Biodegralable Compounds during
Activated Sludge Treatrent 126
Determination of Biodegraiation Rate
Coefficients 198
Multi—solute Activat Sludge Study 247
Effect of Influent Toxics Concentration
on Biodegralation 281
Transient Loa1in Studies 317
11. Results: Int ratal Acttvatal Sludge/Carbor.
Adsarption Bioreactor Studies 341
Bioreactor Operating Curditions 342
PAC Adsorption Studies 342
Effect of PAC-Addition on Overall I cC
Removal
Removal of Norbiodegralable Toxic Organic
Compounds 361
Removal of Biodegrndable Conpoucds 399
Effect of Solids Recent ion Tirne on Overall
Toxjcs Removal 431
Effect of Interwpting PAC—Addit ion on
Overall Toxics Removcl 448
Transient Loading Stuc y 467
12. Summary 492
Removal Mechanism 493
Activacef Sludge Biore tor Sr dies 495
Integrated Ac ivated Sludge/Carbon
Treannent Bioreator Sludies 502
References 509
vi
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FIGURES
Number Page
4—1 Simolifled schematic diagram of tne PACT system 9
3—1 cher’atic diagram of l —l tor o oreactor 17
5—2 Schematic 1l stratior. of experir cntal system 18
5—3 Schematic illustration of the 3—liter bioreactor
design 21
6—1 ?urgin device used for sampling volatile organic 28
compounds
7—1 VolatlllZatiOfl ot selected toxic organic
compounds fron 10—liter bioreactorS without
activated sludge 35
7—2 Data poults and best—fit lines describing the
vo1at2fizatiO rates of selected toxic
organic compounds from 10—iiter bioreactorS
without activated sludge and with air—tight
lids 36
7—3 Effect of aeration rate on oenzer.e volatilization
rate from 10—liter bioreactors with air—tight
lids and wjthout activated sludge 38
7—4 Effect of aeration rate on the toluene volatiliza-
tion rate from 10—liter bioreactorS with air—
tight lids and without activated sludge 39
7—5 Effect of aeration rate on the ethylbenzefle
volatilization rate from 10—liter bioreactorS
with air—tight lids and jithout activated
sludge 40
7—6 Effect of aeration rate on the o—xvlene
volatilization rate from 10—Liter bicreactorS
with air—tight lids and vithout activated
sludge 41
.;ii
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Number
7—7 Effect of aeration race on the chlor beflZefle
volatilization rate from 10—liter bioreactors
with air—tight lids and without activated
sludge 42
7—8 Effect of aeration rate on the 1,2_dichlorobeflZefle
volatilization rate from 10—liter bioreactors
with air-tigflt 1id and without activated
sludge 43
7—9 Effect of aeration rate on the 1,2,4 —trichlOro—
benzene voLatilization rate from 10—liter
bioreactors with air-tight lids and without
activated sludge 44
i—io Effect of aeration rate on volatilization rate
coefficients measured in 10—liter bioreactors
with air—tight lids and without activated
sludge 45
7—11 Data points and best—fit hues for results
from replicate benzene volat lizatiOfl studies
in 10—Liter sealed bloreactorS with 4.0—
hite /mhfl aeration rates 46
7—12 Data points and best—fit lines for results
from replicate benzene volatilization studies
in 10—liter sealed bioreactorS with 3.0—uteri
miii aeration rates 47
7—13 Benzene volatilization from sealed and open
10—liter bioreactors with !..0 liter/aim
aeration rates 51
7—16 Toluene volatilization from sealed and open
10—liter bioreactotS with 4.0—liter/aim
aeration rates 52
7—15 Ethylbenzefle volatilization from sealed and
open 10—liter bioreaCtOrs wjth 4.0—liter/mm
aeration rates 53
7—16 o—Xylene volatilization from sealed and cpen
10—liter bioreactOrS with 4.0—liter/mu
aeration rates 54
7—17 Chlorobenzefle volatilization from sealed and
open 10—liter bioreaCtOrs with 4.0—liter/mill
aeration rates 55
viii
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Number
7—18 Data points and best—fit lines describing the
relationship between the benzene volacil.ization
rate coefficient and the aeration rate for
sealed and open 10—liter bioreactorS 57
7—19 Data points and best—fit lines describing the
relationship between the taluene .:olatilization
rate coefficient and the aeration rate for
sealed and open 10—liter bioreactorS 58
7—20 Data points and best—fit lines describing the
relationship between the- ethvlbenzene volatili-
zation rate coefficient and the aeration rate
[ or sealed and open 10—liter biorea:torS 59
7—21 Data points and best—fit lines describing the
relationship between the o—xylene volatili-
zation rate coefficient and the aeration rate
for sealed and open 10—lit’r bioreactorS 60
7—22 Data points and best—fit ines describing the
relationship between thu chlorobenzene
volatilization rate coefficient and the
aeration rate in sealed ano open 10—liter 61
bioreactorS
7—23 Experimental data and best—fit lines used to
determine the oxygen reaeratiofl rate coeffi-
cients for aeration :ates iron 1.0 to 6.0
liters/mm in the IC-liter bioreactorS with-
Out activated sludge 64
7—24 Experimental data and best- f it line describing the
effect of aeration rate en the oxygen reaeritiOfl
rate coefficient for the 10—liter bioreactOrS 65
81 Sorption of lindane by activated sludge rixed
liquor suspended solids in a completely mixed
batch ( NB) reactor 68
8-2 Freundlich isothertus for the sorption of lindane
and 1,2,4_trichlorobeflzene by activated
sludge mixed liquor suspended solids 70
8—3 Linear partioning isotherins for the sorption of
lindane and 1,2,4_trichlorobeflzefle oy acti-
vated sludge mixed liquor suspended solids 71
8—4 Correlation between the bi coflceflt’atiOfl factor
and octanol/water partition coefficient for
selected hydrophobic organic compounds 73
ix
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Nurnbe r
9—1 Relati nship between the volatiliZat1 fl r3ce
coefficient and the reduction in aqueous
concentration of volatile compounds in
10—liter bioreactors wiih air—tight lids 79
9—2 Sensitivity of the air—stripping model to
changes in the hydraulic retention time in
the 10—liter bioreaccors 80
9—3 Relationship between the biosorptl.on coefficient
and the reduction in aqueous concentration
of hydrophobic organic compounds due to
sorption by activated sludge 83
9—4 Effect of steady—state rn’ed ‘iquor suspended
solids concentration on removal of hydro-
phobic organic compounds due to sorption
by activated sludge 84
9—S Effect of increasing volatilization rate
coe ficiOfltS on the removal of hyarophobic
organic compounds due to sorption by
activated sludge 86
9—6 Pelationship bet .een the biodegrada ion tate
coefficient and the reduction in aqueous
concentration of a non—volatile o. ou u
9— Effect of increasing volatilization on the
disappearan Ce of a compound due to
biodegradation by activated sludge in a
10—liter sludge bioreactor 90
to— i Soluble TOC reroval in a 10—liter activated
sludge bicreac:or operated with a 3—day SRT 97
10—2 Soluble TOC removal in a 10—liter activated
sludge bioreactor operated with a 6—day SRT
10—3 Soluble TOC removal in a 10—liter activated
sludge bioreactor operated with a 6—day SRI 99
10-4 Soiub e TOC removal ir a 10—liter activated
si dee bioreactor operated with a 6—day SRI 100
10—5 Soluble TOC removal in a l0-lite- activated
sludge bioreactor operated with a 12—day SRI 101
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Number
10—b Cos ’parison of results from soluble TOC
degradation rate studies in 2.6—liter and
10—liter experimental bioreactors with
activated sludge 104
10—7 Coumarison of results from soluble ICC
degradation rate studies conducted in 10—
liter activated sludge bioreactors operated
with 6 and 12—day SRT’s 105
10—C Lindane results from a 10—later activated sludge
bioreactor study conducted with a 3—day SRT 106
10—9 L ndane res :lts from a 10—liter activated
sludge b oreactor study conducted ith a
6—day SRT 107
10—10 Lindane results from a 10—Liter .ictivated
sludge bioreactor study conducted with a
9-day SRT 108
10—11 1,2,4—Trichlorobenzene result3 from activated
sludge studies conducted in 10—liter
bioreactors operated with 6 and 12—day SRI’s
10—12 1,2,4—Trichlorobenzene resilts from the 6—day
SRI activated sludge study olotted without
off—gas concentration data 1!4
10—13 [ ,2,4—T-ichlorobenzene effluent and of f—g3s
concentrations preoicced by the aIr—
stripping model for the case of no bIodegra-
dation in the 10—liter activated sludge
bioreactors 116
10—14 1,2,4—Trichlorobenzene off—gas concertrations
and N/No values predicted from effluent
concentrations measured during the 6—day
SRT activated sludge stuay lie
10—15 l,2—Dichlorobenzene influent, effluent, and
off—gas concentrations and fractional recoveries
(N/No) from 6 and 12—day SRI activated sludge 119
studies
10—16 Influent, effluent, and off—gas concentrations
and N/Nc ’ values from a 6—day SRT activated
sludge study conducted in a 10—liter
bioreactor 120
xi
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Number
10—17 Influent, effluent, and off—gas fluxes and
anounts of l,2—d. . hlorobenzene removed by
b odegradatiofl during me 6—day SRT
activated sludge study 122
10—18 Experimental data and off—gas concentrations
and N/No values predicted from measurad
effluent concentrations for the 6—day SRT
activated sludge study with 1,2—aichloro—
benzene 125
10—19 Nitrobenzene influent and effluenc concentra—
tions and ratio of effluent to influent
concentrations, Co/Cl during a 6—day SRT
activated sludge study 126
10—20 Benzene influent, effluent, and off—gas
concentrations and fractional reco ’eries,
N/No, measured during the 3—day SRT
activated sludge study. 130
10-21 Benzene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during a 6—day SRT activated
sludge study 131
10—22 Benzene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during the 12—day SRT
activated sludge study 132
10—23 Comparison of influent, effluent, and off—
gas c ncentrat1oi s and fractional recoveries,
N/No, from benzene activated sludge studies
conducted In 10—liter bioreactors
operated with 3 and 6—day SRT’s 133
10—24 Comparison of influent, effluent, and off—
gas concentrations and fractional recoveries,
N/No, from benzene activated sludge studies
conducted in 10—liter bioreactors operatee
with 6 and 12—day RT’s 134
10—25 Overall benzene removals due o biodegradation
measured during activated sludge studies
conducted in 10-liter bioreactors operated
with 3,6, and 12—day SRT’s 135
10—26 Benzene influent, effluent and off—gas fluxes
and amounts renoved by biodegradation during
the 3—day SRT 8Ltivated sludge study 138
xii
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Number
10—27 Benzene influent, effluent, and off—gas mass
fluxes and amounts removed by biodegradation
during the 6—day SRT activated sludge study 139
10—28 Benzene influent, effluent, and off—gas mass
fluxes and amounts removed by bIodegradation
during the 12—day SRT activated sludge study 140
10—29 Comparison of benzene and 1,2,4—trichlorobenzene
results from 10—liter bioreactor activated
sludge studies without considering amounts
of each compound stripped to the atmosphere
in bioreactor off—gases 141
10—30 Beozene and 1,2,4—trichlorobenzene influent,
effluent, and off—gas concentrations and frac-
tional recoveries, N/No, from activated sludge
stt.dies conducted in l0—liier bLoreactors
operated with 6—day SRT’s 142
10—31 Experimental data and off—gas concentrations and
fractic”ial recoveries, N/Nc ’, predicted from
measured effluent concentrations for the 3—day
SR” activated sludge study with benzene 144
10—32 Experimental data and off—gas concentrations and
fractional recoveries, N/No, predicted from
measured effluent concentratiJns for the 6—day
SRT activated sludge study with benzene 145
10—33 Experimental data and off—gas concentrations and
fractional recoveries. N/No, predicted from
measured effluent concentrations for the 12—
day activated sludge study with benzene 146
10—34 Toluene influent, effluent, and off—gas concen-
trations and fractional recoveries, N/No,
measured during the —ciay SliT act .vated sludge
study 147
10—35 Toluene influent, effluent, and off—gas concen-
trations and fractional recoveries. N/No,
measured during the 12—day 31T activated sludne
study 149
10—36 Comparison of influent, effluent, and of f—ges
concentrations and fractional recoveries. ‘/No,
from toluene actIvated sLudge studies con-
ducted with 6 and 12—da ” soliis retention times 150
xiii
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Number
10—37 Toluene influent, effluent, and off—gas mass
fluxes and amounts removed by biciegrad tiOfl
during the 6-d.iy SRT activated sludge study 153
10—38 Toluene in luent, effluent, and off—gas mass
fluxes anc amounts removed by biodegradation
during the 12—day SRT activated iudge
study
10—39 Experimental data points and off—gas concentra—
dons and fractional recoveries, N/No, predic-
ted from measured effluent concentrations
for the 6—day SRT activated sludge study
for toluene 155
0—40 Experimental data points and off—gas concentra-
tions and fractional recoveries, N/No,
predicted from measured effluent concentra-
tions for the 12—day SRI activat’ u sludge
study with toluent. 156
10—41 Ethylbenzene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during a 6—day SRT ethyl—
benzene activated sludga study, EB—ASI 158
10—42 Ethvlbenzene influent, effluent, and off—gas
mass fluxes and amounts removed by bio-
degradation during the 6—cay SRI activated
sludge study, EB•ASI 155
10—43 Ethylbenzene influenc, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during a 6—day SRI ethyl—
benzene activated sludge study, EB—AS2 160
10—44 Ethylbenzene ipfluent, effluent, and off—gas
mass fluxes and amounts removed by biodegra-
dation during the 6—day SRT aLtivated sludge
study with ethylbenzene, EB—AS2 161
10—45 Comparison of influent. effluent, and off—gas
concentrations and fractional recoveries,
N/No, from two ethylbenzene activated sludge
studies, EB—AS1 and EB—A52, conducted with
6—day SRI’s 162
,C iv
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Number
10—46 Ethylbenzefle inuluent, effluent, and off—gas
concentrationS and fractional receveries,
N/No, measured during the 12-day SRT
activated sludge study 164
10—67 Ethvlbenzefle influent, effluent, and off—gas
mass fluxes and amounts removed by biodegra-
dation during the 12—day SRT ethylbenzene
activated sludge study 165
10—48 Comparison of influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, from echylbenzene activated sluage
studies conducted with 6 (EB—AS2) and
12—day SRT’s 166
10—49 Overall ethylbettZene removals due to biodegra-
dation measured during activated sludge
studies conducted in 10—liter bioreactorS
operated with 6 and 12—day solids .‘tentiofl
tiaes 167
10—50 Experimental data points and off-gas concentra-
tions and fractional recoveries, N/No, pre-
dicted from measured effluent concentrations
for the 6—day SRI activated sludge study
with ethylbenzefle. EB-ASI 168
10—51 Experimental data points and off—gas concentra
dons and fractional recoveries, N/No,
predicted from measured effluent concentra-
tions for the 6—day SRI activated sludge
study with ethylbenzene, EB—A52 169
10—52 Experimental data points and off—gas concentra-
tions and fractional recoveries, N/No,
predicted from measured effluent concentra-
tions for the 12-day SRI activated sludge
study with ethylbenzene 1.71
10—53 o—Xylene influent, effluent, and off—gas
concentraLions and fractional recoveries,
N/No, measured during a 6-day SRI o—xylene
activated sludge study, XYL—ASI 173
10—54 o—Xylene influent, effluent, and off—gas maSS
fluxes and amounts removed by biodegradat 1 ofl
during the 6—day SRT o—xylene activated
sludge study, XYL—AS1 174
xv
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Page
10—55 o—Xylene niluent, effluent, and off—gas
concentrations and fraccicoal recoveries,
N/No, i easured during a 6—day SRT o—xylene
activated sludge study, XYL-AS2 175
10—56 o—Kvlene influent, effluent, and off—gas mass
fluxes and amounts removed by biodegradation
during the 6—day SRT actLvated sludge study,
XYL-AS2 17€
10—57 Comparison of influenc, effluent, and off—gas
concentrations and fractional recoveries,
N/No, from two o— cviene activated sludge
studies, X’ L—ASt and XYL—AS2, conducted
with 6—day solids retention times 17?
10—58 o—Xylene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during a 12—day SRT o—xylene
activated sludge study 180
10—59 o—Xvlene influent, effluent, and off—gas
mass fluxes and amounts removed by biodegra-
dation during the 12—day SRI activated sLudge
study 181
10—60 Comparison of influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, from o—xvlene activated sludge
studies conducted with 6 (XYL-AS2) and
12—day solids retention times 183
10—61 Overall o—xylene removals due to biodegradation
measured during activated sludge studies
conducted in 10—liter bioreactors operated
with 6 and 12—day solids retention times 184
10—62 Experimental data points and off—gas concentra-
tions and fractional recoveries, N/No,,
predicted from measured effluent concentra—
ticns for the 6—day SRT activated sludge
study with o—xylene, XYL—AS1 186
10—63 Experimental data points and off—gas concentra-
tions and fractional recoveries, N/No,
predicted from measured effluent concentra-
tions for the 6—day SRI activated sludge
study with o—xylene, XYL—AS2 187
xv i.
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Number Page
10—64 Experimental data points and off-gas concentra-
tions and fractional recoveries. N/No,
predicted from measured effluent concentra-
tions for the 12—day SRT activated sludge
study with o—r lene 188
10—65 Chlorobenzene influent, effluent, dnd off—gas
concentrations and fractional recoveries,
N/No, measured during the chlcrobenzene
6—day SRT activated sludge study 189
10—66 Chlorobenzene infl e it, effluent, and off—gas
mass fluxes and amounts removed by
biodegradation during the chlorobenzene
6—day SRT activated sludge study
10—67 Chlorobenzene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during the chlorobenzene
12—day SRT activated sludge study 191
10—68 Chlorobenzene influent, effluent, and off—gas
mass fluxes and amounts removed by blo—
degradation during the ch1orober ze e
12—day SRT activated sludge study 192
10—69 Comparison of influent. effluent, and off—gas
concentrations and fractional recoveries,
N/No, from chiorobenzene activated sludge
studies conducted with 6 and 12—day solids
retention times 194
10—70 Experimental data points and off—gas concentra—
dons and fractional recoveries, N/No.
predicted from measured effluent concentra-
tions from the 6—day SRT activated sludge
study with chlorobenzene 195
10—71 Experimental data p .uints and off-gas concentra—
dons and fractional recoveries, N/No,
predicted from measured effluent concentra-
tions from the 12—day SRT activated sludge
study with chlorobenzene 197
10—72 Experimertal data and best—fit line describing
benze.ie biodegradation by acclimated
activated sludge in a completely-mixed
batch (CM ) reactor withou: aeration 206
xvii
-------
Mumber
10—73 Exoerisental data and best-fit line describing
benzene biodegradation by acclimated acti-
vated slidge in a completely—mixed batch
(CNB) reactor witheut aeration 208
10-74 Experinental data and be ,t—fit line describing
be zene biodegradation by acclimated
activated sludge in a compl.etely—mixed
batch (CNB) reactor without aeration 210
10—75 Experimenta]. nata ar.d best—fit line describing
benzene biodegradation by acclimated
activated sludge in a completely—mixed
batch (CMB) reactor without aeration 212
10—76 E. perimental data and best—fit line describing
toluene hiodegradatiOtl by acclimated
activated sludge in a completely—mixed
batch (c13) reactor without aeration 215
10—77 Experimental data and best—fit line describing
toluene biodegradation by acclimated
activated sludge in a completely—mixed
batch (c 1B) reactor without aeration 217
10—78 Expermental data and best—fit lina describing
tolueie biodegradation by acclimated
activated sludge in a completely—mixed
batch (CIB) reactor without aeration 219
10—79 Experimental data sind best-fit line describLog
ethylbenzene bIodegradation by acclimated
activated sludge in a completely—mixed
batch (CNB) reactor withoi.t aeration 222
10—80 Experimental data and be’ t—fit line describing
chlorobenZefle biodegradation by acclimated
activated sludge in a completely-mixed
baich (CIB) reactor without aeration 224
10—81 Experimental data and best—fit line describing
benzerte removal by biodegradation and
volatilization during a completely—mixed
batch rate study in a 10—liter bioreactor
with a 4.3—liter/mm aeration rate 229
10—82 Experimental data and best—fit line describing
benzene removal by biodegradation and
volatilization during a completely—mixed
batch rate stuoy in a 10—liter activated
sludge biereactor with a 4.0—liter/mm
aeration rate 231
xviii
-------
Number
10—83 Experinmntal data and best—fit line describing
benzene removal by biodegradation and
volatilization during a completelymixed
batch rate study in a 10—liter activated
sludge bioreactor with a ! .I—liter/mln
aeration rate 233
10—84 Experimental data and best—fit line describing
benrene removal by biodegradation and
volatilization during a completely—mixed
batch rate study in a 10—liter activated
sludge bioreactor with a 4.5—liter/rn -in
aeration rite 235
10—85 Experimental data and best—fit line describing
chlorobenZefle removal by biodegradation
and volatilization during a completely—
mixed batch rate stud’i in a 10—liter
acLivated sludge bior actor with a 4.3
liter/nan aeration rare 239
10—86 Experimental data and best—fit line describing
chlorobenZefle removal by biodegradation
and volatilization during a com 1etelymiXed
batch rate study in a 10-liter aativated
sludge bicreactor with a 4.3 lit?r/mlfl
aeration rate 241
10—87 Comparison of benzene influent, effluent, and
off—gas concentrations and fra tional
recoveries, N/No, measured duTi .ng single
s.)lute and multi—solute activated sludge
studies 252
10—88 Comparison c toleene influent, effluent, and
off—gas concentratiOnS and fractional
recoveries, N/No, measured during single
solute and multi—solute artivated sludge
studies 253
10—89 Comparison f ethylbenzene influent, effluent,
ama off—gas concentrat OflS and fractional
recoveries, N/No, measured during single
solute and nulti—soluce activated sluage
studies 254
10—90 Comparison of o— cylene influent, effluent, and
off—gas ccncentrationS and fractional
recoveries, N/No, measured during single
solute and aulti—solute activated sludge
studies 255
xix
-------
Number
10—91 Co’r arison of chlorobenzene thfluent, effluent,
and off—gas concentrations and fractional
recoveries, N/No, measured during single
solute and multi—solute activated sludge
studies 256
10—92 Conmarison of benzene,ethvlbenzene, and chioro—
benzene overall removals due to biodegradation
neasured during the multi—solute activated
sludge study 258
10—93 Conparison of benzene, toluene, and o— cy1ene
overall removals due to biodegradation
measured during the multi—solute activated
sludge study 259
10—94 Effect of an increase in Lafluent toxic-,
concentrations and an interruption n
toxics addition to the . ioreactor n
benzene effluent and off—gas concr.ntra—
tions and fractional recoveries, N/No,
during the multi—solute study 261
10—95 Effect of an increase in influent toxics
cancencrations and an lnterruDtion in
toxics addition to the multi—solute
actIvated sludge bioreaceor on ch]orobenzcne
effluent and off-gas concentrations and
fractional recoveries, N/No 262
10—96 Effect of an increase in influent to dcs
ccncentrations and an interruption in
toxics addition to the multi—solute
activated sludge bioreactor on echylbenzene
effluent and off-gas concentrations and
fractional recoveries, N/No 263
10—97 Effect of an increase in influenc toxics
concentratIons and an interruption in
toxics addition to the multi—solute
activated sludge bioreactor on toluene
effluent and off—gas concentrations and
fractional recoveries, N/No 264
10—98 Effect of an increase in influent toxics
concentrations and an Interruption in
toxics addition to the multi—solute
activated sludge bioreactor ono-xylene
effluent nd off—c as concentrations
and fractio a1 rccovcries, N/’ o 265
xx
-------
Number Page
10—99 initial activated sludge acclimatJO to benzerte
and reacclimatiofl aftc. a 14-day interruption
in toxics addition to the influent during
the multi—solute activated sludge study 268
10—100 initial activated sludge acclimation to toluene
and r acclim3t10fl after a 14—day interruption
in toxics addition to the inf)uent during
the multi—solute activated sludge study 269
10—101 Initial activated sluage acclimation to
ethyl.benZefle and reaccilmatiOn after a
14—day interrl.lptiOfl in toxi:s addition to
the influent during the multi—solute
activated sludge study 270
10—102 Initial activ ced sludge acclimation to o—xy]ene
and reacclinatiofl after a [ 4—day interruptiOfl
in to,d.cs addition to th thfluent during
the multi—s l tte activated sludge study 271
10— 103 Initial activated sludge acclimation to
chl.orobenZefle aid raacclimatiOfl after a
li—day interruption in toxics addition to
the influent during the multi—solute
activated sludge study 272
10—104 Effect of spike toxics loadinbs n benzene
effluent and off—gas concentrations and
fractional recoveries, N/No, during the
multi—solute study 274
10— 105 Effect of spike toxics loadings on ethylbcnzcnc
effluent and off—gas concentrations and
fractional recoveries, N/No, during the
multi—solute activated sludge study 275
10—106 Effect of spike toxics loadings on chiorobcnzefle
effluent and off-gas concentrat1 Ofl5 and
fractional recoveries, N/No, during the
multi—SOldte activated sludge study 276
10—107 Effect of spike toxics loadings on tol iene
effluent and off-gas concentrations and
tractional recoveries, N/No, during the
multi—solute activated sludge study 277
10—108 Effect of spike toxicS loadings ono—xylene
effluent an i of f—gas concentrations
and fractional recoveries, N/No, during the
multi—solute activated sludge study 278
xxi
-------
Number Paee
10—109 Benzene influent, effluent and off-gas
concer.trati01 5 and fractieflal rect)veries,
N/No, measured during an cttvated sludge
study with an average influent benzene
concentration of 23 ug/]. 285
10—110 Benzefle influent, effluent, and off—gas mass
flu: es and amountS removed by biodegradation
during the activated sludge study with an
average influent benzene concentration of
23 ugh 286
10—111 Comparison of benzene effluent and off—gas
concentrations and fractional recoveries,
N/No, measured during activated sludge
studies with average influent benzene
concentrations of 23 ugh and 118 ugh 287
IO- 12 Chiorobetizefle influent. effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during an activated sludge
study with an average influent chiotO—
benzene concentration of 28 ugh 289
10—113 Chlorobefl efle jnfluent, effluent, and off—gas
mass fluxes and amounts removed by bio-
degradation during the activated sludge
study With an average influent chioro—
benzene concentration of 28 ugh 290
10—114 Comparis fl of chlorobenZefle effluent and
off-gas concentrations and fractional
recoveries, N/No, measured during activated
sludge studies with average influent
concentrations of 28 ug/l and 130 ugh 292
10—115 Ethylbenzefle influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during an activated sluc.ge
study with an average influent ethyl—
benzen2 concentration of 23 ugh 294
i0—i. 6 EthylbeflZene influent, effluent, and off—gas
mass fluxes and amounts removed by
biodegradation during the activated sludge
study wit an average ethylbeflzefle
influent concentration of 23 ugh 295
xxii
-------
Number
10—117 Compari oCl of ethvlh&nze e effluent and off—
gas concentrations ana fractional
recoveries, N/No, measured during activated
sludge studies with average influent
concentrations of 23 ig/l and 119 ugh 296
10—118 CompariSon of benzene and ethylbenzene
jnfluent, effluent, and c.f f—gas concentra-
tions and fractional recoveries, N/No,
me2sured durirg the activated sludge
study with low influent toxics concentra-
tions 298
10—119 Comparison of benzene and chlorobeflzene
influent, effluent, and off—gas concentra-
tions and fractional recoveries. N/No,
measured during the activated slt.dge
study with low influent toxics concen-
trations 299
10—120 Comparison of etnylbenZefle and chlorobenZefle
influent, effluent. 4 nd off—gas conc ntra
tions and fractional recovecieS, N 1 N0,
measured during the activated sludge
study vith Low influent toxics concentra
tions 300
10—121 Cornoarison of beozene, ethylbeozefle, and
chiorobeozefle overall removals due to
biodegradation during the activated sludge
study with low influant concentrations 303
10—122 Effect on effluent and off—gas concentrations
and fractional recoveries, N/No, of
10 to 30—fold increases in influent benzene
concentration to the activated sludge
bioreactor receiving a 23 ug/l average
influent benzene concentration 305
10—123 Effect on effluent and off—gas concentrations
and fractional recoveries, N/No, of
10 to 30—fold increases in influent
ethylbenzefle concentration to the activated
sludge bioreactOr receiving a 23 ugh
average ethylbenZefle concentration 308
XX1 L i
-------
Number
10—124 ffect. oa effluent nd off—gas concentra—
rlcns and fractinnal recoveries, ‘ INc,
of 10 to 30—fold increases in influenc
chlorobenzene concentrations to tne
activated sludge bioreactor receiving a
28 ugh average influent chlorobenzene
concentration 310
10—125 Coroarison of benzene, ethylbenzene, and
chlorobenzene overall removals due to
biodegradation during periods of low
(15 to 30 ugh) and high (600 to 750
ugh) influent toxics concentrations
to an activated sludge bioreacto 313
10—126 Effect of a 25,000 ugh influent nitro—
benzene concentration on activated sludge
degradation of synthetic wascewater
soluble TOC 316
10—127 Benzene influent, effluent, and off—gas
concentrations and fractional recoveries,
N/ ’ o. measured during the activated sludge
study with transient loadings of benzene,
echylbenzene, and c lorobenzene 320
10—128 Ethvlbenzene influent, effluent, and off—gas
concentrations and fractional recoveries,
‘/No, measured during the activated sludge
study with transient loadings of benaene,
ethvlbenzene, and chiorobeozene 321
10—129 Chlorobenzene influent, effluent, and off—gas
concentrattons and fractional recoveries,
N/No, measureu during the activated sludge
study with transient loadings of benzene,
ethylbenzene, and chlorobenzene 322
10—130 Senzene, ethvlbenzene, and chlorobenaene over-
all removals h.e to bioacgradaticn during
the initIal 66 days of the activated sludge
study with transient tox cs loadings 324
10—131 Comparison of benzene effluent and off—gas
concentrations and fractional recoveries,
N/No, measured during activated sludge
studies wi transient (2 days added!
3 days omitted for days 0—56) and steady—
state toxics 1oadinc s 323
xxiv
-------
Number
10—132 Compariscfl of ethvloenZefle effh.eoc and
off-gas ccncentratic.nS and fractional
recoveries, N/No, measured during activated
sludge studies with transient (2 days added/
3 days cmitted for days O-55) and steady—
state toxics 1oadin s 326
10-l 3 Comparison of chlorobenzefle effluent and
of f-;as concentrations and fractional
recoveries, N/No, measured during activated
sludge studies with transient ( added/
3 days omltted for ajn ‘)—56) anc steady— 327
state toxics loadings
10—134 Changes in benzeae, ethylbenzefle, and chloro-
benzene effluent and off-gas conce tra
tions and fractiondl recoveries, N/No,
due to increased microbial degradation
during the 2-day toxics addition period,
Days 42 to 43. 329
10—135 Changes in benzene. ethy1ben ene. and chioro—
oenzene effluent and off—gas concentrations
and fractional recoveries, N/No, due to
increased microbial degradation during
the 1 -day toxics addition period, Day 51
331
10—136 Comparison of the reductions in beazene
effluent Lnd off—gas concentrations and
fractional recoveries. N/No, measured
during two roxics ndd tion ,eriods
10—137 Comparison of the reductions in chlo o—
benzene eff.uen.. and of f— as concentra-
tions and fractional recoveries, N/No,
measured during two to dcs addition
periods 334
10—138 Comoarison of the reductions in ethylbenzene
effluer’t and off—gas concentrations and
fractional recoveries, N/No, during two
toxics addition periods
10—139 Comparison of benz e effluent and off—gas
concentrations and fractional recoveries,
N/No, measured during toxics loading
cycles of 2 days added/3 days omitted
and 2 days dded/6 days omitted 337
xxv
-------
Number
10—140 CompariSOn c’f ethvlbenzene effluent and off—
gas concentratiOns anO tracdoflal
recoveries, N/No, measureo duruig toxics
loading cycles of 2 days added/3 days
emitted and 2 days added/6 days omitted 338
10—141 Comparison of chlorobeflzene effluent and
off—gas concentrations and fractional
recoveries, N/No, measured during
toxics loading cycles of 2 days added!
3 days omitted and 2 days added/6 days
omitted 339
10—142 Comparison of benzcne, ethvlbenzefle, and
chlorobenZene overall renovals due to
biodegradatiCfl during the final 70 days
of the transient toxics loading activated
sludge study
u—i Experimental data and best—fit lines descri-
bing the adsorption of lindane by three
powdered activated carbons: Hvdrodarco C,
SA—15, nd PX—21 343
11—2 Experimental data and best—fit lines
describing the adsorption of lindane
from activated sludge bioreaCtOr
effluent by three powdered activated
carbons: MvdrodarCO C, SA—15, and PX—21 344
11—3 Experimental data and best—fit lines
describing the adsorp iofl of 1,2—
dichlorobenrefle [ rot’ deionized_distilled
water by various activated carbons 345
11—4 Experiaefltal data and best—fit lines
describing the adsorption of 1,2—
dichlorobeflZene from synthetic wastewatet
by various activated carbons 346
11—5 Experimental data and best—fit lines
describing the adsorption of nitrobenzefle
from deionized—distilled water by various
activated carbons 347
11—6 Experimental data and best—fit lines
describing Freundlich isotherms for
the adsorption of benzene. toluene.
ethylbenzene. o—xyiene. and chlorobeflZefle
from activated sludge bioreactQt effluents
by HydrodarCO C 350
xxvi
-------
NLmb e r
11—7 Experimental data and best—fit lines
describing Freundlich adsorption isotherms
for the adsorption of nitrobenzene, 1 ,2—
dichlorobenzene, lindane, and 1,2,14—
trichlorobenzene from activated sludge
bioreactor effluents by Hydrodarco C 351
11—8 Experimental data and best—fit line
describing the adsorption of lindane
from activated sludge b oreactor ef ltient
and activated sludge mixed liquor by
Hydrodarco C 352
11—9 Experimental data and iest—it line
describing the adsorption of Ann Arbor
wastewater treatment plant final effluent
soluble TOC by Hydrodarco C 353
11—10 Experimental data and best—fit lines for
the adsorption of soluble TOC from synthetic
wastewater and bioreactor effluent
by Hydrodarco C 351k
il—Il Experimental data and best—fit line describing
the adsorption ot effluent soluble TOC
from a PAC—bioreactor receiving a 100—mg/i
influent PAC dose by Hydrodarco C
11—12 Typical results from lindane adsorption rate
studies conducted in D.C—liter completely—
mixed batch (c.MB) t actors
11—13 Comoarison of results from lindane adsorption
rate studies conducted in 3.0—liter
completely—mixed batch reactors with
background solutions of activated sludge
bioreactor effluent and activated sludge
mixed liquor
11—14 Compariscn of results from lindane adsorption
rate studies conducted in 3.0 -liter
completely—mixed batch reactor (mixed at 3 0 r im)
and a 10—liter bioreactor with a 4.0 liter/ mn
aeration rate (batch mode)
11—15 Comparison of synthetic wastewater soluble
TOC biodegradation by activated sludge
to removal by adsorption by Hydrodarco C 360
xxvii
-------
Number
Effect of a 12.5 mg/i influent i ydrodarCo C
dose on the effluent lindane c ncentr3tiOfl
frcm a 10—liter bioreactor 363
11—17 Effect of a 25 mg/I influent HydrodarcO C
dose on the effluent lind?ne concentration
from a 10—liter bioreactor 364
11—18 Effect of a 50 mg/I influent HydrodarCo C
dose on the effluent lindane concentration
from a 10—liter bioreactor 365
11—19 Commarison of lindane removals measured during
a control acc vated sludge study and PAC—
bioreactor studies with influent HydrodarCO
C doses of 12.5, 25, and 50 mg/I 366
11—20 Effect of a 25 mg/i irtfluent SA—IS dose on the
effluent lindane concencrat -ofl from a
0—1iter bioreactor 368
11—21 Effect of a 50 mg/i influent SA—15 dose on the
effluent lindane cencentratlon from a
10—liter bioreactor 369
11—22 Comoarison of lindane removals measured during
a control activated sludse bioreaCtor
study and PAC—bioreactOr studies with
influent SA—15 doses of 25 and 50 mg/I 370
11—23 Comparison of ] .!ndane effluent concentrations
from PAC-bioreaCtOr studies with 25 mg/i
influent PAC doses of Hydrodarco C and
SA—15 371
11—24 Comparison of lindane effluent concentrations
from ?AC—bioreactOr studies vith 50 mg/I
infiuent PAC doses of Hydrodarco C
and SA—15 372
11—25 Effect of influerit PAC doses of Hvdrodarco C,
SA—15. and PX—21 r ’n lindane effluent
concentration ace overall re vals 373
11—26 Effect of influent Hvdrodarco C dose on
lindane effluent oncentratiofl and overall
removal measured during PAC—bioreaCtor
studies with 3—liter and 10—liter
bioreactor s
xxviii
-------
Number
11—27 Effect of a 25 mg/i influent PAC dose on
I,2,4_trich1OrOben2& e effluent and uff—
gas concentrations and fractional
recoveries, N/No 378
11—28 Effect of a 50 mg/i influertt PAC dose on
1,2,4_trichiorobeezefle effluent and of f-
gas concentrations and fractional
recoveries, N/No 379
11—29 Effect of a 100 mg/i influent PAC dose on
1,2,4_trichlorobenzene effluent and off—
gas concentrations and fractional
recoveries, N/No 380
11-30 Comparison of effluent and off—gas concentra
dons and fractional recoveries, N/No,
from a benzene control activated sludge
study and a 1,2,4_trlchlorobeflzefle PAC—
bioreactor study with an influent PAC
dose of 50 mg/i 382
11—31 Comparison of effluent and off—gas concen-
trations and fractional recoveries, N/No,
from a benzene control activated sludge
study and a 1,2,4_trichl0r0bZ te
PAC—b ioreactOr study with an influent
PAC dose of 100 mgI 1 383
11—32 Comparison of l,2,4_trichlorObeflzefle overall
removals measured during a control
activated sludge study and PAC—bioreactor
studies with influent PAC doses of 25, 50.
and 100 ng/l of Hydrodarco C 384
11—33 Effect of jncreasing the influerit PAC dose
from 25 to 200 mg/I on the 1,2,4—
trichlorobeflzene effluent and off—gas
concentration and fractional recovery, N/No 388
11—34 RelationshiP between the amount of 1,2,4—
trichlorubeflzefle adsorbed by the PAC and
the influent mass flux of 1,2,4—trichlorO
benzehe during the 25/200 mg/i PAC
bioreactor study 390
11—35 Effect of influent PAC dose on the amount of
1,2,4_rrichlorObeflze adsorbed durinz
PAC-bioreactor studies 391
xxix
-------
Number
11—36 Effect of a 25 ng/l influent PAC dose on
1,2..dichlcrcbeflZefle effluent and off—
gas concentrations and fractional
recoveries, N/No 392
11—37 Effect 3f a 50 rug/i influent PAC dose on
l;2_dichlorobenZene effluent and off—gas
concentrations and fractional recoveries,
N/No 393
11—38 Effect of a 100 mg/i influent PAC dose on
l,2_dichlorobenzefle effluent and off—gas
concentrations and fractional recoveries,
N/No 394
11—39 Comparison of 1,2_dichlorobenzefle overall
removals measured during a control acti-
vated sludge study and PAC—bioreactor
studies with influent PAC doses of 25, 50,
and 100 mg/i of Hydrodarco C 396
11—40 ffect of increasing the influent PAC dose
from 25 to 200 mg/I on the 1,2—dichioro—
benzene effluent ano off—gas concentration
and fractional recovery, N/No 398
11—41 Effect of a 50 mg/i PAC concentration on the
effluent nitrobenzene concentration 400
11—42 Effect of a 100 r ug/i PAC infiuent concentra-
tion on the nitrobenzerte effluent con-
centration 40].
11—43 Comparison of effluent nitrobenzene concentra-
tions from PAC—bi reactor studies with
influent PAC doses of 50 and 100 mg/i 402
11—44 Effect of a 25 mg/i influent PAC dose on
benzene effluent and off—gas concentra-
tions and fractional recoveries, N/No 405
11—45 Effect of a 50 mg/i influent PAC dose on
benzene effluent and off—gas concentra-
tions and fractional recoveries, N,No 406
11—46 Effect of a 100 mg/I influent PAC dose on
benzene effluent and off-gas concentra-
tions and fraccicnal recoveries, N/No 407
x xx
-------
Number
t1 —t 7 Effect of increasing the influent PAC dose
from 25 to 200 mg/I on the benzene effluent
and off—gas concentration and fractional
recovery, N/No h08
11—48 Comparison of benzene overall removals due
to biodegradation and PAC adsorption
measured during a control activated sludge
study rctd PAC—bioreactor studies with
influent PAC doses of 25, 50, and 100 mg/i of
Hydrodarco C 409
11-49 Overall De ’lzer.e removals measured in continuous
flow 10—liter bior actor studies with
ectivated sludge, Hydrodarco C PAC without acti-
vated sludge, and activated sludge with PAC 411
11—50 Effect of a 25 mg/l influent PAC dose on
ethvlbenzene effluent and off—gas concen-
trations and fractional recoveries, NfNo 414
11—51 Effe:t of a 50 mg/i influent PAC dose oc
et hylbenzene effluent and off—gas concen—
tiations and fractional recoveries, N/No 415
11—52 E fec. of a 100 mg/i influent PAC dose on
ettylbenzene effluen and off—gas concen-
trations and fractio: al recoveries, N/No 416
11—53 Comparison of ethylbenzene removals due to
l,iodegradatiofl and PAC adsorption measured
during a control activated sludge study
and PAC—bioreactor studies with influent
PAC doses of 25, 50, and 100 mg/i of
Hydrodarco C 419
11—54 Effect of increasing the influent PAC dose
from 25 to 200 mg/i on the ethylbenzefle
effluent and off—gas concentration and
fractional recovery, N/No 421
11—55 Effect of a 25 mg/i influent PAC dose on
chlorobenzene effluent and off-gas concen-
trations and fract onal recoveries, N/No 422
11—56 Effect of a 50 mg/I influent PAC dose on
chlorobenzene effluent and off—gas concen-
trations and fractional recoveries, N/No 423
x xxi
-------
Number
11—57 Effect of a 100 tn /l Influent PAC dose on
chloobenzefle effluent and off-gas concen-
trations and fractional. recoveries, N/No 424
11—58 Comparison of chlorobenzene overall removals
due to biodegradation and PAC adsorption
measured during a control activated sludge
study and PAC—bicreactor scudi s with influent
PAC doses of 25, 50, and 100 mg/i of ydro—
darco C 426
11—59 Effect of increasing the influent PAC dose
from 25 to 200 mg/I on the effluent and
off—gas chlorobenzene concentrations
and fractional recovery, N/No 428
11—60 Effect of a 200 mg/i influent PAC dose on toluene
effluent and off—gas concentrations and
fractional recoveries, N/No. 429
11—61 Effect of a 50 m2/l influent PAC dose on effluent
and off-gas o-xylene concentrations and
fractional recoveries, N/No 432
11—62 Effect of solids retention tine on effluent
lindane concentrations from 10—liter bio—
reactors receiving 25 mg/i influent PAC 434
doses
11—63 Effect of solids retention time (SRI) on
lindane removal due to PAC adsorption in
10—liter bioreactors r ceiving 25 mg/i
influent PAC doses 435
11—66 Effect of a 50 mg/i influent PAC cicce on 1,2,4—
trichlorobenzene effluent and of f—ga:
concentrations and fractional recoveries,
N/No, measured during 12—day SRI bioreactor
studies 438
11—65 Effect of a 50 mg/i influent PAC dose on
1,2—dichlorobeazene effluent and off—gas
concentrations nd fractional recoveries,
N/No, measured during 12—day SRI bioreactor
studies 440
11—66 Comparison of effluent and off—gas concentra-
tions and fract±onal recoveries. N/No,
measured during 1,2—dichlorobenzene PAC—
bioreacror studies with 6 and 12—day
solids retention times 441
xxxii
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Number
11—67 Effect of a 50 mg/i influent PAC dose on
benzene effluent and off—gas concentrations
and fractional recoveries, N/No, measured
during 12—day SRT bioreactor studies 443
11—68 Effect of a 50 mg/i influent PAC dose on
chlorobenzene effluent and off-gas concen-
trations and f actional recoveries, N/No,
measured during 12—cay SRT bioreactor
studies 446
11—69 Comparison of chlorobeiizene effluent and of f—
gas concentrations and fractional recoveries,
N/ o, measured during 50 mg/i PAC—bioreactor
studies conducted with 6 and 12—day
solids retention times (SRT) 447
11—70 Effect of interrupting the addition of 100 mg/i
PAC to activated sludge on benzene effluent
and off—gas concentrations and fractional
recoveries, N/No 449
11—71 Effect of interrupting the addition of 100 mg/i
PAC to activated sludge on ethvlbenzene
effluent and off—gas concentrations and
fractional recoveries, N/No 450
11—72 Effect of interrupting the addition of 100
mg/i PAC to activated sludge on chloro—
ben ene effluent nd off—gas concentrations
and fractional recoveries 451
11—73 Effect of interrupting the addition of 100 mg/i
PAC to activated sludge on 1,2—dichioro—
benmene effluent and off—gas concentrations
and fractional recoveries, N/No 452
11—74 Effect of interrupting the addition of 100 mg/i
PAC to activated sludge on 1,2,4—trichioro—
benzene effluent and off—gas concentrations
and fractional recover_es, N/No 453
11—75 Comoarison of benzene, ethylbenzene, and
chlorobenz ne overall removals due to
biodegradation and adsorvtion measured
during the PAC interruption study 454
11—76 Comparison f benzene, 1,2—dichlorobenzene, and
1,2,4—trichlorobenzene overall removals
due to biodegradation and adsorption
measured during the PAC interruption study 455
xxxiii
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Number
11—77 Experimental data and best—fit line describing
benzene biodegradation by activated sludge
in a completely_ru.xed batch rate study
in a 10—liter bioreactor with 4.2 liter/mm
aeration rate 461
11—78 Effect of interri.’pting the addition of 23 mg/i
PAC to activated SLudge on lindane effluent
concentration from a 10—liter bioreactor with
a 9—day SRI 465
11—79 Effect of interrupting the addition of 25 mg/i
PAC to activated sludge on lindane effluent
concentrations 466
11—80 Benzene influent, effluent, and off—gas
cortcentrat].On Gad fractional recoveries,
N/No, measured during a 100 mgIl ?AC—
bioreactor study with transient toxics 468
loadings
11—81 Ethylbenzene influent, effluent, and off—gas
concentrations and fra tiona-l recoveries,
N/No, measured Jurthg a 100 z g/l PAC—
bioreactor study with transient toxics
loadings 469
11—82 ChlorobenZefle influent, effluent, and off—gas
concentrations and fractional recoveries,
N/No, measured during a 100 mg/I ?AC—bio—
reactor study with transient toxics loadingS 470
11—83 Comparison of beazene effluent and off—gas
concentrations and fractional recoveries,
N/No, measured during [ 00 mg/i PAC—
bicr actor studies with steady—state and
transiet t (added 2 da ’;s,’o’titted 3 davs 472
toxics addition to influent
11—84 Comparison of ethylbenzefle effluent and off—gas
concentrations and fractional recoveries,
N/No, measured during 100 mg/I PAC—
bioreactor studies with steady—state and
transieiit (a ded 2 da:7s/o ited 3 c ays)
toxics addition to influent
11—85 Comparison of chlorobeflZefle effluent and
off-gas concentrations and fractional
recoveries, Nho, measured during 100 mg/i
PAC—bioreactor studies with steady—state
and transient (a ’.dcd 7 lay /omittcd 3 days
toxics addition to influent 475
,cxxiv
-------
Number
11—86 Comparison of benzer e, ethylbenzene, ar.d chinro—
benzeno overall removals due to biodegrada-
tioi and adsorption 1urtng roe 100 mg/i
PAC—btcreaCtor stidy with transient
toxics loadings 476
11—87 Effect of a 100 mg/i influent PAC dose on
beozene effluent ama off—gas concentrations
and fractional recoverieS, N/Nob measured
during transient toxics loading studies 478
11—88 Effect of a 100 mg/i influent PAC dose on
benzene overall renovals measured during
transient toxics loading studies 79
Effect of a 100 mg/I. influent PAC dose on
ethyloenzene effluent and off—gas coricentra—
tions and fractional recoveries, N/No.
measured during transient toxics loading
studies 481
11—90 Effect of a 100 mg/i iafiuent PAC dose on
overall etlwlbenzene removals measured
during transient toxics loading studies 82
11—91 Effect of a 100 mg/i influent PP 1 C dose on
chlorobenzene effluent and off—gas concen-
trations and fractional re overics, • /* ,
measured during transient toxics 1oadi’ gs
studies 483
11—92 Effect of a 100 mg/i influtt PAC dose on
overall chlorobertzene rerno Ls measured
during transient toxics ioaa 5 ig studies 484
12—i Comparison of overall removal of vola.ile toxic
organic compounds due to biodegradat ‘n
during single—solute activated sludge s.tdtes 499
12—2 Effect of increased degree of chlorination of
benzene on overall removal due to biodegradati..
during activated sludge treat enc 500
xxxv
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TABLES
Number
5—I Physical çrooerties of toxic organic comoounds 14
5—2 Physical oroperties of activated carbons 15
5—3 Synthetic feed compositiOn 19
6—1 Analytical r.ethods used for açueous samples 27
6—2 Sumrnary of pertinent operating conditionS
used in the purge and trap analysis of
benzene, toluene, et ylbenzene, o—xylene
and chlorobe izefle 30
6—3 Su unary of pertinent operating conditions
used in the purg and trap analysis
of 1,2—dichloroben7ene anc. l.2,3
crich lorobenzefle 31
7—1 Effect of air stripping on renovals ot
toxic organic conmounds froc bi.oreactors
without activated sludge 34
7—2 Volatilization rate coefficients from air—
strippiig studies conducted in the IC—
liter bioreactors with an aeration rate
of 4.0 1/ruin 37
7—3 Volatilization parameters relating k to
for at stripping of volatile coripounds
from 10—liter bioreactors with air-
tight lids 48
7—4 Predicted ef-fluent and of f—eas concentrations
from bioreactors without activated sludge 50
7—5 Volatilization ate coefficients in c en and
sealed bioreactorS at art aeration rate
of 4.0 1/win 56
7—6 Ratios of volatilization rate coefficients
of each compound to that of benzene 56
7—7 Volatilization parameters relating k to
for air stripping of volatile compounds
from 10—liter bioreactors without air-
tight lids 62
xxxvi
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Number Page
7—8 ComparIson of L values from sealed and open
10—liter bioreactor volatilization studies 62
7—9 Proporticjnalitv coefficier ts relatine vola—
tilizacion rate coefiicients of the toxic
orc ar.ic comocunds to oxygen reaeracion
rate coefficients 66
8—1 Isotherm ncdel nara ueterS for sr,rotion of
toxic organic compounds by activated
sludge 72
8—2 Comoarison of K 5 values from this study to
those renorced by Veith, et al. 74
9—1 predicted fate of three example compounds 91
io—i Occurrence of organic priority pollutant
in municipal waStevatetS 93
10—2 Fate of toxic organicS in acclimated
activated sludge bioreactors operated
at 6—day SRT’s under steady—state
conditions
10—3 Bioreactor operating conditions used during
activated sludge studies 96
10—4 Summary of typical mean influent and effluent
soluble TOO co icentr tionS and percent rerovals
from bioreactor studies opcr ’ted t 3,6,9
and 17—day flT’s. 102
10—5 Lindane removal in activated sludge bio—
reactors operated with 3,6, and 9—day
solids retention times 109
10—6 Comparison of measured and predicted results
from lindane activated sludge studies 110
10—7 Comparison of measured and predicted effluent
and off—gas 1,2.4_trichlorobeflzefle
concentrations from activated sludge 112
bioreac cars
10-8 Fate of 1,2,4_crichlorobeflzefle in 6 and
12—day SRI activated sludge studies 113
10—9 Comparison of measured and predicted stë dy—state
effluent and off—gas 1,2—dichlorobenaene concen-
trations from activated sludge bioreactorS 123
10—10 Fate of 1,2_dichlorobenzefle in 6 and 12—day
SRI activated sludgo bioreactOrs 121
xxxvii
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Number pa
10—it Summary of influettt, effluent, and off—gas
concentrations of ‘uitrobenzeoe from an
activatec sludge reactor operated with
a 6—day SRT 128
10—12 Coroa ison of neasured and predicted steady—state
effluent and off—gas benzene concentrations from
activated sludge bioreactors 136
10—13 Fate of benzene in 3,6 and 12—day SRT
activated sludge studies during steady— 13
state biouegradatiofl
10—14 Su u,ar ’ of sleady—state results from the toluone
activated sludge bioreactor stu y conducted 148
at a 6—d’) SRI
10—15 Cor parison of veasured and predicted effluent
and off—gas coluene concertratiOns
fron activated sludge b or.’actors 151
10— 6 Fate of r Luene thiruig sted’;—st te
bjodegraaatiofl by activated sludge 152
10—17 Pate of ethylbeozene during steady—state
b odegradaticn by activated ]udge 163
10—18 Co parison of -ieas. ied and orea:cteo effluent
and off—gas hv1 enzene cor ,centracioflS
frcrn activated sludga bioreactors 172
10—19 Co- parisc of nea;ured and predicted effluent
and off—gas o-xv ene concentrations from
activated s1ud e o ioreactors 182
10—20 Fate of o—xylene during steady—state
biodegradation by activated sludge 185
10—21 Suamtarv of sreacv—state average chioribeozefle
concentrations from activated sludge
bioreactor studies conducted with 6
and 12—day SRT’s 196
10—22 Fate of chlorobenzene during steady—state
biodegradation by activated 1ucge 198
10—23 First or .cr biodegradation rate coefficients
calculated from CMF reactor mass 200
balances
10—24 Effect of u creased volatility on biodegrada-
tion rate coefficients of cr,mpr un(is with
the same overall removals 702
x x xviii
-------
10—25 Effect of aeration rate on r’le biodegradation
rate coefficicnt of benzene 203
10—26 Effect of ‘wdraulic retention time on the biodeg—
radation rote coeflicient of benzene 203
10—27 Results from 2.6—liter CIB biodegrada—
tior rote study without aeration 207
10—23 Results from 2.6—liter C{B biodegrada-
tion rate study without aerstion 209
10—29 Results from 2.6—liter C!B biodegrada-
tion rate study without aerat1 ’1 211
10—30 Results from 2.6-l rer C B odegrada—
tion rate study without aeration 213
10—31 Results from 2.6—liter CMB biodegrada-
tion rate study without aeration 216
10—32 Results from 2.6—liter CM3 biodegrada-
tion rite study witt out aeration 218
10—33 Results frcrn 2.6—lIter CIB biodegrada-
tion rate study without aeration 220
10—34 Results from 2.6—liter cMB
biodegradation rate study without aeration 223
10—35 Results from 2.6—lIter CdB biodegradation
rate study without aeration 125
10—36 Summary of values measured ir. CMB
degradation studies, and comparisoa
of overall re’sovals measured In C’IF
bioreactors and predicted from kb values
neasuced in 2.6—liter CMB degradation studies 226
10—37 Results from 10—liter C 3 biodegrada
tioa rate study with aeration 230
10—38 Results from 10—liter 0M3 biodegrada-
tion rate study with aeration 232
10—39 Results from 10—liter C”B biodegrada-
tion rate study with aeration 234
10—40 Results from 10—liter 01B biodegrada-
tion rate study with aeratiOn 236
10—41 Results from 10—liter CIB biodegrada-
tion rate study with aeration 237
2cxxix
-------
Number
10— 2 Results from 10—liter C 3 b odegradatiOfl
— 4O
study with aeration -
10—43 Results prom 10—liter CM.3 biodeeradatiOfl
rate study d.th aeration 242
10—4k Results from 10—liter CMB biodesradation
rate study with aeration 243
10—45 Results from 10—liter C!3 biodegradatiOn 24’
rate study with aeration
10— t6 Summary of results from aerated C 1B
biodegradation rate studies 245
i0—- 7 Fare of three compounds calculated with
equations 10—16 through 10—18 using
indeuendently measured rate parameters
k, andk 248
o V
10—48 Bioreactor ooeratlng conditions for the
- ulti—solute activated slucige stucy 249
10—49 ulti—so1ute bioreactor operating periods
zith respect to the concentrations of
the toxic solutes 250
10—50 Comparison of acclimation periods and
steaey—state tcxi.cs removals from
single solute and multi—solute activated
slunge studies 257
10-Si Effect of pH—induced upset on biodegradati
rate coefficients and overall remov, lS
of biodegradable compounds 260
10—52 C mpari&ofl of initial acclimation and
reacclimatiofl after 14 days without
toxics adeed to the influent 273
10—53 Bioreactor operating periods in the activatea
sludge toxics’ influent concentr3tiOn study 283
10-54 Operating conditions for the bioreactor study
evaluating the effect of influent toxics
concentrations on biodegradation 284
10—35 Comparison of benzene removals in bioreactors
operated with different influent benzene
concentrations 288
xl
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Number Page
10—56 Chlorobenzefle removal in activated sludge
b ioreactorS 293
10—57 Ethylbenzefle raroval in activated sludge
bioreactors with different infl” nt
toxics’ conce tratiOflS 297
10-58 Comnarison f benzene, ethylbenzefle, and
chlorobenzefle re tova1s in the low
toxics’ influent co’ centratiOfl bioreactor
during days 35—63 301
10—59 Comparison of steady—state removals of
benzene, eth,lbenzefle, and cnlorobenzefle
in single solute activated sludge studies 304
1 0—60 Effect of influent co-,rentratiofl on the
:emoval of benzene from an ac:ivated
sluoge bioreactcr 306
10—6 1 Effect of jnfluent concentration on tl’e
removal of ethvlbenzefle from an aLtivated
sludge bioroactoc 309
10—62 Effect of influent concefltr tiOfl o the
removal of chlorobeflzefle from an activated
sludge bioreactor 311
10—63 Steady—State results from nitrobeflzefle
activated sludge study with inc eaSifl
influent concentrations 314
l0 —61 Effect of influent nitrobeuzene concentration
on soluble TOC removal 318
10—65 Bioreactor operating periods with resoect
to toxics addition iuring the transient
loading activated sludge study 318
10—66 Comparison of overall removals and biodegra-
dation rate coefficients measured on
Day I and Days 52—5 of the transient
loading study 319
10—67 Comparison of overall removal and biodegra-
dation rate coefficients at 2 and 38
hours during the toxics addition period
Days 42—43 330
xli
-------
Number page
10—68 CompariSon of overall removal and biodegra-
dation rate coefficients at 2 and 24
hours during the tcxics addition
period of Day 57 330
u—i Pertinent ope:ating conditions used
during the PAC/activated sludge
bioreactor studies 348
11—2 Freundlich sothertn parameters for adsorption
of toxic organics by Hydrodarco C trom
control activated sludge bioreactor effluent 348
11—3 Freundltch parameters for wastewater soluble
TOC adsorption by Hvdrodarco C 356
11—4 Effect of influez’t PP C dose on effluent
lindane concentrations from 19—liter
bioreactors with 3—day SRT’s 367
11—5 :ffecr of ?AC dose ott lindane a’ sorrtion
per weiçht of activated carbon 74
11—6 Linuane removal in 3—liter bioreactorS
receiving Ann Arbor prin. r g effluent 377
11—7 Effecr of influent PAC dose on effluent and
off—gas 1,2, 4_trichlorobenzefle concentra-
tions 385
11—8 Effect of PAC dose on the fate of 1,2,4—
trichlorobeflzefle during PAC/activated
sludge treatment 386
11—9 Summary of PAC bioreactor results for
1 ,2—dichlorobenaefle 197
11—10 Effect of PAC addition to activated sludge
on removal of nicrobenzefle 403
11—11 Effect of influent PAC dose on steady—state
ben-ene removal in 10—liter bioreactors
operated with 6_day SRT’s 410
11—12 Benzene removals measured in continuous
flow 10—liter bioreactor studies with
activated sludge, FAG without activated
sludge, and activated sludge with FAG 412
xlii
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Number
11—13 CompariSon of ethvlbenzene :;/No values from
acclimation periods and steady—state
conditions in control and 25 mgIl PAC
b ioreactorS 417
11—14 Effect of jnfluent PAC dose on steady—state
ethyibenzene removal u 10—1 ter
bioreactorS with 6—day SRI’s 420
11—15 Comparison of N/No data from control and
PAC bioreactors for chlorobenzefle 417
11—16 Effect of influent PAC dose on steady—state
chiororbenrene remova 1 in 10—liter
bioreactors with 6—day SRI’S 427
1 1—17 CompariSOrt of coluene ren ovalS in control and
200 /l PAC bioreactOrS 430
11—18 Effect of solids retention ti. re on the removal
of lindane from bioreactOrS receiving
25 mg/i Hvdrodarco C 436
11—19 Effect of solids retention time on remcval
of l,2,4_trichlotOber,zefle and 1,2-dichiorO
benzene in SO mg/i PAC bioreactOrS 439
11—20 Effect of solics retention time on the removal
of benzene in 50 mg/i PAC bioreactotS 444
11—21 Oreratiflg periods for the 100 mg/i PAC
interruptiO r t study with a 6—day SRI 448
11—22 Steady—state toxics removals neasurad during
the three operating periods of t ie PAC
ii terrupC1Ofl study 456
11—23 Steady—state rP” V dS of toxic organic
compounds from bioreactOrs ; ceiviag
100 mg/i PAC doses 457
1I—2 Effect of spike loading period Ott removals
of individual toxic organic co oounds 458
11—23 Results from iC—liter CB biodegradation
rate study jith aeration 662
xliii
-------
Pao e
Number
11—26 Surrr arY f average toxics re’ovalS from
the 100 mg/i PAC interruPtiOn bioreaCtor
study 464
11—2? Resul S fcr benzene, ethylberzene, and
chlorobenzefle from the 100 mg/i PAC
bioreactor operated with transient
influent toxics’ loadings Days 21—43) 471
11—28 Cotrparisofl of benzene removal in control
activated sludge and 100 mg/i PAC bioreac—
tors operated under transient toxics
loadings 480
11—29 Average influent toxics concentrations
- during Days 51 to 88 of the transi flt
toxicS Loading 100 mgIl PAC bioreactor
study 4
11—30 Beozene results From Days 51 to 88 of the
transient to dcs loading 100 ag/i PAC
bioreactor study 487
11—31 thy1benzefle results from Days 51 to 83
of the crans ent toxics loading 100
mg/i PAC bioteactOr study 489
11—32 chlorobenZefle resultS from Days 51 to 83
of t e transient toxics loading 100 mgil
PAC b:oreactOr study 490
12—1 Computed half—life for volatile organic
compounds during batch stripping studies
in 10—liter bioreaCtOrs without activated
sludge 494
122 Fate of toxic organicS in acclimated
activated sludge bioreactOrS operated
under stea,y—State conditionS 497
12—3 Average overall percent removals due to biodeg-
radation and PAC adsorption measuted during
single solute PEtC bioreactor studies with
influent toxics concentrations between 100
and 120 ugh 504
xliv
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ABBREV1ATIO S AND SY IBOLS
B empirical volatilization co,stant (dilnensLonless)
.3
BOU niological oxygen demand (NIL
C or C aaueous effluent concentration (MIE 3
C off—gao concentration (NIL 3 )
S 3
C or C aqueous influ nt concentratlol (M!L
waste sluc ’ge concentration (NIL 3 )
COD chemical oxygen demand (NIL 3 )
D diffusivity (L’/T)
fraction of influent biodegraded
f fraction of influent present in cha effluent
C
f fraction of influent volatilized
V 3
H Henry’s Constant CL at ’nlmol)
kb pseudo first order bLodegradation rate CoefficlOtit (lIT)
k gas phase mass transfer coefficier.r (LIT)
liquid phase mass transfer coefficient (LIT)
oxygen reaeration ratL coefiicicnt (l/1)
k overall pseudo first order removal coefficient (l/T)
k first order volatilization rate coefficient
k emp:rical volatilization coafficient (l/T)
K 3 bioconcentratloat factor (dimensionless)
K 1 Freundlich adsorption constant
KOL overall mass tra. sfer coefficient (LIT)
octanol water partition coefficient (ci1men ionless)
K linear partition coefficient (L 3 I .)
L empirical volatilization proportionality coefficient (L 3 )
N concentration of bio’ogical solids (NIL 3 )
MLSS mixed liquor suspended solids concentration (NIL 3 )
xlv
-------
Ne mass flux of a compound out of a bioreactor (MIT)
Ng mass flux of a compound in i.he off—gas (MIT)
N mass flux of a compound into a bioreactor ( MIT)
N/N fractional recovery of ..i compound in the experimental
system (dimensionless)
n FreundliCh adsorption constant
P pressure (atm)
3
influent aeration rate (L IT)
effluent aqueous flow rate (L 3 /T)
Q influent aqueous flow race (L 3 /T)
Q off—gas flow rate (L 3 ’T)
g 3
solids waste rate (L /T)
q solid phase ccncentrdtiofl of a compound (M/M)
e 2 2o
R universal gas constant ( ll_ /T / K)
r resistance to mass transfer (T/L)
S empirical reacration rate proportionalitY constant
SRI solids retention time (I)
t time (T)
r hydraulic retention rime (T)
T temperature (°C)
TOC total organic carbon concentration (M/L 3 )
V volume (L 3 )
Vg volume of gaseous phase (L 3 )
xlvi
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S T ION 1
INTRODUCTION
The presence of toxic organic compounds in natural water systemS
and drinking .nter supplies has significantly modified the emphasis of
wastewater treatanent during the past several decades. Wastewater
treatment systems have been designed to removu the traditionally
regulated pollutants such as BOB, sust*nded solids, pathogenic
organisms, and possibly nitrogen and plusphorus; but the removal of
these su atances alone is no longer sufficient to prot t the quality of
receiving eaters. Future discharge reguLations are likely to imposa
limitations on specific toxic substances such as the 114 organic
compounds designated as priority pollutants by the U.S. Environmental
Prot tion Agency (EPA).
The presence of toxic organic compounds in municipal and
industrial waste ters necessitates an understanding of the
capabilities of conventional wast ater trea ent systems for removing
such substances. Some of the toxic organic compounds are adequateLy
removed, but the specific removal mechanisms for thnse substances must
be identified and quantified so that treatment systems can be operated
to achieve maximum removals. Other compounds are not removed to levels
considered acceptable for discharge; treatment of these substances will
require modifications of or alternatives to existing waste treatment
systems.
Little information is available on the fate of specific toxic
organic compounds during conventional vaste ter treatment. Four
mechanisw.i . control their removal dur 1.ng conventional treatment:
chemical transformations, volatilization, biodegradation, and
bioaccumulation or biosorption. Current knowledge about the role of
each mechanism and their interactions w th regard to trace toxic
organics removal ir insufficient to develop treat±ility models that
explain the behavior of tbose substances during treatment.
Various modifications of and alternatives to c nventiona1
biological treatment processes have been suggeBted and evaluated in
bench—, pilot—, and full—scale treatment systems during the past
several decades. The addit ion of powdered activated carbon (PAC) to
the aeration basins of existing activated sludge facilities has emerged
as an attractive application of carbon adsorption technology to toxic
organics removal. The int rate process using activated sludge and
1
-------
carbon (albo known as PACT°) was originally introduced as a method for
upgrading activntsd sludge waste treatment in removing conventional
pollutants. The process’s ability to provide enhanced removal of toxic
organic compounds may be tore significant. Only a few sti dies have
detailed the removal of tax ic organcs in such int rata1 systems.
Little direct informat ion exists on either the fate of specific toxic
compounds during int rated activatel sludge/carbon treatment or on the
factors that control the effectiveness of PAC addition to activated
sludge for removing toxic organics from wast aters.
This project was designed to study the effectiveness of adding PAC
to activated sludge systems for providing enhanced removal of specific
toxic organic compounds. Completely—nixed-f]nw (C F) biological
reactors re used to study the integrated PACT process. The
effectiveness of the int rat system was evaluated by comparing
removals of the toxic organic compounds in parallel, control—activated
sludge bioreactors and activated sludge bioreactors receiving slurried,
powdered activated carbon. Since little information exists on the
behavior of toxic organics during activated sludge treatment, a major
portion of this project was directed toward identifying and quantifying
the fate of each test compound in conventional activated sludge
systems. Major operating parameters that .ere studied under steady—
state operating conditions included carbon type and concentration,
solids retention tine, concentration of the toxic substance(s),
hydraulic retention time, and organic composition and concentration of
the vastewater.
A secondary objective of the project was the quantification of the
mechanisms effecting removal of toxic organic compounds during
activated sludge treatment and int rated activated sludge ned carbon
treatment. Three removal mechanisms are important during activated
sludge treatment; volatilization, bios rption, and biodegradation. The
addition of PAC provides carl.’,n adsorption as a fourth significant
remo:al uechani n in int rat. systems. Completely—mixed batch rate
and equilibrium studies ware used to qua itify each removal mech nism to
develop a steady—state trace organic s removal model.
2
-------
S TION 2
CONCLUSIONS
This study has provided important information concerning the
removal cf toxic organic compounds during activated sludge treatment
and tntc ratai activated sludge and carbon trea ent. Foui. renoval
mechanisms re identified as affecting the fate ef the compounds
during treathent: volatilization, bicdegraiation, biosorption, and
powdered carbon adsorption. The study dennastrates the importance of
using C1 bioreators designed to enable collection and analysis of
off—gases fo.- evaiuating the fate of specific volatile compounds, both
biodegradable and nothiodegralable.
The results indicated that conventional activated sludge systmos
can accli.mate to and hence effect significant reductions in both
effluent and off—gas co centrati ns of the tmcic organic compounds at
microgram—per—liter concentrations. Owrall reductions in effluent and
off—gas concentrations resulting from b odegradat ion cveragei75% to 85%
for the volatile compu-inds benzene, toluene, ethylbenzene o—xylene,
and chiorobeazene under steaiy—state operating conditions.
Accimat ion periods ranged from 7 to 14 days.
The addition of PAC provided enhanced removals of 1,2—
dichlotcbenzene, 1 ,2,4—trichorobenzefle, and liridane. Powdered carbon
addition effected reduct tops in both the effluent and off—gas
concentrations of volarile, nonbiodegradable compounds. PAC doses as
small as 25 to 50 mg/ produ d significant improvements in
nonbiodegradable toxics removal compared with control activated sludge
systems. Creater than 90% removals occtwrel at influent carbon doses
of 100 mg/ . The eddit ion of PAC at influent doses less than 100 mg/i
did not enhance the removal of the biodegradable tcattc organics.
PAC bjoreaitor studies conducted at solids retention times (SRT’s)
of 0.25 to 12 days and a 50—mgi ;- carbon dose showed that the removal of
nothiodegradable taxics was the same over the range of SRT’s studied.
The most important operating paraueter with respect to removals of
toxics was the influent PAC concentration.
3
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Results from th s study shoued ti t the propo8ed stealy—state
trace organics removal model (STORM) could oc Used to descr be
adequately the fate of e h organic compouad in the activatad sludge
bioreactors. Mass balance c terminations showed that PAC adsorption in
the intc rat actLvatad slu ge and carbon treath ent systea could not
be modeled based on equihbrium considerations.
4
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S TI0N 3
RECcJ1MENI TI0NS
This study has laid a strot foundation in the overall assessment
of the f .te nd behavior of specific categories of organic priority
pollutants in a conventional and an advanced wast iater treatment
system. Add it wnal research is needed tu bu id on this f undat ion to
define the capabilities and limitations of conventional and alternative
wastewater treatment systems for providing suffic ent removal of toxic
materials to prot t tne int rity of water courses and drinking water
supplies. Outlined below are specific recommendations for future
research:
1) Investigate the fate and behavior f additional categories of
toxic organic compounds in convent 3onal waSte nter treatment systems.
Studies should be conducted at envirotmentally realistic wastewater
concentrations, and treatment systems should he designed to facilitate
mass balance determinations.
2) Comeuct activated sludge sbidies with actual municipal
waste mter LO evaluate the effect of h kground solution on
biodegradation of tr e levels of organic compounds.
3) Specifically evaluate the effect of influent concentratonS On
biodegradation rates of additional COmpOUndS.
4) Examine the bio1egrndation potential of tr e organic priority
pollutants as a function of the type if waste ter treatment procese.
Studies should include trickling fiitt , rotating biological
contactors, anaerobic digesters, etc.
5
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SECTION 4
BAU( GROUND
4.1 0C JRRENCE 01 TOXiC ORCANIC CtM1POLJNDS IN WASTEWATER
Information regarding the numbers and concentrations of toxic
organic con oands being dischar : . from wastewater treatment facilities
before the mid—197O’s was j ited. Prior to the adoption of the Water
Pollution Control Act Aaendra nts (PL92—500) 1972, concern about
wa tewator discharges foQised on the conventionPl pollutants such as
300, suspended solIds, çathogenic organisms, oil and grease,
nitro nn and phosph rus. The assimilative capacities of receiving
streams was considered in the formuLJt 1On of effluent standards for
politants such as BUD and cuspendeil solids. In 1972 the EPA was
reqLtred by I’L 92—5 O to forns.ilate national discharge regulations for
munt :ipal and indi.scrial wascc4ater treatment facilities and to
estaoiish a list of toxic con iunds for development of specific
discharge standards. The resulting riority Pollutant List” contained
I i . toxic organic cor oiinds, 13 metals, anu cyanide and asbestos (1).
A number of studies have been conducted during the past several
years to evaluate the presence and behavior of toxic organics in
conventional wastewater treatment facilities (1,2,3). The ma]ority of
these studies f. cused or the identification and quantification of
specific con ounds. An investigatIon of fifty municipal Wasteijater
tre - tmeut facilities f,und a total of 88 different organic priority
pollutants in influents and 76 organIc priority oollutants in effluents
at least once (2). The major Undin ,s of this study were:
-The l ’ rger the inthstrial contribution to a Publicly Owned
Treatment Works (P0 1 1 4), the higher the concentration of priority
pollutants in the P01W influents
—50% of the secondary treatment pLrtts achieved miniwum organic
removals of 82% for volatli -es and 65% br oase/neutral
o xtractables
—tertiary treatment processes effected greater removals of priority
pollutants than secondary processes
—primary trea ment was less effective than either aecondary or
tertiary processes In removing priority pollutants
6
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—mass loadings of priority pollLtants were higher on weekdays
than on weekends
—in general, as irifluent concentrations increased, effluent
concentrations also increased implying that the removal rates
for priority pollutants were relatively constant.
A thirty consecutive day study of one activated sludge treatment
facility found a total of 58 toxic organics in the influent and 40 toxic
organics in the effluent at least once (3). Average removals of organic
priority pollutants weto reported as 95% for volatiles, 87% for
base/neutral extractablec, and 77% for acid extractables. The major
findings of the thirty—day study were (3):
—by—products from industrial processes were the primary sources
of priority pollutants in the influent
—primary treatment did not prov1 1e significant removals of
priority pollutants, ranging tree less than 20% for volatiles
to no removal of acid and base/neutral extractables
—secondary treatment provided th most significant removals of
all classes of organic priority pollutants
—bio—floc adsorption was the primary removal mechanism for acid
and base/neutral extractables
—increases in influent concentrations :esulted in corresponding
increases in effluent concentritlons
—regression analysis between the most frequently occurring
priority pollutants and t.o cvnven:ional pollutants, BOD5 and TSS
were not indicative of the levels of toxic pollutants in the
secondary effluent
A recent study of the wastec’ater treatment facilities of five
organic chemical manufacturing plants found that conventional activated
sludge treatment provides removals of most organic priority pollutants
sufficient to produce effluent concentratinns of 10 partc—per—billion or
less (4).
One of the conclusions of the five—plant survey was that while no
reliable correlation existed between conventional and non—conventional
pollutants and toxic organic cori ,ounds, to a limited extent it may be
possible to utilize selected toxic organic compounds as indicators of
the removal of other organic compounds with similar biotreatability
properties.
While such studies have contributed important information on the
removals of toxic organic compounds by conventionel wastewater treatment
systema, they have not provided insight into the role of specific
removal mechanisms.
7
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4.2 LNTEGR.ATED ACTIVATED SLUDGE/CARBON TREATMENT
4.2.1 Background
Interest in tne applications of carbon adsorption technology to
wastewater treatment began in the late 1950’s under the Advanced Waste
Treatment Research (AWTR) Program of the U. S. Public Health Service.
The program was developed to Investigate various types of
physicochemical processes to remove the increasing numbers of
recalcitrant synthetic compounds causing pollution of water systems and
drinking water supplies (5). Adsorption by granular activated carbon
(GAC) was demonstrated to be an effective method of removing a broad
spectrum of organic compounds of concern during extensive studies of
physicochemical treatment systems in the 1960’s and 19 7 0’s. The most
effective applications of GAC treatment were in a tertiary mode
following secondary biological systems for providing advanced waste
treatment (5—13). GLanular activated carbon in tertiary treatment
systems functions to reduce the overall organic content of the
wastewater by Lemoving biologicaLly resistant cornr’ounds. A major factor
that limited the use of CAC tertiary systems was the large capital costs
associated with installing and maintaining such systems. Capital and
operating costs for tertiary CAC adsorption systems with carbon
regeneration facilities can equal or exceed the costs of the entire
activated sludge process. Additionally, land requirements of tertiary
systems often can make their Implementation impossible.
Independent physicochemical treatment (tPCT) of clarified raw
wastewater has been investigated as on alternative to secondary
biological treatment followed by a tertiary GAC adsorption system
(6—2U. Major problems associated with independent physicochemical
treatment systems have been their inability to remove biodegradabLe, low
moleculat weight compounds which exert a BOD in the wastewater effluent,
and excessive odor generation resulting in high operating costs to
Overcome it.
An attractive alternative use of activated carbon in wastewater
treatment is the integrated activated sludge/carbon treatment system.
In this proceus, po idered activated carbon (PAC) is added in a slurried
fortn directly to the aeration basin of an activated sludge fac llty. A
schematic illustration of this process is presented in Figure 4—I. Once
introduced into the aeration basin the PAC is rapidly incorporated into
the biological flocs of the activated sludge forming a matrix of
activated carbon and biomass. The residence time of the PAC in the
aeration basin is the mean solids retention time of the biological
solids. Integrated activated sludge/carbon treatment systems combine
the synergistic interactions of biodegradation and carbon adsorption to
achieve effluent qualities coaparable to or better than secondary
biological treatment followed by tertiary physicochemical treatment with
granular carbon adsorption. Low molecular weight organics not amenable
to carbon adsorption are removej through biodegradation while larger,
more complex molecules which are not biodegradable are removed by
adsorption onto the powdered activated carbon.
8
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POWD R AarIvATF
CPJt8GN ADDITICIU
ftAW
INFW f
‘C
EFFWE T
FIGURE 4—1. Simplified schematic diagram of the PACt ’i3ystem.
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An attractive feature of the integrated activated sludge/carbon
treatment system is the ease with which it can be adapted to e’cisting
activatud sludge plants. The addition of PAC to activated sludge nas
been demonstrated as a viable method of improving the performance of
biological vastewater treatment with respect to improved (22—35):
—organics removal measured as SOD, COD. andfor TOC;
—color removal;
—process stability;
—hydraulic capacity;
—oxygen transfer;
—resistance to shock loadings;
—low temperature performance;
—sludge settleabil itv, thicken ir’ ,, and dewatcri g;
—anaerobic digestion;
—nitrificatlon;
—toxic organic removal.
The concept of adding PAC to activated sludge was originally
introduced as a method of improving the performance of existing
activated sludge with respect to the r . duction of overall organics
expressed as SOD, COD and/or TOC. Mdition oF PAC to activated sludge
was first investigated nearly fifty years ago in an effort to improve
performance of overloaded sewage plants (35). The process was largely
ignored until the early 1970’s when more stringent discharge regulations
required advanced wastewater treatment to remove refractory organic
compounds.
Improved performance of activated sludge processes by the addition
of PAC has been reported for a variety ot municipal and industri l
wastes. The most thoroughly studied full—scale use of the PACT process
has been at the DuPont Cor?oration’s Chambers Works organic chemicals
manufacturing facility where much of the developr ent work on the process
was conducted (27, 30, 31, 33). It was the first full—scale
modification of activated sludge treatment by PAC—addition. An influent
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PAC dose of approximately [ 30 mg/I has been used with a 45—day sludge
age to successfully treat a 40 ingd complex wastewater since the mid
1970’ s.
4.2.2. Toxic 0r anics Removal
While the effectiveness of adding PAC to activated sludge for
improved process performarica with respect to conventional pollutants has
been well documented, there have b en only a limited nunbtr of stud as
on the rerroval of toxi organics in PACT® systems. These studies have
focused on the effect of ?AC—addltion for enhanced toxics removal frora
industrial wastes (40—44).
Hutton and Temple (41) and Hutton (42) reported on th emova s of
specific priority pollutants from the full—scale 40 mgd PACTChasbers
Works facility treating a complex waste from a.t organic chernicil
manufacturing industry. The influent PAC concentration was biven as
134 mg/ i of which 68 was virgin produced carbon and 32 was regenerated
carbon. Results from that study indicated removals of all bt.t four
compounds exceed 90%.
Hutton and Temple (41) also eported on bench scale studies of
parallel activated sludge and PP.C reatment systems of toxic organic
removals. The results from their study sh ied that removals ot volatile
organics from activated sludge reactors were in excess of 96% and that
the addition of 100 and 300 ng/l PAC to the influent produced no
additional removals. Removals of less volatile base/reutral and acid
extractable compounds were significantly improved by the addition of
[ 00 and 300 rag/i PAC. Results presented by Hutton and Temple (41)
indicated that PAC—addition to activated sludge reduced the effluent
concentrations of non—volatile, non—biodegradable compounds. A
significant aspect of the results reported by Hutton (42) was the
ability of PAC to adsorb toxic pollutants present at trace
concentrations from a complex background solution. Hutton (42) reported
that the s of all of the priority pollutants constituted less than 5%
of the total diqsolved organic caroon present in the wastewater.
Another study by Hutton (43) compared the removal of specific
organic priociLy pollutants by PACT® activated sludge to conventional
activated sludge foll ed by a tertiary GAC adsorption system.
;tctivated sludge alone produced at least 85% removal of 23 of the 36
toxic organics detected in the influent. Compounds exhibiting the
greatest removal were also the most volatile. The addition of 100 mg/i
PAC to the irrflu2nt increased performance so that greater than 85%
removal was obtained for 30 of the 36 compounds. Results from the
tertiary GAC column studies shcMed an interesting chromatographic effect
in which the concentrations of twelve compounds were larger in the
column effluents than in the feed for a period of time. At the point of
TOC and color breakthrough Hutton (43) reported that only 11 of the 36
compounds had removals greater than 857. and 17 were removed by 50% or
greater. A conclusion of this study was that PAC addition to activated
11
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sludge provided superior removals of organic priority pollutants
compared to activated sludge follc ed by tertiary GAC adsorption.
Kincannon and Esfandi(44) reported on the removals of organic
priority poLlutants in a pilot plant study of the PAC/activated sludge
process for creating phari iaceutical manufacturing wastes. A comparison
of the removals of the toxic organic compounds from an activated sludge
systen’ and a PACT® activated sludge system receiving an influent PAC
concentration 3f 347 mg/l sho4ed that the addition of PAC provided
better removals of the toxic organics when average effluents
concentrations were compared. Comparisons of the daily values reported
by the authors sho ed that in many cases the activated sludge was able
to achieve treatment levels comparable to the system with PAC. The
primary benefit o adding PAC was reported to be enhanced toxics renoval
that occurred during periods of shock loadings when removals in the
activated sludge system decreased. The shock loadings had no apparent
effect on the performance of the PACT® activated sludge system with
respect to the removal of the toxic organics.
12
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SECTION 5
EXPERIMENTAL DESIGN
This section reviews 1) the seLection of tile toxic organic
compounds and powdered activated carbons, 2) the design of the
experimental systems used to study the fate of the compounds in
continuous flow activated sludge and integrated activated sludge/carbon
treatment systems, and 3) tne experimental methodologies used to conduct
the variouq equilibrium and rate experiments designed to study
individual removal mechanisms of volatilization, biodegradation,
biosorption, and carbon adsorption.
5.1. SELECTIO J OF T1XIC ORLANft. COMPOUNDS
Nine specific organic compounds were included in the study. These
compounds, presented with pertinent physical properties in Table 5—1,
encompass a broad range of volatility, biodegradability and adsorptive
properties. All of the compounds except r—xylene are included in the
EPA list of PriorIty Pollutants. An important and unique featur of
this study was the use of toxic pollutants known to be present in
wastewaters and at concentrations representative of tho’e actually found
in municipal and industrial wastewaters. Influent concentrations used
in the bioreactor studies primarily wire in the 50 to 200 _g/i range.
5.2. Sr.LECTION OF POWDERED ACTIVATED CARBONS
Background adsorption studies were conducted with a variety oi
adsorbents to select a iowdered activated carbon as the primary
adsorbent to be used in the continuous—dow bi reactor studies. The
initial studies considered a total of five adsorbunts; three of which
were powdered activated carbons, one was a powdered form of a granular
carbon, and the last was a non—activated carbonaceous material. A
sitamary of the pertinent properties of each adsorbent is given in Table
5—2.
The powdered activated carbons Hydrodarco C and SA—IS are
recomn nded by their manufacturern for use in the PACT process.
Amoco’s PX—21 is an experimental powdered activated carbon with a very
high surfac. area. Based upon adsorptive pe&iormance in equilibrium
studies and comu rcial availability for wastewater treatment Hydrodarco
C was chosen as the primary adsorbent for the bioreactor studies.
13
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TABLE 5-1
PHYSICAL PROPERTIES CF
TOXIC ORGANIC COMPOUNDS
Compound Solubility Vapor Pressure tI2nry’s Log Octanol/
(mg/i) (atm) Constant Water Partition
(m 3 atrn/moi x io ) Coefficient
Purgeabie
1. Benzen 1750 0.125 5.49 1.95
2. Toluene 534 0.0374 6.66 2.69
3. Ethylbenzene 152 0.0125 8.73 3.15
4. o—Xylene 175 0.00868 5.27 3.12
5. Chlorobenzene 488 0.01382 3.71 2.84
Base Neutral Extr cLah1e
6. 1,2—Dichlorobenzene 145 1.32x 10 3 2.96 3.38
7. 1,2,4—Tt [ chlorobenzene 30 5.53x10 4 2.32 4.26
8. Nitrobcnzeiie 1900 1.97x10 4 0.023 1.85
Pesticide
9. Lindane 7.3 4.34x10 7 0.00043 3.72
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TABLE 5—2
PHYSICAL PROPERTIF., OF ACI’IVATEI) CARBONS
Surface 2 Area, Iodine No.
Cbon j Manufacturer BET (mj ni) (rn rn) Base_Material
Hydrodarco C IC!, Americas 550 N.A. Lignite
Nuchar SA—15 Westvaco 1400 — 1800 80 Bituminous Coal
PX—21 2 Amoco 2800 — 3500 2800 - 3600 N.A.
Flit r,isorb 40( 1 Cnl 8 oi 1050 — 1200 1000 Bituminous Coal
Anthrauilt IJni,ilt N.A. N.A. Anthracite Coal
N.A. Not Avaflab1e
1 Recommended by manufacturer for PACT process
2 F.xpcrinicntal PAC
3 Powdered version of this granular activated carbon
4 Non—activated carbonaceous material
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5.3. BIOREACTOR DESIGN
Completely—mixed flow (CMF) biorea tors were used to study the
E. te of the toxic organic compounds during activated sludge and
in egrated activated sludge/carbon treatment processes. A variety of
laboratory—scale CMF reactors have been used in both activated sludge
and PAC addition to activatud sludge studies. Bioreactors for this
project were designed to satisfy the following criteria:
—provide adequate mixing to be modelled as a C 4F reactor;
—enable codection of volatilized organirs in off—gases;
—contain an internal clarification unit to control solids
retention time;
—be small enough to perTr t ease of handling;
—be constructed readily .nd economically.
Two different rea-tor conf urations were employed during the
project. A 10—liter bioreactor was used for all of the studies with
the synthetic wastewater, and a smaller 3—liter unit was used for
studies conducted with se:tled prin ry effluent from the Ann Arbor
wastewater treatment faciUty. Studies with the 3—liter unit were
confined to the most recalcttrant compound, lindane. A description of
the experimental system for each reactor configuration is presented
belc i.
5.3.1 Bioreactor Studies Using Synthetic Wastewater
The 10—liter bioreactor design w s an adaptation of the sliding
baffle type CMF reactors common y used for activatet sludge studIes.
The bioreactors were cor.structed of quarter—inch plexiglass and
contained 10—liter aeration sections and one—liter internal clarifiers
separated by adjustable baffles. A schematic illustration of the
bioreactor design is presented in Figure 5—1. Each bioreactor was
fitted with an air—tight lid that covered both the aeration and
clarification sections. Three stone diffusers, located at the rear of
each bioreactor, supply compressed air to aerate the mixed liquor and
maintain completely—mixed conditions in the aeration section.
The influer.t to each bioreactor was composed of three separate
flows: a synthetic wastewater flow, a toxic organic solution flow, and
a slurrjed powdered activated carbon flow. The PAC slurry was prepared
with tap water and stored in well—stirred glass containers. A schematic
diagram of the experimental system is shown in Figure 5—2. Bioreactors
without powdered activated carbon received tap water in place of the
slurried carbon flow. Individual peristaltic pumos were used to deliver
the influent flows to each bioreactor from appropriate storage
reservoirs allowing selccted operating parameters to be varied
16
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H U
- u uH
STONE DIFFUSERS
INFLUENT
PORT
EFFLUE;f I
L
1 5”
L
J
V
—4
FICtIRF S—i.
Scheni,It Ic Ii .u ram of iO— iter 1,1 reacror
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FFWb T AND
OFF-GA$ DISCKA E
LI H
PAC
I-
CUPR S
AIR
OFF-GAS
SAMPLING
TRAP
EXPU IM NTAL
Bloh AC OR
CUN TANT D .}’1It
KES RVOIH
FTCIJRF. 5-2.
Scli& rnuF Ic II tist ration of expt rImeiit al svst cn .
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independen’ly. Wastewater ar”l toxic organic solutions were stored at 4°
C to minimize biodegradation aria volattlization,respeCtiVelY. The mean
solids retention tune (SRT) was controlled by ntermittentIy pumping a
specified volume directly frori the aeration section each day.
A synthetic wastewater was used to ensure adequate experimental
controls on the system and to provide a common ha fs for data
interpretation. The criteria used in the selcction of the s tLletiC waste
were that it b similar in charact& r to domestic waste, be reproducible,
and not interfere wtrh the analyses of the toxic organic compounds. The
composition ot the synthetic waste is detailed in Table 5—3.
The air—tight lids were an Lmp)rtant and unique feature of the
e’ perinentai system that permitted colLection and sampling of bioreactor
off—gases for analysis of each toxic organic compound. Analyses of th
off—gases combined with analyses of infLuents, effluents and waste
siudges c’uihle fornulation of a mass balance for each toxic compound an !
determination of ic face during treatment.
5 -3.2. Bioreactor Studies Usi. g Prunary Effluent
A smaller, modified version of the 10—liter bioreiccors was used to
study lindane removal from an integrated activated sludge/carbon
treatment system receiving wascewater from the Ann Arbor treatment
facility. the smaller reactr’rs were uses to reduce the volume of
wastewater that had to c e transported from the treatment facility to the
Env,ronmental and Water Resources Laboratory. The biore ctors were
constructed of quarter—inch plexiglass and contained 3—ilter aeration
basins and 0.4 liter internal clarifiers separated by adjustable
baffLes. A schematic illustration of the 3—liter unitc is presented in
T ’3Lf 5—3
SY 1 THET1C FEEl) co 1poS1 l0N
Compound Percentage as TOC
Dextrin 30
Bacto Peptone 20
Sodium Acetate 15
Sodioin Citrate 15
Glycine 10
Potassium Biphthalate 10
Inorganic compounds ne-essary for proper bacterial
gr . th
NaHCO 3 for p11 control
19
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Figure 5—3. Two stone diffusers, located at the re ir of each reactor
supplied compressed air to aerate the mixed liquor and rcaintain
completely—aixed condi’ ions in the aeration section. Background studies
sh .ed lindane was nou—volacile, therefore the rca. tors were not
equipped for off—gas balnpling.
The intluenr to the 3—liter rnactors was conpo ed of two seaaraze
flows: pri :.ury effluent spiked .iich lindane and ‘.lurrted pcwder .d
activated carbon. Con .r3I activated sludge reactors received tap water
instead or the powdered activated carbon. The wastewater used as feed
for bioreactors was collected from the effluenc of the primary s ttlLng
basins every four days and stored 4° C. Solids ware wasted daily
from the acraL. n section on a batch basis after samples for lindane
analyses, bC, and U..SS were collected.
5.4 O tPLEThL.Y—M1XED BATCH RATE STUDIES
An integral part of this researc.h was the quantification of the
mechanisr s that effected removal - toxic orgalic compounus from the CMF
bioreactors. Batch studies were conducted to evaluate:
(1) volatili acion removal rate coefficients
f or air stripping of volarile compounds
(2) oxygen reaerdtiori
(3) biodegradation rate coeffzci*.nts for TOG removal and
toxic organics removals
(4) I’AC aosorptlon
5.4.1. Volatilization Rate Studies
The volatilization of each toxic organic compound was studied in
10-liter bioreactors operated in batch modes to determinc the first
order volatilization rate coefficients for each compound. These studi.es
were conducted in the absence of accivatee sludge to ensure that
volatilization was the only removal mechanism. Bioreacters used to
quantify volatilization were operated with air-tight lids to simulate
the configuration of the CMF units. Additional volatilization studies
were conducted in 10—liter bioreactors without air—tight lids to
determine the effect o sealing the bioreactors upon air stripping.
Volatilization rate studies were conducted at aeration rates from 1.0 to
5.0 1/mm to evaluate the relationship between aeration rate and
volatilization rate coefficient for each compound.
Volatilization studies were conducted by spiking the bioreactorc
with 2O— i of a methanol solution containing o e or more todc onpounds
to produce initial concentrations between 8C and 100 ag/Z. After mixing
for five minutes with a magnetic stir bar, air fLow %‘3S begun to the
20
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C OF ES S ED
AIR
INFLUEt T:
WASTEWATER
SLURRIED PAC
4
•1
i ±
— — — — — — — — -
__ d’ __ t
— — — — — - — —
:.
: : : :
9’,
—
12”
_ :. i i __ __ : _ 3 —
FIGURE 5—3. SchenatiC illustration of the 3—liter bioreaCtOr design.
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biorcactors. Samples withdrawn from a sampling port on the side of each
reactor were collected at specified times and analyzed or the
?articular cornp”und(s) present.
5.4.2. Oxygen Rcaeration Studies
Oxygen reaeration rate studies were conducted in the 10—liter
bioreactors operated in batch modes in the absence of a ttvated sludge.
R.eaeration studies were conducted by bubbling N 2 (g) through the water to
reduce the dissolved oxygen concentration to less than 1.0 mg/i. The
bioreactors were then aerated with compressed air and the concentratioa
of dissolved oxygen measured with an Orion dissolved oxygen probe. D ita
from the reaeration stuziies was evaluated by plotting —ln(Cc— /Cs—Co)
versus time to determine the reaeration rate coefft iauits.
5.4.3. I3iodegradation Rate Studies
Completely—mixed batch (CMB) rate studies were conducted to
evaluate the biological degradation of overall organics as measured by
soluble TOC and each of the toxic organic compounds. The TOC
degradation studies were conducted in the 10—liter bioreactors used for
the continuous flow studies. Prior to adding a concentrated synthetic
wastewater solution to produce an initial TOC concentration of
approximately 100 mg/i, influent and sludge waste flowsuere stopped to
make the bioreactors operate in batch modes. Samples were taken
directly from the aeration section, filceredthrough Gelman AlE glass
Fiber filters into sample bottles, acidified with phosphoric acid, and
stored at 40 C. Soluble bC was then measured with a Dohrman model DC
80 total organic carbon analyzer.
Two types of completely-mixed batch reactor studies were conducted
to investigate the biodegradation of specific volatile toxic organics
observed in the C 1F bioreactors. Initial CMB biodegradation studies
were conducted in 2.6—liter reactors with lids to minimize
volatilization. Biodegradation rate studies with volatile compounds
were begun by qui&ly transferring 2.6 liters of activated sludge from
the a racion section of a 10—liter CMF bioreactor to the glass C’IB
reactor and aerating it with compressed air to produce dissolved oxygen
concentrations of 6 to 7 mg/I. A dissolved oxygen probe was inserted
through a hole in the reactor lid to continuously monitor the dissolved
oxygen concentration. After the aeration was stopped the reactor was
spiked immediately with 10—pP. of a methanol solution containing the
toxic compound to which the activated sludge had been acclimated.
Mixing was accomplished with a teflon—coated magnetic stirring bar.
Samples were withdrawn from the reactor with a 10 inI syringe, filtered
through 25 mm Gelman AlE glass fiber filters directly into 4 —mI sample
bottles with teflon—lined caps and immediately stored at 4 C for
subsequent analysts. The rate studies were run until the dissolved
oxygen concentration was reduced to approximately 1.0 mg/i.
Biodegradation studies of the non—volatile compounds were conducted in a
similar manner except the 2.62. CMB reactor was vontinuously aerated with
compressed air to maintain dissolved oxygen levels in the 3 to 5 mg/i
range.
22
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The second type of biodegradation rate study was conducted in the
10—liter experimental bioreactors operated with aeration. The dnits
were temporarily converted from continuous—flow to batch modes by
stopping the influent flows to and sLudge waste flows from the reactors.
The bioreactors were spiked with 20—ui of methinol solution containing
the toxic organic compound to which the particular units had been
acclimated, producing initial concentrations of 30 to 60 ugh. ration
rates used during the CMB biodegradation studies were the same as those
used when the biore ctorc were operated in cofltinuous flow modes and
ranged from 3.8 to 4.2 ŁImiui. Reductions in the aqueous concentrations
of the toxic organic compounds were a result of both air stripping and
biodegradation.
5.4.4. Carbon Absorption Rate Studies
CompleteLy—mixed batch studies were conducted to evaluate the rate
of adsorption of selected toxics by powdered activated carbon.
Adsorption r te studies were conducted to 2.6 and 3.0 liter glass
reactors mixed with paddle stirrers. Adsorption experiments were begun
by filling the appropriate reactor with a desired background solution
and spiking tt’e contents with 10 to 50 ut of a methanoL solution
containing one of the toxic compounds. Samples to measure the initiil
concentration were taken after the contents were well—mixed. A known
weight of powdered carbon in a slurried form was added to the reaction
vessel and samples were taken at specified time intervals. The powdered
carbon was slurried approximately 20 to 30 minutes prior to being added
to the batch reactor to ensure complete wetting of the carbon surface.
Samples were withdrawn with a 2O— t glass syringe and either filtered or
centrifuged immediately to remove the powdered carbon.
5.5 COrIPLETELY—MIXEO BATCH EQlJlLl Rl1JM STUDIES
5.5.1. Carbon Adsorption Isotherma
5.5.1.1. Toac Organic Compounds
Equilibrium adsorption isotherms were conducted to quantify the
adsorption cInract istics of each compound with various powdered
activated carbons in background solutions which included deionized—
distilled water, reactor effluent, and synthetic wastewater. All
isotherms were performed by a bottle point technique employing 150—cit
Hypo vialsa sealed with teflon—lined aluminum caps. Known amounts of
PAC in a slurried form were pipettad from a concentrated slurry to each
bottle, and the bottle was filled with the appropriate background
solution. The maximum volume of slurried PAC transferred was 10 mt to
minimize dilution of the background solution. Each bottle was spikec
with 10 to 20 ut of a methanol solution containing one of the toxic
organics, sealed, and mixed until equilibrium conditions were achieved.
The type of mixing used depended upon the volatility of the
compound. Isotherma for the most volatile compounds, benzene, toluemme,
23
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ethylbenzene, o—,cylene, and chlorobenzene, were conducted in Ifypo_vialse
without headspace. Mixing for these studies was accomplished with small
teflon—coated magnetic stirring bars. The bottles were stirred with a
gang—mLcer at speeds sufficient to maintain well—mixed conditions. Care
was taken to prevent heat from the stirrer Eros. changing the temperature
in the isotherm bottles. Lsochermts with 1,2—dichlorobenzene,
1,2,4—trichlorobenzene, nitrobeozene, and lindane were conducted in
bottles filled to a total volume ot 100 mIs. Mixing was accomplished
with a reciprocal shaker.
isotherm bottles containing benzene. toluene, ethylbertzene,
o—xylene. and chlorobenzene were filtered to remove tne powdered carbon.
Samples were withdrawn with a 20 mi syringe and filtered with an in—line
F titer apparatus containing a 25 mm Gelman AlE glass—fiber filter.
Background studies showed no significant adsorption of the five volatile
compounds on either the filter apparatus or filter paper. The filtrates
were collected in 8—mi sample bottles filled without a headspace, sealed
with teflon—lined caps, and stored 40 C for subsequent analysis by
the purge and trap procedure outlined in Section 6.
Samples from isotherm bottles containing 1,2—dichiorobeniene,
1,2,4—trichlorobenzene, nitrobenzene, and lindane were transferred into
15—mR. test tubes with teflon—lined screw caps and centrifuged
at approximately 2000 rpm for 15 minutes. A.liquots of the supernatant
were pipetted into 6—dram vials containing a knL*lrt volume of hexane.
The vials were capped with teflon—lined lids and agitated on a
reciprocal shaker to facilitate partitioning of the toxic organic into
the hexane. Extraction vials were stored inverted at ! cC for subsequent
analysis by a gas chromatograph equipped with a 63 Ni eluctron capture
detector.
5.5.1.2. bC isotherss
Equilibrium isotherme were conducted to quantify the adsorption of
wastewater soluble TOC by the powdered activated carbons. isotherimis
were conducted in 150-mi hypo—vials by adding nown weights of dry
carbcn and 100 mis of the appropriate wastewater solution. Mixing was
accomplished with a magnetic stirrer. After equilibrium conditions were
reached a sample from each bottle was filtered through a 25 mm GeLman
A/E glass—fiber filter and acidtfi .md with two drops of concentrated
phosphoric acid. Analyses for TOC were conducted with a Dohrman low
level Total Organic Carbon Analyzer, Model 0C80.
5.5.2. Biological Sorption Studies
Biological sorption studies were performed to evaluate the
partitioning of the three most hydrophobic crganics 1,2—dlchlorobenzene,
lindane and 1,2,4—crichlorobenzene, between the aqueous and biological
solid phases. The experiments wer . conducted with activated sludge of a
known suspended solids concentration from an activated sludge bioreactor
not receiving any of toxic organic compounds in the influ?nt. Activated
sludge was transferred to a two—liter graduated cylinder and gravity
24
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settled to concentrate the biological solids. A standard suspended
solids procedure was used to measure the concentration of the settled
sludge. Various volumes of the concentrated biological solids were
added to 150—mi Hypo—vials® and diluted to 150 mis with distilled water
to eliminate headspace and minmize volatilization. Each vial was
spiked with 10 uP, of a methanol solution containing a toxic organic
compound, sealed, and mixed with a magnetic stirrer for three hours.
Samples from each vial were centrifuged and the supernatarit was
extracted with hexane. A1 extracts were agitated for fifteen minutes
and stored at 40 C for subsequent analysis. Uncentrifuged samples
cont2 nur.g biological solids were also extracted to complete a SaSS
balance on the cor ,ouad and determine if any biodegradation had
o c cur red.
25
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SECtION 6
ANALYTICAL NETHODOLOGIES
Considerable energy was devoted to developing the analyi cal
methodologies necessary to maasure microgram—per—liter concentrations of
the toxic organic compounds in hioreactor influents and effluents and
nanogram—per—liter concentrations in the bioreactor off—gases. The
ability to measure influent, effluent, and off—gas concentrations in an
efficient, reproducible manner was essential for completing mass
balances for each toxic organic compound. A sunmary of the analytical
procedures developed for aqueous and off—gas analyses of the toxic
compounds is presented in this section.
6.1 UEOUS SAMPLES
Two gas chromatographic techniques were u d to measure tne
individual compounds in aqueous samples: purge and trap and
liquid/liquid extraction. A sunmary of the analytical methods used in
the aqueous analyses of each compound is given in Table 6—1.
6.1.2 Purge and Trap
A purge and trap procedure was used to analyze the volatile
compounds benzene, toluene, ethylbenzene, o—xylene, 1, 2—di chlorobenzene
and 1,2,4,—trichlorobenzen . It represents an extension of the static
headspace analysts to a dynamic system in which volatile or ariics are
continuously purged from the aqueous phase by an inert gas and collected
on a short chromatogtaphic column.
The purge and trap procedure used in the volatile organics
analyses represents a modi c-ti n of various methods reported to give
reproducible results at low mlcrograte—perliter concentrations ( .5,46).
A 1—to S—mi aI.iquot of aqueous sample was added to the purging device
shown in Figute6 and purged for 15 minutes at room temperature with
N 2 (g) at a flou rate of SO mi/rain. The purging temperature was
increased to 550 by placIng the purging device in a water bath for
aqueous samples containing 1,2—dichlorobenzene and
1,2,4—trichlorobenzene. Volatilized organics were continuously
collected ott a 6 in x 4 mm ID glass trap packed with Tenax GC and
attacned to the e :it tabe on the purging device shown in Figure 6—1.
Glass wool plugs were placed in each end such that the trap contained
approxi.rnately 5 inches of adsorbent.
26
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TABLE 6—i
ANALYTICAL METHODS USED FOR AQUEOUS SANPL S
Compound Pr tdure Detector Limit of Detection (jig/Q .)*
Benzenc Purge/Trap FlU 0.2
Toluer,e Purge/Trap FID 0.2
Ethylbenzene Purge/Trap FID 0.2
o—Xylene Purge/Trap FID 0.4
Chiorobenzene Purge/Trap FID 0.4
1 ,2—Dichiorobonzefle Purge/Trap Fl 1) 1.0
Liquid/Liquid Extraction EC(Ni 63 ) 0.1
i,2,4_Trich lorobenZefle Purge/Trap FED 1.0
Liquid/Liquid Extraction EC(Ni 63 ) 0.1
Nitrobenzene Liquid/Liquid Extraction EC(Ni 63 ) 0.1
Lindane L quid/LiqUid Extracti n EC(Ni 63 ) 0.1
*Based upon: 10 ml sample size for P..rEe and Trap
10—fold concentration during extraction procedure
-------
10mm
MEDIUM POROS
SAMPLE INLET
6 rhm 0.D. RUBBER
SEPTUM
10 mm 0.D.
INLET.
1/4 IN. 0.0.
FIGURE 6—1
Purging device used for sanpling volatile organic coripounds.
1/4 IN. 0.0. EXIT
E
E
E
C)
0
28
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The collected organics were measured by attaching the sampling
trap to the modified injection port of a Tarian 2740 gas—chrornatograph
(CC). An 2 (g) carrier flow was introduced through the trap while it was
heated at 250°C to transfer the collected organics to the front end of
gas chromatographic colwnn maintained at 20°C in the CC oven.
A temperature program was used to heat the chromatographic column from
20°C to 140°C at 20°C/man to separate the compounds fcr detection by a
flame ionization detector (FID).
Two different gas chromatographic columns were used. One column,
2 ft x 1/8 in stainless steel packed with 0.2% Carbowax 1500 on
Carbopack C, effected good separation of benzene, toluene,
ethylbenzene, o—xylene and chlorohenzene. The second column, used for
o—dichlorobenzene and 1,2,4—crichlorobenzene, was 6 ft x 1/8 in
stainless steel packed with 10% OV—17 on 60/80 Gas Chrom Q. A snnmary
of the p ’rrinent operating conditions used in the puige and trap
procedure is given in Tables 6—2 and —3.
6.1.2 Liquid/Liquid Extraction
Liquid/liquid extraction takes advantage of the preferential
partitioning of hydrophobic organics into an organic solvent from an
aqueous sample when the two phases are mixed. This procedure was used
in the analysis of nitrobenzene, lindane, 1,2—dichlorobenzene and
1,2,4—trichloro enzene. Extractions were performed by adding an
aliquot of sample to a 25—mi Teflon—lined screw top vial cont in ng 2 to
4 ml. of hexane. The vials wereagitated using a reciprocal shaker to
effect partitioning of the toxic organic compounds into the hexane
solvent. Samples were analyzed with a Hewlett-Packard 5880 gas
chromatograph equipped with an electron capture (Ni 63 ) detector. A 6 ft
x 1/8 in glass chrornatographiC column packed with 3% 60/80 Gas Chrom Q
wa used
6.2. 0FF—GAS SAMPLES
The volatile nature of most of the compounds used in this study
necessitated the development of a sensitive, reproducible method for
measuring the concentration of each compound in the bioreactor
off—gases. The procedure used in this study was an adaptation of various
methods developed for sampling air pollutants (45—48), all
of which are essentially an extension of the purge and trap procedure
previously explained.
Approximately one hour prior to sampling the reactor, the off—gas
sampling valve located in the reactor lid wac closed. The off—gases
were then forced through the effluent drainage Line and discharged
approximately two feet under water in a constant depth discharge
reserqoir creating a slight positive pressure in the reactor. An
of f—gas sample was collected by connecting a sampling trap to a closed
off—gas sampling valve on the reactor lid. Sampling traps used for
off—gas analyses weta identical to those used in the purge and trap
procedure. 0ff—gas samples were collected by opening the sampling valve
29
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TA8LE 6—2
SUMMARY OF PERT1NF 4T OPERATING CONDITIONS
USED IN HE PURGE AND TRAP ANALYSIS OF BENZENE, TOLUENE,
ETHYLBENZENE, O—XY’ ENE AND CHLOROBENZENE
PURGING SEQUENCE
Time 15 mm
Purge Gas Nitrogen
Flow Race 50 mi/ruIn
Temperature 20°C
Trap 5” x 4 mm ID gLass packed with
Tenax CC
DESORPTION SEQUENCE
Time 4 san
Temperature 250°C
Carrier/Flow N 2 (g) at 40 mi/ruIn
GAS CHROMATOGRAPHY OPERATING CONDITiON
Temperature Pcogram Sequ’ nce
in, cial oven temp. 20°C
final oven temp. L40°C
temp. program race 20°C/ruIn
Carrier/Flow N 2 (g) at 40 mi/ruin
Column 2’ x 1/8” statniess steel
packed with O.IZ Carbowax 1500
on Carbopack C
Detector FID air flow 300 mI/stin
hydrogen flow 30 mi/mm
30
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TABLE 6—3
SU? NARY OF PERTINENT OPERATI9G CONDITIONS
US t) IN THE PURGE AND TRAP ANALYSIS CF J,2—D ICHI,OROBENZENE
AND 1, 2,4—TRICHLORO4ENZENE
PURGING SEQCENCE
Time 15 mm
Purge Gas/Fl Nitrogen/5 0 mZI in
Temperature 55°C
Trap 5” x 4 mm ID glass packed with
Ten GC
DESORPTl JN SL QUENCE
Time 5 mi n
Temperat re 250°C
Carrter/Fl ’ ft (g) at 40 m2/min
GAS CHRONATOGRAPHY OPERATING CONDITION
Temperature Program Sequence
initial oven teirp. 20°C
final oven temp. 140°C
temp. program rate 20°C/mm
Carrier/Flow N 2 (g) at 40 mi/mm
Column 6’ 1/8” stainless steel
packed with 10Z OV—17 on
60/80 Gas Chrom Q
Detector FID air flow 300 mI/mm
hydrogen flow 30 tat/mm
31
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and allowing a portion of the off—gas to pass through the sampling trap
and a calibrated air flow meter for 4 to 10 minutes at flow rates
ranging from 60 to 80 mi/sin. The procedure used to analyze the
volatilized organics co1lect d on the sampling trap was identical to the
one described for the purge anJ trap procedure. The small flow of the
off—gas diverted through the sampling trap (approximately 2Z of the
total off—gas flows was insuff cierit to alter t ’e steady state
conditions inside the blureactor.
32
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SECTION 7
RESULTS: VOLATiLIZATION STUDIES
7.1 EFFECT OF AIR—STRIPPING ON FATE OF TOXIC ORCANICS IN
BIORCAcTORS WITHOUT ACTIVATED SLUDGE
Activated sludge treatment systen typically employ diffused or
mechanical aerators to supply oxygen to the bacteria and to maintain
sufficient mixing to keep the bioTnass i suspension. Such mixing and
aeration can effect purging of iolatile compounds from wasteuater3. A
significant number •.f the 1.14 orgar.ic priority pollutants can be
characterized as volatile compounds, suggesting that air stripping could
be a significant factor affecting the fate of these compounds during
treatment. Five of the toxic compounds used in this study can oe
classified as pu geable organics; benzenc, toluene, cblorobenzene,
ethylbenzene and o—xyiene, and two more, o—dichlorobenzene and
1,2,4—rrichlorobenzene are considered volatile.
Initial studies conducted with the [ 0—liter bioreactors operated
in continuous flow modes without activated sludge and with ii fluents of
synthetic wastewater spiked with a to’:ic organic compound identified the
importance of air stripping. The surunary of representative influent,
effluent and off—gas values for each compound given in Table 7—1 shows
that air stripping effected a 90 to 96% reductLort in the aqueous
concentrations of all of the compounds except nitrobenzene and lindane.
The mean hydraulic residence time and aeration rate used in the baseline
air stripping studies were 5.5 hours and 4.0 Z/ntin,respectively.
7.2 DETER.MINATION OF VOLATILIZATION RATE COEFFICIENTS
The transfer of a volatile compound from a dilute aqueous phase to
a gaseous phase can be represented by the first-order expression
dC
— —— k pC (71)
cit
where C (ugh) is the aqueous concentration, t (mm) is time and k
(min ) is the first order volatilization rate coefficient. Air
33
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TABLE 7—1
EFFECT OF AIR STRIP LNG ON REMOVALS OF Tf,XIC OF ANiC
C0 0U DS FRO 1 BICREACTORS WITHOUT ACTIVATED SLUDGE
Off Gas
Influent Effluent (Z of
( g/t) ( pg/i) ( % of Tnf. ) Inf. )
Beozene 108.4 3.6 3.3 835 9 •7
Toluene 114.8 4.2 3.7 829 96.
Ethylbenzene 95.1 2.8 2.9 765 97.1
o—Xylene 105.1 4.0 3.6 838 96.2
Chlurobenzene 100.6 3.5 3.5 805 96.5
o—Dichlorobenzene 98.5 9.5 9.6 648 90. .
1, 2,4—Tn—
chiorobenzene 104.2 10.0 9.6 674 90.4
Nitrobeozene 95.0 71.3 75.0 188 25.0
Liiidane 100.0 100.0 100.0 0 0
strippuig studies were conducted in the 10—liter bioreactors operated
in batch modes at 20°C without activated sludge to evaluate
volatilization rate coefficients for benz. ne, toluene, ethvlhenzene,
o—xylene. chlorobenzene, o—di hlor benzene, and l,2,—trichiorobenzene.
The bioreactors were spiked with lOpt of a methanol solution containing
one or more toxic co -po nds and mix 1 for five minutes to produce
initial concentrations ranging from 70 to 100 ugh. Air flows were theo
begun, and samples were witn rawn at four to five minute intervals from
a sa.’npling port on the side of each reactor. The volatilization of a
single toxic compound was not affected by the presence of aadttional
toxic compounds at the low concentrations studied. Typically,
volatilizarfon studies were condu ted with two or more toxic organic
compounds.
Results for each toxic organic compound from stripping studies
conducted under identical conditions have be n plotted in Figure 7—1.
initial concen:rations for the rebults Ln Figurz 7—1 ranged from 70 to
85 ug.’L. There was no removal f lindane and only a small reduction in
the concentration of nitrobenzene after 60 minutes, therefore no further
attempts were made to quantify the scrippinZ or lindane and
nitrobenzene. Sig-tificant removals of the other compounds occurred and
the following relative order of vo ari1ization was observed:
ethyibenzene > toluene benzene ) o—xylene > chlorobenzene >
1,2—dichlorobenzene 1,2,4—trichlorobenzene
Volatilization rate coefficients, k , were obtained from th slope of
the least—squares linear regression line for data plotted as the natural
logarithm of concentration, in C, versus time as shown in Figure 7—2 for
an aeration rate of 4.0 i/can. The volatili a:ion rate coefficients
from air—stripping studies conducted at 4.0 i/mm are summarized in
Table 7—2. The last column in Table 7—2, k (solute)/k (benzene)
compares the volatility of each compound to that of benzene.
34
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U
U
z
c i
I-
LU
U
Ce
LU
>
1-4
ci
-J
We:
FiGURE 7—1. Volat.llzatiOfl of selected toxic organic
compounds from 10—liter bioreactOrS without activated
sludge. (Aeration rate = 4.0 liters/’Tufl.)
20 30 40
TIME UIINUTES)
35
-------
-J
ID
z
F-
F-
z
w
C-)
z
C
FIGURE 7—2. Data points best—fit lines describing the
volatilization rates ot selected toxic organic compounds f rbn---
10—liter bioreactors without activated sludge and vith air-
tight lids. (Aeration rates 4.0 liters/nun.)
0 10 20 30 40 50 60
TIME (MINUTES)
36
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TABLE 7-2
VOL ;TILI zArIo RATr CC JFICIENTS FROM AIR—STRIPPING STUDIES
CUNDUCTED IN THE 10-LITER BIOREACTORS
WITH AN AERATION RATE OF 4.0 1/rain
Compound k(min 1 ) corr. k(solute)/k (benzefle )
Erhv lbenzefle 0.0874 0.997 1.16
Toluene 0.0/65 1.000 1.02
Benzene 0.0754 1.000 1.00
o—Xvlene 0.0615 0.999 0.82
Ch l crobenzena 0.0493 0.999 0.65
1, 2—Dichioro—
be-rzene 0.0240 0.997 0.32
1,2,4—Trichioro—
benzene 0.0236 0.991 0.31
7.3 EFFECT CF AERATION RATE ON THE VOLATILIZATION RATE COEFFICIENTS
The effect of the aeration rate, Q , upon the volatiliration
rate coefficients was determined by conducting strioping studies for
each conpound at aeration rates ranging from 1.0 to 5.0 i/aim.
Results from each of these studies, plotted as In C versu time, are
preserrte’ in Figures 7—3 through 7-9. The volatilizatL.,n rate
coefficients from each compound were observed to iiccease linearly
with the aeration rate as shown by Figure 7—10. The relationship
between k,. ,, and Qa can be described by the equation
k =k +QL (7—2)
v V,O a
where k (min ’) is the calculated intercept and L(l 1 ) is the
slope or’ he line from a least—squares linear regression of the
data, and Q (I/rain) is the aeration rate. Values of L, k. 0 and
the correlation coefficient for each of the lines in Figure 7—10
are listed in Table 7—3.
Replicate srudie conducted wit.i benzene demor. trated that
values of k . , were reproducible and not affec:ed by different initial
concentrations. Average vilues of k , were used to calculate the
volatilization parameters in Table 7—3 when replicate studies were
run. Results from replicate benzene air stripping studies conducted
at 4.0 1/mm and presented in Figure 7—11 yielded volatilization
rate coefficients of 0.0751 a 1 d 0.0755 uiin’ for Run 1 and Run 2,
respectively. The correl? ion coefficient was 0.999 in each
case. Figure 7—12 shows results from benzene stripping studies
with initial concentrations of 47 and 80 ugh and aeration rates
of 3.0 1/mm. Values or were 0.0566 and 0.0573 cin for the
runs with initial concentrations of 80 and 47 ugh, respectively.
37
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FIGURE 7—3. Effect of aeration rate on be zene
volatilizaticn rate from 10—liter bioreactors with air—tighi
lids and without activated sludge.
38
0 tO 20 30 40 50 60
TIME (MINUTES)
-------
=
ľ
z
cc —a’
F— N
z
LU
C.) Li
z
C.)
FIGURE 7—4. Effect of aeration rate on the toluerie
volatilization rate from 10—liter bioreactors with air—tight
lids and without activated sludge.
0 10 20 30 40 50 60
TIME (MINUTES)
39
-------
-J
( D
uJ
C-)
z
C
0 10 20 30 40 50 60
TIME (MINUTES)
FIGURE 7—5. Effect of aeration rate on the ethylberizene
vo1atil zacion rate from 10—liter hioreaccors with air-
tight lids and without activated sludge.
40
3.0 Liter/mm
4.0 Liter/mm
Liter/mm
-------
FIGURE 7—6. Effect of aeration rate on the o—xylene
volatilization rate from 10—liter bioreactors with air—tight
lids and withoct activated slud;e.
41
0 10 20 30 40 50 60
TIME (MINUTES)
-------
10 20 30 40
TIME (MINUTES)
50 60
FIGURE 7—7.
volatilization
tight lids and
c i , lorobenzen
with air-
Effect of aeration rate on t -e
rate from 10—liter bioreactorS
.rithout activated sludge.
62
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FIGURE 7—8. Effect of aeration rate art the
1,2—dichlorc’bcnzene volatilization rate from 10—liter
bioreactors with air—tight lids atd without activated
sludge.
4;
0 10 20 30 40 50 60
TIME (MINUTES)
-------
FIGURE 7—9. Effect of aeration rate on the
1,2.4_trichlotobeflzefle volatilization rate from 10—liter
b oreaCtOrS with air—tight lids and without activated
sludge.
-J
CM’
Ł..0 Liter/mm
C,,
N
0
20 30 40
TIME (MINUTES)
50
60
44
-------
‘-S
‘-4
=
I-1
>
I-
(J
1-4
LL
w
C)
(-)
w
I—
Cr
Zu,
1-1
I - .
cr
NJ
-J
I-1
-J
C)
6.0
FIGURE 7—10. Effect of aeration rate cn volatili .atiOfl
rate coefficients measured in 10—liter bioreactorS ,ith
air—tight lids and without activated sludge.
U,
1.0 2.0 3.0 4.0 5.0
AERRTON R TEI 0 (LITERS/i1IN)
4S
-------
c. I
—
-
N
(0
U’.
c, .
-J
z
Q
N”
( . ) U’”
c i
—— U •
I I 10 20 30 40 50
TitlE (MINUTES)
FIGURE 7—U. Data points and best—fit lines for results
from replicate benzene volatilization studies in 10—liter
s iied bioreactors with 4 .0—liter/mjn aeration rates.
46
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FIGURE 7—12. Data points and best—fit lines for results
from replicate benzene volatilization studies in 10—liter
sealed bioreacrors with 3.0—liter/mm aeration rates.
-J
CD
rn
C..
0 10 20 30 40 50 60
TThE 11INUTES)
47
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TABLE 7-3
V0LATILIZATI0 ’ PARAMETERS RELATING k TO Q
FOP AIR STRIPPING OF VOLATILE CO OU DS FROl 1O!LITERaBIOREACTORS
WITH AIR-TIGWt LIDS
Compound k 0 ( mIn 1 ) L(1 ) Corr. Coef.
Benzene 0.0012 0.0183 0.999
Toluene 0.0023 0.0188 0 99
Ethvlbenzene 0.0027 0.0205 0.999
o-Xvlene 0 0.0148 0.999
Chlorobenzene 0 0.0126 1.000
1 • 2—Dichl.oro—
benzene 0 0.0064 0.993
1.2 ,4—Trichloro—
henzene 0 C.C063 0.992
7. AIR STRIPPING MODEL FOR C BIOREACTORS
E uation 7-2 was used o calculate k,, for a ,v aeration rate
used in the 1O—1 ter b1 reactors operated in continuous f. ow
nodes. Calculated values of k were ircorporated irto an air
stripping model ceveloo d from a CME reactor LaSS balance equation
to predict uoth effluent a, d off—gaa canc€ntrat .-onS from otoreactors
in which volatilization was the only t . hanism effecting a
reduction to aqueous concentration of an organic cor und.
The n’iss balance ecuation ror the aqueuus phase ncencration
V QC — QC - kC’I (7—3)
48
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Under conditions of tc l ’— tjtC the effluent concentration can be
predicted by:
Ce CjI(l + k t) (74)
where C (ug/Z) is the effluent concentration, Cj ( ig/i) is the unfluent
c nceuitr rion, t (miii) is the mean hydraulic retention time, VfQ 1 ,un the
aeration s ctt.on, V (2 .) is the aqueous volume iii the aeration section
and Q 1 (i/tnun) is tie . ci ’teous flow rate. The masa balance equation on
the gaseous phase, assunung toicic compounds are riot present initially in
the aeration gas, and that the g iseouS phase is uniform in co ”centratton
overall, is
dC
Vg __g •• gCg + k C v (7—s)
dt
jhere Cg (ag/i) is the off—gas concentration, ( (i/win) is the off—&i
fl rate, and Vg(Z) LS the volume of the gaseous phase. Under
conditions of steady—state , the off—gas concentration can be predicted
by
CeVkv
Cg (7-6)
Qg
Substituting Equaturir’ 7—2 for the volatilization rate coefficient, k, ,,
in Equations 7—4 and 7—6 yields Equations 7—1 and 7—S which were used to
tre’lict effluent and off—gas concentrations, respectively, from the
10—liter CMF bioreactors without activated sludges.
Ce c 2. / [ t(k , 0 + QaL)J (7—7)
Ce(V)
Cg (k , 0 + QaL) (78)
Qg
Influents during the baseline strip iLng studies were composed of
synthetic wastewater spiked with one or ‘sore toxic organic compounds.
ks compared in Table 7—4, the predicted effluent .iiid off—gas values
chewed excellent agreement with measured values aver ed Iron at least
five bioreactor sampling periods. The bioreactors weru operated with
mean aeration rates and hydraulic tet ntion times of 4.0 2/mu and 5.5
hours, respective]y. Equation 7—S was used to successfully predict
off—gas concer’trattons from measured effluent concentrations in
bioreact’,rs with acclimated activated sludge.
49
-------
TABLE 7—4
PREDICTED EFFLUENT AND OFF—GAS CONCENTRATIONS FRO?1 BIOREACTOKS
WITHOUT ACTIVATED SLUDGI.
1easured Pr•dicted Measurel Predicted
Influent Effluent Effluent 0ff—Gas Off—Gas
( ugh) ( ugh) ( pg/i) ( ng/i) ( ! g/t )
Benzene 120.3 4.6 4.5 846 835
Toluene 121.9 4.5 4.1 784 786
Ethylbeazene 112.0 3.5 3.7 75 787
o—Xylene 111.5 5.2 5.4 796 764
Ch lorobenzene 130.9 6.8 6.7 790 828
1, 2—Dichloro—
bcnzene 105.2 10.8 11.0 691 706
1,2, 4—Trichioro—
benzene 1L7.7 12.2 12.2 765 772
1•5 EFFECT OF USING SEALED BIOREACTORS ON VOLATILIZAFION RATE
COF.FFICjENTS
Off—gas sampling neeessitated conducting all of the
completely—mixed flc i bioreactor studies in bioreactors sealed with
air—tight lids. Such a reactor configuration is not representative of
actual treatment facilities which utilize open reactors. The batch
volatilization studies previously described were conducted in
bioreactors equipped with air—tight lids to simulate the configuration
of the eperimental CKF units. An additional set of volatilization
studies was conducted in open 10—liter bioreactors without air-tight
lids to evaluate the effect of sealing the bicreactors with air-tight
Lids on air stripping.
Volatilization rate coefficients obtained from the open reactor
stripping studies were greater than those obtained from the sealed
reactor studies for a given aeration rate. Comparisons of results froti
volatilization rate studies conducted in open and sealed bioreacto’s at
aeration rates of 4.0 P./.Din ..re presented in Figures 7—13 through 7—17
for benzene, toluer.e, ethylbenzene, o—xylene and chlorobenzene,
respectively. Volatilization rate coefficients for the f].ve most
volatile compourus measured in open and sealed bioreactors at aeratior.
rates of 4.0 i/rain are given in Table 7—5. The ratio k (sealed)/
kv(open) for an aeration rate of 4.0 i/rain was similar for the five
compounds and averaged 0.82.
50
-------
C
z
w
U
C
U
FIGURE 7—13. Benzene volati1izatiO frori .,i 1ed and
open 10—liter bioreactorS with 6.0 Iiter/m n acr it1on rates.
I - ..
(0•
U )
— a
WITH AIR”
LID
rn
OP EN
0 10 20 3U 40 50 60
TIME MINUTES)
51
-------
-j
z
0
z
LU
L)
z
0
L)
FIGURE 7—14. Toluene volatilization from sealed and
open lO—litet bioreactors with 4.0—liter/mm aeration rates.
SEALED WITH AIR-TIGHT
LID
N
U,
C’,’.
0 10 20 40 . 50 60
TIME (MINUTES)
52
-------
-J
CD
z
0
z
w
( )
z
0
C-)
50 60
FIGURE 7-•15. Ethyll’enzene volatilization from sealed and
open 1O—lit r bioreactors vith 4.0—liter/mm aeration rates.
c.,1
U,
N
(0
‘I)
EALED WITH AIR-
TIGHT LID
C,,.
OPEN
0 10 20 30 40
TIME (MINUTES)
53
-------
C.’
—t —
I .- ..
In..
-J
cs..
2
—. SEALED WITH \IR—
TIGHT Lit.
—a)-.
c
I— -.
OPEN
In..
z
C. . ..
C-)
C l..
-a. a -* —
0 10 20 30 4.0 50 60
TIME (MINUTES)
FGURE 1—16. o—Xylene volatilization from seakd and
open 10—liter bioreactors with 4.0—liter/mm aeration rates.
54
-------
c . J
-J
CD
2:
0
I— •; -
CZa
c
1 -•
2:
uJ
C.) II)
2:
0
C)
C 10 20 30
TIME (MINUTES)
FIGURE 7—17. (.hlorobenzene volatilization from sealed
and o .en 1O-iiter bioreactors with 4.O—1iter/ ir. aeration
rates.
L.
50 60
C ,,
SEALED WITH AIR-
TIGHT LID
OP El”
rn
55
-------
TABLE 7—5
VOLATILIZATION RATE C0EFFICI NTS [ N OPEN AND
SEALED 8IOREACTORS AT AN AERATION RATE OF 4.0 i/mAn
Volatilizat on Rate Coefficient, k (min’)
Compound Sealed k (sealed)/k (open )
Benzene 0.0754 0.091 0.83
Tol , ene 0.0765 0.093 0.82
Ethylbeozene 0.0874 0.104 0.84
o—Xylene ‘L06 15 0.074 0.83
Ch lorobenzene 0.0493 0.063 0.78
The ratios of the volatilization rate coefficients of eacL compound to
that of benzene, k /k (benzene), was the same for values of k measured
in open bioreactor air—stripping studies as reported in Table 7—2 for
air—stripping studies conducted in hioreactors with air—tight Lids.
Table 7—6 gives a comparison of these ratios for the most volatile
compounds.
TABLE 7—6
RATIOS OF VOLATILIZATION RATE COEFFICIENTS
OF EACH COMPOUND TO THAT OF BENZENE
k /k (benze . e) k /k (benzene)
Compound Sealed Bioreactor Qpen Bioreactor
Ethylbenzene 1.16 1.14
Tojuene 1.02 1.02
Benzene 1.00 1.00
o—Xylene 0.82 0.81
Chlorobenzene 0.65 0.69
The linear relation .hip between tho first order volatilization rate
coefficient, ks,, measured in the open bioreector stripping studies and
the aeration rate, Qa’ can be described by Eqi atinn 7--2. Comparisons of
the results from open aud sealed stripping studies, plotted as versus
Qa’ have been ?rasented in Figures 7—18 to 7—22 for benzene, toluene,
ethylbenzene, o—xylene, and chlorobenzane, respectively. A summary of
L, k , 0 , and the correlation coefficients from the open bioreactor
volatiliz3tion studies is given in Table 7—7.
56
-------
I-
z
>
-
U
U-
LU
U.
L U
cL
L1
c c
-J
I-
-J
C
FIGURE 7—18. Data points and best—fit lines descri.tng
the relationship bet’JFen the benzene volatilization rate
coefficient and the aeration rare for seab. d and open
iC—liter bioreactor .
OPEN
SEALED WITH AIR-
TIGHT LID
U 2.0 3.0 4.0 5.0
AERATION RPTE, °A (LITERS/MIN)
8.0
57
-------
It,
>
S
C-)
I-1
Li..
w
C
L)
w
I- ..
z:Lr)
NJ
-J
-j
>
6.0
FIGURE 7—19. Data points and best—fit lines describing
the relationship between the toluene volacilizaticn rate
coefficient and the aeration rate for sealed and open
10—liter bloreacto:s.
U ‘2.0 3.0 4.0 5,0
AERATION RATE, °A (LITERS/IIIN)
58
-------
>
I—
U
(L
LL
w
C)
L J
z .I-
C ;‘
I-s
I-
i -i
1 - s
I —
C
6,0
YIc,URE 7—20. Data points and best—fit lines describing
the re1atior ship between the ethylbenzene volatifization
- te coefficient and the eracion rar.e for sealed ind
open 10—liter bicre.ictors
z
I-I
OPEN
SEALED WITH AIR-
TIGHT LID
1 .0 2.0 3 0 4.0 5.0
AERRTION RATE. A (LITERS/NIN)
-------
z
=
I—
I-1
C—,
LL
U-
U i
0
U
Ui
I—
Z
I—
-J
-J
0
Ct I
1.0 2.0 3,0 4.0 5.0 8.0
AERATION RATE. O (LITERS/MIN)
FIGURE 7—2 1. Data points and best—fit lines describing
the relationship between the o—’cylene volatilization rate
coefficient and the aer cion rate for seaLed ana open
10—liter bioreactor .
OPEN
SEALED WITH AIR-
TIGHT LID
60
-------
U)
d
-I
=
1 .:
-
I-4
C-)
Lt
LL.
U i
0
C—)
Ui
ztI,
0c
r4
F—
F- i
-J
F-i
F-
ct
-J
C D
tO 2.0 3.0 4 .0 5.0 6.0
AERATION RATE. 0 A (LITERS/tlIN)
FIGURE 7—22. Data points and b’ st—fit lines desL 1htng
the relationship between the cl’ orobenzene volatilization
rate coefficient and the aeration rate in sealed and
open 10—liter bioreactors.
OPEN
SEALED WITH AIR-
TIGHT LID
4
61
-------
TABLE 7—7
VOLATILIZATION PARAMETERS RELATI G k TO Qa FOR
AIR STRIPPING OF VOLATILE COMPOUNDS FROM 10—LITER BIOREACTORS WITHOU1’
AIkTICHT LEDS
Compound Corr. Coef .
Benzene 0.0200 0.0109 1.000
To luene 0.0217 0.0063 0.999
Ethylbenzene 0.0255 0.0140 0.999
o—Xylene 0.0148 0.0153 0.999
C lilurobenzene 0.0125 0.0126 0.997
An ilreLescing findtng was that the values of L, the dope of the
bQst—tir I .e L i- xigh data plotted as versus Qa approxinately the
me in open and sealed bioreactor vo1attl ..ation studies as sh n in
ra Le 7. .
TABLE 7-8
C0 1PARIS0N Of L VALUES F 0M SEALED AIJD OPEN
lO—LIrER BIOREACTO VOL TILtZATION SUDIES
Con pound L(I ), Sea i L(Sealed)/L(Open )
aen. ene 0.0183 0.0200 0.92
Tc,luene 0.0188 0.0217 0.87
Ethyl e.. tene 0.0205 0.0225 0.91
0—Kylene 0.0148 O.014 1.00
Ch lorobenzene 0.0124 0.0125 0.99
62
-------
7.6 OXYGEN REAERATION
The final phase of the volatilization studies was designed
to evaluate rh proportionality coeffic icnts relating the rate of
volatilt compounds from an aqueous to gaseous phase (volatilization)
to the transfer rate of oxygen from a gaseous to aqueous phase
(reaerat!on). Various studies, i.icluding this one, have demonstrated
that the volatilizatio,i rates of volatile cot-pounds are proportional
to one anothe’- (49—51). The two—film gas transfer model
assumes that the rate of phase transfer of volatile compounds
(H 5 x io atTn rn /mol) is controlled by the liquid—phase resistance.
Oxygen reacration also is controlled by the liquid—phase resistance
according to this model. Therefore, oxygen can be used as a convenient
reference compound to which the transfer of volatile compounds
can be related. The proportionality relationship can be expressed as
= B (kLa)O (7—9)
where (ku). (nan ) is the volatilization rate coefficient of an
organic compound, kLa (min 4 ) is the oxygen reacration rate
coefficient, and B is the proportionality coefficient. This
principle of proportanalitv using oxygen as a reference compound
has been demonstrated for a variet of volatile compounds over a
wide range ot environti ital conditions (49— l). The proportionality
coefficient is dependent upoo the l:quid phase diffusivity ratio,
D ’Do 2 , and is relatively constant over a wide range of mixing
conditions.
Oxygen reaeration rate studies were conducted in 1O—l ter
biort ’actors according to the procedure described in Section 5.
Results f tom oxygen reaeration studies conducted at various
aeration rates are presented in Figures 7—23 and 7—24. The
relat onThip between oxygen reaeration rate coefficient, kLa, and
aeration rate, 0 a’ shown by Figure 7—24, can be described by
k La = k .La, + a (7—10)
where kLa (min ’ ) is the oxygen reaeration rate coefficient,
L 1 a, 0 (min ) is the calculated intercept and S (liter—I) is the
slope of the best—fit line relating kLa tO Qa’ Values of
and S were J.058 mln and 0.0895 F ’, respectIvely, and the
least-squares linear regressior. coefficient, r 2 , was 0.999.
The proportionality coefficient,- B, was determined by comparing
the L values for each compound to the S value for oxygen,
L
S (7—11)
An seen in Table 7—9 the values of B calculated usinc data from sealed and
open bioreactor studies do not vary significantly.
63
-------
FIGURE 7—23. Exp tim ntal data and best—fit lines
used to determine the oxygen reaerat .on rate coefficients
for aeration rates from 1.0 to 6.0 liters/mm In the
10—liter bioreactors without activated sludge. (20°C)
a
L
‘I )
C i
IC ’.
C i
z
-J
o.o U 2.0 3.0 4.0 5.0 6.0 7.0
TIME (MINUTES)
64
-------
2:
Q
I-1
a:
a:
w
2:
w
>-
FIGURE 7-24. Experimental data and best-fit line
describing the effect of aeration rate on the o\-vgen
reaeration race coefficient for the TO—liter hioreactorS.
(2O ’C)
-4
z
LO 2.0 3.0 4.0 5.0 6.0
AERRTION RAT. 0 A (LITERS/MIN)
65
-------
TABLE 7-9
PROPORTIONALITY COEFFICIENTS RELATING VOLATILIZATION
RATE COEFFICIENTS flF THE TOXIC ORGANIC COMPOUNDS
TO OXYGEN REAERATION RATE COEFFICIENTS
B B
C 2 ound ( Sealed B oreactor)+ ( Open Bioreactor)
Benzene 0.20 0.22
Toluene 0.21 0.24
Ethjlbenzeflt 0.23 0.25
o—Xylene 0.16 0.17
Chlorobenzene 0.14 0.14
1,2-Dich1orobenzen 0.07 N.D.
1,2,4—Trichlorobenzefle 0.07 s.D.
N.D. = Not Determined
+ Bioreactors with air—tight lids
+4- Bioreactors without lids
66
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SECTION 8
RESULTS: BIOSORPTION StUDIES
Rate and eouilibrhnn studies were conducted to evaluate the
importance of bi scrption as a ‘emoval mechanism during activated sludge
treatment, The three compounds used in the biosorption experiments,
1,2—d chlorobenzene, l,2,4—t . 1chlorobenzene, and lindane were selected
because they have the largest octanol/water partition coefficients, K 0 .
Various studies have sh n that the degree of bj.oaccumulation of
hydrophobic organics by fish and other aquatic organisms increases with
increasing values of K (52.53).
8.1 RATE STUDlES
Sorption rate studies were conducted with lindane to evaluate the
time required to reach equilibrium conditions. The studies were
performed in 2.6—liter glass completely—mixed batch reactors stirred
with a teflon paddle attached to a glass stirring rod. The sorbent used
was mixed liquor suspended solids from a bi..,reictor not receiving toxic
organics in the influent. After transferring 2.6 liters of mixed liquor
to the CMB reactor, the contents f the CMB reactor were s7iked with 10
pi o methanol containing l ndane. Samples were taken with a 10—mi
syringe, filtered through 25 mm glass fiber filters, and extracted with
h exa ne.
Results from a sorption rate study pcesented in Figure 8—1 3hoi., a
rapid uptake of lindane by the bacteria. Equilibrit c ndit1ons were
achieved etihin 15 to 20 minutes. At the end of 150 injtcs mixed
liquor sa nples containing both the solid and aqueous phases were
extracted for lindane. The result yielded a complete recovery of
lindane indicating that 9orption was a reversible proces’; and that
removal was r t attrilxitnble to biodegradation.
8.2. EQUlLIi I1JM RESULTS
The sorption equilibrium experiments were performed with settled
activated sludge with a knaeri suspended solids concentration from an
activ ’:ed sludge bioreactor not -ecei sing toxic organic compounds in the
influent. Various volumes of the settled sludge were ddded to [ 50 c ii
hypo—vtils anci diluted to 150 mis to eliminate headspace ai.d minimize
‘olatilization. Each vial was spiked with a toxic organic conpo* nd in a
67
-------
L)
2:
( 3
I-1
I—
2:
C D
z - C!) 0
(3d
Li
uJ
>c
I—d
cE
-J
Lu
0 30 60 90 120 150 180
TIME (MINUTES)
FIGURE 8—1. SorptIon of lindane by activated sludge mixed liquor su pcnded solids
in a completely mixed batch (CMIi) reactor. (C 84 ugh and MLSS 3800 mg/I)
-------
methanol carritr, sealed, and mixed with magnetic stirrer for 3 hours.
Samples fraa cach vial were centrifuged, pd the supernatanc was
e’ct:acted with hexane.
Freur.dlich and Linear Phase Partitioning isotherm model; were used
to evaluate the data from the biosorption experiments. The Freundlich
model has the form
= KfCe 1 1
where qe (I g sorbed/mg MI..SS) is the amount of solute removcd per unit
weigh of sorbent, Ce (ug/Q.) is the equilibrium solution concentration,
and Kf and 1/n arc characteristic constants. The Freundlich model
linearizes in logarithmic form:
log qe log Kf + 1/n log Ce (8—2)
Figure 8—2 shows tne sorptiofl data and best—fit lines for the Fre ndlich
model. As expected, l,2,4—trichlorobenzene showed a greater degree of
sorption than lindane due to the higher octanol/vater partition
coefficient. Values of Kf and 1/n are given in Table 8—1.
The Linear Phase Partitioning model for biosorption has the form:
= KpCe (8—3)
where Kp, the partition coeff3cient, is the ratio of the amount sorbed
to the equilibrium solution concentration. A similar model, in wh_ch
is replaced by KB/10 6 , has been used for describing the bioconcentra—
tion of hydrophobic compounds by aquatic organisms (52,53). K 8 is the
bioconcentratton factor. Plots of the amount sorbed versus the eçuili—
brium solution corcentration in Figure 8—3 revealed a reasonably linear
phase partitioning. The characteristic constants and the correlation
coefficients for the Linear Partitioning model are giver in Table 8—1.
Results from the biosorption equilibrium studies shcwed that the biocon—
concentration factor, , for l,2,4—trichlorobenzene was greater than
that for lindane.
8.3. CORRELATION OF KB WITH
Various studies have attempted to correlate bioconeentation with
other physical paraneters. Work by Neely (54), Vetth (52), Wind Mackay
(53) have shown that bioconcentration af hydrophobic organic compounds
69
-------
TI
— C)
I A
I l)
C . )
1,2 1 1 -TR
C /)
U)
—a
C-)
w 0 )
cr
C) to
U)
I —
C)
cr
0
L I NDAI4E
C..
T
9
2
3 4 5 678 I 2 3 4 5 6709.
EOUILIBRIUM SOLUTION CONCENTRATION (UG/L)
I x I0
FIGURE d—2. Fretindlich isorhernis for the sorption of lindane and I,2,4—trlchlorobcnzene
by activated sludge mlxnd liquor suspended solids.
-------
(0
(J
-J
=
C D
CD
LtJ
c
C D
(I,
I—
z
=
cd
0• — • t - I I I I I
20 40 60 80 100
EQUILIBRIUM CONCENTRRTION (UG/L)
FIGURE 8—3. Linear pardoning isotherms for the
sorption of lindane and l.2.1 —trichlorobenzene by
activat d sludge mixed liquor suspended solids.
TRICHLOROBENZENE
0
0
Li NDANE
71
-------
TABLE 8—1
IS0TqE?y. MODEL PARMfETERS FOR SORPTION OF
TQUC 0I AN1C COMPOUNDS B ACTIVATED SLUDGE
Linear Freendlich+
Compound Corr . j j 1/n Corr .
Lindane 5b8 0.987 0.0014 0.789 0.992
1, 2,4—Trichloro—
benzene [ 030 0.991 0.00039 1.24 0.987
+ Ev. 1uat d using Ce in ugIZ .uid q 0 In ,.iglmg MLSS
++ Intercept at C = 1.0 ugl’.
can be corr2lated to the octanol/water partition coefficient. Veith
(52) found the foll ing equation described this relationship
log K 3 = 0.85 log K 0 — 0.70 (8—4)
while Mackay (53) suggested a one parameter correlation
log K 3 log — 1.32 (8—5)
The lines described by equations 8—4 and 8—5 were plotted in Figure 8—4
along with results from this study and data reported by Iackay (53) and
Veith (52) for representative todc, organic compounds. Data given oy
Mackay (53) and Vuith (52, cap e from varius bioconcentration studies
using fish as the test organimes, while results fron this study were
obtained with activated sludge mixed liquor biological suspended solids
as the test organisms. The results from this study agreed quite well
with results from other bloconcentration studies. As sh in by th2
comparison in Table 8—2, lind ne and [ ,2,4—trtchlorobenzene
bioconcentration factors were approxinately t e same in this study as
were reported by Veith (52). Such correlations are useful for
72
-------
FIGURE 8—4. Correlation bt i ccn Ihc b [ oconcciitratlon aLI0i and octaliol/Water
part t ion coeffic lent tar sd ected hyth o 1 .hohic 0 , ganl Lomp()LIn k..
If)
0
0
z
0
I—
-r
Li
0
z
0
0
0
C-)
a
-J
-4
(N
0.0
1.0
2.0 3.0 4.0 5.0 6.0 1.0
LOG OCTANOL/WATER PARTITION COEFFICIENT
80
-------
estimating the de rec to uch specific coi pounds are likely to be
removed by bio p ‘ ., ±ur.ti activated 1udge treatment since
octanol/water srt ,..oet icients are available for many
ervironmentally ft : ant organic cor ounds. Ass*n ing equ1IibLii m
c-ndittons exist b ,een the sorbed and aqueous concentrations, as the
results shown in Figure 8 —1 sugge,t, the amount of a cor ound sorbed by
the activated sludge blomass can t e quantified for any set of operating
conditions encountered jO actIvated sLudge processes.
TABLE B—2
COMPARISON OF KB VALUES FROM THIS STUDY TO THOSE REPORTED
BY VEITH, CT AL. (52)
Log KB Log K 3
Compound Log K , This Study Veith et al. (41
Lindane 3.35 2.75 2.67
I, 2,4—Trichloro—
henzene 4.23 3.01 3.32
74
-------
SECT [ U 9
D r LOP ’1E 4T OF TRACE (JRCANICS IfttOVAL MOI)EL
FOR ACTIVATEI) ‘JJDGE
9.1. t troduct cn
Current models for the removal of soLuble nrganics durir.g
wastewater trpatment typically originate from tne tradittonal substrate
mass balance equation which has the for n
dC
V () QjC 1 — Qe ’e + v( ——) (9—1)
dt dt 8
Change of mas’ mass mass change of
in reactor entering — leaving + cass due to
reactor in reactor in biodegradation
influent effluent
Such a mass balance does not include removal mechanisms of air—strtpptng
and hiosorption, and therefore cannot accurately pr d.ct the fate o a
wide variety of toxic organic conpounds. A more conpiete substrate mass
balance wnich includes the three dominant tr c• organic removal
mechanisms of volatilization, biodegradation and hiosurpcion has t’ e
form
dC tC dC
v(——) Q 1 Cj — QeCe + v(—.-) + v(——) +. v(——) (9—2)
dt d t dts dt 8
Change of mass mass change of change of change of
mass in entering — leaviitg + nass due to + ass due to + mass due to
reactor reactor in reactor air biosorp— biodegra—
influent in stripoing tion dation
effluent
75
-------
This equation wher applied to steady—st ite operating conditions beco
the Steady—State Trace Orgaints Removal Model (STuR.4) for activated
sludge. The fo11c ing sections present development of the model for
various classifications of toxic orga&iic compounds based upon .heir
physical and biochemical ?roperties.
9.2. GP NERAL STOI M D EL WME T
9.2.1 . Air Stripping
The etc—stripping of a voletile trao or anlc can be conveniently
represented by the first—order removal expression
dC
(——) = — c (9—3)
dt
as was detailed in Section 7.
9.2.2. Siosorption
Res i.Lts presented in Section 8 sug. est that biosotptiOfl is
controlled by equilibd.um rather than fnasn transfer rate considerations.
The hiosorpt on term ai; he based upon an assi iption that equilibrium
exi ts between the solution and sorbed phase concentrations of a toxic
orga”ic. That equilihriinn condition can be represented as
KpCe
The term in the CMF reactor mass balance equation representing the mass
removed by biosorprion can he written a; q M 5 Q 5 , wher . q (i gImg) is
sorbed concentration of a to’dc organic, M 5 (mg/L) 1, the mixed liquor
susperded solids concentration and Q 5 C. Imin) is the sludge waste removal
rate.
9.2.3.. Biodegt3datton
The biodegradation of a trace organic compound can be
represented as a pseudo first order romovaL express ion represented as
dC
(——) =—i c (9—5)
dt
4here kb(lifl’) is the pseudo first order biodegradation r,te coefficient.
76
-------
Substituting for each of the rerac’val ter in equation (9—2) yields
dC
v(——) Q 1 C 1 — — Vk,,C — ‘:k 5 C —qe sQ 5 (9—6)
dt
which can he simplified under conditions of steady—state to
QjC 1 QeCe + VkvCm+ Vk 5 C. q ’l 5 Q 5 (97)
‘nis model cai be used to predict the fate of toxic organic compounds
during activated sludge treatment if basic information about the
individual removal mechanisms is kti n.
9.3. APPLLCAT1O ’I OF STORM TO NON—BIOUEGRADA8LE COMPOUNDS
The removal of non—biodegradable compounds can occur as a result
of volatilization and hiosorption as indicated by equation 9—8.
Q 1 C eCe + (9—8)
Depending upon the physical propertLes of a compound one or the other
removal mechanisms iay dominate. on—biodegradab e compounds with large
values of Henry’s constant and small hiosorption c9efficients will
likely be removed by air—stripping while compounds with small Henry’s
constants and large hiosorptlon coefficients will be sorbed by the
bionmss. Compounds in an intermediate range Lay be subject to removal
by a combination of the two occh nisms. Consideration will be given to
vol iIization as the domliant removal mechanism, then biosorption as
the dominant rmech nicm, and finally a combination of the two.
9.3.1. Volattlizati ’n
The mass balance equation for conditions of steady—state that
reptesont the air—stripping of a volatile, non—biodegradab’ e and
non—biosorbabte compound is:
QjC 1 QeCe + V .vCe
where QiCi is the irtfluent mass flux, 4 , QpC is the effluent mass
flux, Net and VkvCe is the off—gas sass flux, tn the context of
this work the amounts of a compound stripped to the atmosphere were not
77
-------
regarded ss uItun -ktely removed, but rather redistri jted. The off— as
mass flux an aLso be written as :he product of the concentration of a
coapound in the of L—gas, CgP and the off—gas flow rate,
Ng v t ’e CgQ (9—10)
The of I lient and of f—ga concentrations of volatile
non—htodcgradable poorlj ,orbed cor ounds ai’ be predicted by the
following equation. developed in Sectlin 7:
Ci
Ce =—--——-- (91 1)
1-+k t
VCekv
Cg (9—12)
- Qg
The ratio of effluent to influent concentrations, Ce/Ct, has been
plotted as a functLon of k in Figure 9—1 for a 5.5 hour hydraulic
retention time, t. The circles represent vaLueq of k calculated for
the volatile cot ounds by EquatIon 7—2 for an aeration rate of
i/rein. A 90% reduct ion in the aqueous concentration occurs for
compounds ith values of k greater than 0.025 m1n • ks shown in
Figure 9—1, over 907. of the influent mass flux i.i.ll leavc the
bioreactors in the cIt—gas for non-biodegradable compourds with
volatilization rate coefficients greater than 0.025 5 i —L. Both
1,2—dichlorobepzene and 1,2,4—trichlorobenzene have volattltza [ on
coefficients of about 0.025 min’ at an aeration rate of 4.0 ) /min.
Approci tely one third of the organic priority pollutantc can be
considered to have relative volatilittes equal to or greater than
1, 2,4—trichlorobenzene.
The sensitt’ -ity of air—stripping removal to the hydraulic
retention time, t, has been shown by Figure 9—2 to be small. A decrease
in the hydraulic retention tiTnO by nearly 507. to 3.0 nours still remults
in at least arm 85Z reduction in the aqueous concentration for om ounds
with relative volatilittes greater than or equal to 1,2—dichlorobenzene.
9.3.2. Biosorptiorm
A steady—state mass balance equation for non—biodegradable,
non—volatile con ouinas that are removed by biosorption has the form
73
-------
C,
0
0.0
Qi
N W
OW
0.0
— 0
. I”
00
,.. .
E—U
C.”
0.06 0 08
VOLATILIZATION RATE COEFFICIENT, k
FIGURE 9—1. RelatIonship between the volatlliz don rate coetficient aod
the reduction In aque’ ’iS conc nt ration of volatile compounds in 10—liter
blureactors with ar_tighr. lids.
r-1
t robensene
timated)
C’
‘0
c
I —
U i
-J
L)
I —
U i
-J
U-
I L
Ui
C.—)
—3
0
C”'
d
0
0
N
0
. 0
0
I ..
0
.0
C.)
0
C
.3 ’
0
0
C
0
‘-3
C
oW 0
.0
aj s -
N
.0
00 3-’
Ui
0.02 0.04
0. O 0.12 0.14
(MIw )
0.16
-------
VOLATILIZATION RATE COEFFICIENT, k (MIU )
FIGURE 9—2. SensItivity of the air—stripping model to changes in the
hydraulic retention time in 10—liter bioreactor .
0
-4
d
0
I-
w
-J
LL
-J
4J-
LA
w
0
c
E = 3.0 hours
0
0.0 0.04 0.08 0.12
0. l’
-------
QC QC +q lQ
ii ce ess
Substituting for q in Equation 9—13 gives
Q 1 C QCe+ KpCe tsQs (9—13)
The sludge waste (low from tht exp rtaen:ai hioreactars was smaLl arid
the effluent flow was appr imately equal t the inuLu nt ŁIo . In
additio’i, sludge was wasted dirt ctly froo the ierat 1 oasin section Ct
the btoreactcrs. Therefore Equation 9—14 can be rearranged and written as
r trt M 5
—— I 1+ (9—15)
c L (24)SRTJ
ihero SRT (days) is the mean solids retentioui time.
Results presented in f ct ton 8 shower chat the bioconLant ration
factor K 8 fr the , ort,ounds used in this p:ojecc were similar co those
ohtiined for other test organisms. The value of K must be oultiplted
by 11)6 to convert the units ( Jg/mg)/(pg/&’a to a dtrnensionles form.
Substituting the bioconcentration factor, K 8 , icr K in Equat ton 9—15
g I yes
—1
Ce f 3 1
—— Ii + I (9—16)
Cj L (24)SRT J
Various stu iies have shown that a reasonably good correlation exists
between the btoconcentr ition factor aid the octai’ol/water partition
coefficient, Kow which is generaly sore avail b1.e than values of K 8 .
While numerous correlations have beer suggested, th2 single constant
correlation given by lackay (53) of
KB O.O4BK 0 (9—17)
is the si iplest. After substttuti’ g for KB, Eqi.attor 1 9—16 can be
written
-------
Ce I sKow2x10 9 1
—— Ii + ———— I (9—18)
L SRI
The removal of a hydrophobic, non—volatile, non—biodegradable compound
by iosorpt ion can be predicted by Equation 9—18 for any set of
activated sludge operating conditions.
quatton 9—18 was solved as a function of ana the results in
Figure 9—3 ar given as C 0 fC versus Log fur operating ondit ions of
3r00 og ‘1LsS/ , SRT 6 days and t 5.5 rtours. The resuLts
indicate chat hiosorption will not s ignihrantly affect the aqueous
concentration of compounds with Log K 0 values less than 4.0. Predicted
removals are given [ or specific non—volatile compounds assL-ling
biodegradation does not occur. Equation 9—18 predicts a 457. removal for
compounds with Log Kow values of 5.0 and 907. removals for compounds with
Log Kow values greater Lhart 6.0.
Results presented in Figure 9—4 sh i h the concentration of ILSS
affects the removal of trace otgaitics by sorption for an a tvated
sludge operated at h draul c and soLids residence times of 5.5 hours and
6 days. respectively. The lines represent predicted removals for
constant values cf K 0 . For a compound with a Log K 0 value of 5.0
removals at steady—state !LSS concentrations of 3000 a d 4000 mg/i are
predicted to oe approximately 35 and 457., respectively.
Q,3•3• Volatilization and Biosorption
The steady—state equation for non—biodegradable compounds that are
removed by volatiLization and hiosorption has the form
QC QC +VkC +qMQ (9—19)
ii ce ye ess
Using the same sdbstitutions as previously described for the idividual
removal mechanisms, Equation 9—19 car he written as
Ce r • &do 6 1 —1
—— L1+ v + j (9—20)
Cj (24)SRT
The bioconcentration factor, K 8 , can be replaced by the octanol/ iater
partition coefficient, K 0 , using the relationship suggested by Mackay
(53), and Equation 9—20 can be rewritten as
82
-------
b
4.0
LOG KB
FICURE 9—3. elntionshiD h toeen the btosnr’ tion
reduction in aqueous concent rat ion of hydrophobic
to sorption by activated sludge.
coefficient and the
organic compouflds due
2.0 3.0
5.0
6.0
7.0
0 1.0 2.0 1.0 5.0
6.0
-------
C)
6000 8000
I. S S (r /1)
FIGURE 9—4. Cffeci of slendy—state mixed liquor suhpendud solids con centration on
removal of hydrophobic organic coinpound clue t .. sorption by activated Iudgc.
0
‘-I
d
C-,
L X = 4.0
-4
C-,
C ) 5
C
‘-4
I-
0
b - I
I-i
U
0
C)
F•-.
LOG K = 5.0
04
‘N
0
0 200L 4000
LOG - b.O
-------
Ce I — EM 5 K 0 2XlO 9
— — jl + t k , + I (9—21)
c L SRT J
The effluent to tnfluent co , centration ratio Ce/Cip in Equation 9—21
.ias solved as a function of 1.og Kow for various values of k , and the
results have been plotted in Figure 9—5. As volatility increases, the
effect of biosorpcion on the overall reduction in th’ aqueous
concentration is significantly reduced. The predictel reduct ton in the
aqueous concentration of 1,2,4—trt ’hloroberIZene shown in Figure )—5
indicates that removal due to bi .osorption uill he insignificant con ared
. ith volatilization.
9.4 APPLICATION OF STORM TO BIODEGRADABLE COMPOUNDS
A variety of the organic priority polliitant have been reported to
be potentially biodegradable in controlled laboratory studies by
microorganisms typically found in act. vated sludge. Many uf these
co ounds are characterized by Henry’s constants that tndicat’ high
volatility in activated sludge syste jnd/or octanol/water partition
coefficients that suggest the potential for bioso ptLOfl. Thernfore, the
removal of biodegradable conpound5 from a CMF activated sludge system,
operated under conditions of steady—state can be expressed as
Q C 1 QeCe 4 . VkbCe+ VkvCe4 q 1 5 Qg (9—22)
Depending on the relativ magnitude of the various removal cern one Of
the removal mechanisms isay dominate and control the fate of a trace
toxic organic conpound during activated sludge treatment. Consideration
will be given to removal mechanisms of biodegradation and volatilization.
9.4.1. Biodegradation
The steady—state equation for the removal of non—volat Lie,
nonbiosorbable trace organics by biodegradation can be written
Q iCi. QeCe VkbCe (9—23)
Solving equ itLon 9—23 for the eU uent concentration, Ce, gives
85
-------
1.0 2.0 3 3 Li.0 5.0 6.0 7.0
lUG
0
C)
0
-4
C)
0
0
C)
C)
C)
C)
C)
-1.0
0.0 1 ,0 2.0 3.0 ‘4,0 5.0
LOG kb
6.0
on the re nov i1
F1(URF 9—S. Effect of Lncrca ’ilng vojatflization rate coefficients
of liutirophohic compu-und due to oorpt Ion by act tv’ tcd sItid c.
-------
c i
c — (9—24)
1 +k t
The of flu.mt/influent concentration ratio Ce/C i . has been solved for a
hydraulic retention time of 5.5 hours end the results plctted to Figure
9—o. The result ing curve has the sa — c shape as the one representing
rei,oval due to air—s rtp ing in Figure 9—1. , n 8O reduction in the
aqueous concentration i predicted for cu uun’s with biodegradation
rat-f coefutcient , kb, • approdmate y ‘).i
9.4. . bide radatthn and Volatiiizaticn
This situation repreaents one of the most Interesting combinations
of removal mechanisms, and the mass balance eqiiatton for conditinas of
steady—state which incorporates removaL t chant i S of bio egradJtion and
vo latilizatLon ciri be written as
Q Cj Q 0 C 0 + VkvCe + VkbCe
While many organic priority pollutants classified as purgeahie have been
shown to be biodegraiahie, removal of trace concentrationS
(nicrogram—per—liter) of these co umnds ha been atcrL ited primarily
to air—strt iping.
With the appropriate substitutions, Equation 25 can he
rearranged and written as
Ce — —1
—— [ 1+t( v+kb) } (9—26)
ci
A more cosçlete method cf predicting the fate of volatile,
biodegradable corr,ounds which incorporareS off—gas ‘ass fluxes into
the mass balance e’pressiofl can be written as
(hci Qece ÷ QCg 4- VkbCe (9—27)
87
-------
I
0 0 1 0.2 0.3 0 4 0. 0.6
BIoDEG; ADA1 ION RATE COEFFICIENT, , (M1N 1 )
FIGURE 9—6 . Re mt bush ip between the btodegradatboii rate 1 t
an.i thii’ etItict t ii III (hII(ot 4 ( oiu :.It r it Ion of n non—vol attic (OI pCIIlI(h
C,
co
C)
0
o
I—
C D
—
I-
LU
C-)
CD
I—
LU
LL
I— ..
I—
LU
—I
Li
LU
-------
Dividing both sIdes of Equation 9—27 by the influent eass flux, QjC 1 ,
g i ye a
+ Q, C 1 , VkbCe
I ‘ + (9—23)
0 1 C 1
whxc c in be written as
N
—— - (9—29)
N 0 Q C
where N is the st n of the effluent and off—gas mass fluxes and is the
mas; flux into the re jct0r ri the Influent. The ratio N/N 0 represents
the fraction of the mass flux entering the reactor that Leaves the
reiccor n the effluent and nfl—gas combined. Solving Equation 9—26
for e and substLtutirtg it intu Equation 9—29 gives
N tkb
-- 1 - --- [ ) (9-30)
C L+t(kb+kv)
After rearranging and si,plifying, Equation 9—30 can be written as
N 1+tk
—— = ————————— (9—31)
The ratio N/N 0 , was solved as a fun:t ton o , f r vario is values
of k ,, and the results are given in Figure 9—7. For a given value of
kb, the ratio N/N 0 decreases as the volatility of a compound decreases.
The st niutcance of such a plot is that the decrease in N/N 0 with
increasing values ot kb indicates reductions in boch the effluent and
off—gases of volatile, biodegradable compounds. s a further
illustration, a specific exa ,iple is given for three different compounds
with the foll iing characteristics:
Compound A: non—biodegradable, volatile (k 0.075 min )
Compound R: biodegradable (kbO.OO 7 S ‘niatile
(kvO.O75 in1n )
Compound C: biodegradable (kb=O. 2 nin ), volatile
(k 0.075 min )
89
-------
0. 0 0.LiO 0.50 0.60
BIODEGRADATION RATE COEFFICIENT, kb (M1N 1 )
FIGURE 9—7. Effe t of increasing volatilization on the
disappearance of a compound due to biodegradation by
activated lud3e in a 10—liter sludge bioreactor.
a
0•
-4
a
C
0
=
>-
w
L)
LLi
F-
L )
0•
C
0.0
0.10 0.20
90
-------
The effluent concentration can be calculated from Equation 9—32
C i
Ce = (9—32)
1 +t ( k b
and t ie off—gas concentration from Equation 9—33
7kvCe
(9—33)
Qg
The effluent, off—ga’., Ce/Ci and values have been calculated f . r
each comj,ound assuning steady—state conditions in the experimental C F
bioreactors with volumes of 10—liters.hydraulic retention times of 5.5
hQ.lrs, and a total aeration rate of 4 i/mm. A cori arison of the
results in Table 9—1 indicates that increasing the biodegradation rate
coefficient resulted in a significant reduction in the off—gas
concentration.
TABLE 9—1
PPEDICTED FATE OF THREE EXI MPLE CO 1POUNDS
Para neter Compound A Compound B Compound C
k (m.in ’ ) 0.075 0.07S 0.075
kb(min ) 0 0.073 0.2
Influent (i g/L) 100 100 100
Effluent (ugh) 3.8 2.0 1.1
Effluent
(Z ef influent) 3.8 2.0 1.1
Ce/Cl 0.04 0.02 0.01
0ff—Gas (ugh) 0.73 0.37 0.02
Of f—Gas
(•% of influent) 96.2 49.0 27.0
1.0 0.51 0.28
Bi odegraded
(% of influent) 0 49 ‘2
91
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SECrION 10
RESULTS: CONTROL ACTIVATED SLUDGE BIOREACTOR STUDIES
The fate of each toxic organic compound during activated sludge
treatment was studied in the 10—liter bioreactors wIth activated sludge.
The bioreactors were operated ir continuous flow mod s with influents
composed of syarhetic wastewater and a toxic r rganic solution. Influent
concentrations of the toxic compounds typically were maintained betweLn
50 and 150 uguI to simulate concentrations representative of those found
in influents to full scale municipal wa,cewater treataenc facilities.
Table 10—1 su imarizes results from a study of the occurrence OF priority
pollutants in ‘nunLcipal wastewaters for the compounds used in this
project (2).
The activated sludge studjes were conducted to fulfill three
primary objectives:
1) provide a reference point to which the results from bioreactor
studies with PAC could b& compared to evaluate the effect of PAC
addition on the removal of the toxic organic compounds,
2) determIne which of the toxl organic compounds could be
biodegraded by activated sludge under conditions representative of
municipal activated sludge treatment and,
3) ev tluate the relative importance of the three removal
mechanisms: volatilization, biodegradation, and biosorption; and model
how each affected the fate of the toxic organic compounds during
activated sludge treatment.
Previous studies have reported many of the organic priority
pollutants to b degraded by activated sludge biomasses (55—59). An
extensive review of microbial degradation of crganic priority pollutants
was reported by Kobayashl and Rittrnann (55). Typically biodegradation
studies have been conducted in static incubators to minimize
volatilization and at concentrations stgnlflcantly greater than those
encountF red in municipal wastewaters. Such studies are valuable, but
92
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TAEL 10—1
0CWR ENCE OF ORCANIC PRIORITY POLLUTANTS IN
MUNICIPAL WASTEWATERS
INFLUENT EFFLUENT
Compound Mm. Max. % Detected Mm. Max. 7 Detected
Toluene 1 13,(ii 0 96 1 100 53
Ethylbenzene 1 130 80 1 49 24
Benzene 1 1560 61 1 72 23
Lindane 0.02 3.9 26 0.01 1.40 33
1, 2—Dichloro—
benz ne 1 440 23 1 27 8
Chlorobenze ; . 1 150 13 1 9 3
I ,2,4—Trichloro—
ben2ene 3 4300 10 3 310 4
Nitrcbenzene — — ND 4 — — ND
0—Xylene — - NM — - NM
+ Percent of saz p] .. s in which co ound was detected.
++ Concentrations in ugh.
++-f ND Not Detected
till NM Not Measured; 0—Xylene is not included on the Priority
Pollutant List.
93
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their results cannot necessarily be extended to actual treatment
cendittons. This study evaluated btoclegraaation in completely—mixed
flow, aerated, activated sludge systems by monitoring mass fluAcs of
indLvidual compounds into and out of the bioreactors.
Biological, degradation of a toxic organic compound in the 10—liter
experimental bioreactors operated in continuous flow modes was evidenced
by a significant difference between the mass fluxes into (lr’rluent) and
out of (effluent, off—gas and waste sludge combined) ne bioreactors.
The mass flux of a toxic organic compound into the bioreactors is given
by
No Q , x C (10—1)
and the mass flux out of the hioreactors by
N Q 0 Ce + QgCg + C 5 Q 5 (10—2)
where Qj(fImin) is the influent I 1 .ow rate, is the effluent
flow rate, ( (t/min) is the waste sludge flow rate, Q (i/lain) is the
off—gas low rart and is equal to Qa’ the aeraticn rate, C 1 (ugfZ) is
the influent concentration, Ce(p /i) is the effluent concentration,
Cg(’ .gil) is the off—gas concentration and C 5 ( gIZ) is the concentration
in the waste sludge. B . ckgtound studies conducted in the 10—liter
experimental bioreactors wituout activated sludge demcnstraced that
measured mass’flu>.es into and out of the bioreactors were nearly
identical for both volatile and non—volatile compounds. Values of N /N 0 ,
the fractional recov& ry of a toxic compourd, averaged between 0.93 to
1.00 when the bioreactors were operated without activated sludge.
Therefore, N/N 0 values greater than 0.90 were evaluated as complete
recovery while values less than 0.9 were interpreted as evidence of
biological degradation.
Results from the activated slud e studies conducted in the
10—liter CMF bioreactors with single toxic solutes s’ owed significant
biodegradation of benzene, toluene, ethylben ene, o—xylene,
. .iorobenzene and nitrob nzene. Lindane and 1,2,4—trichlorobenzene were
found to be non—biodogradable while 1,2—dichloroben ene was poorly
biodegraded. Table 10—2 suiimarizes the fate of each compound durtog
activated sludge treatment in experimental bioreactors operated at 6—day
SRT’s under steady—state conditions.
10.1 ACTIVATED SLUDGE BIOR.EAcTOR OPERATING CONDITIGNS
All activated sludge studies were begun by filling the biore ctors
with activated sludge from the aeration basin of the Ann Arbor
wastewater tre?tment facility. The bioreactors were operated in
continuous flow modes for at least two weeks to acclimate the
adcroorganisms to the synthetic wastewater prior to adoing the toxic
organics to the influent. A stsnmary of the pertinent operating
conditions used during the activated sludge bioreactor studies is
reported in Table 10—3.
94
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TABLE 10—2
FATE OF I IC O ANICS IN ACCLIiIATED
ACTIV T D SLUDGE BIOREACTORS OPERATED
Ar 6-DAY SRI’S U ’IDER STEADY—STATE CONDITIONS
Percent of InfluenL
Compouid ffluenc 0ff—Gas Bthsoroed Blodegraued*
Benzene <1 16 0
To1 u€r.e <1 17 0 83
Ethylbenze ie <1 22 0 78
O—i(ylenc <1 25 0 75
Chlosobenzene <1 20 0 80
1, 2—Dlchioro—
benzene 6 59 0 35
1, 2,4—Trtchloro—
benzene 10 90 <1 0
Nitrobenzene 2 <1 0 98
1.indane 95 0 5 0
C 1cu3ated
MLSS = 3200 — 3800 mg/ic
c 5.5 — 6.0 hours
Q . = 3.8 — 4.2 Q/min
= 1.67 1/day
95
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TABLE 10—3
BIOREACTOR OPERATING CoNDITIONS USED
DURING ACTIVATED SLUDGE STUDiES
Influent fl 28—30 mi/mm
i{ydraulic retention time 5.5—6.0 hrs.
Aeration rate 3.8—4.2 i/win
Ir 1 fluent soluble TOC 90—110 mg/I.
Effluent soluble TOC 10—20 mg/i
Solids retention time ( .SRT) 3—12 days
MLSS (3—day SRT) 1700—2100 mg/i
MLSS (6—day SRT) 3200—3800 mg/i
tLSS (12—day SRT) 6800—7500 mg/i
p 11 7.0—7.2
10.2 SYSTE 1 PERFORMANCE WITH RESPECT TO TOC REMOVAL
While the prin ry focus of the project was the removal of specific
organic oa ounds, data was collected on overall organics removal as
measurec by soluble total organic carbon (TOC). The decision to use TOC
as the indicator of system performance with respect to overall organics
removal .as based on the need to process large numbers of samples.
Analytical procedures fnr the toxic con ounds were time constaning and
precluded tl’e use of the more lengthy BOD or COD analyses. Influent and
effluent TOC samples were typically conducted every two to four days
during steady—state operating conditions and more frequently during
non—steady—state periods.
The removal of soluble TOC typically ranged from 80 to 90Ľ for all
bioreactor studies. Average TOC ret ovals were not dependent upon the
solids retention time between 3 and 12—days as shown by resuLts from
bioreactor stud.es conducted at 3, 6, and 12—day SRT’s in Figures 10—1
thrc.ugh 10—5. A sunrnary of average influent, effluent and percent
removals for cach control activated sludge biore.. ctor study presented in
Figures 10—1 through 10—5 is given in Table 10—4. The average TOC
removal of 5 Z for those stuuies was the same as the overall TOC removal
averaged from all of the steady—state control activated sLudZe studies.
96
-------
I 4 4— 4
I -1- 4
L)
I
0 7 14 21 28 35 42 48 56
TIME (DRYS)
FIGURE 10—1. Soluble TOC rern,val in a 1O—lit r actijated
sludge bioreactor ocerated with a 3—day SRT.
0
-------
4 -4 -t
=11 )
WC 4
0
0 7 14 21 26 35 42 49
TIME (OPYS)
FIGURE 10—2 Soluble TOC re’noval ir a tO-liter activate’!
sludge bioreactor operated with a 6—aay SRT.
98
-------
c : tn
Q
‘—U,
I-
I-
Zc’
Wu )
Li_ ‘ ‘
z
CD
C)
c
w
LL
U.
FIGURE 10—3. SoluD 1 e TOC removal in a 10—liter act1vate’
s1ue ge bioreactor operatea ith a 6—day sfl:.
N
-J
>U?
0 7 14 21 28 35 42 43
TInE (OFiYS)
99
-------
L
cD
4—
Zc,
wu,
z
-Ju,
C-.,
C-)
I-
zc I
LU
.—j
U-
Wc3
-j
>u,
C
I:u,
/\N e- e
4 I •I
I I I
0 7 4 21 28 35
TIME (DRYS)
FIGtRE 10—4.
42 49 56
Soluble TOC re o tal in a 10—liter activated
sludge bioreacLu operated with a 6—day SRT.
100
-------
2, —. a 4 4 S S I s s
0 7 14 21 42 56 63 ; -
IDlE (DAYS)
FIGURE 10—5. Soluble TOC removal, in a 10—liter activated
sludge bioreactor operated with a 12—day SRT.
101
-------
No correlatton between TOC remo’ al and tile removal of an
individu . 1. toxic compound existed for data collected during activated
sludge bioreictor studies with influent toxics in the concentration
range cypical of i inicipal wastewaters, 0 co 10)0 hg/P.. There wai
evidence that shock loadings of n rcbenz ce sufficient to cause an
inhibition of nItrobe ene de adation also resulted in periods of
reduced TOC r aoval. A more complete analysis f these findings will be
includel in a discussion of the effect of high ir.fluent toxics
concentratio.2s. In bioreactor studies with influent toxic
concentrations in tbe 50 to 150 g/t range no change i i o rall TOC
removal was observed during periods tmri diately foll i1ng the initial
addition of a toxic organic to the tnfluent.
TABLE 10—4
SW*IARY OF TYPICAL MEAN INFLUENT AND EFFLUENT SOLUBLE
TOC CONCENTRATIONS AP D PERCENT REMOVALS FROM
BIOREACToR STUDIES Ol’RATEI) AT 3,6,9, AND 12—DAY SRTS
Solidc . ention Influe’tt TOC Effluent TOC roc Removal
Time (days) ( nc /i) ( mg/ P .) ( % )
3 100.8 (8.9) 13.7 (2.8) 86.2 (2.2)
3 105.6 (10.2) 14.7 (2.3) 85.9 (2.6)
6 97.8 (6.7) 13.5 (1.8) 86.1 (1.8)
6 96.5 (7.3) 12.9 (1.8) 86.4 (2.4)
107.1 (8.1) 14.7 (2.9) 86.3 (2.7)
6 102.6 (8.4) 14. (2.0) 83.8 (2.0)
9 104.7 (12.2) 14.8 (3.0) 86.7 (3.5)
9 101.9 (8.4) 14.4 (2.1) 85.7 (2.5)
12 106.3 (13.5) 13.5 (1.6) 87.1 (2.2)
All Single S’,Lute 103.2 (10.2) 14.1 (2.2) 86.3 (2.4)
Actt ated Sludge
St udLcs
+ Vaiues in parenthests are the standard deviation
102
-------
Completely—mixed batch TOC DLcdegradation rate studies were
conducted in two different reactors; the 2.6 Litet glass CMB reactors
and the 10—liter experuaental bioreactors operated in batch modes by
temporarily stopping the influenc and sludge waste flows.
Biodegr.idation r ite coefficients for TOC renoval aeas’ red in the
2.6—liter CMB reactor and 10—liter bioreactor with the same activated
sludge (6—day SRT) were nearly identical. A comparison of the results
from two such studies is presented in Figure 10—6.
The biodegradation rate coefficient in each case w s 0.016 rnin 1 .
Subsequent measurements ef TOC biodegradation rate coefficients were
made in the 10—liter e’cperlmental bLoreactors temporarily o ’erated in
batch modes. The average bLudegradatior ’ rate coefficient measured in
bioreactors operated at 6—day SRI’s was 0.016 min .
TOC biodegradation rate utudies were also conducted with mixed
liquor from 12—day SRT bioreactors. The average biodegradation rate
roefficient for the 12—day SRI activated sludges was 0.’)18 nin . A
comparison of typical results from TOC biodegradation rate studies usi g
activated sludges frnu 6 and 12—day SRI bior actors is given in Figure
10—7.
10.3 FATE OF NON-BIODEGRADABLE AND POORLY BIODEGRAI)AftE
ORCANIC C0 1POUND
0.3.1. Non—volatile Comi’ound
Activated sludge bioreactor studies showed lindane to oe a
non—volatile, non—biodegradable compound in the experimental system. A
small amount of lindarie was biosorbed by the activac o sludge resultir.g
in effluent concentrations slightly lower than th2 influenc
concentrations. Results from activated sludge studies conducted in
bioreaccors operated at 3, 6, and 9-day solids retention times are
presented in Figures 10—8, 101, and 10—13, respectively. Each figure
presents infl’ierit and effluent concentrations and C/C 1 values, the ratio
of effluent to influent concentrations. Off—gas samples were a’ot
collected because results from oaseline CMF bioreactor studies conducted
without activated sludge demonstrated lindane was non—voLatile. A
suamary of resulis from the lindane activated sludge studies is given in
Table 10—3. The reduction in the aqueous lindane concentration in
bioreaccors wIth 6 and 9—day SRT’s was the sane and averaged about 8%.
Slightly less removal, approximately 5%, was observed in the bioreactc:
with the 3—day solids retent.ion tine. Near cc.mplete recoveries of
lindane were obtaine.i from each btoreactor when waste mixed liquor
suspended solids were extracted with an organic solvent and the
concentration of lindane was measured.
emoval of a non—volatile, non—Liodegradable compound during
activated sludge treatment can he modeled by Equat 4 on 9—16 developed in
103
-------
FIGURE 13—6. Cor parison of results from &oluble TOC
degradation rate studies in 2.6—liter and 13—liter
experimental bioreactors with activated sludge.
10 - LITER BIOREACTOR
C,
x
10 23 30 40 50 60
TIME (MINUTES)
104
-------
cn
l .
U,
z
C
12-DAY SRT BIOREACTOR
L.) C
0 0 20 30 40 50 60
TIME (MINUTES)
FIGURE 10—7. Co ar son of results from soluble TOC
degradation rate studies conducted in 10—liter activated
sludge bioreactors operated wits 6 and 12—day SRT’s.
105
-------
c. 4
-J
C:,
z
D
I-
z
w
(-)
Cr ,
w
-
—
(N
—U,
LL1
L)
FIGURE 10—8. Lindane results from a 10—liter activated
sludge bioreactor study conducted with a 3—day SRT.
0
e— - & Le
0 7 14 21 28 35 42 42
TItlE (ORYS)
7 14 21 28 35 42 43
106
-------
I
S —.
7 14 21 28
TItlE (DRYS)
35 42 49
FiGURE 10—9. Lindane results from a 10—liter activated
sludge bioreactor study conducted u’rh a 6—day SRT.
-J
(D
—9
I-
I.,_
z
w
C-)
U,
=_
uJ
ci
7 14 21
28 35 42 49
L.)
107
-------
—J
—.9
z
z
w
C-)
C-)
U)
w
C
C d
a
c
0
0 7 14 21 28 35 42 49 56
TIME (O YS)
L)
FI L’RE 10—10. Lindane results from a 10—liter activated
s!Ldge bioreactor study conducted with a 9—day SRT.
—
7 14 21 26 35 42 49 56
108
-------
TABLE 10-5
LINDANE REMOVAL TN ACTIVATED SLUOGE BJOREACTONS
OPERATED WIll 3,6, and 9—DAY SOLIDS RErENFION T1’ lES
a
‘ 0
Solids
Re:ention
Time
(days)
3
6
9
MLSS (mg/&)
Mean
1600
3300
4500
INFLUENt (pg/u.)
Mean S.D.
97.5 13.5
108.0 5.2
88.4 9.9
EIL’LUENT (i’g/ 2 )
Mean S.D.
92.5 12.3
99.4 4.8
81.7 11.6
C IC
ci
Mean s.D.
3.95 0.04
0.92 0.03
0.92 0.04
S.D. Stand trd Deviatiolk
-------
Section 9. The value of K 5 from the equilibrium sorptton study was
incorporated into Equation 9—10 along with values for the appropriate
bioreactor operating parameters to predici the effluent lindane
concentrations from the 3, 6, and 9—day SRT activated sludge units.
Concentrations of ML TS used in the model were those reported in Table
10—5, and the hydraulic retention time was 5.5 hours. Comparisons of
measired and predicted effluent concentrations and C /c 1 values for
lindane acttvated sludge studies conducted in bioreactors operatea at 3,
6, and 9—day SRT’s given in Table 10—6 shc that there was good
agreement between predicted and measured values.
TABLE 0—6
COMFARISf. OF MEASURED AND PREDT.CTED
RESULTS FROM LINDANE ACTIVATED SLUDGE STUDIES
SRT Influent Effluent (ug/ ) Ce/Ct
( days) ( pg/i) Measured Predicted Measured Predicted
3 97.5 92.5 91.2 0.95 0.94
6 108.0 99.4 99.8 0.92 0.92
9 88.4 81.7 83.0 C.92 0.94
10.3.2. Volatile Compounds
10.3.2.1. 1,2,4—Trichloroberl2ene
Activated sludge studies with 1,2,4—trichlorobenzene were
conducted in bioreactors operated with 6 and 12— iay solids retention
times. Results from these studies demo-istratud that
I,2,4—trichlorobenzene was a volatile non—biodegradable compound in the
eqerimental activated sludge system. Influent, effluent, and off—gas
concentrations recorded during the two scudies are p’otted in Figure
10—11 along with N/N 0 values represcnting the fractional recovery of
1,2, 4—trichlorobenzene.
Results from the 6 and 12—day SRT activated sludge studies were
not significantly different. Effluent and off—gas concentrations daring
the 6—day SRT study averdged 12.0 ugh and 706 ng/t, respectively, for a
mean influent concentration of 116.6 pg/i. The slightly l er influent
concentration during the 12—day SRT study, 101.5 pg/i, resulted in
average effluent and off—gas concentrations of 10.2 pg/i and 622 . .g/Z.
110
-------
-J
z
w
-J
L I-
z
-J
c i
-S
-I
L
L&J
I- ’
-J
C,
z
U)
(I,
L
I L.
0
I I $ 4 I I I I I 4 $
_____ ___ . —
C,
z
7 1421 835424 6637aT7
TIME (DAYS)
FlouR: 1O li. 1,2,4—Trichlorobenzene results frot ctivared
sludge studies conducted in 10—liter bioreactors operated with
6 and 12—day SRT’s.
1,2.4—TRICHLOROOENZENE: Activated Sludge
O 12—DAY SRT BIOREACTOR
O 6—DAY SRT BIOREACTOR
c
(0
lii
-------
TABLE 10—7
COMPARISON OF MEASUREI) AND PREDICTED EFFL.UEN’r AND OFF-GAS
1,2,4—TRICHLOROBENZENE CONCENTRATIONS FROM ACTI.VATED SLUDGE BIOREACTORS
InflLcnL ( p g ! 2 .) Effluent (pg/9 ) Off—Gas (ngIP ..) N/N 0
6-DAY SRT BIOREACTOR
Measured 116.6 (11.8) 12.0 (1.8) 706 (112) 0.93 (0.05)
Predicted if no Biodegradation 12.3 (1.5) 712 (95) 1.00 (0.0)
Predicted from Effluent 754 (115) 0.99 (0.16)
12—DAY SRT BIOREACTOR
Measured 101.5 (27.7) 10.2 (2.7) 622 (181) 0.94 (0.05)
Predicted if no Biodegradation 10.5 (3.2) 662 (204) 1.00 (0.0)
Predicted from Effluent 61.6 (173) 0.98 (0.06)
+ ( ) Standard Deviation
-------
In both studies the amount of 1,2,t.—trichloroben7efle in the effluent
represented only t0 o the total amount entering the bioreactors. The
remaining L,2,4—trlchlorobenzene was tripped from solution and exited
the units jO the off—gas. Recoveries of l,?,4—trichlorobenzene averaged
93 anci 94%, respectively, in the 6—day and 12—day SRT bioreactors. The
recovery of 1,2,4—trichlorobenzene during baseline ‘ tudies conducted in
the 10—liter bioreactors without activated sludge averag. d approximately
94%. The results from the activated sludge qtudies indicated that
within experimental error complete recoveries of l,2,4—trichlorobenzene
occurred. Influent, effluent, and off—gas concentrations and N/N 0
values measured during the two studies are recorded in Table 1U—7. The
fate of 1,2,4—tricblorobenzene observed in the experimental activated
sludge system is summarized by Table 10—8.
TABLE 10-8
FATE OF l,2,4—TRICHLOROBENZENE IN 6-AND
12—DAY SRT CT1VEtTED SLUDGE STUDIES
Percent of Influent Flux
6- ay SRT 12—Day SRT
Effluent 10.3 10.0
0ff—Gas 89.2 89.5
Biodegraded 0 0
Bi.osorbed <0.5 <0.5
The use of off—gas analyses to facilitate a mass balance for the
volatile compounds was an important and unique contrilijtion of this
work. Data from the 6—day SRT study has been plotted in Figure 10—12
without the measured amounts of L,2,4—tri hlorobenzene stripped to the
atmosphere. The value of Ce/C 1 which represents the effluent to influent
concentration ratIo indicates only th,.t an approximate 90% reduction in
the aqueous concentration of 1,2,4—trichlorobenzene occurred. The
infori acion in Figure 10—12 does not provide insight into the fate of
the 90% of the 1,2,4—trichlorobenzeflc that disappeared from the aqueous
phase. Amounts of the volatile compounds stripped to the atmosphere
were not considered as removed, nor should they be in actual treatment
systems since this constitutes a redistrilxitio’ of the compounds in the
environment.
While overall recoveries of both lindane and
1,2,4—trichlorobenzene exceeded 90% in the experimental system, effluent
concentrations of the two compounds were significantly different.
Effluent lindane concentrations were approximately equal to influent
concentrations whereas effluent 1,2,4—trichlorobenzene concentrations
averaged only 10% of the irifluent concentrations.
The air—stripping model developed in Section 9—3 was used to
predict the effluent and off—gas concentrations of
113
-------
-J
I I
- 1 -
I I
0 7 14 2 28 35 42 49 58
TIME (DIRYS)
FICCRE 10—12. 1,2,4—Trichlorobenzene results fron the
6—day SRT activated sludge study plotted without off—gas
concentration data.
114
-------
1,2,4—trichl robenzene. Equations 9—Uand 9—I 2 were used to calculate
e fiuent and off—gas concentrations from measured irifluent
concentrations, intluent flow raLes, and aeration rates. Predi’red
effluent and of [ -gas concentrationb for the 6—day SRT study ilotted as
dashed lines in Figure 0—13, shc .ied dood agreement with trie measured
data points.
A sLnmary of measured and predicted ‘alties for the activated
sludge bioreactors operated at 6 and 12—day SRF’s is given in Table
10—7. Predicted and measured effluent concentrations averaged 12.3 and
11.0 jig/i, respectively, during the 6—day SRT study. The ability of
the iir crippi—lg modi I :o iic essfully predict efriucat and off—gas
1,2.4—trichioroberizene concentratlon suggests that the biological
solids in the rrii’ed liquor had -iti Le effect on air—stripping since the
volatilization rate parameters sere developed from atch experi r.ents
without activated sludge.
The modet used to generate the predicted values in Figure 10—13
did not tn. lude a sorption term. WhJle results from batch equilibriwt
studies indicated a significant ,orption of 1,2,4—trichlorobenzer ie can
occur, olosorpcion must be considered in relation to other removal
mec.hanlsris such as volatilization. Figure 9—5 showed that the eftect of
iosorptton on the ratio of infl .ent ta effluent concentration decreased
aa the volatility of a compound increased. Results given by Figure 9—5
si gest that the effluent and off—gas concentrations of
I,2,4—trtchlorobenzene should not be significantly affected by the
Inclusion of a sorption term in the model. Effluent and off—gas
concentrations of 1,2,4—trichlorobenzeae predicted by the removal model
ahich included volatilization and sorption were the same as presinted in
Figure 10—13 for the 6—day SRI bioreactor. There were no signiftcant
differences between effluent and off—gas concentrdtions predicted with
and without including a biosarption term in the toxics removal model for
1,2,4—’richlorobenzene because air-stripping was the dominant
mechanism.
Conc2ntrations of t,2,6—trichlcrobenzene ‘ x sured in the waste
sludge from the 6—day SRI unit by extracting the mixed Hquor su3pended
solids averaged approximately 40 tig/i or four times greater than the
effluent concentrations. Therefore, although sorption of
1,2,4—trichlorobenzene onto the biotnass did not significantly affec the
effluent concentrations, it did result in concentrations in the sludge
significantly greater tha . in the aqueous phase. Settling and
thidening of biological solids would produce cignificantly larger
concentrations in secondary sludges.
The unique feature of this work was the off—gas analyses that
enabled fortailation of complete mass balances and determination of the
fate of each compound. While off—gas sampling was possible under
controlled laboratory conditions, it is generally not feasible at full
scale treatment facilities. A a important finding of thIs work was that
off—gas concentrations could accutately be predicted fro’n measured
effluent concentrations. Measured influenc and effluent concentrations
115
-------
I — I I —
2 -c ---e-- D --
I — I
4 • -
-- --- I
- I
m - o
(fl 0 +
- —
o
— - S
56
TThE (DAYS)
FIGURE 10-13. 1,2.4-Trichlorobenzene effluent and
off—gas concenrrat1 ns predicted b ’ the air—strippjn
ode1 for the taso of no ode rd j ton in tl’e 10—li:er
activated sludge biore ctors.
116
-------
were combined with predicted off—gas concentratiens to determine N/N 0
values of a volatile compound. Otf—gas concentrations from the
expe—imental bioreactors were predicted by substituting the equivalent
value of Qa for Q,, in Equation 7—8:
VCe(Q 1 L+kv,o )
Cg (10—3)
Predicted off—gas concentrutions and N/NQ values, represented by dashed
lines, are compared with measured values in Figure 10—14 for the 6—day
SRT actIvated sludge bloreactor. The results, sunrnarrzed in Table 10—7,
hcM that th effluent concentrations could he used to accurately
quantIfy the amount of a volatile compound stripped to the air. The
abIlity of the model to predict off—gas concentrations was dependent
upon the accuracy with which effluent concentrations could he measured.
A comparison of rigures 10—13 a’id 10—14 indicates that either the
.nfluent or effluent concentration can be used to predict the off—
gas concentration.
10.3.2.2. l,2—Dichlorohenzene
Batch air—stripping studies conducted in the 10—liter bioreactors
demonstrated that the volatihties of 1,2,4—trichiorobenzene and
l,2—dichlorobenzene were nearly identical. Eq ilibrium sorption studies
indicated that the amount of l,2—dict-lorobenzene soLbed by the activated
sludge was considerably smaller than the amount of l,2,4—trichlorobenzene.
Activated sludge studies witn 1,2—dichlorobenzene w re conducted
in 10—liter CMV bioreactors opsrated at solids retention times of 6 and
12 days. Results from the two studies presented in Figure [ 0—15 in:lude
measured influant, effluenL and off—gas conc tr tions and N/’i 0 values
rept senting the fractional rccoveries of 1,2—dichlorobeozene. Results
from the 6—day SRT study havu been replotted in Figure 10—16 with
effluent and off—gas concentrations predicted by the air strippi ’g model
to occur if volatilization was the only removal mechanism operative in
the system. The model generated values depicted by dashed lines
represent the steady—state partitionIng of 1,2—dichlorobenzene between
aqueous and gaseous phases for the operating conditions used in this
partic ’lar bioreactor study. mass balance with the predicted eftluent
and at-f—gas concentrations would give a complete recovery of
L,2—dichlorobenzene. Including a biosorptio’i term in the model had no
effect upon the predicted concentrations of L,2—dichlorobenzene In the
effluent aad off—gas. Extractions performed on the waste activated
sludge failed to yield concentrations in excess of the aqueous
cancentration.
Unlike the results for 1,2,4—trichlorobenzene, thece was a
significant difference between measured effluent and off—gas
concentrations and those concentrations ptedicted by the air—stripping
mo l which assunes only volatilizatior. effects a reduction in the
aqueous concentration. The fact that the measured concentrations were
less than the predicted ones resulted in N/N 0 values lass than 0.90. The
incomplete recovery indicated that another removal mechanism was producing
117
-------
—4- I I - I
! T TTTTT
— -‘ D
c i:
U-
U-
I I I I
I I I I I I
‘I
0 7 14 21 28 35 42 49 56
TIlIE (O R’i’ )
FIGURE 10—14. 1,2,4—T ich1or berizene off—gas
concentrations and N/ values predicted from effluent
concentrations n aasure during the 6—day SRT activated
sludge study . (tashed lines give pr icted values.)
118
-------
-J
0
I—
z
LaJ
-j
U-
z
4 I *—•- 4 I e t t 4
1.2—D CHLOROBENZENE. Activated Sludge
12—DAY SRT B;OREACTOR
6—DAY SRI BIOREACIOR
.1—.—. i i i I I $ I I I I
-J
C-,
1L
U-
w
-J
Z
(I ,
9
U-
0
0
z
z
0 7 14 2! 28 35 42 49 56 62 70 77
TIME (DAYS)
FIGURE 10—15. l,2—Dlchlorobenzene influent, effluent, and
off—gas concentrations and fractional recoveries (N/N 0 )
from 6 and 12—day SRT activated sludge studies.
]19
a,
C,)
-------
0
w
-J
L&.
0
—
0
I 4 4 4 4 I I
—J
c i
z
V)
1&..
U-
0
0
z
I.
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE lu—16. Influent. effluent, a,d off—gas
concentrations ani /N values frori a 6—day SRT activated
0
sludge study conthwted in a 10—liter bioreactor.
1,2—DICHLOROBENZENE (ACTIVATED SLUDGE)
O MEASURED DATA POINTS
- - PREDICTED IF NO BIODEGRADATION
0
0
Ca
‘.4
O-_ --u
J20
-------
a disappearance of 1,2—dichlorobenzene from the experimental system.
Baselir.e studies conducted withotit activated sludge under similar
conditions demonstrated average recoveries in excers of 90%. The
disappearance of t,2—dichlorobenzene was attributed to biodegradation by
activated sludge rnicro. rganisns. As shown by the results in rigure
10—15, fractional recoveries of 1,2dichlorobenzene began at
appro ctmately 0.90 on Day I indicating a near complete recovery and no
biodegradation. f ring the first 14 days of th . studies the fractional
recovery steadily decreaseu to a steady—state value of 0.62. Both
effluent and off—gas concentrdlions decreased during acclimation periods
by appro dmately 38%. The effect ot biodegradation on the fate of
1,2—dichlorobenzene is shown in Figure 10—17 • hich compares the effluent
and off—gas fluxes to the amount removed by biodegradation during the
6—day SRT study. Effluent and off—gas fluxes averaged 6.8% and 56.2Z
respec:ively, in the 6 and 12—day SRI studies combined compored with a
37.0% removal of 1,2—dichlor)benzene due to biodegradation
Results observed in the 6 and 12—day SRI units were not
significantly different as shown by the comparison presented in Figure
10—15. Table 10—9 summarizes influent effluent, and off—gas values
averaged from periods of steady—state l,2—dichlorobenzene biodegradation
following acclimation of the microorganisms. Influent concentraticns
averaged nearly 110 ugh while effluent concentrations averaged 7.8 and
6.8 i g/L, respectively, in the 6 and 12—day SRT studies. 0ff—gas
concentrations were between 470 and 480 ng/9. in both studies. Table
10—10 provides a comparison of the fate of 1,2—dichlorobenzer ’e in the
two bioreactor studies. The amount biodegraded was calculated from a
reactor mass balance from measured influenc, e. fluent, and off—gas
concent rat ions.
TABLE 10—10
t’ATE OF 1,2,—DICRLOROBENZENE IN 6 AND 12—DAY SRI
ACTIVATED SLUDCE BIOREA(.TORS
PERCENT OF INF UENT FLUX
6-Day SRI 12-Day SRI
Eff lueat 7.1 6.4
Off—Gas 56.3 56.1
Biode:;raded 36.6 37.5
Biosorbed 0 0
In an effort to demonstrate that the disappearance of
1,2—dich]orobenzene w’s not due to an experimental anomaly,
1,2,4— richlorobenzene was added to the influent of the 12—day SRI
activated sludge unit. Recovery of 1,2,4—trichiorobeuzene averaged
greater than 90% during the two—week period it was added to the
influent.
12J
-------
0
N
C
z
L I.
q
.2 -z
0
0
0
0
0
-j
Lz 0
FIGURE 10—17. Inflizent, effluent, and off—gas fluxes
and amounts of 1,2_dichlorobenzene removed by
biodegradation during the 6—day SRT activated sludge study.
7 14 21 28 35 42 49 56 63 70
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
122
-------
TABLE 10-9
COMPARISON OF MEASURED AWl) PRcr)crcl) STEAI)Y—SIATE EFFLUENT AND 0FF—GAS
1, 2—DI CHLOROBENZ’NE CONCENTRATI ONS rR0M ACTI VATED SLUDGE BlOW EACTORS
1nf1uent(Ug/Y ) Effluent (pg/c) 0ff-Gas (ngI ) N/N
6-DAY SRT BLOREACTOR
Measured l09.7 (13.3) 7.8 (1.5) 477 (93) 0.63 (0.06)
Predicted if no biodegradation 11.7 (1.7) 736 (101) 1.00 (0.00)
Predicted from effluent 483 (90) 0.65 (0.08)
12—DAY SRI BIOREACT0R
Measured 107.1 (9.4) 6.8 (1.2) 471 (61) 0.62 (0.08)
Predicted if no biodegradation —— 10.9 (1.0) 699 (64) 1.00 (0.00)
Predicted from effluent 435 (78) 0.61 (0.06)
+ Mean
) Standard viation
-------
The air—stripping model w s used to predict off—gas concentrations
and N/N 0 values from measured effluent concentrations for the
1,2 —dichlorobenzene activated sludge studies. As shown by the
comparison in Figure 10—18, there was excellent agreement between
predicted and measured values during the 6—day SRT study. Meast red
off—gas concentrations and N/N 0 values averaged 477 iig/2. aiid 0.63,
respectively, compared with predicted values of 483 rig/i and 0.65. A
su mary of off—gas concentrations and N/Na values predictad from
effluent measurements has been included in Table 10—9. These results
demonstrate the 3bility of the air—stripping model to predict the
disappearance of a volatile, poorly—degradable compound. Thir finding
suggests that the fate of 1,2—dichLorobenzene could have been
well—characterized without the continual monitoring of the amounts
stripped to the atmosphere. The accuracy ith which off—gas
conc ntratlons could be predicted was dependent upon two important
factors: 1) well characterized volatilization rate parameters, and 2)
analytical techniques which enabled accurate determinations of ]
part—per—billion concentrations of l,2—dichlorobenzene in the e:rluent.
10.4 FATE OF BIODEGRADABLE C0&fl’OUNDS DUR1 G ACTIVATED SLUDGE
T REATMENT
Signtfcant biodegradation was found to occur for Si’C compounds:
benzene, toluene, ethylnenzene, o—xylene, chlorobenzene, and
nitrobeazene. Activated sludge bioreactor stuJies were conducted with
each compoind in the 10—liter cioreactors opetated with 6-day solids
reter.tjon times. ‘tdditional studies were run at solids retention tl-’es
of 3 and 12-days with selected toxice. Initial activated sludge studies
were conducteo with only a single toxic organic in the influents while
Later multi—solute studies invol d the addition of two or more
compounds to the influents.
10.4. 1 Non—volatile Compound: Nitrobenzene
Results from baseline volatilization stidies in 10—liter
bioreactors without activated sludge showed only a small amount of
nitrobenzene was stripped to the atmosphere. Reductions in the aqueous
concentrations averaged approximately 20% at operating conditions of 4
i/win aeration, 5.5 hour hydraulic retention time, and a 100 pg/i
irifluent nttrobenzene concentration. Initial activated sludge studies
with nitrobenzene included off—gas analyses but since steady—state
njtrobertzene off—gas fluxes represented only a very small fraction of
:he influent loadings, iater studies did not include off—gas sampling.
Nitrobenzene activated sludge studies were conducted in
bi,reactors operated a 6-day solids retention times. Results from an
activated sludge study presented in Figure 10—19 include influent and
effluent concentrations acd Ce/C i values, the ratio of effluent to
influent concentrations. There was no significant difference between
steady—slate Ce/Ci and N/N., values because the off—gas contribution to
the flux out of the reactor was small. Effluent concentrations averaged
less than 3 pg/i. in activated siudge studies with influent nitrobenzene
124
-------
1 , 2-D I CHLOROSENZENE
ACTIVATED SLUDGE
0 I I S 4 I I
0
I I 1 I I I I I S
E 11 : : : : :
C MEASURED DATA POINTS
. -— PREDICTED FROM EFFLUENT
z
—— C
o ‘ ._ ,‘ •....
0 s I S.
C
:±
0 7 14 21 28 35 42 49 58 83 70
TIME (DAYS)
FIGURE 10—18. Experimeital data and off—gas
conrentraticns and N/N values predicted from measured
0
effluent concentrations for the 6—day SRT activated sludge
study with 1,2-dichlorobenzene.
125
-------
U,
-J
0
I—
z
Li
-j
U-
z
-J
0
z
Li
-J
U-
I L .
Li
If,
0 7 14 21 28 35 42 49 56 63
U,
0
C.)
7 14 21 28 35 42 49 58 63
TIME (DAYS)
FIGtRE 10-19. Nitrobenzene influent and effluent
conce tra ions and ratio of effluent to influent
concentrations, ce/Ci , during a 6—day SRT activated sludge
study.
NITROBENZENE (6—doy SRI)
( “I
(N
0
7 14 21 28 35
42 49 56 63
126
-------
levels between 100 and 120 g/&; 3ff—gas concentrations typically were
less than 10 ng/L. Biodegradation effected overall nitrobenzene
removals of 95 to 97%. A s n ary of steady—state results for the 63—day
activated sludge studs is given in Table 10—11
The activated sludge studies exhibited an approximate two week
acclimation period prior to steady—state nitrobenzene removal by
microbial degradation. Day I analyses resulted in near co p1ete
recoveries (effluent and oft—gas fluxes combined) indicating no
biodegradation. Nttrobenzene recovery decreased dramatically between
Day 7 and 14 from greater than S3Z to less than 57. s the activated
sludge developed the capability to degrade nitrobenzene. Once a
steady—state biodegradation rate w3s established, the bioreactor
jerforinartce with respect to nitrobeozene removal was consistently good.
10.4.2. Volatile Conoounds
Results from activated sludge titdies conducted with the volatile
con ounds benzene, toluene, ethylbenzene, o—xy ‘.ene, and chiorobeuzene
have been presented in figures which include influent, effluent, and
off—gas concc ’ntrations, and N/N 0 values representing tne fraction of the
influerit mass fluxes measured leaving the bioreactors in the effluents
and off—gases combined. The addition of the toxic organic cos 5ound to
the influent was begun on Day 0 in each cage. PLotted as dashed lines
in various figures are effluent and eff—gas concentrations predicted by
the air—stripping modei to occur if only volatllLzatlOfl effected a
reduction in the aqueous concentration in which case N/N 0 1.0 ‘nd a
complete recoveiy uoull occur. P .ackground studies conducted in the
e q erimental bioreactors without activated sludges indicated that
. .rage re.toveries of each cor ound were approximately 9 %. Recoveries
less thar. 90%, or N/N 0 values less than .90, were considered evidence of
biological degradation. The overall removal or disappearance of a
cocrpound, defined as the fraction of the influent flux not found in
effluents, off—gases, and waste sludges combined, was used as a measure
of the amount of the co ound biodegraded. Batch biodegradation studIes
with acclimated sludges were conducted to confirm that biological
degradation of the con ounds was occurring In the CMF bioreactors.
10.4.2.1. Benrene
Activated sludge studies witi benzene were cor.d.icted Ln 10—liter
bioreactors maiatained at three solids retention times: 3, 6,
and 12—days. Each study was conducted for at least seven weeks after
benzene was added to the influent wastewater. The three activated
sludge bioreactors were not run concurrently but rather they spanned .i
period of approx aate1y [ 8 months. Results from the 3,6 and 12—day SRI
studies are presented in Figures 10—20, 10—21, and 10—22, respectively.
Each figure includes: 1) measured iofluent, effluent, and off—gas
concentrations connected by solid lines; 2) dashed lines representing
effluent and off—gas connentratic r s predicted assuming iio biodegradation
occurred and coly volatilization effected a reduction in the aqueous
concentration of henzene; and, 3) N/N 0 values representing the fraction
of the influent benzene measured leaving the bioreactors in effluents
and of f—gases combincd.
127
-------
TA1 LE 1 )—11
SUM tAR? OF INFLUENT, EFFLUENT Ahi) OFF—GAS
coNc:NTRATtO: S OF NITROBENZENE FROM AN
ACTIVATED SLUDGE REACTOR OPERATED WITH A 6—DAY SRT
Standard
Parameter Mean 4 Deviation
Influent (ugh) 117.8 8.0
Effluent (pg/9 ) 2.6 1.4
Off—Gas (ngli) 9.0 4.1
C/C 1 0.024 0.013
0.026 0.015
Reduction in Aqueois Conc. ( ) 97.6 1.3
OveralL Removal (Z) 97.4 1.5
Hydraulic Retention Time (hours) 5.6
Aeration Rate (R.,fmin) 4.0
MLSS (mg/i) 3360
+ Data summarized from Days 14 to 63
128
-------
While baseline str.xiieq without activated sludge demonstrated that
the average recovery of benzene was greater than 90% (N/N 0 >0.90),
maximum recoveries of benzene in the 3,6, and 12—day SRI activated
sludge studies ranged from only 50 to 60% (N/N 0 0.50 to 0.63). The
disappearance of benzene resulted in measured effluent and off—gas
concentrations t ’at were considerabLy less than the predicted values as
illustrated by the differences between the dashed lines arid the data
points in Figures 10-20 through 10—22. Batch equi1ibri sorption
studies sho .zed no signIficant sorption of benzene by Ihe activated
sludge bi .omass. The disappearance of benzene was attri .ited to
biodegradat ton by activat. d sludge microorganisms. Biodegradation WaS
confirtned in batch biodegradation rate studies.
Effluent and off—gas concentrations to some degree reflected
variations in influent concentrations; therefore N/N, va1ue. were used
to assess overalL activated sludge perforaance with re Ipect Lu benzene
removal. The N/Ne plots in Figures 10—20 through 10—22 shcMed two
distinct phases. During the first Il . to 21 days, Phase 1, the N/N 0
valueN decreased from approximately ‘).SO to less thin 0.20 indicating
that the overall Imount of benzen€ removed from the bioreactors
increased from 50% to grear- r than 80%. This two to three week period was
indicative of an acclimation phase when micrGorganisas in the activated
sludge were becoming more effective at removing benzene. Phase 11 was
c’ aracterized by relatively constant N/N 0 values ‘ndicating a period of
steady—state bertzene removal. Steady—state toxla renoval was defined
as no significant change in N/N 0 values during period o time equal to
three tines the solids retention time. There was no difference in
steady—state bioreactor performance with respect to benzene removal at
the three SRT values evaluated as sh n by the co arisons in Figures
10—23 and 10—24. Overall steady—state benzene removal, defined as
1J0x [ 1—( /N 0 )J, averaged 83.6, 83.1, and 83.6% in the 3, 6, and 12—day SET
units, respectively, during approximately five weeks of steady—state
operation. O erall removals measured in the three activated sludge
studies have been coc ared in Figure 10—25.
A stsnmar-y of steady—state results from each activated sludge study
is given in Table 10—i2. Average influent concentrations ranged from
112 to 118 ug/2. while effluent dnd off—gas concentraL ons averaged less
than 1.0 i gI . and 150 ng/t, respectively, in each study.
Benzene removal during the acclimation periods was found to be
more variable than during steady—state operating periods. The N/N 0
values measured during the acclimation periods of the 6 and 12—day SET
studies were similar to each other but dif erenc from the values
recorded it. the 3—day SRI study. From initial values of approximately
0.51) on Day I the N/N 0 values constantly decreased to less than 0.20 in
the 6 and i2—day SRT bioreactors. The N/N,, values in the 3—day SET unit
fluctuated between 0.53 and 0.59 for the first ten days before
decreasing to their steady—state levels.
The eftect of biodegradation on the fate of benzene is readily
apparent by coirparing the measured effluent and off—gas concentrations
129
-------
1
C-,
ZQj
<0
U.
U.
0
0
0
TIME (DAYS)
FIGURE 10—20. Benzene ir.fluent, effluent, anc off—gas con—
ce’ rracions and fractional reccveries, ‘:/‘ o, ieasure during
the 3—da: SR acttv ted 3lud2e scu ’:. (Dashed lines give
values predicted o occur n tne absence of iodegrada:ion.)
BENZENE: Acfiva ed Siudge (3—IJcy SRI)
O MEASURED DATA POINTS
- - PREDICTED IF NO BIODEGRADATION
— .
s’
130
-------
•:: I I I I I I I I S —
BENZENE 6—DAY SRI ACThfATED SLUDGE
3 I EASURED DATh
- - PRED!cTED IF NO BIODEGRADATION
o ‘ t I I I I —-
—I I I I I t I I I—
-
———— ——..— —‘——‘ %__
g _____,#/
I I I ( I S I ———--$—— I—
0
o
o 7 14 21 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE iO—21. Benz ne influent, cffluent, and off—gas
concentrations and fractional recoveries, N/N 0 , measured
dtaing a 6—day SRT activated sludge study. (Dashed lines
give values predicted to occur in the absence of
biodegradation.)
131
-------
0
0 I I t 3 4 4 4 4
BENZENE. Acuvcited Sludge (12—Dcy SRT)
(5
0
N S4
Li
MEAcURED DA
- - PREDICTED IF NO B: )DECRAOATlCN
0 $ I I . 4 I * I
0
(0 . I I I I I I I
0 .__ S —
(5 . _—— S_____,. — S ____ F
—
S.’ ,
C’d
0 — — -— — — — — —
LL ____
- ° ___
wo
0
0 __________
‘ ‘
-J . ‘1
0 .. — .. I ..
-s
—
S
I
C) — r——..... _
— I ——
__ 5_ p
‘4,
(I ’) I’
<0 ‘p
0
0
1— 4 I 1 4 I 4 0
re J
z
0
0
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 10—22. Be zene nfluent , effluent, and off—eas con—
cer*trations and fract1c na1 recoveries, /\o, i easured during
the i2—dav SRT activated sludge studs’. (Dashed ii es :ive
values predicted to occur in the absence of biode;radaticn.)
132
-------
.1
0
u - I
-J
z
-J
0
( 4
w
-J
0
z
LL
L&
0
0
z
z
0 7 4 21 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE 10—23. Comparison of influent. effluent, and off—
gas concentrations and fractio1al recoverieS. N/No, from
henz ne ac:ivated sludge studies c ”ducted in 10—liter bioreactOrS
operated with 3 and 6—day SRT’s.
—.——-—4—— I I I I I I I I I —
e e -e
133
-------
-J
0
I-
z
L i i
-J
z
0
L i
Li
I — ’
-J
z
U-
U-
0
0
z
z
TIME (DAYS)
FIGURE 1O—2 ę. Comparison of influent, effluent, and off—
gas concentrations and fractional recoveries, N/No, frorn
benzene actr;ated sludge studies conducted in 10—liter
bioreactors operated with 6 and 12—day SRT’s.
to
0 7 4 21 28 35 42 49 6 63 70
.7 -,
134
-------
0
0
0
-J
>0
,-‘ 0
l ii
c q
0
_J .
-j
LtJ
>
0
0
0
F I CURE 10—2 5. Ovt’ral 1 I)tnzene removals due I i.i lii odegr .id i1 Inn iiie.is ircd during .ic Livat d
sludge studies conducted in 10—liter hinreactors operated wIth 3, 6, and 12—day SRi ‘s.
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
70 77
-------
TABLE 10—12
COMPARISON OF MEASURED AND PREDICTED STEADY-STATE EFFLUENT AND 0FF—GAS BENZENE CONCENTRATIONS
FROM ACTIUAI LI) SI.UI)GE D I OREACTONS
Influent Effluent Off—Gas N/N 0 Removal
( ugh) ( ig/ i) ( ugh ) (—) ________
3-DAY SI T BIOREACTOR
Measured 115.3(19.9) 0.6(0.1) 128(25) 0.164(0.021) 83.6(2.1)
Predicted if no biodegradation —- 6.3(0.8) 794(143) 1.00(0.0) 0.0(0)
Predicted from effluent —— 110(23) 0.140(0.026) 86.0(2.0)
6—DAY SRi BIOREACTOR
I - ,
Measured 117.8(8.4) fl.8(O.4) 141(40) 0.169(0.052) 83.1(5.2)
Predicted if no biodegradation —- 4.4(0.3) 814(5 ) 1 00(0.0) 0.0(0)
Predicted from effluent —— —— 139(49) 0.168(0.046) 83.2(4.6)
12-DAY SRT BIOREACTOR
Measured 112.5(24.4) 0.5(0.2) 116(41) 0.164(0.041) 83.6(4.1)
Predicted if no biodegradation —— 4.3(0.8) 806(150) l.OO(’).O) 0.0(0)
Predicted frovn effluent —— —— 91(31) 0.120(0.039) 88.0(3.9)
Data Summarized from Steady—State OpeTating Periods
3 day SRI Study —— Days 21 to 49
0 ddy SRI Study —— Days 21 to 77
12 day SRT Study —— Days 21 to 70
-------
to the co cencrations precicted if biodegradation had not occurred.
Biodegradation caused re actiors in effluent and off—gas concentrations
of approximately 81 and 83%, respectively, during conditions of
steady—state ben ene rertoval.. Measured on a mass flux basis, o r 80Z
of the benzene that enterad the bioreactors was biodegraded and less
than 20% left t ie reactors in the off—gases. The effluent contrib. tion
to the mass fluxes nut of the bioreactots was less than 1%. FIgures
10—26, 10—27 and 10—28 compare the effluent and off—gas mass fluxes tD
the r.mount of beozene remo d by biodegradation during the 3,6, and
12—day SRT activated sludge studies, respectively. The amount
biodegraded was caiculeted by subtracting the effluent and off—gas
fl .ixes from the influent fluxes. Table 10—13 summarizes the fate of
benzene in each activated sludge study.
The importance of msasuring off—gas fluxes to forrailate a mass
balance for each compound as been illustrated by the comparison of
results for beozene and 1,2,a—Prichlorobenzene with and without
considering the amounts stripped to the atmosphere. Results for the two
volatile compounds plotted by the ‘sore traditional method in Figure
10—29 of considering ooly influent and effluent concentrations and Ce/Cj
values were quite similar and sh aied reductions in the a ieouS
concentration o: 90% or greater for both compounds. This method does
not facilitate interpretation of the specific removal mechanisms in the
manner that the same data does in Figure 1 —30 which includes of f—gas
concentrations. ReadiLy apparent in Figure 10—30 is the effect of
TABLE 10—13
FATE OF BENZENE IN 3,&-AND 12—DAY SRT
ACTIVATED SLUDGE STUDIES DURING STEADY—STATE
I t0DECRADATION
Percent of Influent Flux
3-Day SRT 6—Day SRT 12—Day SRT
Effluent 0.5 0.7 0.4
0ff—Gas 15.9 16.2 16.0
Biodegraded .33.6 83.1 83.6
iS osorbed 0 0 0
biodegradation on the fate of benzene which resulted in N/N 0 values less
than 0.20, while N/N 0 values for the. non—biodegta able
1,2,4—trichlorobenzene averaged greater :han 0.90.
1 37
-------
0
N
0
2W
0
xo
-J
(/)C4
(I )
<0
0
ci
0
x
-J
Li
0
z
Li
—ito
z
0
zo
LaJC’
0
Li
0 0
FIGURE 10—26. Benze ,e infiu nt, effiue t d off—gas
fluxes and amour s rp,ioved by biodegradation during the
3—day SRT activ l s1ud tudv.
0 7 14 21 28 .5 42 49
TiME ( ,‘ YS)
1 3E
-------
0
N a i
INFLIJENT
X EFFLUENT
OFF—GAS
BLODEGRADAT1ON
0
,. ) - -— —.-
o
(.1) C 4 ,
o 7 14 21 35 42 49 56 6 3 70 77
0
9-— . p - • p * —. .
-J
-
p . —
z i -.
uJ T
— Co
/
Q
0 7 14 21 28 35 42 49 56 63 70 77
TIME D# )
FTr.URE -2’ Eenzene f1uent, efflue,t, and off
as mass f1ux . amount re’noved by biode2radat1 p ‘ut_l -
d e 6•uav SRT cttvared sj udv.
I i9
-------
z
0
x
-Jr.,
LL
0
(I) (N
U-,
0
0
x
-J
I—
z
LU
2,
-J
0
tc 5 t
I-
Zo
Li
0
w
TIME (DAYS)
FIGURE 10—28. Senzene influent, eff1 . en .. and off-gas
mass fluxes and axnount removed b’ biode radation dur .ng
the 12—day S T activated sludge . cudy.
0
N
P
I ’ ,
q
0
0
0
(0
0
7 14 21 28 35 42 49 56 63 70
140
-------
-J
BENZENE
1,2,4—TRLQILOROBENZENE
I •
C)
I I 4
C)Q75 2’ 26354243 So
ii E (DAYS)
FIGURE 10—29. Co iparison a! benzene and ‘ 2. - -
benzene results from 10—liter bioreactor activated slLdge
studie . .‘ithoul coisidering .jn ounts o! each compour’d
strippei. o the arnosphe. tn hior iac.t’r off—gases * as)
141
-------
—..— I I I I I I
... . ACTWATED SLUDGE STUDIES
BENZENE
0 1,2.4—TR CHLOROBENZENE
I I I I I I I
I
0
zu,
4 21 28 35 42 49 56 63 70 Ti
TIME (DAYS)
FIC2 E 10—30. ber- ’. and 1,..—cricn1orob nzene influent,
eff1uent and •E —g:c icentr cions and fr ictiona1 rec iertes,
N/\’o. from acL v3Led s1ud e zud es cor.ducted in 10—1ir er
bioreacto s c perrt”d with 6—aav
142
-------
The fate of a trace, vlatlIe biodegradable organic cortpound can
be evaluated without measuring the off—gas concentrations if the
air—stripping characteristics of the coapound are known. Results for
1,2,4—trichlorobenzene sh ed rhat effluent concentrations could be used
to accurately pcedict off—gas concentrations of a noa—biodegradable
compound. l’he results in Figures 10—31, 10—32 and 10—33 demonstrate
that the sane procedure can be applied to biodegradable compounds.
Off—gas concentrations predicted from effluent values by the air
stripping model were combined with measured effluent arid influcint
concentrati ’ns to predict the N/N 0 values which ere used to distinguish
between air—stripping and hiodegradaticn. The accuracy witn which
off—gas and N/N 0 values could be predicted was ciependon; upon the
reltability of the effluent analyses. Table 10—12 includes a comparison
of measured off—gas and N/N 0 values with the vaLues predicted from the
effluent analyses. The average off—gas concentration predicted from the
effluent concentration averaged 139 na/i in the 6-day SRT study compared
. measured value of 141 ng/L. Similar good agrecisent between
predicted and measur—d values occurred for the other berizene activated
sludge studies.
10.4.2.2. Tok.ane
The fate of toluene during activated sludge treatment was studied
in activated sludge bioreactors operated with 6 and 12—day solids
retention times. influent, effluent, off—gas, and N/N 0 values for the
6—day SRT b oreactor study are presented in Ftgure 10—34 and s mimartzed
by Table 10—14. The results were neatly identical to those obser ied for
benzene. There was an approximate two week cclimatiori period
cnaracterized by a gradual decrease in the N/N 0 values from 0.43 to
approximately 0.16. The mean overall removal of toluene due to
biodegradattor’ during the steady—state o e at ng period of the 6—day SRI
study, Days l2 to 56, was 84 . tnfluent and effluent concentrations
during that period averaged L20 and 0.8 ugh, respectively. The 1arge t
effluent concentration measured ias 2.1 ugh on Day 1. Biodegradation
was the dominant re ’toval mechanism during the 12—day SRI activated
sludge study, also. Effluent and off—gas concent:ations, as sh n in
Figure 10-35, were significantly less than the values preoicted to occur
in th absence of biodegradation. As observed during the 6-day SRT
study, the 12-day SRT unit experienced an in .tial acclimation phase
fol1 iing the addition of toluene to th influent on DaY 0. Influent,
effluent and off—gas concentrations averaged 101 uig!f, 0.5 ugh and 127
ng/L, respectively, dueing the period of steady—state toluene removal.
Biodegradation effected ar’ 83 rcmovsl of tolueao during the
12-day SF! activated sludge study compared to 84% in the 6—day SRI
bioreactor. As sha n by the comparison of mea .ured effluent and off—gas
concentrations and N/N 0 values in Figure 10—36, there was no significant
difference in the fate of toluene during the t’.o studies. Lnfluent,
effluent, and off—gas concentrations averaged from data collected after
the acclimation period are tat ilated in Table 10—15. Table 10—16
si marizes the fate of toluene in this experi .eatal activated sludge
S ys t em.
143
-------
_j N
(; 1
a
z
Li
-J
L.
z
—0
0
-J
s.
‘ -0
z
0
0
(j
( o
I c
Cl
IL
0
0
0
0
z ,
7
TIME (DAYS)
FIGURE 10—il. Ex eri enta1 dat2 r1fl off—Sds ccncentrat ons
a’ fractional reco; r ?s. N/sc, ?reiicted frci neasured eff1 . t
- .centrations mr he 3—day SRi activated sludge stuc y with
bentene.
BENZENE: Activated Sludge (3—Day SRT)
—1 — —
MEASURED DATA PCINTS
-- , REDICTCD FRC 1 1 EFFLLJEN’
o
--o-- -c3 0 D
I — —.
28 35 4 49
144
-------
BENZENE. Activated S’udge (6—Day SRT)
e • t 4 —f 4
0
‘::i I- • s
0 UEASURE DATA PC 4TS
-J —— PRED CTEO FROM ŁFFLLEf iT
z,q .
%___ i% .
J
U)
i 0’ _‘
I 0 sri ma ... _. —. — —
LA.. ‘ .J m LJ
Li.. -C) OO
0
o t . I I 4 I.
S I I I S S S 4 I
0
14 2 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE 10—32. E perirent. 1 data and oFf—gas concentraticns
and fractic na1 recoveries. s/No. predicted from - easured
efflueit concentrations for the s—day SRT activated s1u e
study with benzene.
145
-------
0
0 4 t .4 —4—
BENZENE: Activated Sft dge (12—Day SRI)
z
Li
— 0
4 4 4 I I I I I —i
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Li 0
0
MEASURED DATA PO NTS
- PREDICTED FROM EFFLIJEWI
0
z I
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$ ‘
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o ‘- --ci ’
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0
— I I $ I • I 4 I 4 4
- • : ,
z I
I %
01
0
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 10—33. Experinental dac and off—gas concentrations
anc fractional recoveries. N/No, pred ctei from measured
effluent concentrations for the 12—day SRT activated s1u-i e
study with benzene.
146
-------
— ‘
S I
‘I
‘s I• ’ __—,
1 ——
I
)
TIME (DAYS)
FIGURE 13—3.. Toluene influent, effluent, and off—gas
conceotrations and fractional recoveries, ‘/No, rncas ired
during the toluene 6—day SRT activated sludge study. (Da&’ d
lines give values predicted to occur in the absence of
biodegradation.)
0 MCASUR D DATA POINTS
- - PREDICTED IF NO BI.ZDEGRADATION
I
I
0
— 5 . 0
0
z
Lu
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—0
0
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(-‘1.
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0
C)
0
0
it)
0
C..
0
7 14 21 28 35 42 49 56
147
-------
TABLE 1O—1!
SIJHNARY OF STEADI—STATE RESULTS FROM
THE TOLUENE ACTIVATED SLiJL’GE BIOREACTOR
STUDY CONDUCTED A A b-DAY SR
Standard
Parameter Mean+ Deviation
Influent ( ig/ .) 119.6 11.6
Lffluent (ugIZ) 0.8 0.2
Effluent (Z of Influent) 0.6
Off—Gas (ng/L) 141.7 32.0
Off—Gas (% o Influent) 15.6
N/N 0 0.16 0.04
Overall Removal (Z) 83.8
Ce/Ci 0.006 0.002
Reduction in Aqueous Conc. ( ) 99 .!
Hydraulic Retention Time (hrs.) 5.7 0.2
Aeration Rate (1/mm) 4.0 0.1
MLSS (mg/I) 3920
+ Data Suuun rized from Days 21 to 56
148
-------
0
— 0
C,
5
0
‘ —9
DATA POI S
U
-j
- - PREDICTED IF NO BIODE’RADATION
z $ $ 4 I I I I I
—0
‘
0
0
1 I .4 .1 4 4 $ • —e —
— 5
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f_s
o 0
S I
S
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4 —
08
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0
O I l 4 I -4 $ I $ *
0 _____________________ _____________
I l I l 4 I — l
z
0
0 7 14 21 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE 10—35. roluene :nfluent, efflueit, ard off—gas
-r f ac.io—a1 recoveries, reasured
durine the toluene 12—day SRT activated uLudze study. (Dashed
lines give values predicted to occur in the absence of
biodegradation.)
49
-------
-J
Li
-J
U-
z
-J
0
U-
Li
0
-J
0
z
0 7 t4 21 28 35 42 49 36 63 70 77
TIME (DAYS)
FIGURE 10—36. Conparison of influent. effluent, and off-
2as concent:ations and fractional recoveries. s/No, from
toluene activated sludge studies conducted with 6 and 12—day
solids retention times.
c’J
150
-------
TABLE 10—15
COMPARISON OF MEASURED AND P EDLC1ED EFFLUENT AND OFF-GAS TOLUENE
CONCENTRATIONS *ROM ACI IVATED SLUDGE 8IOREACTORS
Lnfluent Effluent Off—G is N/N 0 Removal
( pg/Z) ( i g/ ) ( ngfl) ( — ) (%)
6—DAY SRT 6IO EACTOR
Measured 119.6(11.6) 0.8(0.2) 1/41(32) 0.162(0.04) 83.8(4.0)
Pre’Iicted if no biodegradation —— 4.3(0.5) 836(101) .0O(0.0) 0.0(0.0)
Pred1 ted from effluent 142(33) 0.162(0.03) 83.8(3.0)
V.
12—DAY SRT BIOREACTOR
Measured 101.3(21.6) 0.5(0.1) 127(45) 0.170(0.045) 83.0(4.5)
Predicted if no biodegradation - — 3.8(0.5) 737(150) 1.00(0.0) 0.0(0.0)
Predicted from effluent —— —— 106(27) 0.145(0.30) 85.5(3.0)
-------
TABLE 10—16
FATE OF TOLIJENE DURING STEADY—STATE
BIODEGRADATION BY ACTLVkTED SLUDGE
Percent of Influent Flux
6—Day SRT 12—Day SRI
Effluent 0.6 0.5
OU—Gas [ 5.6 16.5
Biodegiaded 83.8 83.0
Days 21—56 26—77
The effect of biodegradation on the fate of toluene is readily
apparent in the coWarison of measured effluent a ’id off—gas
concentrations to the concentrations predicted by the air—stripping
model which ass nes biooegradat ion does not occur. Biodegradation
effected reductions of 83 a d SbZ in effluent and off—gas
concentrations, respectively, during the steady—suite operating period
of the 6—day SRT studj. Figures 10—37 and 10—38 di tail the fate of
toluene during toe two activated sludge studies by ci aring the
fraction of the influent flux leaving the bioreactors in effluents and
off—gases to the amount removed by biodegradation. ktring both
activated sludge studies the amount, of toluene leavin. the units in the
effluents W3S extremely small. The most significant effect of
biodegradation was the reduction in the mass flux of roluene in the
off—gases. Table 10—16 provides a sienmary of the data plotted in
Figures 10—37 and 10—38.
Effluent concentrations were used to predict off—gas
concentrations and N/N 0 values, and as indicated by Figut. . 10—39 and
10—40, the predicted values ere generally in good agreement with the
measured ones. As effluent concentrations approached t ie limit of
detection for toluene, the ability of the nodel to predict the off—gas
concentrations decreased. The air—sLripping model predicted mean
off—gas con.entrarions of 142 and 106 ng/L for the 6 and 12—day SRT
studies. Those values were nearly the same as the measured
concentrations of 141 and 127 ng/9.. Using only measured influent and
effluent concentrations, the air—stripping model predicted an overall
removal of toluene that was nearly identical to the observed values.
Predicted removals averaged 84 and 86Z while neasured values were 84 and
83Z for the 6 and [ 2—day SRT studies, respectively.
152
-------
0
p..
0
z
0
‘-.- 1
>(
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0
(I)
0
0
>c
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I—
z
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z
0
0
zo
0
a:
U
a-
TIME (DAYS)
FIGIRE 10—37. Toluene infljent, effluent, and off—gas
mass flixes ano amounts removed by bioue radation during
the 6—day SRT act v ced s1udg study.
0
0
0
C D
0
0 7 14 21 28 35 42 49 56
153
-------
0
r- .
0
z
0
_ r
LL
a
(I )
0
0
0
0
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0
I-
z
t J
Do
z
0
0
Zo
0
Li
Q-o
FLCURE 10-3 8. Toluene inf1uen . effluent. and off-gas
mass fluxes and amounts removed by biode radation during
the 12—day SRT activated sludge study.
o 7 14 21 28 35 42 49 56 63 70 77
TIME (DAYS)
154
-------
0
,- 0
_jC’4
! tTTTT TTT
_J *
u-o
tiJ d
0
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‘—S MEAZUR DATA POtj4TS
—S --- PREDKTED FRO 4 EFFLU T
z*
(1)
<0
o o
L.
L.
0
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0
I I
z
0
a I
0 7 14 21 26 35 42 49 56
TIME (DAYS)
FICCRE 10-39. Exper inent l data points ard off— as
ncPntrarionc and frac Jona1 recoveries. /No, prt dicte
from eas red effluent concencrat ons for t e 6—day SRT
activ i. d lud e stjdv for toluene.
155
-------
C
C
i
2
MEASURED
PREDICTED
DATA POINTS
FROM EFFLUENT
)
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g’
0
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0
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0
1 0
0
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0
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In
: See
07 14 21 28 5 42 49 56 6 70 77
TIME (DAYS)
F:cuRE IO—-’O. Experi enta1 data points and o f—oas
onrenrrnr ions and fracrion i1 recoveries. ‘ /\c’, predicted
from measured efflucit concetr t cn f3r rr e 12—day SRT
activated slud e sru&.’ with toluene.
-J
0
z
Li
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LL
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0
D
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0
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0
0
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156
-------
10.4.2.3. Ethvlbenzene
Activated sludge studies w3.th ethyLbenzene were conducted in
10—liter bioreactors operated with mean solids retention times of 6 and
12 days. Results from the first of two 6—day SRT bioreactor studies
are presented in Figures 10—41 and 10—42 (Reactor EB—. .Sl), and results
t roe the second study conducted approx.irnately three m.nths later 1 are
given In Figures 10—43 and 10—4’. (Reactor EB—Ao2). While both activated
sludge units exterienced similar overall ethylbenzer.e removals during
steady—state operating periods, the reactot performance with respect to
ethylbtozene removal during the accll.rsation periods was significantly
different as sho . n by the copar 4 sofl of results in Figure 10—45.
Steaey—sta: racoveries were achieved between 14 and 21 days in each
system and were characterized by mean ethylbertzene removals of 80 and
61 1 (or Re . ctors EB—ASL and EB—AS2, respectively.
The acclimation period in Reactor E8—AS2 was similar to those
observed for )enzene and tnluene. Both effluent and oft—gas
concentrations derreased gradua ly during the initial two to three weeks
resulting in a reduction in the fractional recovery of cthylbenzene,
N/N 0 , from 0.12 to the steady—ctate level of 0.19. By contrast, the
acclimation period of the activated studge n Reactor EB—ASI was
characterized by a sharp drop in the affluent and off—gas concentrations
between Days 14 and S. Ikiring the first 14 days littLe change was
observed in the effluent and off—gas concentrations, and the fractional
recovery ranged between 0.’S and 0.80 indicating only a small amount of
ethylbenzcne was being biadegraded.
Both rea&tors were operated under ondittons of steady—3tate
ethylbenzene removal for four to five weeks, rt spectively, during which
time effluent and off—gas concentrations remained relatively constant.
E2fluenr end oft—gas concentrations averaged 0.5 pg/f and 133 ng/L,
du’ing stuoy EB—AS1 and 0.6 pg/t and 166 ng/t during study EB—AS2, res
pecrivelv. Slight variations in effluent an off—gas concentrations
tvpicall reflected changes in the influent concentrations, therefore, the
N/Ne, values provide a better ref.resentatiofl of the system performance
with respect to ethylhenzene removal. The mean values of 0.20 and
0.19 recorded during FB—ASI and EB—AS2, respectively, indicated the amount
of ethylbencene emove . by biodegradation was quite reproducible.
A significant dev’tarior. from sr.eady—state conditions occurred in
Reactor EB— SL on Day 43, as depicted in Figure 10—. .l, when effluent and
ott—gas concentrations sudienly increaaed by a factor of three. The
fractional recovery, N/N 3 , f ethylbenzene rose to 0.73 on Day 43
coc ared to t! mean steady—state value of 0.20 indicatir a signiEica t
reductio . in biodegradation had occurred. The overall removal of
ethylbenzene returned to steady—state levels within two days. Neither a
change in TOC removal nor decrease in the MLSS concentration oLLurred
durtng this periol. The upset which signifirancly reduced the
157
-------
0
0
( ‘4
8 e e1
MEASURED DATA POINTS
-- PREDICTED F NO BIODEGRADATION
0 7 14 21
28 35 42 49 56 63
TIME (DAYS)
FIGURE 10—41. Ethy1be izene influent, eff1ucn , and off—gas
concentrations and fractional recoveries, N/N , measured during
a 6-day SRT ethvlbenzene activated sludge study, EB—ASI.
(Das ed lines ive values predicted to occur in the absence of
biodegradation.)
ETHYLBENZENE. Activated Sludge
Study EB—AS 1
6—day SRT
-J
0
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Li
0
0
0
0
0
0
0
0
0
(‘4
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(I ,
<0
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0
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0
z
z
0
0
158
-------
0
0
z
0
JI’)
0
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0
0
0
0
x
-J
TIME (DAYS)
FiGURE IC—42. Ethylbenzene influent, effluent, and
off—gas mass fluxes and amounts removed by biodegradation
during the 6—day SRT activated sludge study. E --AS 1 .
0 7 14 2 28 35 42 49 56 63
159
-------
0
,— 4 I I —.4.— J I
—j ETHYLBENZENE- Activated S’udge 6—dcy c-
0
w
0 MEASURED DATA POINTS
I L. - - PREDICTED iF NO BIODEGRADATION
z
— o I I I I I —
0
I I I I I
•..-. o 1
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(. ,4. — —— — _ . . s,
N
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we
4-
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Z ‘ —— %
V
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0
z
0
0 I
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
FIGURE 10—43. Fthylbenzene influent, effluent, and off—gas
concentrations and fractional recoveries, N/ , n’easured
during a 6—day SRT ethylbenzene activated sludge study, EB—AS2.
(Dashed lines give values nredicted to occur in the absence
of biodegradation.)
160
-------
0
N
0
,— (0
z
0
Q
)c’.
U)
0
0
0
0
x
-J
11 0
z
Li
z
0
I —
zo
WC4
0
Li
Q-o
63
TIME (DAYS)
FIGURE 10—44. Ethylbenzene influent, effiuent, and off—gas
mass fluxes and amounts removed by biodegradation during the
6—day SRI activated sludge study, EB—AS .
0 7 14 21 28 35 42 49 56
161
-------
I- ’
-i
0
D
I—
z
U
-J
LL
z
-J
C:,
U-
U-
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0
z
(I)
0
0
z
z
Q
0 ‘1 14
TIME (DAYS)
FIGURE 1O— 5. Cornaarison of .nfluent, effluent, and off—gas
concentrations and fractional recoveries. ‘ 1’o, from two
ethvlbenzefle activated sludge studies, !3— Sl and E3— \S2,
conducted wi:h 6—day SRI’s.
c , ’
U ,,
21 28 35 42
49 56 63
162
-------
biodegradation rate of ethylbenzenc occurred following a temporary drop
in the mixed liquor pH from a oteady—state value of 7.2 to approximately
6.0 on Day 42. The pH decreased during the nIght of Day 42 as a result
of tubing fatigue within the pumphead of t’ie peristaltic pump
delivering buffered (NaHCO 3 ) tap water to reactor EB—AS I. The exact
length of time the pH as reduced was estimated to have Leen less than
12 hours.
Results from an activated sludge bioreactor operated at a 12—day
solids recentior. time are graphically presented in Figurea 10—46 aa
10—47. Significant biodegradat .on was evidenced by the fact that the
effluent and off—gas concentrat ons were lest. than the ialuas predicted
to occur by the air stripping model if ethylbenzene was not removed by
oicdegradation. As shown by the coirparison of results from the 6 and
[ 2—day SRT activated sludge studies in Figure 10—48, no variation in
effluent and off—gas concentrations or amounts biodegraded was observed
at the two SRT’s studIed. Overall removals of erhylhenzene, during
approximately five weeks of steady—state conditions, averaged 81Z in the
6—day SRT study (teactor EB—AS2) c reo with 82Z in the 12—day SRT
study.
The overall removals of ethylbenzene due to biodegradation during
the two 6—day SRT studies and the 12—day SRT st dy have been co ared by
the plots in Figure 10—49. Following the two to .tree week acclimation
phase there was no signiftcnnt difference in th amount of ethylbertzcne
b odegraded. The amount of ethylhenzene removed by biodegradation
a’ eragtd 81Z for the three activated sludge studies. The amount ef
eihylbenzene in the off—gases and effluents averaged 18.5%
and 0.SZ, respectively. Table 10—17 suomarizes the fate o ethylbenzene
during activated sludge treat. ent in the experimental system.
TABLE 10—17
FATE OF ETHYLBE 4ZEME DURING STEADY—STATE
BiODEGRADATION 3? ACTIVPITED SLUDGE
Percent of Influent Flux
6—f’ay SRT 6—Day SRT 12—Day SRT
( EB—ASI) ( EB—AS2 ) __________
Effluent 0.5 0.5 0.5
Off— Jas ‘9.5 18.5 17.5
Biodegraded 80 81 82
Biosorbed 0 0 0
Days 21—42,45—63 21—63 21—52,58—70
163
-------
0
..— 0
C .,’
0
z
URED DATA POI S
LaJ
-J
- - PREDICTED IF NO OIODE( RADATION
-4 4 I I I C I I
0
‘-S
-t I 4 4 I 4
0 — — — — — — — —% — — — — —‘
0 — — — — — — — — — —
( 4 — —
U-
0 ____ ___
j 0
0
0
4 i C I I I I
-J
z 1
I
,—— I
S.— 4 — — — — —.5 I I
I F S.. I —
(I) ‘I
I
0
00
U-
0
0
0
— I I • 4 4 I * I I —
0
0
z
0
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 10—46. Erhvlben.’ene inf]uenr, effluent, and
off—23s concer.tr.3rlons and fractional recnv ties, ‘/No.
measured durin th 12—day SRT activated sludge study.
(dashed lines give values predicted to occur i.n he
abserce of biodegradation.)
164
-------
0
N
0
z
0
x
_jr )
0
(I)
0
0
0
0
x.-
-J
U - 0
I —
z
LU
_j(O
U-
z
0
U-
0
zo
Wc 4
0
LU
Q-o
TIME (DAYS)
FIGtJR 1O•47. Echylbenzene jnf1uen , effluent, and off—
gas mass fluxes and ar ou ts rernoved by biode2raoat on during
the 12-day SRT ethylbenzere activated sludge stuay.
0 7 14 21 28 35 42 49 56 63 70
165
-------
“3
-J
0
z
Li
-i
L
z
—
-J
0
U.
U-
U
-J
-v
.. . .
(1)
0
LL
U-
‘0
0
z
z
TIME (DAYS)
FIGURE 10—48. Comparison uf influent. eff1ue it. and off—
aas concentracieflS and fractional recr,veries. N/’o. fror’
eth:lbenzene accivatcd sludge studies conducted c’irh 6 (E3—AS2)
ano 12—da: SRTs.
( ‘4
I0
CN
U,
0 7 14 21 28 35 42 49 56 63 70
]66
-------
0
0
0
0
0
0
0
(0
0
0
0
0
c.J
0
0
0 7 14 21
28 35 42
TIME (DAYS)
F1C1JI E 10-69
activated sludge
•;r l I ds retont 1OI
Overall etlylbenzeu.e rcm va1s due to bIodc radatlou mca ured during
tmtiIi s conduc t ed in fO—liter binreacrors operated wIth 6 and 12—day
t 1nu
a’
>
0
Li
c
— I
-J
Li
>
C-)
O 6—DAY SRT BIOR(ACTOR (ER—AS 1)
* 6—DAY SRT SIOREACTOR (En—As2)
O 12—DAY SRT oI0 EACT0R
49 56 63 70
-------
Volatilization of ethylbenzene was sufficiently characterized in
the 10—liter bioreactors to enable predictions of off—gases and overall
removals based upon measure i effluent concentrations, as was sh in for
the previous compounds and is demonstrated for ethylbenzene in Figures
10—50, 10—51 and 10—52. In general, there was good agreement between
predicted and measured off—gas concentrations and values for the
three ethylbenzene activated sludge bioredctor studies. The predicted
off—gas cancentrations ‘ ere typically slightly less than the measured
concentrations in each study. Ratios of predicted:measured average
off—gas concentrations ranged from 0.76 to 0.81 for the three activated
sludge studies. The smaller predicted values likely resulted from
aEfluent concentrations that consistently were less than 1.0 pg/i and
approached the lim it of detection for ethylbenzene. Amounts of
ethylbenzene removed by biodegradation and hence not leaving the
reactors were quite well modeled from the effluent analyses. Ratios of
predicted:measured percent overall removals were approximately 1.05 in
each stuoy. The larger than measured removals resulted from the model
predictir.g less flux out of the bioreactors in the off—gas than was
actually observed.
A complete sislimary of the activated sludge bioreactor data for
eth 5 nzene is given in Table 10—18. The results include measured
inf i:it, effluent, and off—gas concentrations; effluent and off—gas
conce crations predicted to oca.ir if o ily air—stripping effected a
reduction in the aquec us ethvlben.zene concentration; and off gas
concentrations predicted from measured effluent values. The mean
values were cal ilated for cond tions of steady—state ethylbenzene
removal and do not inckde either accliraa ion periods or upset periods
resulting in reduced ethylbenzene biodegradation.
10.4.2.4 0—Xylene
Activated sludge bioreactor studies with o—xylene were conducted
at solids retention times of 6 and 12—days. Two activated sludge
bioreactor studies were conJu ted with 6—day SRT’s and results from the
first study (XYL—ASI) are given in Figures 10—53 and 10—54 while results
from the second study (‘ ?L—AS2) conducted six months later are given in
Figures 10—55 and 10—56. Biodegradation of o—xylene by the activated
sludge was observed in both studies and was evidenced by significant
differences between measured mass fluxes into (inuluent) and out of
(effluent, off—gas and waste sludge combined) the bioreactors. The
dashed lines in Figures 10—53 and 10—55 represent the amount of o—xylene
predicted bj the air—stripping model to occur in effluents and off—gases
if only air—stripping effected a reduction in the aqueous
concentrations. Differences between the measured data points and das ’ed
lines represent reductions in effluent and off—gas concentrations due to
microbiaL degradation of o— cylene. Both activated Judge units
e,perienced similar o—xyl-te removals during steady—state operating
periods as sh n by the comparison of results from the two studies in
Figure 10—57. Sceady—sta:e removals in each bioreactor were achieved
after approximately three weeks and were characterized by mean o—xylene
168
-------
0
0
0
0
0
0
0
c d
0
0
0
0
0
0
0
c
0
zu)
0
z
0
0
p--,
00
I
. ‘
‘
‘9
I I I •- t - I I
.‘ 0 MEASURED DATA POINTS
—— P ED CTED FROM EFFLUENT
‘
I
0
I
I
I
I II
t II
I I
I’
II
‘%4D
0 7 14 21 23 35 42 49 56 63
TIME (DAYS)
FIGURE 10—50. E cperimental data points and off-gas
concentrations End fractional recoveries, N/Nc predicted
from measured effluent concenrrjtions for the 6-day c’RT
activated sludge study with ethylbeizene, EB-ASI.
EThYLBENZENE: AcU’icted Sludge (6—day SRT )
Study EB—AS I
-J
c i
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C.)
S.-,
L&
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-J
C.)
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V)
C.)
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L 1
0
169
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C
ETHYLBEt ENE: t Acuv ted Sudge 6—day SRT
U i
_J I
Li I
z
— I I I I
._i * I I I I
I&. ____
Li 0 _____
0
o I I I
0 MEASURED DATA POINTS
—j - - PREDICTED FROM EFFLUENT
0
z
o
j)O
.
o
I I ‘o 0
Li_ + Ľ
L i.. 0
— — — — — — — — .. —
0 • 4 I
0
I i. I I
o
z ‘0
2
—S.- 0
o
o I
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
FIGU3E 10—51. E’ perirnenta] data pc nts and off-gas
concen.rations and fractional —‘ -—verie:. N/N 0 , predicted
fro i rneasurec 1 effluer.t coflCCflttuL1’fl for the 6—daySRT
activated sludge study with t!thvlS -r’zeI.e, EB—A52.
170
-------
-J
C-,
I—
z
z
-j
0
Lj
Li
-J
0
z
U)
C)
LL
0
0
z
z
0
0
0
0
0
‘I ,
0
0
0
0
0
0
0
0
0
I I . I I I I
O MEASURED DATA PO! 4TS
-- PREDICTED FROM EFFLUE 4T
?
‘
0
,
‘
I
A
I’
I’
:
%
\
I I I I I I I I I
4 I I I I I I I
o
I
A
“
I
S
‘0
‘ ! i
-
0
0
0
0
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 10—52. txperi:.iencal data pc nts and off—gas
concentrar ons ard fracriona rec ’veries, N/No, precicted
from measured effluent concentr cions for tne 12—day SRT
activated sludge study with ethvlbenzene.
J 71
-------
T’\lUk. 10—18
COIPAR1SON OF MEASURED AND PREUICTLD LI’ILUENf AND OFF-(.AS
EThYL ENZENE CONCEN FP.Nf IONS FROM ACTLVA1 El) SLUD( E 81 OREACTORS
Influent Effluent Off-Gas N/N 0 i emoval
( pg/i ) (pg/ _ ( i _ gR) ( —) ( X )
6—DAY SRI; REACTOR EB—AS1
Measured 97.6(8.5) 0.5(0.1) 133(17) 0.20(0.02) 80(2)
Predicted If no biodegrudat1o. —— 3. 1(0.4) 653(7b) 1.00(0.0) 0(0)
Predh’ted from effluent —— —— 111(34) 0.17(0.05) 83(5)
6—DAY SRI; REACTOR EB-AS2
-4
Neasuced 119.4(14.4) 0.6(0.2) 1b6(43) 0.19(0.04) 81(4)
Predicted if no btodegra ation —— 4.0(0.5) 850(121) 1.00(0.0) 0(0)
Predicted from effluent —— —— 125(43) 0.15(0.04) 85(4)
12—DAY SRT
Measured 105.2 O.5 O.1) 135(30) 0.18(0.03) 82(3)
Predicted If no bIodegradation 3.5(0.4) 756(80) 1.00(0.0) 0(0)
Predirted from effluent 110(30) 0.15(0.04) 85(4)
-------
0
N
o—XYLENE: AcUvoted S iudge (6 d RT)’
Study XYL—AS1
MEASURED DATA POINTS
- - PREDICTED IF NO BIODEGRADATION
I I I I • &
j
-j
0
I—
z
Li
-‘
-a
-J
U-
z
—0
, 0
0
1*
U-c
UJO
0
0
-J
C ’,
<0
I
U-
LI-
0
0
z
z
0
0
TIME (DAYS)
FIGURE 10—53. o—X 1ene influent, effluent, and off—gas
conce tr ’tiOflS and fractional recoveries, N/’ o, ineas :red
during a 6—day SRI o—,cvlene 4 ctivated siud e study, XYL- S1.
( ashed lines give values predicted to occur in the absence of
biodegradation.)
0 7 14 21 28 35 42 49 56
63 70
0
0
0
I4
0
173
-------
C
0
‘ —C
x
-Jo
0
0
0
0
0
-J
U- 0
I —
z
Li
-J(o
U-
z
0
0
Zo
0
Li
Q-o
TIME (DAYS)
FIGURE 10—54. o—Xvlene influent. effluent, and off—gas mass
fluxes and an’ounts re’ioved by biodegradation dur r the 6—d3v
RT o—xvlene act vated sludge study. XYL—AS1.
0 7 14 21 28 35 42 49 56 63 70
174
-------
——
— — “ I
‘I
—‘
— %
t
/
*
‘I
0
01
a
0
Ze)
0
Z
0
0 7 14 21 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE 10—55. o—Xvlene inflijent, effluent, and off—gas
c ncenrrarions and f actionaj recoveries. N/No, rneasured durinc
a 6—day SRI —‘cy1ene activated sludge study, XYL—AS2. (Dashed
lines give values oredicted to occur in the absence of
biodegradation.)
o— ’XYLENE: Activated Sludge (6—day SRT)
O MEASURED DATA POINTS
- - PREDICTED IF ’ NO BIODEGRADATION
0
0
0
0
0
0
0
0
0
0
C
0
0
-J
0
I-
Z
w
-J
U-
z
-j
0
U-
U-
U i
-J
0
z
(I )
Li
0
— I I I I I I I t S I
1 — —.
II ‘ — __
I ‘ —— •“
175
-------
0
0
x
-Jo
L ’
(1)0
( P C . , 4
0
0
0
0
x—
I-
z
w
Do
-J’D
1L
z
0
L1-*
0
zo
WC. ’4
0
IJJ
0 0
TIME (DAYS)
FIGURE 10—56. o—Xylene influent. effluent, and off—gas mass
fluxes and amounts re’ oved by bic de r dation during the 6—day
SRT activated sludge stucv. XYL—AS2.
o—XYLENE (6—Day SRI)
L I I INFLUENT
X EFFLUENT
0 0 ’F—GAS
SIODEGR.WED
C 7 14 21 26 35 42
49 56 63 70
0 7 14 21 28 35 42 49 56 63 70
176
-------
-J
0
I-
z
U
-j
z
-J
C,
Li
U
-J
0
-v
(I)
U-
U-
0
0
z ______
z
0 7 4 21 28 35 42 48 56 63 7
TIME (DAYS)
FIGURE O-5. Co spariscn of influent, effluent, and ,ff—
gas conce tration and fractional recoveries, N/\o, frcn’ two
o—xvlene activated sludge studies, X7L—AS1 and XYL—As2,
conducted with 6—day solids retention ti. es.
(0
177
-------
remcvais of BOf and 76X fo: reactors XYL—ASI and X?L—AS2, respectively.
Figures 10—54 and 10—55 compare mass fluxes of o—r ’1ene out of the
reactor in effluents and off—gases to the amount removed by
biouegradation. The amount biodegraded was calculated from the C1F
reactor mass balance equation for o— cylene. In both studies the initial
sample on Day 1 indicated that mote than 70Z of the o—xylene wa
stripped to the atmosp iere, less than 25 was removed by biodegradation ana
less than 5% was measured in the effluent. The orimary effect of
microbial biodegradation on the distribstion of o—xylene was a
significant reduction in the amount stripped to the atiiosphere. After
th acclimation phase over 707. of o— ylene was degraded, less t an 25% was
measured in the off—gas, and less than 2% was Lot.nd in the eff uent.
Bioreactor performances with respect to o—xylene removal during
the acclimation periods were different in the two 6—day SRT units. The
acclimation period in Reactor XYL—ASZ was characterized by significantly
lcs er effluent and off—gas concentrations compared with Reactor XYL—ASI.
After an nitzal drop from 0.’4 on Day 1 to 0.47 on Day 4, the N/N 0
values recorded for Reactor XYL—AS2 remained relatively constant for two
weeks, and then decreased to approximat steady—state conditions. Thc
acclimation period in Reactor XYL—AS I resembled the acclimation period
observed for ethylbenzene in Reactor EB—ASI. The N/N 0 values averaged
approximately 0.80 until Day 16 and then rapidly decreased to 0.20 in
two days.
Both 5—day SRT activated sludge units were operated under
approximate steady—state conditions for at least five weeks. Effluent
and off—gas concentrations remained :elatively constant in Reactor
XYL—AS2 after the acclimation period and averaged 0.9 pg/i and 2 ng/i,
respectively, comp4red to valuec of 4.8 ug/ . and 731 ng/i that were
predicted to occur in the absence of o—xylene biodegradation. The
results for Reactor X—ASI presented in Figure L0—5 3 she ., two periods
when the removal of o—xylene deviated from steady—state effluent and
off—gas concentrat Ions of 0.7 pg/i and 141 ag/i, respectively. On both
occasions the effluent and off—gas concentrations significantly
increased resulting in N/N 0 values of 0.68 on Day 35 and 0.96 on Day 43.
The 96% o—xylene recovery on Day 43 ir dicated essentially no
biodegradation of o—,cylene occurred and all of the o—xylene entering the
bioreactor was recovered in the effluent and off—gas combined. After
both upsets the reactor returned to steady—state levels wIthin several
days. No variations in TOC removal or HLSS concentrations
occurred during the period of reduced o—xylene biodegradation. A
sudden, temporary (less than twelve hours) drop in pH from 7.2 to
between b.O and 6.2 coincided with both upset periods with respect to
o—xylene biodegration. The reduced pH of the mixed liquor had an
inhibitory effect on the microorganisms responsible for o—xylene
degradation.
The results from an activated sludge bioreactor operated wits a
12—day solids retention time presented in Figures 10—58 and 10—59 were
characterized by three distinct operating periods with respect to
178
-------
o—xylene removal: an acclimation period. steady—state removal period,
and an upset period folla.ied by a return to near steady—state levels.
Follcwing the three to four week long acclimation phase was a period of
relatively steady—state removal of o—xylene which occurred between Days
29 and 63. The mean steady—state overall o—xylene reeDval due to
biodegradation was 7Z. Effluent and off—gas concentrations and NJN 0
values observea during the 12—day SRI study were 3imllar to those
measured in the 6—day SRT activated sludge unIts as shown by the
comparisons in Figure 10—60. DurIng the steady—state o—xylene
degradation phase, the effluent and off—gas concentrarions averaged 1.1
ugh and [ 90 ng/i, respectively, while the mean influent concentration
was [ 00 ugh for the 12—day SRT study.
An upset period during the 12—day SRT study occurred on Day 65
when the recovery of o—xylene suddenly increased to approximately 95%
indicating a significant reduction in the amount of o—xylene being
biodegraded. Poor o—xylene biodc’gradacion Wa’ observed during the next
seven days as N/N 0 values averaged 0.63. The overall removal of o—xylene
ircieased to approximately 70% on Day 75 and remained at that level for
the next 2 da’.s after which time the study as ended. As observed in
previous activated sludge studies, the sudden decrease in o—xylene
biodegradation coincided with a temporary reduction in mixed liquor pH
to approximately 6.0. Unlike the results from studies with benzene and
ethylbenzene, o—xylene biodegradation in the 12-day SRT bioreactor did
not iiumediateiy return to previous steady—state Levels. While the exact
length of time the pH was reduce.! is unknown, the redvetion appears to
have been of sufficient duration to have a pronounced impact upon the
organisms responsible for o— cyiene biodegradatior.. The reactor response
aetween Days 65 and 75 represented a reacclimation period of the
activated sludge to o—xylene. The study was not continued long enougi
to determine whether or not the amount of o—xylene removed by
biodegradation would return to the level observed between Days 29 and
63.
Compilations of influent, effluent, and off—gas concentrations
averaged during steady—-tate periods of o—xylene biodegradation are
given in Table 10—19 for the three activated sludge studies. Table
10—19 also lists mean effluent and off—gas concentration predicted to
occur by the air stripping ‘odel if only volatilization effected the
distribution of o—xylene between the aqueous and gaseous phases. The
stead’s—state overall removal, or amount biodegraded, wa-i approximately
the same in all of the o—xylene activated sludge bioreactors as shown by
the comparisons in Figure 10—61. While steady—state removals were
similar, significant differences existed among the removals observed
during acclimation phases. The effect of biodegradation on the fate of
o—xylene during activated sludge treatment in the 10—liter bioreactors is
summarized by Table 10—20.
The air—stripping model previously developed was used to predict
off—gas concentrations and N/Ne, “alues from the measured effluent
concentrations. Comparisons oF measured data points and predicted
values represented by dashed lines ar” shown in Figures 10—62, 10—b3 and
179
-------
0
0
C M
-j
0
‘—9
z
w
-J
z
—0
-J
UJ
- J
z
‘I)
<0
( o
0
0
0 7 14 21 28 3.5 42 49 56 63 70 77
TIME (DAYS)
FIGURE 10—5 8. 0 -Xvlene i flu2nt. effluent. and off-gas
concentrations and fractioral recoveries. NIXr. neasured
during a 12—day SRT o- lew acti ated sludge study.
(Dashed lines sive values predictea to occur in the absence
of biodegradation.)
0
0
0
0
r 4
180
-------
0
0
00
‘0
-Jo
( /)0
0
0
0
0
x—
-J
I L . 0
I-
z
Li
—J .o
z
0
C
I—
- 0
0
Li
a. 0
TIME (DAYS)
FIGIRE 10—59. o—Xylen influenc. effluent, and off—gas tass
fluxes and amounts renoved b biocegradarion during tne 12-day
SRT activated sludge stud :.
0 7 14 21 28 35 42 49 So 63 70 77
181
-------
-J
0
I—
z
U
-J
U-
z
-J
0
U-
U-
Li
(‘4
—S
0
z
(I.)
I ’1
U-
0
0
z
z
TIME (DAYS)
FIGURE 10—60. Comparison of nfluent, effluent, and off—gas
concentrations and fractional reco/erles, s/No, from o—xvlene
activated sludge studies conducted with 6 (XYL—AS2) and 12—
day solids retention tines.
tt
0 7 14 21 28 35 42 49 56 63 70 77
182
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TABLE 10—19
COMPARISON O MEASURED AND PREDJCTED ErE’I.UENI ANI) OE’F—GAS O—XYLENE CO 4CENTRATI0NS
PROM ACfLVATED SLUDGE. BIOREACTORS
Influent Effluent Off—Cas N/N 0 Rcinoval
Jg/ ) ( pg/i) ( ng/t ) (—) ( R )
t —I)AY SRI; REACTOR XYL—ASI
Measured 1O3.(1O.2) 0.7(0.3) 141(21) 0.20(0.04) 80(4)
Predicted if no biodegradation —— 4.8(0.7) 731(54) 1.00(0.0) 0(0)
Predicted form ef:luent 107(38) 0.15(0.06) 85(6)
6—DAY SRI; REACTOR XYL-AS2
Measured 111.9 0.9(0.2) 192(33) 0.24(0.05) 76(5)
Predicted if no biodegradation 5.3(0.9) 782(135) 1.00(0.0) 0(0)
Predicted from effluent —— 125(30) 0.17(0.05) 83(5)
12—I)AY SRI
Measured 100.2(17.]) 1.1(0.4) 190(5)) 0.25(0.06) 75(6)
Predicted if imo biodegradation 4.9(0.8) 720(121) 1.00(0.0) 0(0)
Predicted from effluent 167C ,2) 0.24(0.07) 76(7)
-------
TIME (DAYS)
FIC.URE 10—61
a.tlvatcd sllIdo t
sc Itd reiont Inn
Overall o— y •iw rtinoval c due tc hi nd idai Ion mea urod dur Eng
cOHItirLL’l Iii 10—I ter I.1ort at I or opcr.iu’d wil Ii 6 and 12—day
t I int’.
0
0
0
‘—, C)
a,
-J
>
0
LU
-J
-J
Li
>
0
I-
C0
0
0
(0
0
0
‘4.
0
C
“4
q
0
0
7 14 21 25 35 42 49 56 63 70 77
-------
10—64 for thu threu acti”aced sludge st jdIes. In general, the model
predicted values were in reaso- able agieement with the measured values.
TABLE 10—20
FAfE OF O—XYLENE DURING STEADY—STATE
BiODEGRADATION Wt ACTIVATED SLUDGE
Percent of Influent Flux
6—Day SRT 6—Day SRT 12—Day SRT
(XYL—A l) (XYL-AS2)
Effluent 1 1 1
0ff—Gas 19 23 24
Biodegraded 80 76 75
Bioserbed 0 0 0
Days 18—31,44—55 27—66 29—63
10.4.2. S. CI,lorobenzene
Activated sludge bioreactor studies with chlorobenzene were
c,jnducted at solids retention times of 6 and 12 days. Results from the
6-cay ERT study are presented in Figures 10—65 and 10—66, while result3
from the 12—day study are given by Figures 10—67 and 10—68,
respe tive1y. Figures l0—f 5 and 10—67 depict influent, effuent and
off--gas concentrations and N/N 0 values measured during the accivated
sludge studes. Dashed lines represent effluent and off—gas
concentrations predicted to occur if only air—stripping effected a
reduction in the aqueous concentration. Figures 10—66 and 10—68
show mass flux values obtained by cotnbir.ing measured concentrations
with ap rooriate aqueous and off—gas flow rates. The amount
b odegraded, represented by a dashed 1in , was calculated from a
mass b.lance equation for chlorobenzene.
85
-------
-J
0
-J
I L
C
.—... C
c l
IL
I L 0
L U 0
-J
0
z
(1)
0
L
IL
0
0
ZU)
z
0
0
0 7 14 21 28 35 42 49 56 6 3 70
TIME (DAYS)
FIGURE 10—62. ExperImental data pointc and off—gas con-
centrations and fractional recoveries, Nf o. predicted fro ’
measured effuent concentrations for the 6—day SRI activated
sludge study with o-wlene. XTh—AS1.
a
—
I I 4 I- —I-
I ;
I
I I
I I
I I
‘ , .---o-Q:,
0-
186
-------
TIME (DAYS)
FGURE 10—63. E cperir ent tl data points and off—gas con-
centrations and fr criona1 recoveries, N/’ o. predicted from
measured effl’ient concentrations foc the 6—day SRT activated
sludge study with o—xvlene, XYL—AS2.
o—XYLENE. Activated S udçe (6—dcy SRT)
dy XYL—AS2
0
0
0
0
0
0
I0
C
0
c,1
0
c i
0
0
I I I I I I I
-j
0
I—
z
w
-J
11
z
-J
0
D
LL
U-
Li
-J
0
z
0
I i .
0
0
z
z
0
I I
0 MEASURED CATA POI S
- - PPEDICTED FROM EFFLUENT
§ c!
E 1 HHHH
0 00 0
i
]
0
0
0 7 14 21 28 5 42 49 56 63 70 77
187
-------
C ’4
0
0
0
0
Co
0
0
0
C
0
0
-J
0
w
-j
IL
z
- j
0
I L
LL
L J
-J
0
z
IL
IL
C
0
z
z
TIME (DAYS)
FIGURE lO—& . Exoerirnental data points an off—gas con—
cen :.3tions ‘no fractional recoveries N/No, predicted from
tneasured effluent concentrationt for the 12—day SRT activated
s1ud e study with o-xvlene.
0 MEASURED DATA P01’4TS
—— PREDICTED FRO’A EFFLUENT
CD
0 A
14)
— I.
\o —
C
,
--
0 _ I
000
0
0
1%
A A
I’ I
0 ; - I
I
,.
I I I I 4 4
0
,
0
I I I I
— 4
0
%%
_ ——
; i
I’
‘
I —
‘I
‘--c9 - I
0
0
0 7 14 21 28 35 42 49 56 63 70 77
188
-------
0
0
..J 0 MEASURED DATA POtN1S
Li.. - - PREDICTED IF NO B ODEGRADAT ]ON
z I I I I I
—0
0
‘.- 0
—4 I I i•__._\ I I
——
0 , .—.
- -
I n ,
Li ci
W 0* I
0
0
I I I I
-J
0
—
o ——
0 ——. —
_1 — %___ ..
I ‘
(I ) --S
I V
<01
Oo’
0 i I 1— I •1
0
— I I I I I
z
O ’
0
0 7 14 21 28 35 42 49 56
TIME (DAYS)
F1G E 10—65. Chlorobenz ne influent, effluent, and off—
gas concentrations and fraction;] recoveries, N/No, measured
during the chlorobenzene 6—day S T activated sludge study.
(Dashed lines give values predicted to occur in the absence
of biodegradation.)
189
-------
z
0
D
x
-J
C l
U)
x
-J
LL
z
Li
-j
z
0
I —
z
Li
0
Li
0
N
0
0
U,
0
0
0
N
0
0
0
0
0
0
0
U,
0
U,
0
0
N
0
TIME (DAYS)
FIGURE 10—66. Chlorobenzene influenc, effluent, and
off—gas mass fluxes an’1 amounts re ovea o ’ biodegradation
durIng the chlorobenzene 6—day SRT activated sludge study.
7 ‘i4 21 28 35 42 49
56
0 7 14 21 28 35 42 49 56
190
-------
0
CHLOROBENZENE: Activated Sludge (12—Day SRI)
MEASUR&D DATA PO UTS
U.. - - PREDICTED IF NO B ODECRA AT} N
0 4 4 4 I I 4 I —
0
I I 4 —t 4 I I I I-
I ———
C, —————
0 — .—..
o o
Z 9
I —.——— .—
\ —— A
(I) — ——
S
<0
TIME (DAYS)
FIGURE lO—b7. Chlorobenzene inflt ent, effluent, a. d off—
gas c ncenrrarions and fractional recoveries, s/No, measured
dLring the chlorobe zene 12—day SRI activated sludge study.
(Dashed lines give values p -edicted to occur in the absence
of biodegradation.)
]91
-------
56 6.3 70
FIGURE 1)-68. C 1ornbeizene influent, effluent, and
off—gas -na;s fluxes and amount: re roved by bi degradat1on
dur3.ng toe cnlorobenzene 12—day SRT activated sludge stuay.
0
N.
0
0
‘I,
0
0
0
0
0
I - ’
z
0
x
-J
C i )
U -,
x
z
U
-J
z
0
0
I.-
zo
UN
0
U
0
0
0
0
0
0
0 7 14 21 28 35 42 49
TIME (DAYS)
-C
192
-------
Biodegradation of cnlorobenzene was observed in both of the
activated sludge studies and was evidenced by maasured mass fluxes out
of the bioreactors (effluent and off—gas fluxes combined) whlth were
significantly less than the measured luent fluxes. This
disappearance of chl robenzene averagen greater than 80% during
steady—state operating periods. The eff ct of biodegradation is
illustrated by the differences between measured effluent and off—gas
data points and the dashed lines in Figures 10—65 and 10—67. While
recoveries of chlorobenzene in baseline studies without activated sludge
averaged approximately 95%, the maximum recoveries in the activated sluage
studies of 50 to 55% on Day 1 indicated t iere was an immediate, partial
acclimation of tne activated sludge microorganisms to chlorobenzene.
The acclimation period lasted between two and three weeks during which
time the amount of chlorobenzene biodegraded increased from 507. on Day 1
to steady—state levels of greater than 80%. Effluent and off—gas
concentrations were both reduced by similar emounts which averaged
approximately 80%. Since the off—gas flux represented nearly 95% of the
total flux out of the reactor, the primary effect ‘f biodegradation was
a reduction ip the amoant of chlorobenzene stripped to the atmosphere.
The two activated sludge studies were continued for at least five
weeks after the initial acclimation periods. Average effluent and off—gas
concentrations during the steady—state period in the 6—day SRT study
were 1.1 ig/t and 184 ag/i, respectively, conpared to values of 7.4 ug/&
and 911. ng/i which would have occurred if chloroben.ene had not been
degraded by the activated sludge microorganisms. Similar results were
recorded during the 12—say SRT study; effluent and off—gas
concentrations averaged 1.0 jg/L and 169 ngIL, respecrively, coiçared to
values of 6.7 and 832 predicted to occur in the absence of chlorobenzene
biodegradation. The conparison of results from the two studies in
Figure 10—69 sh s there was no significant differt nce in the fate uf
c’ lorobenzene in activated sludge maintained at 6 and 12—day solids
retention times. Summaries of average influent, effluent and off—gas
concentrations are tabulated in Table 10—21.
Effluent and off—gas fluxes averaged from the two studies
accounted for approximately 0.8 and 17.8%, respectively, of the influent
mass flux; the remaining 81.47. was removed by biodegradation by the
activated sludge. Table 10—22 summarizes the steady—state mass flax
data depicted in Figures 10—66 and 10—68.
Chlorobenzene volatilization in the 10—liter bicreactors was
sufficiently characterized to enable off—gas concentrations and N/No
values to be accurately predicted from measured effluent ‘ oncentra—
tions. As shown by the comparisons in Figures 10—70 and 10—71, values
predicted by the air—stripping model agreed ‘ell with the measured
data. As an illustration, the predIcted off—gas concentration for
the 6—day SRT study was 147 ugh, and the measured value was 184 ugf 1.
The model predicted an era1.1 chlorobenzene removal for that study
of 84% while the measur u value was 82%. Similar agreement between
predicted and measured ,alues occurred for the 12—day SRT study.
193
-------
F-.’
-j
-j
z
0
w
-j
0
z
v)
0
0
z
z
TIME (DAYS
FIGURE 10—69. Comp risc’n of influent. effluent, and off—gas
concenttatLOflS and fracrional recoveries. N/’o, from
chlorobenzefle activated sludge studies conducted ich 6 and 12—
day solids retention times.
56 63 70
N
C,
C,
N
: 4
0 7 14 21 28 35 42 49
194
-------
1 ARLF 10—2 I
h1? ThlAIlY 0l SI’FADY—STI. l’E AVI l A( :i: ClIl.COlflllrN/I.NE (:ON(:rN I Il 41 I ONS
Il (IM A(:TIvA’IEI) SIAlIu;l . IIIfll lACIoi 51111)! rs ONl)ll( I I U WIIU
6 AUI) I 2—UAY .R
m l 1 iiint ri Fluent 01 f—( . N/N Rernov i I
(u/I) (u / 1) (ugh) (7.)
6— UAY ‘,R I’
Nea’,iired 133.4 (2I.6) 1.1 (0. 1) 184 (57) 0.18 (0.03) 82 (2.9)
I’, eiI I toil if no Iii odagratlatlon — — 7.6 (I . I) 911 (I 6/i) 1.00 (0.0) 0.0 (0.0)
I’redii Intl 1Ii)flt c l i Itient ——— I’s? (42) 0.16 ( 05) 8’ . (5.1)
12—l )AY sor
Me.mtired 1 70. / i (27. 3) 1.0 (0.5) 169 (82) 0.18 (0.03) 82 (3.0)
I red I i nil II no U I clegratl:it I on 6. 7 (I . 2) 8 32 (ui 6) I .00 (0.0) 0.0 (1)0)
l’redlttcd 1mm effluent ——— 126 (60) 0.15 (0.05) 85 (5.0)
+ Niiniltt rs I n pa rent lieses are st . niI m rtl ilevi at inns
-------
0
—S 0
C,
0
z
Li
-j
L I-
-
—0
0
C,
LL
La 0
LJO
0
0
—S
-J
z*
5
U,
<0
0
0
0
0
Zu)
z
0
0
0 7
TIME (DAYS)
FIGURE 10—70. Eperi er.tal data pr,ints and off-gas con—
centrati.ons and fractional recoveries, N/so. çredicted from
tneasured effluent concentrations from the 6—day SRT activated
sludge study w th chlorobenzene.
0
O MEASURED DATA POLNTS
PR D CT D FROM EFFLUENT
-i
0
S —
— m
S d —
Os’
-‘0
‘0 0
I
* I
14 21 28 35 42 49 56
196
-------
C’
0
C..’
0
C)
0
0
C
0
0
0
0
w
C
0
0
C )
0
0
‘I,
0
0
0
O MEASURED DATA P NTS
FROM EFFLUENT
—— PREDICTED
D
‘
0
‘
‘
C
%
D -
ii
‘
I
0/
—‘
I
\ 0
‘0
I I I I
--
———-0—
I I— I
)
_____ -
TiME (DAYS)
FIG 1RE 10—71. E:çeritiental data points and off—gas con—
centratlcns and fractional r overieS, /‘ o. predicted from
measured effluent concentratio S frci the 12-day SRT activated
s1udc c stud’: with chlorobenzene.
-J
0
I —
z
w
-J
U-
z
-J
0
U-
U-
U
-J
C-)
z
(1
4:
Cf
I L .
Lj
0
0
z
z
197
-------
TABLE 10-22
FATE OF CI{LOROBEN2 N DURING
StEADY-STATE Z IODEGRADATION BY ACTIVAThD SLUDGE
Percent of Influen: Flux
6—Day SRT 12—Day SRT
Effluent 0.8 0.8
Off—Gas 18.5 17.2
Btodegraded 80.7 82.0
Blosorbed 0 0
21—56 26—70
10.5 DFTCKMINATION OF BIODEGRADATION RATE COEFFICIENTS
Tvo methods were used to quantify the biodegradation rate
coefficients for the biode :radabJe compounds. The first procedure
1nLoruora ed data from the continuous flow bli, eactor studies into a CNF
rea t r mass balance equation which included vo1 tilization and
biodrgradation terns. The second approach invol’ed directly measuring
the reTov . 1 of r 1 toxic compounds in batcn rate studies with accitmated
activated sludges.
10.5.1. C”F 3ioreaccor iass Balance Approach
me mass balance equation for a biodegradable compound in a CNF
reactor under conditions of steady—state can be written as
Q C. = Q C + Q C + VC k. Q C K 9 (10-4)
ii ee gg eb seps
mass mass mass mass mass sorbed on
entering = leaving in + .eaving in + removed + solids removed
reactor affluent off—gas die :.o bio— in waste sludge
degradation
Background equilibrium studies showed that sorption of the biod. gradab1e
compounds by the activated sludge biomass was not significant for the
low concentrations used in the activated sludge bicreactor stuales.
Eliminai .ing the sorptio.i term, dividing boto sides ‘,y the influent f1ux
QjC 1 , recognizing that Qj = Qe and rearranging gives
VCekb Q C+Q C
1 (10—5)
QjC 1 Q 1 C 1
198
-------
The term (QjCe+QgCg)/Qj i is the fractional recovery of a compound which
has been repre5enced by N/N 0 . Substituting N/N 0 in Equation 10—5 yields
VC
—f—— 1 - N/N 0 (10—6)
QjC 1
Rearranging and .ubscituting t = V/Qj, Equation 10—6 can be written as
— 1—N/N 0
tkb (10—7)
Ce / C 1
Substituting fur Ce/C i by Eauation 9—26 yields
tkb
= 1 — N/N 0 (10—8)
l+E(kb+kv)
Solving [ or kb
(1.’t)(l+tk, ) — —
— (1/t)(l+tk ) (10—9)
Biodegradation rate coefficients for each biodegradable compound
were caiculated by Equation 10—9 for the single solute activated sludge
studies and summarized in Table 10—23. The biodegradation and
voiati1tz tion rate coefficients reported in Table 10—23 represent the
averages of rate coefficients calculated eath day bioreactor samples
were collected during steady—state biodegradation periods. Rate
coefficients determined during the two to three week acclimation periods
a d upset periods of low toxics removals were not Included in the
calculations.
The results in Table 10—23 show, that for a given compound, there
was not significant variation ir. cne calculated biodegradation rate
coefficient, kb. as a function of solids reterttion time. S’ ch a result
was anticipated since there were no significant differences ii overall
removals from acti”ated sludge studies conducted at different SRT’s.
Values of kb for benzene varied between 0.43 an! 0.49 nin 1 for SRT’s
ra’tging from 3 to 12 days. The range of biodegra4ation rate
coeif5cients calculated for the other biodegradable cnnpounds was:
toluene, 0.42 to 0.45 min 1 ; ethylbenzene, 0.37 to 0.43 mln’; o—xylene,
0.20 to 0.28 min ; chlorobenzene, 0.26 min ; l,2—dichlorobenzene, (‘.017
199
-------
TABLE 10—21
FIRST ORDER BIOI)ECRADATION RATE COEFFICIENTS
CALCULATCI) I ROM CMF REACTOR MASS BALANCES
Compound Solids Retention Riodi gr.idation Rae Volatilization Rate Overall
Time (days) Coefficient, kb (niln’) Coeffic1t iiL, k (mLn _ l)* Removal ( )
Benzenc 3 0.43 (0.07) 0.081 (0.002) 84
0.43 (0.12) 0.075 (0.002) 83
12 0.49 (0.15) 0.075 (0.004) 86
Toluene 6 0.45 (0.10) 0.078 (0.003) 83
12 0.42 (0.13) 0.077 (0.005) 83
Ethylbenzene (EB-ASI) 6 0.37 (0.06) 0.091 (0.006) 80
(EB—AS2) 6 0.43 (0.13) 0.087 (0.004) 81
12 0.43 (0.11) 0.087 (0.004) 82
o—Xylene (XYL—AS1) 6 0.28 (0.07) 0.062 (0.002) 80
(xYL—AS2) 6 0.20 (0.05) 0.060 (0.002) 76
12 0.21 (0.06) 0.060 (0.003) 75
Chloroben?ene 6 0.26 (0.04) 0.050 (0.OOL) 82
12 0.26 (0.07) 0.052 (0.004) 82
Nitrobenzene 6 0.12 (0.02) 0.0Ol 97
6 0.09 (0,01) 0.O01 96
1,2—Dichlorobenzene 6 0.017 (0.004) 0.02’i (0.001) 36
12 0.018 (0.007) 0.026 (0.001) 38
* Calculated from Equation 7—2
-------
to 0.018 mir ; and nitrobenzene 0.0 to 0.12 min . The fol1 ing
decreasing order of values for the biodegradabl.e cor ounds was
o bs e r d:
benzene toluene ethy .benzene > o—xylenc ci;loroot-enc
> nitrobenzene ) l,2-dtchlorobenzene
This order was slightly different than the order of overall removals:
nitrobenzene > benzene = toluene > chlorobenzene = ethylbenzene
> o—xylene > 1,2—dichlorobenzene
Biodegradrtion rate coefficients calculated by Equatlokl 10—9 from
N/N 0 values (or overall removals) arc a function of the volatilization
rate coefficient, k.,. For a given N/N 0 value the larger the
volatilization rate coefficient, the larger the biodegradatinn rate
coefficient must be to accomplish the same level of removal. Assuming
the amount of each compound bioaegraded during activated sludge
treatment averaged 80%, the data in lable l0—2 illustrates that as the
compound volat lity increases, the rate of biodegradation also
t’ reases. The ratio kb/k 3 , where k 0 = kb + k, ,, is approximately 0.80
for each compound,exceot 1 .2—dich.orobenzene and nitrobenzene,in Ta’ile
10—24 indicating that biodegradation accounts for 30% of the reduction
in aqueous concentration. This explains why the biodegradation rate
coefficient of rhlorobenzene was cons de ab1y smaller than tnat of benzene
even though the amount of each compound biodegraded was approximately
the same. The same cplanation applies to the extremely different
positioning of nitrobenzen. in the relative orders of overall reiiovals
and biodegradation rate coefficients. while the amount of niLrobenzene
removed by biodegradatIon was the largest, its biodegraoation rate
coefficient was the 3mallest of the six highly biodegradable compounds.
Nitrobenzene was otily slightly volatile in the experimental sistem; its
volatilization rate coefficient (estimated) was approximately two orders
of magnitude less than those of benzene. toluene, and ethylbenzene.
Therefore, the biodegradation i ite coefficient required to effect overall
remc ,als in excess of 95% was •,roximately one—fourth the value of
those calculated for the volatile compounds.
Although all of th activated sludge studies were conducted w .th
aeration rates in the range of 3.5 to 4.5 i./min, the average aeration
rate of individual studies varied prom study to study. Table 10—25
illustrates the sensitivity of the model ‘tsed to calculate kb to
variations in the aeration rate coefficient. The examples were
calculated for benzene assuming a 5.5 hour mean hydraulic retention time.
An increase in aeration rate from 3.5 to 4.5 resulted in an increase
in kb from 0.39 to 0.49 min 4 for an overall removal of 85%.
Another operating parameter that entered jnto the model to
calculate kb was the hydratslic retention time, t. Aa Table 10—26 shows,
variations in t, from 4.5 to 6.5 hours, did not have an effect upo’ the
calculated valuec of kb. The examples in Tabla 10—26 ‘ere calculated
assuming an 85% overall retn val of benzene at an aetation rate of 4.0
9/min. The range of mean nydraulic retention times was between 5.5 and
6.0 hours during the continuous flow studies.
201
-------
TABLE 10—24
EFFECT OF INCREASED VOLATILITY ON BIODEGRADATION
RATE COEFFICIENTS OF C0 IPOUNDS WITH
THE SA OVERALL RE VALS
+ -4-4-
Ompound Ramoval kb
(2) (mln ) (ciin )
Ethylbenzene 80 0.086 0.35
Toluene 80 0.078 0.32
Benzene 80 0.074 0.31
o—Xylene 80 0.059 0.25
Chlorobenzene 80 0.050 0.21
1,2—Dichlorobenzene 80 0.026 0.03
Nitrobenzene 80 <0.001 0.02
+ Calculated by Equation 7-2 for a 6.0 liter/mm
aeration rate
4-4- Calculated by Equation 10—9 for a 5.5 hour
202
-------
TABLE 10—25
EFFECT OF AERATION RATE ON THE
BIODEGRADATION RATE COEFFICIENT OF BENZENE
(t 5.5 lir)
Removal Aeration Rate + kb
(Z) (i/mm) (rnin ) (nin 1 )
85 3.5 0.065 0.39
85 4.0 0.074 0.44
85 4.5 0.084 0.49
+ Calculated by Equation 7—2
++ Calculated by Equation 10—9
TABLE 10—26
EFFECT CF HYDRAULIC RETENTION TINE ON THE
B1ODEGRA )ATION RATE COEFFICIENT OF BENZENE
(4.0 i/mm Aeration)
RemovaJ t + kb
(%) (hrs) (min’) (min ’,
85 4.5 0.074 0.44
85 5.0 J.07. 0.44
85 5.5 0.074 0.44
85 6.0 0.074 0.44
85 6.5 0.074 0.44
+ Calculated by Equation 7—2
#1- Calculated by Equation 10—9
203
-------
[ 0.5.2. CMB Biodegradation Rate Studies
Completely—mixed batch biodegradation race studies were conducted
with and without aeration as detailed in Section 5. These studies were
conducted for two purposes: 1) to confirm that the disappearances of
the toxic organic compc’unds observed in the CMF bioreactors were due to
biodegradation; and, if) to independently measure biodegradation rate
coefficients for selected organic compounds. Batch degradation studies
were conducted with the biodegradable compounds benzene, coluene,
ethylbenzene, chlorobenzene, and nitrobenzene.
10.5.2.1. Non—aerated CMB Biodegradation Studies
Batch biodegradation rate studies were conducted without aeration
to study the biodegradation of microgram—per—liter concentrations o the
volatile compounds bcnzene, chlorobenzene, and ethylbenzene. A
2.6—liter glass reactor equipped with a lid ‘as used for the batch rate
studies, and mixing was accomplished with a magnetic stir bar.
Descriptions of the experimental system and procedures were giveti in
Section 5.
Data from the CMB biodegradation rate studies without aeration was
rno’Ieled as an overall first order removal process which can be
de .cribed by
dC
— —— kbC (10—10)
dt
Values of kb, th€ biodegradatt n rate coefficient, were obtained from
the slope of the ieast—squares linear regression line for data plotted
as the logarithm af concentration versus time.
An initial series of control studies were conducted in de1onized
distilled water to evaluate what effect volatilization and adsorption
onto the walls of the batcr. reactor had on the removal of each compound
from the 2.62. CMB reactor. Control studies were conducted under the
same conditions as the biodegradation studies with activated sludge.
Results of those studies sha.ied negligible removal attributable to
volatilizat ion and adsorption onto the reactor. A second set of
badc.ground studies was conducted with activated sludge treated with
HgC1 2 to inhibit biological activitiy, as measured by dissolved oxygen
uptake. Those studies were conducted with three compounds: benzene,
ethylbenzene and chlorobenzene. Initial concentrations were between 40
and 65 ugh, and the test results shcA ied no measurable change in the
aqueous coflcentration of each compound over the thirty in nute sample
period. This finding indicated that aorpclon of the biodegradable
compounds by the activatea sludge biomass was not significant and would
not affect he aqueous concentration.
204
-------
Results from four benzene studies, three toluene studies, one
ethylbenzene study and one chlorobenzene study are presented in Figures
10—72 through lO-bO. Each figure is a semi—logarithmtc plot of
concentration versus tire data fram one non—aerated, biodegradation rate
study with activated sludge from an acclimated activated 3ludge
bioreactor. Fol1 ing each figure is a stanmary of the results, fables
10-27 through 10—35, from the bl ,odegradation study, operating conditions
for the bioreactor from which the activated sludge was obtained, aod a
comparison of measured effluent end off—gas concentratior.. to
concentrations predicted usl-g the biodegradation rate coefficient
determined in th ,atch biodegradation rate study. Predicted effluent
and of [ —gas concentrations were calculated from equations lescribed in
Sections 7 and 9. The effluent concentration, C , , was calculated by
Cj
Ce
lt [ (QgL+k.,,,o)+kbJ S (10—11)
in which the aeration rate, Qa, is equal to the off—gas flow rate Q...
The off—gas concentration, Cg was calculated by
Cj(Qg L+k ,o )V/Q
C — ——— (10—12)
g
l+ [ (QgL+kv ,o)+kblt
Overall removals were determired from a CMF reactor mass balance
approach
CeQe4CgQg
Removal (7.) 1 ——— x 100 (10—13)
Q 1 C j
in which Qi = Qe. An overall summary of the biodegradation rate
coefficients from the non—aerated C iB uiodegradation SLU3ieS is
presenteG by Table 10—36.
The four biodegradation rate studies in Figures [ 0—72 through
10—75 for benzene show that the first order removal rate codel adeque : y
described the biodegradation data. Least squares lin. ar regression
coefficients rsnged from 0.978 to 0.995. Removal of benzene was very
rapid in each case with a 507. re iction in coicentration occurring
within approximately five minutes. The background TOC in each case was
between 12 and 18 mg/i and represented the effluent TOC from the
bioreactor from which the acclimated sludge was withdrawn.
biodegradation rate coefficients for benLene measured in the batch
degradation studies were rearly identical to the rate coefficients
calculated from a c r reactor mass balance using measured influent,
effluent, and off—gas concentrations. As shown in Tables 10—27 through
205
-------
4 BENZENE BIODEGRADATION
4 ACCLIMA iED ACTIVATED SLUDGE
r ¶ \ 2.6—hter C?A8 Ruoctor
4 \ Without Aeration
I \ Run EIO—BZ1
I1 3+
C ,,
x
— C,.
Lfl
TIME (MINUTES)
FIGURE 10—72. Experimental data and best—fit line
describing benzene biodegradation by acclimated activated
sludge j a completely—mixed batch (CMB) reactor without
aeration. (Acti’,ated sludge from the 6—da, SRT benzene
biore2ctor study.)
-J
z
0
4:
z
LU
(-)
z
0
0
C,,-.
0
0 4 8 12 16 20
206
-------
TA IE 10-27
RESUlTS FR 4 2.6—LITER CMB BIC EGRADATION
RATE STUDY WIThOUT AERATION
CMB BIWEGRADATION RESUlTS
Solute: Ben ene
Activates S1 dge Source: Acc1i t Activatal Sludge
6—day SET
Run: BI0—BZJ
kb (mm’): 0.224
Corr. Coef.: 0.978
C) DIOREACTOR OPERATING CONDITIONS ON TEE
DAY OF ThE BIODEGRADATiON STUDY
lofluent (ugh) 116.2
Effluent (ugh) 0.5
Oft—Gas (ng/1) 197
0.23
0ve a .1 Re val 77
kbP Calc?latst (mm ) 0.26
k (mm ) 0.074
QV (litexsln 4 in) 4.0
(hrs) 5.6
MISS ( g/l) 3440
PREDICTED EFFLI NT, 0FF-GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURFD IN CMS STUDY
Effluent (ugh) 1.2
Off—Gas ( g/1) 215
NIN 0.26
Ove?all Ren val (Z) 74
207
-------
BENZENE BtODEGRADAT1QN ±
ACCU TED ACTIVATED SLUDGE
2.6—titer CMB Reactor
Without Aeration
Run BtO—6Z2
I”
—J
0
z
0
<
z
LiJ
U,.
z
0
C-)
4 - 8 - t
TIME (MINUTES)
FiGURE 10—7 3. Ex-perimencal data and best—fit line
describing betizene biodegradation by acclimated activated
sludge in a completelv— iixed batch (O B) reactor without
aerat on. (Activated sludge froa the 6—day SRT biore ctor
study with berizene.)
208
-------
TAB1 10—28
RESULTS FRQI 2.6—LITER CKB BI EGRADATION
RAfE STUDY WITHOtTT AERATION
CMB BI EGRADATION RESULTS
Solute: Benzene
Activatal Sludge Source: Acclimat d Activat S 1 udge
6—day SRT
Run: BIO—BZ2
—1
(mm ): 0.28
Corr. Coef.: 0.995
C)’ BIORE CTOR OPERATING CONDITIONS ON TUE
DAY OF THE BIODEGRAflATION STUD?
Icfluent (ugh) 516.9
Effluent (ugh) 3.4
Off—Gas (ng/l) 617
N/N 0.17
Ove a1l Re va1 (U 1 83
1 kb’ Calc?lat 1 (mm ) 0.39
k (i in ) 0.076
(1 ite Imm) 4.1
t (bra) 5.6
MLSS (z ig/I) 3760
pR&)ICr D EFFLL NT, OFF-GAS ANT) OVERALL TOXICS
R (0VAL USING kb MEASITRFD IN CUB STUD?
Effluent (. .g/l) 4.3
Off—Gas (nghi) 802
N/N 0.22
0ve’ a1l Retxuv l (U 78
209
-------
— T BENZENE B ODEGRADAT ON
ACCLIMATED ACTIVATED 3LUDGE
2.6—liter C)4B Reactor
Without Aeration
Rwi BIO—8Z3
C.) —0)
- I-
z
o
I—
z
LU
z--
O a
o
U,
— 0 4 8 12 16 20
TIME (MINUTES)
F1G RE 1O—7 ’. Experimental data and best—fit line
describing benzene biodegradation by acclirtated activated
sludge in a conpletely—m.1\ed batch (CIB) reactor without
aeration. (Activated sludge was from tn 6—day SRI bicreactor
study with benzene.)
210
-------
TABLE 10-29
RESULTS FR I 2.6—LITER C 1B BI EGRADATI0N
RATE STUDY WITHOUT AERATION
CMB BICVEGRADATION RESULTS
Solute: Benzene
Act vat I Sludge Source: Acclinat 1 Activata Sludge
6.-day SRT
Run: BIO—BZ3
—1
kb (mm ): 0.58
Corr. Coef.: 0.993
CW BIOREACTOR OPERATING CONDITIONS ON THE
DAY OF THE BIODEGRADATION STUDY
Influent (ugh) 140.2
Effluent (ug/ ) 0.5
Off—Gas (ng/l) 112
N/N 0.11
0
Overall Reinval 89
kb, Cilc 1atu1 (mm ) 0.62
k (mm ) 0.074
V
(lmtezs/nm) 4.0
t (bra) 5.6
MLSS (mg/ I) 3310
PR})ICT FLUENT, 0FF-GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURU) IN CMB STuDY
Effhzent ( ig/l) 0.6
Off—Gas (ng/l) 111
N/N 0.12
O ,e?al1 Reux,val (Z) 88
211
-------
BENZEP JE BIODEGRADATION
ACCLIMATED ACT /ATED SLUXE
2 6—titer CMB Reactor
U) \ Without Aerthion
\ Run BIO—BZ4 (1.2—Day SRI)
-J
z
0
4:
z
w
C
z---
O °
C)
U)
in
I ’ .
0 4 8 12 lb 21)
7 ’
TIME (MINUTES)
FIGURE 10—75. ExperimentaL data and best—fit l ne
describing beizene bLodegradacion b acc1i ated acdvated
sludge in a completelv—mixea Datch (C ) reactor without
aeration. (Activatec, slLdre was from t e 12—day SRT biorector
srud with benzene.)
M
— 0 )•
U).
U).
In -
0
N
0
212
-------
TABLE IG—30
RESULTS FRC?I 2.6—LITER CMI3 B1 )ECRADATION
RATE STUDY WITHOUT AERATION
CMB BIcDEGRADATION RESULTS
Solute: Beuzene
Activatul Sludge Source: Acclimatel Activat Sludge
12—day SRT
Run: B O—BZ4
kb ): 0.57
Corr. oef.: 3.979
CW BIOREACTOR OPERATThG CONDITIONS ON TILE
DAY OF THE BIODEGRA .)ATION STUDY
Influe t /i) 112.2
Efflu it tug/i) 0.3
Off—Gas (rig/i ) 91
N/N 0.11
Ove all Rea val 89
kb, Calcylataf (IEI.n ) 0.55
k (mm ) 0.0 T h
QV (litem/min) 3.5
t (hrs) 5.6
MLSS (mg/i) 5890
PREDICTED EFFLUENT, 0/F-GAS AND OVERALL TOXICS
R OVA1 USING kb MEASURED IN CMI STUDY
Effluent ( jgI1) 0.5
Off—Gas (ngIl) 97
N/N 0.12
Ove all Retroval (Z) 88
213
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10—30, there was quite good agreement between predicted and ruaasured
effluent and off—gas concentrations and overall removals. The
s rni1arity between prediLted drd observed values held for bioreactors
receiving influent concentrations ranging from 100 to 500 jig/i. 2acch
degradation studies Bl0—BZ1, BlO—BZ3, and hl0 —5Z4 were conducted with
activated sludge from acclimated activated sludge bioreactors receiving
influent benzene c’,ricentrations averag’ ng about 100 jig/i. Study Bl0—BZ2
was per orined with activated sludge frcm a bioreactor with inflaent
concentrations between 500 and 550 ugh at the time the batch study was
conducted.
Figures 10—74 and 10—75 are results of biodegradation rate studier
with benzene run on consecutive days with acclimated sludge from 6—day
and 12—day SRI bioreactors, respectively. As previously described the
overall removal f benzene from the 6 and 12—day SRI units was similar.
The biodegradation rate coefficients for the 6 and 12—day SRI activated
sludges measured itt the 2.6—liter NB reaLtor studies were approximately
the same, confirming the simIlarity .n biodegradative benzene removal
observed in the CNF bioreactors.
Results of three roljene biodegradation rare studies given by
Figures 13—76 through 10—78 are summarized in rabies 10—31 through
10—33, respectively. A1 . three batch degradation studies were conducted
with activated sludge from the same u—day SRT activated sli dge unit.
Stuay BlO—TOL1, Figure 10—76 and Table 10—31, was conducted at the end
of the acclimation phase, and study BlO—TOL2, Figure 10-77 and Table
10—32, as conducted well into steady—state toluene biodegradation
phase. Agreement between measured and calculated toluene biodegradation
rate coefficients was not as good as occurred for benzene. In the
firrt rate stidy the measured v .1ue was only about one—half the
coeft cjent valuo calculated from the CMF bioreactor data. As a result,
the amount of toluene predicted to be degraded was only 65% compared
with a measured value of 76%. Agreement between the rate coefficient
calculated from the C1F biorcactor data and the measured value obtained
in the CMB reactor was better in the second biodegradation cate study.
The measured value was 0.26 min 1 . The model predicted effluant and
off—gas concenLrations of 0.7 jig’Q. and 139 nghi, respectively, while
the observed values were 0.6 jig/i and 96 ng/Q., ‘espectively. Although
the value of kb differed by more than 30% the difference betwecn
predicted and observtd overall re ’novals, 76% and 82%, respectively, was
small. The reason that considerably different 1 q, values can result in
similar overall removals is attributable to the character of tne
first—order removal mode. 0vL rall removals io the 76 to 82% range fall
on that portion of the exponential curv’ relating kb to overall removal
where large incremental increases in kb are requi:ed to effect small
increases in percent removal.
Data presented in Figure 10—78 and Table 10—33 were obtained during
a temoorary upset period in the activated sludge bioreactor. The
overall toluene removal rneasured in the biorea tor on the day the
batch degradation study was conducted was about 59%, resultthg .n
a calculated biodegradation rate coefficient of 0.116 min . Data from
Table 10—15 indicates that removal of toluene averaged more than 83 over
the steady—state operating period. Results from the batch degradation study
214
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a
—0 ,
I —i.
crm
N°
0
z
0
< 0)•• 0
z
LiJ ‘°
0
z
0
0 TOLUENE BIODEGRADATION
C’) ACCLIMATED ACTIVATED SLUDGE
2.6—liter CM8 Reactor 0
Without Aeration
c Run 610—lOLl
0 4 8 12 16 20
TIME (MINUTES)
FIGURE 10—76. Experimental data and best—fit line
describing toluene bicdegradation by acclimated activated
sludge in a completely—mixed batch (C 2) reactor iithout
aeration. (Activated sludge was frorn tne 6—day SRT bioreactor
study with toluene.)
215
-------
TABLE 10—31
RESUIIS FR I 2.6—LITER CMB BIC )EGRADATION
RATE STUDY WITHOUT AERATION
CMB BIcOEGRADATION RESUI2 S
Solute: Toluene
Activatel Sludge Source: Acclinat Activates Sludge
6—clay SRT
Run: HO-TOLl
kb (mm ): 0.15
Corr. Coef.: 0.956
C BIORE CTOR OPERATThG CONDITIONS ON THE
DAY OF THE BIODEGR.ADATION STUDY
Influent (ugh) 98.1
Effluent (ugh) 0.4
Otf—Gas (ngfl) 170
N/N 0.24
0
Overall ReuDval 76
kb . Ca1c 1at i (nun ) 0.26
k (mm ) 0.078
(1ite /min) 4.0
t (hrs) 5.6
MLSS (‘ng/l) 3250
PR ICTTh EFFLUENT, OFF-GAS AND OVERALL TOKICS
REMOVAL USING kb MEASURED IN CMB STUDY
Effluent (I -ugh) 1.3
0ff—Gas (ng/l) 247
N/N 0.35
Ove al1 Renoval (Z) 65
216
-------
TOLUENE BIODEGRADATION
\ ACCLIMATED ACTIVATED SLUDGE
- \ 2.6—liter C 48 P.ecctor
- P \ Without Aeration
Run BiO—10L2
Lfl
0
Z \ D
0
< 0
I-
w
0
z 0
0
0
C,,.
0
0 4 8 12 16 20
TIME (MINUTES)
FIGURE 10—77. Experir ental data and best—fit line
describing toluene biodegradation Sv acclimated activated
sludge in a completely—nixed batch (c ) reactor without
aeration. (Activated sludge was frc mn t e ó—dav SRI bioreactor
study with toluene.)
217
-------
TABLE 10—32
RESUI S IRCI4 2.6—LITER CNB BIODEGRADAT!ON
RATE STUDY WIThOUT AERATION
CMB BIWEGRADATION RESULTS
Solute: Toluene
Activataf Sludge Source: Acclimat Actj vat Sludge
6—day RT
Run: BIO—TCL2
—l
kb (m iii ): 0.26
Cor:. Coef.: 0.982
C} ’ BIOREIICTOR OPERATING CONDITIONS ON ThE
DAY OF TRE BIODEGRADATION STUDY
Influent (ugh) 85.7
Effluent (pg/I) 0.6
Off—Gas (ng/1) 96
N/N 0.18
Ove all Renoval 82
kb . Calcylatat (mm ) 0.38
k (mi i i ) 0.079
9” (iite /mi.n) 4.1
t (hrs) 5.7
MLSS (mgI!) 3170
PREDICTFD EFFLUENT, OFF—GAS AND OVERALL TOXICS
REMOVAL USING MEASURFD IN CR3 STUDY
Effluent (pg/i) 0.7
Off— as (ng/l) 139
N/N 0.24
0 —
Overall Ren va1 (4,) 76
218
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o,- TOLUENE BIODEGRADATION
- ACCLIMATED ACTIVATED SI UDGE
2.6—liter C 3 F eoctor
• Without Aeration
Run BIO—TOL3 (upset period)
0
U
t
0 4 8 12 16 20
TIME (MINUTES)
FIGURE 10—78. Experit enta1 data and best—fit line
describing toluene biodegradation by acclirrated activated
sludge in a cornvlerelv—mixed batch (01B) reactor without
ration. (Activated sludge as taken during an upset period
in the 6—day SRI bioreactor study with toluene.)
219
-------
TABlE 10-33
RESUI2’S R(X1 2.6—LITER CMB BIC EGRADATI0N
RATE STUDY WITHOUT AERATION
CMB BIWEGRA AT1ON ESUJ2S
Solute: Toluene
Activatel Sludge Source: Acc1itnat Act vatcd Sludge
6—day SRT (Upset Per od)
Run: BIO—TOL3
kb (mm). 0.164
Corr. Coef.: 0.984
CMF BIOREA ?UR OPERATING CONDITIONS ON THE
DAY OF TRE BIODEGRADATION STUDY
Influent (ugh) 100.6
Eff1u. nt (ugul) 1.1
Off—Gas (ng/l) 301
N/N 0.409
0
Overall Revxval
kb , Calc 1 ilate’J (mm ) 0.116
k (mm ) 0.078
Q” (liter /uu.n) 4.0
t (hrs) 5.6
MLSS (mg/I) 3540
PR}DICT D EFFLUENT, OFF—GAS AND OVERALL TOXICS
REMOVAL USING k. 0 MEASURED U CMB STUDY
Effluent (iig/i) 1.2
Oft—Gas (ng/1) 238
N/N 0.33
0
Overall Resoval (2) 67
223
-------
yielded a rate coefficient of 0.164 cn.in 1 . Effluent and off—gas
concentratin s predicted for kb = 0.164 ain were 1.2 ugh and 238
ng/L, respectively, which conpared favorabLy with the measured values
of 1.1 ugh and 301 ng/i. ft e predicted overall removal of 61% was
alightly larger than the measured 59%.
R sLlts of the ethyloenzene biodegradation rate study are given by
Figure 10—7 end Table 10—34. The activated sludge was from a
well—acclimated bioreactc..r that had been receiving ethylbenzene for over
thirty days. The overall ethylbei’iene removal on the clay the rate study
was run w.as 827.; the mean value for the whole study was 81%. .\s sh n
by Figure 10— 79, the first order model adequately described ethylbetzefle
ren val in the biodegradation study and gave a rate coefficient of 0.35
min . The biodegraiation rate coefficient calculated from a CMF
reactor mess balance was slightly larger, 0.42 min t . Predicted . ‘nd
measured overall removals were approximately the same; 79 and 82%,
respectively.
The reoul s from the chlorober.ze’ie biodegradation rate study are
plotted in Figure 10—80 and s.minarized in Table 10—35. The
well—acclimated sludge was obtained from the steady—srate op2rating
period of the 6—day SRT chlorobenzene activated sludge study previously
reported. The overaL. chlorobenzene removal of 87% measured on the day
the biodegradation study was conthcted was larger than the average value
for the whole study, 82X. As sh .in in Figure 10—80 the biodegradation
rate data fit the first order removal model, %iving a biodegiadation
rate coefficient of 0.23 min . The value calculated from a CMF reactor
mass bala”ce aoproach was 0.36 min . While the measured removal of
chlorobenzene by biodegradation on the day of the rate study was
somewhat larger than the valie predicted by the 0.23 min rate
coefficient, 87% conpared to 81%, respectively, the predicted value
was aln’ost iclentical to the average removal observed during the
steady—state biodegradation period. 82%. The cortparison ot mociel
predicted and measured effluent and off—gas concentrations in Tab 1 e
10—35 sh ,s that the model providcd an adequate indication of bioreactor
pe:forniance with respect to chlorobenzcne removal.
221
-------
ETHYLSENZENE BIODEGRADATION +
ACCLIMATED ACThATED SLUDGE t
2.6—liter CMB Reactor
Without Aeration
Run BlO—EB1
1
-r
C ,,..
_J -
0
z
0
—
F— ;-— -
<—C,..
I—
z
LU ‘°
0
C
C ’,.
0 4 8 12 16 20
TIME (MINUTES)
FIGURE 10—79. Experi.rtental data and best-fit line
describing eth lbenzene biodegradation by acc)imated
activated sludge in a con plete1’i—mi’ed batch (CXB) reactor
without aeration. (Activated s1ud e w3s fr ri the 6—day SRT
biorcactor study with ethylbenzene.)
222
-------
TABLE 10—34
RESUIZ’S FRON 2.6—LiTER CMB BIC DEGRAD. TI0N
RATE STUDY WITHOUT AERATION
CMB BI EG ADATI0N RESUIIS
Solute: Ethylbeozene
Act vat Sludge Source; Acchmat Activatel Sludge
6—day SRT
Run: BlO—EB1
kb m ): 0.35
Corr. Coef.: 0.990
CW BIOREP T0R OPERATThG CO1 DITI)NS ON THE
DAY OF THE BIODEGRADATION STJDY
Influent (ugh) 120.0
Effluent C..gli) 0.6
Off—Gas (ng/l) 160
N/N 0.18
0
Overall Renz, al (Z) 1 82
kbl Calc lat ( mm ) 0.42
k (na ) 0.092
QV (liter Imin) 4.4
t 8 (hrs) 5.6
MLSS (mg/I) 3290
PR DICT D EFFLUENT, OFF-CAS AND OVERALL TOXICS
REMOVAL USING MEASURID IN CMB STUDY
Effluent (ugh) 0.8
0ff—Gas (ng/l) 174
N/N 0.21
0ve’ a11 Re val (%) 79
223
-------
(N
x
-o,t
I - .
to. -
-C . ).
I . -.
(0
I’, ,
0
CHLOROBENZENE BIODEGRADATION
ACCliMATED ACTh’ATED SLUDGE
26—riter CMB Recctor
Without Aerct on
Run O-C51
4
8
T
T
T
-1 -
:1:
12 16 20
TIME (MINUTES)
FIGURE 10—80. ExDerimental data and best—fit line
descrihine chlurob’?nzene biodecradaclon by acclimated
activated sludge in a comp1etelv—mi’ d batch (CMB) reactc’r
without aerarion. (Ac ivared sludge as from the 6—dab SRT
biureactor study with chlorobenzene.)
(I )
C.,
-J
0
z
0
z
Li
0
z
0
0
0’
224
-------
TABLE 10—35
RESULTS FROM 2.6—LITER CMB BIODEGRADATION
RATE STUDY WITHOUT AERATION
CHB BIODEGRADATIQN RESUL’S
Solute: Chlorobenzene
Activated Sludge Source: Acclimated Activated Sludge
6—day SRT
Run: BI0—CBI
—1
kb (into ): 0.23
Corr. Coef.: 0.989
CMF BIOREACTOR OPERATING CONDITIONS ON THE
DAY OF THE BIODEGRADATION STUDY
Influent (ugh) 110.0
Effluent (Lg/l) 0.6
Off—Gas (ng/1) 93
N/N 0.127
0
Overall Removal (Z) 87.3
kb, Calculated (mm—I) 0.36
kv (into— I) 0.050
Qa (liters/mm) 4.0
t (hrs) 6.0
MLSS Gng/l ) 3780
PREDICTED EFFLUENT, 0FF—GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURED IN CMS STUDY
Effluent ( g/l) 1.1
Off-Gas (ng/l) 140
N/No 0.192
Overall Removal (2) 80.8
225
-------
TABLE 10—36
SUMMARY OF VALUES ME; SURED Ir CMB DEGRADATION STUDIES, MD
CO IPA U ON OF OVERALL ‘ REMO ALS ME.\SURED IN CMF BlOREACTJt S AND
PREDICTED FROM kb V- LUES MEASURED IN 2.6 LFIFR CMB DE(.RADATlO’ SrLDIES
Overall Removdls (%)
Compound kb (min ) M’ asured Predicted
Benzene 0.22 77 74
0.28 83 78
0.53 89 88
0.57 89 88
Toluerie 0.13 76 65
0.26 82 76
0.16 59 67
Chloroben .ene 0.23 87 81
Echylbenzene O.3 79
226
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10.5.2.2. eLated C 1B Biodegradation Studies
A second type of biodegradation study was conducted with acclimated
accivaced s1ud e to measure the rate of removal of s2lected .ompounds
from the 10—liter activated sludge bioreactorr operaced in batch modes
with aeration. The continuous flow bioreac ors were converted to batch
reactors by temporarily stopping influent and sludge waste flows. A
complete description of the experimental procedures was giver’ in Section
5.
Reductions in the aqueous concentrations of organic corr ounds in
10—liter CMB aerated activated 3ludge bioreactors resulting from
biodegradation and volatilizatjor can be described by the first order
e q ress ion:
dC
— —— k C + kbC (10—14)
Upon integration Equation 10—14 can be written 4 n the linearized form
Zn C = fn C 1 — (kv ”kb)t (LP—15)
A pio of logarithm of concentration versus time, t, yields a
slope equal to the overall, removal rate coefficient, k 0 , which
represents the s rn of the biodegradation, k,, and volatilization, k ,
removal rate coefficients, as described by Equation 10—16
= + kb (10—16)
Results from the batch volatilization studies demonstrated that k coulJ
be calculateci for any aeration rate by the relationship
ky, 0 + LQa Ľ1 017)
The biodegradation rate coefficient, kb, was calculated using the slope
of the best fit linear rtuzression line through the data from the aerated
biodegradation studies, k 0 , and the value of calculated from the
aeration rate, calculated as follows:
kb = k 0 — (LQa t•kv,o) (10—18)
Aerated 10—liter CMB biodegradation .tudies were conduc:ed with
three volatile, biodegradable on ,ounds: benzene, toluene, and
227
-------
chloiobenzene. initial to tics concentrationc ranged from approximarely
21) to 101) pg/i. Results from the aerated CMB are given in Figures 10-61
through 10—86. Foll ing each figure is a table containing a stn mary of
results from the rice study and operating conditions for the bioreactor
in which the study wa 3 conducted. ?n overall s ’on’nary of results from
the aerated C B b iodc radaciorl rate studies is presented by Table 10—16.
Results from biodegradation studies with benzene are presented in
Figures 10—31 through 10—84 and sirumarized by Tables 10—37 through
10—40. The first three rat’ studies identified by B10+ALR—3Z1,
810-’AIP.-BZ2, and B10+AIR—BZ)) were conducted in the same activated
sludge bioreactor. 311)+AIR—BZL as run during the second week of the
acclimation phase wh 1e the other tvo studi.es were conducted during the
steaci —state benzene biodegradation phase. The fourth biodegradation
rate 4tudy (B10+AIR—BZ4) was conducted duriflg th multi—solute activated
sludge study, described in Section 10—6, when the influent beozene
concentration was between 400 and 500 pg/i.
The data from the aerated, biodegradation rate studies iith
benzene fit the first—order overall removal model as evidenced by
Linear rcgressio:. coefficients, r 2 , which ranged from 0.997 to 0.999.
As sl’ovn by Tables 10—37 through 10—40, the overall removal rate coeffi-
cient, k 0 , was significantly larger than the volatilization rate coeffi-
cient, k , calcuiated by 1c = kv,o + Qa for the aeration rate used in
the batch study, the rate study conducted during the acclimation phase
yielded the smallest biodegradation rate coefficient, 0.10 min . The
biodegradation rate uoefficients measured during the relatively
steady—state beozerie rei oval period were s.gniftcantly larger and
approximately the same, 0.36 and 0.40 m1r1 1 -. Measured effluent and
off—gas benzene concentraticus were successfully predicted using
biodegradation rata coefficients obta neo from the batch biodegradatton
rate exoeriments, as indicated by the comparisons of maasured and
predicted exi,eriments, in fables 10—37, 10—38, and 10—39. The ratio
of prea cted to neasurea overall removals ranged from 0.85 to
1.09 for the three rate studies.
The fourth batch biodegradation study yielded an overall rernuval
rate coefficient, ‘c , of 0.582 n.in ” . The volatilization rate
coefficient, k , was caiQilated to be 0.084 man based upon the 4.5
1/mm aeration rate. Subtracting k from gave a biodegradation rate
coefficient, kb, of 0.498 sUn”. The ratio kb/ky wr .s approxImately 6.0
in the batch study as volatilization accounted for less than 15 of the
value of k 0 ; the rest was attrilxited to biodegradation. ‘redicted and
measured overall benzene removal in the CMF bioreactor on the day the
batch degradation stt y was run were 87 and 89Z, respectively.
Results from an aerated biodegradation study with toluene were not
plotted, but are sisemarized by Table 10—41. The overall rate
coefficient fo the batch study of 1).434 min ’ was composed of
volatilization and biodegradation components of 0.081 and 0.353 Jo”’,
respectively. The aeratee biodegradation study was conducted in t ’e
toluene 5—day SRI activated sludge bior actor described in. Section 10.4.
228
-------
c’1
N
C’s” BENZENE REMOVAL
1O—LfTER BIOREACTOR —— BATCH MODE
Partiativ Acclimated Sledge
Aeration Rate 4.3 titers/mm
Rw, 8lO+MR—BZ1
—— — 1 -
0 4 8 12 16 20
TIME (MINUTES)
rICURE 10—Si. Ecpertn’ent 1 data and best—fit line
describin heozene re noval by biode rada:ion
and volat:l :atien during a cor.pletel -ni\ed batrh :ace
st’idy in a 10—liter bioreactor wici’ a 4 .3—liter/nin aera 1on
race. (Study was conducted wIth the benzene 6—day SRT
aczivated sluu2e bioreactor.)
229
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TABLE 10—37
RESULTS FROM 10—LITER CMB BIODEGRADATION
RATE E TUDY WITH AERATION
CMB 3IODEGRADATION RESULTS
Solute: Benzene
Activated SludEe Source: Partially Acciimated Sludge
6—day SRI
Run: BIO+AIR—EZ1
k (m .n 1 ): 0.179
Corr. Coef.: 0.998
k (m .n 1 ): 0.079 a 1/mm)
kb (min ): 0.10
CMF BIOREACTOR OPERATING CONDITIONS ON ThE
DAY OF TEE BIODEGRADATION STUDY
Influent (ugh) 86.2
Effluent ( jgIi) 1.2
0ff—Gas (ng/1) 209
N/N 0.35
Ove al1 Removal (Z) 1 65
1%. Cal 9 lated (mm ) 0.154
k (nmn ) 0.080
(liters 1mm) 4.3
i (hrs) 5.6
MLSS (mg/i) 2850
PRt DICTED EFFLUENT 1 OFF—GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURED IN CMB STUDY
Effluent (j ig/i) 1.4
Off—Gas (ng/l) 268
N/N 0.448
Ove all Removal (Z) 55.2
230
-------
- —-—---- — -
c- - BENZENE REMOVAL
-f 1O -LlTER BIORE CTCR —— BATCH MODE
AccUmcter , ct ,.cted Sludge
c c 4 - A6r ion Rata 4.0 titers/mm
Run 6lO+A R-8Z2
-J
z
0
—
1 . — I c
<—C,..
z
U i
C-)
z
0
0
C.,..
—— — - I - —
0 4 8 12 16 2
TIME (MINUTES)
FIGURE 10—82. E> per .mental data and best—fit line
describing benzene removal by bioaegradation and
volati]itatio ’ during a con pietely—mixed batcri rate study
in a 1Q— itcr act1vate sludge bioreact r ‘ .ci a
4.0—1iter/ in a’ration rate. (Study t.jas conducted wi:n the
benzene 6—day SRI activated sludge bir,reactor.)
231 pp Re 0fl
Denver, Co or dQ
-------
co J f c/o
-Ffii
TA3LE 10—38
RESULTS FR0 1 l0—LLThR C B PIODEGRADATION
RATE STUDY WITH AERATION
CNB BI0DEGRADATIOr RESULTS
3c ute: Benzene
I ctivated Sludge Source: Acclimated Activated Sludge
6—day SRT
Run: B1O+AIR—BZ2
k (min ): 0.436
Corr. Coef.: 0.999
k (mLn ): 0.074 4.0 l/rn.n)
kb (mLn ): 0.361
CNF BIOREACfOR OPERATING CONDITIONS ON THE
DAY OF THE BIODEGRADATION STUDY
lafluent. (ugh ) 187
Effuent (:ig/1) 0.8
0ff—Gas (nghi) 334
N/N 0.247
0
Overall Removal
Calc?lated (mm ) 0.236
k (m n ) 0.074
Q (litersfmi.n) 4.0
tô(hrs) 5.6
MLSS (mg/I) 3360
PREDICTED EFFLUENT, 0FF-GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURED IN CHE STUDY
Effluent (ugh) 1.3
Off—Gas (ag/I) 238
N/N 0.177
0ve all Removal. (Z) 82.3
232
U S. EPA Reqion b uorarv
Denver. CoIora o
-------
C. .,’
cn BENZENE REMOVAL
10—LITER BI0R ACT0R —— BATCH MODE
Acclirrated Activated Sludge
Aeration Rate 4.1 litere/min
Ru.i BlO+AIR—8Z3
I” .
-j
z
0
I-
z
LaJ
0 -.
z
0
0
20
TIME (MINUTES)
FIGURE 10—83. Experimental data and best—fit line
describing benzene re-oval by biodegradation and
volatiLization during a cotrpletelv—r t:ed batch rate study
in a 10—liter activatec sludge bioreactor with a
4.1—lirer/ ir acration rate. (Study vas conaucted with
the ben:ene 6—day SRI activated s1ud e noreactor.)
233
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TABLE 10-39
RESULTS FROM 10—LITER CPB BIODEGRADATION
RATE STUDY WITH AERATION
CMB BIODEGRADATION RESULTS
Solute: Benzene
Acttvat d Sludge Source: Acclimated Activated Sludge
6—day SRT
Run: 5I0+AIR—BZ3
k (mun ): 0.471
Corr. Coef.: 0.999
k mun 1 ): 0.076 = 4.1 1/run)
—1
kb (mi i i ): O. 5
CMF BIOREACTOR OPERATING CONDITtONS ON THE
DAY OF ThE BIODERADATION STUDY
hnfluent (ugh) 155
Effluent ugIl) 0.6
Off—Gas (ng/1) 224
N/N 0.193
0
OverLll Removal (Z) 1 80.7
Calcylated (mm ) 0.308
k (miii ) 0.071
V
2 a (liters/mu) 3.8
t (hrs) 5.6
MLSS (mg/i) 3410
PREDICTED EFFLUENT, 0FF—GAS AND OVERALL TOXICS
REMOVAL USING MEASURED IN CNB STUDY
Effluent (i ig/l) 1.0
Off—Gas (mg/i) 179
N/N 0.157
0
Overall Removal (Z) 84.3
234
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• BENZENE REMOVAL -
• 1O—LflER BIOREACTOR —— PATCH MODE
Acc mated Activated Sludge -
- Aeration Rate 4.5 liters/mm -
Run 8lQ+AIR—BZ4
12
0 16 20
TIME (MINUTES)
FIGURE 10—86. E orinental data and best—fir line
describing benzene rerroval by biodegradation and
volatilization during a corplecelv—mixed batch rare study
in a 10—liter activated sludge bioreactor with a 4.5—
liter/mm aerar on rate. (Study was conducted with the
benzene 6—day SRI activated sludge biore cror.)
4
8
a).
I-.
o.
U,.
c.1 ,
-J
z
0
I—
I .-
z
U
0
z
0
0
U,..
235
-------
TABLE 10-40
RESULTS FROM 1O—L T R CMB IODEGLDATION
RATE STUDY WITH AERATION
CMB BIODEGRADATICd RESULTS
Solute: Beazene
Acti vated Sludge Source: Acclinated Activated Sludge
6—day SRT
Run: BI0+AIR—BZ4
—1 —
k (nun ): O.58L
Corr. Coef.: 0.997
k (tn1n ): 0.084 (Q 4.5 1/mm)
kb (mmn ): 0.498
CMF BIOREACTOR OPERATING CONDITIONS ON THE
DAY )F THE BIODEGRADATION STUDY
Influent ( gf1) 432
Effluent (..g/i) 0.9
Off—Gas (ng/i) 362
N/N 0.115
Ove al1 Removal - 88.5
CdIE?lated (win ) 0.582
k (win ) 0.073
V
(liters/nun) 3.9
t (hrs) 5.6
MLSS (mg/i) 3700
PREDICTED EFFLUENT, OFF—GAS AND OVERALL TOXICS
R IOVAL USING kb MEASUR. IN CMZ STULY
Effluent (.:g/1) 2.3
Off-Gas (ng/l) 420
N/N 0.132
Ove all Removal (p.) 86.8
236
-------
TABLE 10—41
RESULTS FROM 10—LITER CMB BIODEGRADATION
RATE STUDY WITH AERATION
043 IODECRADATION RESULTS
Solute: Toluene
Activated Sludge SourLe: Acclimated Activated Sludge
6—day SRT
Run: BIO+AIR—TOI..
k (uu.n ): 0.434
Corr. Coef. 0.998
k • ‘ 4.2 1/mm)
kb (mmn ): 0.353
CHF BIOREACTOR OPERATING CONDITIONS ON THE
DAY OF THE BIODEGRADATION STUDY
Influent (ugh) 117
Effluent (t,g/i) 0.6
Off—Gas (ugh) 139
N/N 0.l63
Ove all Removal 83.7
kb. Calcylated (mm ) 0.41
k (mmn ) 0.078
V
Q (liters/sun) 4.0
a(h) 5.6
MLSS (ig/i) 3550
PREDICTED ETFLUENT, C. F—GAS AND OVERALL TOXICS
R 4OVAL USING kb MEASURED IN CMB STUDY
Effluent (I g/1) 0.8
Off—Gas (ng/l) 151
N/N 0.186
0
Overall Removal (2) 81.4
237
-------
The batch measured biodegradation rate coefficient, 0.353 min ,
compared favorably with both the value calculated from toluene
bioreactot- concentration data neasured the day of the CMB rate study,
0.41 mln , and the degradation rate coefficient averaged during toluene
steady state removal periods, 0.45 min .
Tables 10—42 and 10—43 st nmar ize results of chlorobenzene aerated
biodegradation rate studies plotted in linearized form in Figures 10-85
and 10—S6 respectiveiy. The first rate study was conducted during the
steady state chlorobenzene removal phase of the 6—day SRT activated
sludge study. An overall removal rate coefficient of 0.333 oin 1 was
measured and used to Lalculate the biodegradation rate coetficient, 0.28
min 1 , The rate coefficient obtaiied from the batch study was
approximacely the sa ne as the value calculated from a CMF reactor mass
balance, 0.30 m1n 1 , on the day the rate study was run. The mean
biodegradation rate coefficient observed during the chloroben.zene
activated sLudge study was 0.26 min . Predicted and measured overall
chlorobenzene removals for the day of the aerated biodegradation rate
study were not . igniftcantly different, 86 and 87?., respectively.
The second aerated biodegradation study with chlorobenzcne was
conducted on Day 61 of the multi—solute activated sludge study described
in Section 10.6. Biodegradation and volatilization rare coefficients of
0.43 and 0.053 mln , respectively, were ohtained from the overall
removal coefficient, 0.48 min 1 , measured iii the batch study. Using the
value of kb measured in thc hatch rate study, the model ,redicted a 90
removal of chiorobeazene due to biodegradation cor.ipared with the
observed 83% degradation on the day of the rate study.
Two aerated biodegradation rate studies were conducted with
nitrobenzene in well—acclimated 10—liter bioreactors Ľ.perated in bat:h
modes. Results from the first rate study are sutmnarized by Table to—iI .
This study was conducted during the steady—state nitrobenzene
degradation period of a 6—day SRT bioreactor receiving a inf_ient
nitrobenzene concentration of approximately 100 ig/&. ALl overall
removal rate coefficient of 0.09 min was calculated for the batch
reactor. Since nitrobenzene was only slightly volatile (k <0.O01 min )
in the experimental system, the overall removal rate coefficient was
considered a good esr mate of the biodegradation rite coefficient. The
value of kb fcr nitrobenzene was significantly smalier than those
measured for benzeite, coluene, ethylbenzene, and chlorobenzene. Whi
the measured biodegradation rate coefficient reported in Table 10—44 was
less than the value calculated by Equation 10—9, it provided a
relatively accurate prediction of the effluent concentration anc overall
removal of nttrobenzene from the CMF bioreactor.
The secon-1 aerated biodegradation study with nitrobenzene was
conducted during the steady state operating period when the influent
nitrobenzene concentration was approximateLy l3OO jg/l. The
biodegradation race coefficient measured during the batch rate study was
0.08 min . P2sults from this biodegradation rate stuoy are given in
Table 10—45. Measured values were significaiitly less than predicted
values for these conditions.
238
-------
.;— — — p p —
a ’ CHLOROBENZENE REMOVAL
iO—LITER BIOREACTCR —— BATCH MODE
Acclimated Acth’ated Sludge
Aeration Rate 4.3 ters/min
Run 5lO+AIR—C61
‘I,..
C,,..
-J
()
< —C , ..
\
o
0
C,,..
0 4 8 16 20
TIME (MINUTES)
FIGURE 10—85. E cperirnental data and best—fit _ine
describing chlorobenzene removal by biode2radatjOn and
voletilization during a completely—riixed batch rate study
in a 10—liter activated sludge bior acror with a 4.3
liter/mm aeration rate. (Study was conducted with the
chlorobenzene 6—day SRF activatea sludge bioreactor.)
239
-------
TABLE 10—42
RESULTS FROM 10—LITER CHB BIODEGRADATION
RATE STUDY WITH AERATION
CMB BIODEGRADATION RESULTS
Sc,lute: Chlorobenzene
Acttvated Sludge Source: Acclimated Act vated Sludge
6—day SRT
u : BIO4AIR—CB1
k (min’): 0.333
Corr. Coef.: 0.980
k (min ): 0.053 (Q 4.3 1/mm)
k . , (min 1 ): 0.280
CMY B 0RL CTOR OPERATIUC CONDITIONS ON THE
DAY OF TiLE BIODEGRADATION STUDY
Influent LgIi) 181
Effluent (‘jgIi ) 2.4
Off—Gas (ng/1) 182
N/N 0.133
0
Overall Removal 86.7
kb, Calc?lated (win ) 0.302
k (inin ) 0.043
(liters/win) 3.5
. (bra) 5.6
MLSS mgii) 3270
PREDICTED VFFLUENT, OFFGAS AND OVERALL TOXICS
REMOVAL USiNG k. 1 , MEASURE IN CMB STUDY
Effluent (ugh) 1.6
0ff—Gae (ng/1) 203
N/N 0.142
Ove atI emovcl (Z) 85.8
240
-------
C. ,’
p — I - p - S 1 —
CHLOROBENZENE REMOVAL
- 10—LITER BIOREACTOR —— BATCH MODE
Acclimated i’ctivcted Sludge
Aeration Rate 4..3 Iiters/rni,
Run 6I0+AIR—C82
Lfl
:\
L J
0 s,, ..
z
0
0
C,,..
C .
0 4 8 12 16 20
TIME (MINUTES)
FIGURE 10—86. Experinenral data and best—fit line
describing chlcrobenzene removal by biodegradation and
volatilization durina a completely—mixed batch rate study
in a 10—liter activated sludge bioreactor with a 4.3
liter/tnin aeration rate. (Study was conducted with the
chlorobenzene 6—day SRI activated sludge bioreactor.)
241
-------
TABLE 10—43
RESULTS FROM 10—LITER CMB BIODEGRADATION
RATE STUDY WITH AERATION
CMB BIODEGRADATION RESULTS
Solute: Chlorobenzene
Activated Sludge Source: Acclimated Activated Sludge
6—day SRT
Run: BIO+AIR—C82
k (min ): 0.484
Corr. Coef.: 0.999
k (min 1 ): 0.053 (Q 8 4.3 )jmin)
kb (nin 1 ): 0.431
CMF BIOREACTOR OPERATING CONDITIONS ON THE
DAY OF TilE BIODECHA.DATION STUDY
Influent ( g/l) 1820
Effluent (LgIl) 8.4
0ff—Gas (ng/l) 2290
N/N 0.169
Ove?all Removal (Z) 1 83.1
k , Calcylated (mm ) 0.246
k (mm ) 0.047
V
Q (litersfmiri) 3.3
a(h) 5.6
MLSS (mg/i) 3940
PREDICTED EFFLUEFT, OFF—GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURED IN CMB STUDY
Effluent ( g/l) 11.0
Off—Gas ( g/1) 1360
N/N 0.104
Overall R€moval (%) 89.6
242
-------
TABLE 10—44
RESULTS FROM 10—LITER CMB BIODEGRADATION
RATE STUDY WITU AERATION
CMB BIODEGRADATION RESULTS
Solute: N, trobeuzene
Act vated Sludge Source: Acclimated Activated Sludge
6—day SET
Run: BI0+AIR—NB1
k (min ): 0.09
Corr. Coef.: 0.972
k (min ): <0.001 (Q 4.2 1/sun)
—1
kb (nm ): 0.09
CMF BIOREE’CTGR OPERATING CONDITIONS ON TIlE
DAY OF THE BIODEGRADATION STUDY
Influent (iig/l) 122
Effluent ( jg!l) 2.5
0ff—Gas (ng/l) ‘ :20
N/N 0.02
0
Overall Removal 98
kb, Cal 9 lated (mm ) 0.18
k (ni.n ) <0.001
V
(liters/mm) 4.0
(hrs) 5.6
MLSS (mg/i) 3630
PREDICTED EFFLUENT, 0FF—GAS AND OVERALL TOXICS
REMOVAL USING kb MEASURED IN CMB STUDY
Effluent ( g/1) 4.0
Off—Gas (ng/1) 30
N/N 0.04
0
Overall Removal (Z 96
243
-------
TABLE 10—45
RESULTS FROM lO—LITEA C 1B BIODEGRADATION
RATE STUDY WITH AERATION
CMB BIODEGRADATION RESULTS
Solute: Nitrobenzene
Run: 310 + Air — NB2
Acti ’ated Sludge Source: Acc imated Activated Sludge;
6-day SRT
k 0 (rn1n ): 0.08
Corr. Coef.: 0.973
kv(!nln’): <0.001 a 40 /min)
kb(rnin’): 0.08
AVERAGE CMF BIOREACTOR OPERATING CONDITIONS FOR
THE DAY OF THE BIODEGRADATION RATE STUDY
t (hrs) 5.6
Influent (ug/L) 1340
Effluent (pg/f) 6.0
Off-Gas (ng/Z) <50
N/N 0 0.01
Overall Removal (%) 99
k (ml&’) <0.001
kb, Calculated (rnin ) 0.01
Q (liters/mm) 4.0
M1 SS (mg/i) 3260
PREDICTED EFFLUENT, OFF—GAS AND OVERALL TOXICS
REMOVAL USING k 1EASURED IN CMB STUDY
Effluent (i g/L) 46
Off-Gas (ng/L) 353
N/N 0 0.04
Overall Removal (%) 96
244
-------
IA8LE 10—46
SUMMARY OF RESULTS FR0 1 AERATED (..Pi 3
B loDEGRADArro RATE STUDIES
kb Overall Removal (%)
Compound ( min 1 ) ( 1/mm) ( min ) ( min ) ieasured Predicted
Benzene 0.179 4.3 o.O 9 0.10 65 55
0.436 4.0 0.074 0.3b 75 82
0.471 4.1 0.076 0.39 81 84
0.582 4.5 0.084 0.50 88 87
Toluene 0.434 4.2 0.08L 0.35 84 81
Chlorobenzene 0.333 4.3 0.053 0.28 87 86
0.484 4.3 0.053 0.43 83 90
Nitrcbenzerte 0.09 4.2 <0.001 0.09 93 96
O.OE 4.0 <3.001 0.08 99 96
245
-------
1O. .3. Conclusions
Results Eros the two types of biodegradation rate studies provided
conclusive evidence that th disappearance of the toxic organic
compounds observed in the CMF activated sludge studies was a result of
biodegradation by 3Ltivated sludge microorganisms. aatch degradation
studies demonstrated biodegradation of benzene, toluene, ethylbenzene,
chlorobenzene, and nitrobenzene occurred at the microgram—per—Liter
concentration range typical of municipal wastewaters. Although
biodegradation rate studies were not conducted with o—xylene or
1,2—dichlorobenzene, sinilar findings would be expected for these
compounds.
The resLlts from -i ,n--aerated biodegradation rate studies
demonstrated that the biodegradation of microgram—per—liter
concentrations of the test compounds could be successfully described by
a first—order model. In general biodegradation rate coefficients
measured in batch rate studies were in good 0 ;reement with values
calculated from a CMF bioreactor mass balance approach. Aerated
biodegradation rate studies conducted in 10—liter bioreactors operated
in batch modes, indtcated that the o’erail reduction in aqueous
concentration (volatilization plus biodegradation) could be described by
a first—order model, also. This finding provided support for the
hypotnesas that independently measured first—order removal coefficients
for volatilization, k , and biodegradation, kb, could be combined to
give an cverall firsc—oroer removal rate coefficient, k 0 . asured
steady—state biodegradation rate coefficients of the highly
biodegradable (overall removals > 75%), volatile compounds were
significantly Larger than their corresponding volatilization rate
coefficients for the operating -.onditions used in the CMF bioreactors.
This result w s indicat.A by the mass balance approach, Equation 10—4,
used to estimate biodegradation rate coefficients from influent,
effluent and off—gas analyses. Ratios of kb/k,, for steady—state
biodegradation of the volatile compounds generally were in the 5.0 to
6.0 range. The ratios kb/kO for the compounds examined in the bdtch
biodegradation studies were approximately the same as the fraction of
the mass fluxes of biodegradable compounds into the CMF bioreactors that
were removed by biodegradation. Li general the ratio of kb/k O ranged
from 0.75 to 0.85.
Equation 10—9 can be rearranged and written to describe the :ate of
the toxic organic compounds in C F reactors using three pieces of
information: independently measured volatilization and b ode radation
rate coefficients and the mean hydraulic retention tins.
kb N
: — —— (10—14)
kb+kv+1/t N 0
246
-------
The left—hand side of the equation, kb(kb 4 + lit) 1 represents th
fractioa of the Iniluenc removed by biodegradation. The fraction of the
influent leavi j the CMF btoreactor. in effluents and off—gas can be
described by
kv + 1/t N
— —— (10—15)
kb +k +l/t N 0
The following three equations can be u3ed to model the fate of the
toxic organic compounds in the CMF bior actors
kb
friction of influent (10—16)
biodegraded, b kb + lit
fraction of influent (10—17)
volacillzea, kb + + lit
l/t
fraction of influent — (10—18)
in effluent, e kb + + l/t
The examples calculated in Table 10—47 for ben:ene, chlorohenzene,
l,2,4—trichlorobenzene and nitrobenzene iUustrate how independently
determined ialiies of kb and k can be used to estimate the fate of each
compound in the experimental system without considering aqueous or gas
phase concentrations. Values for kb for biodegradable compounds used in
the illustration were measured in the batch biodegradation exp . riments.
The value of i: for non—bLodegradable compounds was assumed to be zero.
The hydraulic retention time, t, used in the calculations was 5.5 hours.
The fractions of the influents predicted to be biodegraded, volatilizel
and discharged in effluents by Equations 10—16, 10—17. and 10—18 were
approximately the same as observed n the activatad sludge bioreactor
studies. Values of k , , were calculated using Equation 7—2 and the
volatilization parameters measured in the batch volatilization studies.
10.6 M1JLTI—S( LUTE STUDY
The results presented thus far were obtained from activated s1 :dge
bioreactor studies in which onLy one compouncf ;as added to the influerit
of a given unit. tnfluents to full scale activated sludge facilities
typically have been reported to contain a wide variety of to’dc organic
compounds rathe,- than a single toxic compound (4,5,6). A na lti—solute
study wa designed to evaluate the removal of seven toxic organics added
simultaneously to the intluent of an activated sludge bioreactor, The
removal of each rot ound had been well characterize’ in single solute
activated sludge bioreactors. Five of the seven compounds, berizene,
247
-------
Compound
Bcnzene
Ch lorobenzene
Nit robenzene
1,2 ,4—Trichloro—
henzene
TABLE 10—47
FATE OF THREE COMPOUNDS CALCULATED WI 11! EQUATIONS 10—16 THROUC;U 10—18
USING INDEPENDENTLY MEASURED RATE PARAMETERS kb and k
Biodegraded Volutilized
kb lit kb ‘SI
(minl-) (minl) (mlnl) k 4kTii7 r
____ __ b v by
0.27 0.074 0.003 0.78 0.21
0.57 0.074 0.003 0.88 0.11
0.22 0.050 0.003 0.81 0.18
0.09 <0.001 0.003 0.96 <0.01
0 0.025 0.003 - 0 0.89
Effluent
l/t
kb+k1 1/
0.01
<0.01
0.01
0.04
0.11
4.0 R./mln
-------
toluene, r.hlorobenzene, ethylbenzene, and o—xylene were observed to be
readily biodegr ’dable while the remuining two compounds,
1,2—dichlor - benzene and 1,2,4—crichlorobenzene, were found to be poorly
degraded and non—biodegradable, respectively.
The multi—solute activated sludge unit was operated under
steady—state conditions with respect to influent TOC, solids retention
time and hydraulic retention time. A swnnary of pertinent bioreactor
operating conditions is given in Table 10—48.
The bioreactor was initially seeded with activated sludge from the
secondary aeration basin of the Ann Arbor Wastewater Treatment facility.
Approximately twenty days were provided to acclimate the activated
sludge to the synthetic wascewater hefore the toxic organic compounds
were added to the influent. The multi—soiute study was conducted for a
total cf 100 days which can be divided into five difi rent periods,
s marjzed in Table 10—49, based on the influent concentrations of the
toac compounds.
TABLE 10—48
BIOREACTOR OPERATING CONDITIONS FCR
THE l -I1JLTI—SOLUTE ACTIVATED SLUDGE STUDY
Toxic Organic Solutes: Benzene, Toluene, Ethylbenzene,
o—xylene, chlorobenzene,
1, 2—Dichiorobenzene, and
1, 2,4—Trichlorobenzene
Solids Retention Time: 6 days
Hydraulic Retention Time: 5.5 hours
Avg. Influent TOC: 112 mg/i
Avg. bC Removal: &4.6Z
Avg. MLSS: 3700 mg/i
Aeration Rate: 3.8—4.4 i/win (Avg — 4.1)
249
-------
TABLE 10—49
MULTI—SOLUTE SIOREACrOR OPERATP C P€RtO)S
WITH RESPECT TO THE CO CENTRAT1oNS OF THE
T IC SOLUTES
Time Period j gth (days) Operating Condittnrts
1. Days 0—45 45 Steady—state Influent conc.
of all toxic organic compounds
between 100 and 150
2. Days 46—62 17 Spike loadings of ben.zene,
ethyibenzcne, and chloro-
benzene
3. Days € 3—7€ 14 No toxics added to influent
4. Days 77—83 7 SpIke loadings of benz ne,
ethylbenzen , and chioro—
benzene producing influent
concentrations between 8,000
and 12,000 ugh
5. Days 4—l0O Steady—state influent conc. of
all toxics between 100 and
200 ug!2.
250
-------
An ‘porrant obje ttve of the • ulti—so1ute study was to compare the
remova’. each toxic solute to results obtained from single solute
studies in which only one compound had been added to the influent of a
bioreactor. During the first 45 days of the multi—solute study the
bioreactur was operated . ith influent concentrations of each compound ir .
the 100 to 150 ugh range. lnflue t, effluent and off—gas samples were
collected every three to four days for the five biodegradable compounds,
benzene, toluene, echylbenzene, o-xylene, and chloroben ene and every
four to six days for l,2—dichlorobenzene and l,Z , 4 —trichlorobenzene.
Influent, effluen ’ , and off—gas concentrations and N/N 0 values for
eaco compound during the first 45 days of the multi—solute study were
plotted in Ftgures 10—87 through [ 0—91 with results from s ng1e solute
studies conducted under identical operating conditions. The
aimilarities of the N/N 0 curves in Figures 1O—S7 through 10—91 indicated
that there was no significant difference in the behavior of each
compound in single and nult i—solute systemu. Each biodegradable
compound experienced a 14 to 21 day acclimation phase followed by a
period of re lative l 1 steady—state removal due to biodegradation.
A comparison of acclimation periods and overall removals from Single and
multi—solute studies is given in Table 10—50.
Results from single solute studies produced the follc jing order of
biodegradatlve re’novaj of the five biodegradable compounds, benzene
toLiene > chlo obenzene > ethylbenz , ne > o—xylene. Similar findings
were obtained irom the rmjlti olut study as shown in Figures 10—92 and
10—93 and Table 10—51.
A distir’ctjve feature of the multi—solute results was the sudden
increase in fractional recoveries of the biodegradable compounds on Day
35 as shown by the increase in N/N 0 values in Figures 10— 37 through
10—91. This period corresponded to a decrease in mixed liquor p 14 from
7.2 to .4 due to a problem with the ptnnp delivering the portion of the
influent to the bioreactor containing NaHC()i. The pH was adjusted to
its steady—state ‘evel of between 7.1 and 7.3 within 12 to 18 hours, and
the bioreactor san•oles collected on Day 37 indicated that the overall
removal of each co iu ound except o— cylene had returned to its
steady—state level within 48 hours. During the PH—induced upset period
the recoveries of ethylbenzerie and o—xylene approached the 90Z level
indicating very little biodegradati,n was occurring. Recoveries of
benzene and toluene increased to approximately 707. while chlorobenzene
was least affected with a recovery of 60Z recorded on Day 35. Table
10—51 provides a comparison of overall removals measured unde-r
steady—state conditions and on Day 35 after the approximate 0.8 .:nit
decrease in the mixed liquor p14.
Influent concentrations of benzene , ethylhenzene, and chlorobenzene
to the multi—solute bioreactor were increased from approximately 100 to
1000 ugh on Day 48. Concurrenel , l,2—dichlorobenzene and
l, 2 1 4—trtchlorobenzene were omitted from the influent. Influent,
effluen., and off—gas concentrations and N/N values measured
between D ’,s 0 and 64 for each compound are given in Figures 10—94
through 10—98.
251
-------
-j
I—
z
Li
-J
L
z
-j
0
D
1L
L
U
-J
0
(1 )
U-
0
0
z
-
3 7 14 21 28 35 42
TIME (DAYS)
FtCURE 10—87. Comparison of benzene influent, effluent, and
off—gas concentrations and fractional recoveries, N/\o, measured
during single solute and multi—solute activated sludge studies.
Co
C.,.
9-. i
U,
48 56 63 70 77
252
-------
—I
C,
z
Li
-J
Li
-v
4-
-J
0
U-
L ii
-j
C ,
z
U,
C ,
t L
U-
0
0
z
z
0 7 14 21 56
TIME
FGURE 10—88. Conparison of toluene infl.uent, efluent, and
off—gas conc2ncra:ions and fractional recover es, N/No, ieasured
during single sol’jte and multi—solute act vated sludge studies.
Co
c .J
I I I I I
U)
28 35 42 49
(DAYS)
253
-------
I I I I I — I
01
0
z
z _____
9
0 7 14 21 20 35 42 48 56 63
TIME (DAYS)
FIGURE 10—89. Co parigon of ethylbenzene influertt, effluent,
and off—gas concentrations ar.d ractional recoveries, N/No,
measured during single o1ute and multi—solute activatei sludge
studies.
-J
0
z
-J
z
=
—I
LL
0
z
(I )
(I ,,
L
0
d
254
-------
-J
0
U
-J
L .
z
-J
C.,
Ls
Li
-J
0
z
U)
1’
U.
0
0
zu
z
q
a
a
TIME (DAYS)
FIGURE 10—90. Comparison of c’— lene tnfluent, effluent,
and off—gas concentrations and fractional reccveries, N/No,
measured during single so’ute and multi—solute activated
sludge studies.
a
a
c
a
a
7 14 21 ?9 35 42 49 56
255
-------
C d
-J
0
z
U
-J
L
z
I- ’
-j
0
2D
Li
U
-J
(:1
z
v)
L&
L i.
0
0
z
z
0
TIME (DAYS)
FIGURE 10—91. Cc’i parjson of chlorobenzene Influent, eff1uen
and off—gas concentrations ar’d fractional Lecoverles, J/No,
measured dur fl2 single solute and rnulti—so1u aLtivated sludge
StudlZ?S.
Co
C.
C,
C,
C,
U,
14 21 29
35
42 49 56
256
-------
TABLE 10—50
COMPARISON OF ACCLIMATION PERIODS ANt’ STEABY STATE
TOXICS REMOVALS FRO 1 SINGLE SOLUTE AND MULTI—SOLUTE
ACTIVATED SLUDGE STUDIES
Acclimation Overall ReTnoval
Period (days) (7.
Co pound Single Solute Multi Solute Sin le Solute Multi Solute
Belkzene 14—21 14—21 84 (5) 86 (4)
Toluene [ 4—21 14—21 84 (4) 81 (3)
Ethylbenzene [ 4—21 14—21 80 (4) 79 (4)
o—Xyiene 14—21 21—24 78 (4) 7f (3)
Chlorobenzene 14—21 14—21 82 (3) 81 (2)
1, 2—Djchlcjro—
benzene 14—21 14—21 37 (6) 41 (12)
1, 2,4—Trichloro—
benzene 0 0 0 0
( ) Standard DeviatIon
+ Average of all activated sludge studies for that con ound
conducted at a 6—r!ay SRT
Day 20 through Day 46, excluding Day 35
Includes Day 20 through Day 31 only
257
-------
0
0
0
I-
-J
>0
,—‘ 0
‘-I
U
0
_j*
L&JN
>
0
0
0
0 100
TIME (DAYS)
FIGURE 10-92. ComparIson of benzene, ctliylbcnzenc, and clilorobcnzene overall removals
due to biodegradat Ion neasiirej during l’ie multi—solute activated sludge study.
BENZENE
ETKYLBENZENE
CHLOROBENZENE
10 20 30 40 50 60 70 80 90
-------
0
0
0
-J
>0
F-’ 0
‘-J (0
[ ii
0
-j
WN
>
0
0
0
0
TIME (DAYS)
FIGURE 10—93. ComparIson of Lenzene. toluene, and o—xylene overall removals due
to hiodcgro.lat Ion me Ib.Irt,tI during the mull, i—solute iict I vat d a ititIge tndy
10 20 30 40 50 60 70 80 90 100
-------
T. BLE 10—51
EFFECT OF PH—INDUCED U9SET ON BIODEGRADATION
RATE COEFFICtENTS AND OVERALL RE 10VALS OF
BIODEGRADABLE COMPOUNDS
Overall Removal ( ) Bi degradat1on Rate
Coeff (min t )
Compound Steadj—state 1 Day 35 Steady—state’ Day 35
Benzene 86 31 0.472 0.035
Toluene 81 30 0.340 0.034
Ethylbenzene 79 20 0.322 0.022
o—Xylene 78* <10 0.215 0.006
Chloroben,ene 81 42 0.219 0.038
1 an value averaged from data collecied between Days 20 and 45
omitting Day 35.
* Data frcn Day 20 to Day 31 only.
260
-------
=
-J
0
I.-
z
Li
-J
L.
z
_jCO
U-
Li
0
z
U,
(I,
U-
0
0
z
z
TIME (DAYS)
FIGURE 10-94. Effect of an increase in influen to’cics
concentrations and an interruption in roxics additi.,n to the
bioreactor on benzene effluent and off—gas concer.trations and
fractional recoveries, N/No, during the u1ti—solute study.
0 7 14 21 28 35 42 49 56 63
70 77 84
ACTIVATED SLUDGE BIOREACTOR
TL UT ST U
c. I
261
-------
a
a
( ‘4
-J
0
L.
U-
L J
-J
0
z
U)
U-
0
0
FIGURE 10—95. Effect of an increase in influent toxics
conceritracins and an !nterruption in o,cicr addition to the
multi—solute activated sludge bioreactor on chlorobenzene
effluent and off—gas concentrations and fractional recoveries,
N/No.
TIME (DAYS)
70 T7 84
a
a
a
w
a
a
a
a
a
a
(N
a
ACT 1ATED SLUDGE BIOREACTOR
MULTI—SOLUTE STUDY
CHLOROBENZENE
-j
0
Li
-J
z
a
LI,
a
d
a
U,
a
a
0 7 14 21 28 35 42 49 56 63
262
-------
-J
0
z
w
-J
U-
z
-J
0
=
U-
Li
-J
0
z
U,
c i ,
U-
0
0
zu,
a
a
(DAYS)
FIGURE 10—96. Effect of an increase in influent toxics
concentrations and an interruption in toxics addition to the
inult —so1ute activated sludge bioreactor on ethy1 ienzene
effluent and off—gas concentrations and fraction ü recoveries,
N/No.
ACTIVATED SLUDGE BIORE.ACTOR
MULTI—SOLUTE STUDY
ETHYL8ENZEN
C
C,
C’d
0 7 14 21 28 35 42 49 56 63 70 77 84
TIME
263
-------
i , i —-—— • i • i
—j ACTWATED SLUDGE BIOREACTOR
o MULT—SOLUTE STUDY
z
1.-i
-J
I I 4 I I I I I
I 4 4 I I 4 4 4 I -
-J
Li I . I I 4 I I I I
I • I I I I I I I
C D
-i
IC d
U-
0
I S I S S I I I * I
0 7 14 21 28 35 42 49 56 63 70 77 84
TIME (DAYS)
FIGURE 10—97. Effect of an increase in tnfluent toxics
concentrations and an interruption in toxics addition to the
multi—solute activated sludge blore ctor on toluene efflu nt
and off—gas concentrations and fractional recoveries, N/No.
264
-------
-J
w
z
-J
C,
U..
A J
-J
0
z
U,
LL
0
(,
U)
(0
( ‘4
0
z
z
TIME (DAYS)
FIGURE 10—98. Effect of an increase in influent toxics
concentrations and an intertuotion in toxics additton to the
multi—solute activated sludge biorector on o—’cylene effluent
and off-gas concentratic’r.3 ani fractional recoveries, N/No.
(0 I S S S S -_e I I
j
0 1 14 21 28 35 42 49 56 63 70 77
84
265
-------
The overali removal of benzene was not affected by the spike
loadings of benzene, ethy benzcne, and chlorobenzene as indicated by the
relative constant /N 0 values in Figure 10—94 between 0ay 49 and 63.
With the exception ot the sa p1c collected on Day 55. the overall
removal of bertzene exLeeded 857. ouring ibis period. The mean benzene
removal during the period of higI influent concentrations was 86.5%
compared to 86.2% during the preceding four weeks when the infliient was
in the [ 00— iSO pg/i range. The effluent concentration reached a maximum
value of only 5.8 pg/i even though th nfluenr concentration was
increased to approximately 2000 pg/i. If biodegradation of benzene had
not occurred the effluent concentration resulting from a 2000 pg/i
influent concentration would have been apprcximacely 80 pg/i, according
to the air—stripping model previously developed.
The results for chl’robenzene presented in Figure 10—95 indicated
that, like benzenc, the overall removal did not change as a result of
the increased influent concentrations of benzene, ethylbenzene, and
chlorobenzene, A ‘an overall chlorobenzene removal of 80.6% was
recorded during the period of high influent concentrations compared to
81.4% during the preceding steady—state toxics removal period
characterized by influent concentrations ranging from 100 to 150 pg/i.
The increased chlorobenzene concentration from 90 to approximately 730
pg/i on Day 48 prcduced an increase in the effluent concentration from
the steady—state level of 0.8 to only 4.1 pg/i.
Further increases in the influent ehlorobenzene concentration to
1800 pg/i caused the effluent to increase to 14.7 pg/i. In the
absence of chlorobenzene biodegradation the effluent concentration
would have increased t over 100 pg/i between Days 56 and 63.
The results presented in Figure L0—9’ for ethylber2ene show that
the effluent concentration remained less than 8 pg/i even though the influ—
ent concenrrntlon reached appro’cimatel.’ 1300 i g/ c Overall ethvlbenzene
removal due to biodegradation averaged 79.7% during the operating period
with steady—state influent concentrations between 100 and 150 pg/i,
compared with 75.3% during the period with increased inf jent
concer ’tratLons. As also observed during the first 45 days, thylbenzene
removal due to biodegradation was less than either ber2ene or
chlorobenzene under conditions of elevated influent concentrations.
The influent concentrations of toluene and o—xylene were not
increased on Day 48. Toluene averaged 106 pg/i in the influei.c during
the eriod of tncreased benzene, ethylbenaene, and chlorobenzene
influent concentrations, Days 48 to 63. The increased influent
concentrations of benzene, ethylbenzene, and chloro’ enzene caused no
measurable variation In the biodegradation of toltiene. Overall re- )vals
averaged 81.2 and 81.8% between Pays 0 to 47 and Days 8 to 63,
respectively. As s’ia.rn by Figu:e 10—97 effluent and of f—g s
concentrdtions exhibited only small fluctuations during tne initial nine
weeks of the study once steady—state toluene biodegradation had
been attained.
266
-------
The overall removal of o—xylene was considerably less than the
other four compounds throughout the first nine weeks. The results
presented in Figure 10-98 sh that unlike benzene, toluene,
ethyibenzene or chlorobenzene, the overall removal of o—xylene did not
return to its previous level after the pH—induced upset on Day 35.
Instead, overall o—xylene removal averaged only 32.1 during the ten
days fol’owing the upset compared with 78.8Z measured during the eleven
days preceding the upset. Mter the influent concentrations of benzene,
thylbeozene, and chlorobenzene were increased on Day 48 the removal of
o—xylene increased to approximately 60 wnere it remained through Day
62. While the results were inconclusive whether or not the increased
influent concentrations of benzene, ethylbenzene and chlorobenzene
affected the degradation of o—xylene two points suggest that they di.d
not. First, activated sludge microorganisms were exposed to at most 15
ig/R of any one compound, since the effluent concentration was the
concentration in the aer t1on basin of the CMF bioreactor. Such l ”
levels likely d d no inhibit o—xylene biodegradation.
Secondly, bindegradation of o—xylene actually improved after Day 48 when
the inf1u . nt concentrations of benzene, erhylbenzene, and chlorobenzene
were increased. Lxiring the operating period between the pH—induced
upset on Day 35 and Day 48, overall o—xylene removal remained at a
depressed level of only 32Z. Influent concentrations of all toxic
organic compounds ere in the 100 to 150 ugh range during this time.
No toxic organic compounds were added to the influenc of the
multi—solute bioreactor for a period of 14 days between Days 63 and 76.
This was done to determine if the activated sludge experienced another
acclimation phase or if the microorganisms retained thei r ability to
degrade the toxic organic compounds during the two week period of
non—exposure to tbem, When the toxics were again added to the influent,
the influent concentr...tion of each of the five biodegradable compounds
was approximately 15 ) ugh. Each compound experienced a reaccllmation
phase as shown by Figures 10—94 to 10—98 and by Figures 10—99 through
[ 0—103 in which the initial acclimation and reaccltrsation periods have
been compared. Day 0 of the reacclimation period in Figures 10-99
through 10—103 represents the reintroduction of coxics to the influent of
th multi—sc”lute reactor on Day 77.
The reacelimation period was characterized by a rapid return of
effluent, off—gas an ’! N/ & values to steady—state levels. Within three
to four days overall removals of benzene, toluene, ethylbenzene,
o—xylene, and chlorobenzene increased to Lhc same steady—state levels
observed after the initial two to three week acclimation period as shown
by the comparisons in Taole 10—52.
Influent concentrations of the toxic compounds were Increased a
second time during the final two weeks of the multi—solute study.
Maximum concentrations of benzene, ethylbenzene and chlorobenzene were
between 8000 and 12000 ugh while maxitnuw toluene and o—xylene
concentrations wcre an order of magnitude lower. Also added to the
influent at concentrations ranging from 2U0 to 2000 ugh were
267
-------
-J
z
Li
_J
IL
z
_jco
C,
-, C’)
IL
LLO _________
L J
-J
C,
z
(1,
U-
IL
0
0
z
z
0 7 14 21 28 35
TIME (DAYS)
FICtRE 10—99. Initial activated sludge acclimation
to benzene and reacclimation after a 1 —day interruption
in toxics addition to the influent during the multi—solute
activated sludge study.
MULTI—SOLUTE STUDY
ACCLIMATION PERIODS
BENZENE
INITLA ..
0 AFTER
ACCLJUATiON
14 DAYS. WITHOUT
lOX ICS (Day 76)
e 0
w
In
268
-------
C D
-J
z
Li
-j
1L
z _________________
-j
C,
U-
U-
Li
-J
0
z
U)
LL
U-
0
FIGURE 10—100. Initial activated sludge acclimation
to toluene and reaccilmarion after a lA—day interruption
in toxics addition to the Influent during the multi—solute
activated sludge study.
0
z
z
0 7 14
21 28 35
TIME
(DAYS)
MuLTI—SOLUTE STUDY
ACCLIMATION PERIODS
INIflAL A
0 AFTER 14 DAYS WITHOLT TOX S (Day 76)
—4 -I 4
269
-------
- -
—i
MuLTI—SOL srE STUDY
ACCLiMATION PERIODS
EThYLBENZENE
C INflLAL ACCLIMATION
AFTER 14 DAYS WIfl4OLf TOXICS
4
(Day 76)
—1
-1
d
0
4 —-4 4
7 I 21 28 35
TIME (DAYS)
FIGURE 10—101. InItial activated sludge acclimation
to ethvjbenzene and reacc1Imat on after a l —dav
interruption in toxics additio’i to the influent during the
multi—solute activaced sludge study.
C ,)
-J
0
z
Li
-J
U-
z
-J
0
U-
Li
-J
C.,
z
U)
Cf
U-
I L
0
0
z
z
- 1—
0
U)
a
270
-------
-J
I—
z
Li
-J
L&
z ___
— €3
CD
C,
LL
“-
Li
-J
C,
z
U)
L
L&
0
0
z
-v
€3
€3
0 35
TIME (DAYS)
FIGURE 10—102. Initial activated sludge acclir acion
to o—xylene and reac limation after a 16—day interruption
in roxics addition to the influent during the nulti—soluce
activated sludge Study.
MULTi—SOLUTE STUDY
ACCLIMATiON PERIODS
o—XYLENE
O INflIAL ACCLIW T1ON
O AFTER 14 DAYS WflHOLJT TOX (Day 76)
U)
€3
7 14 2 28
271
-------
C.,’
-J
C,
1•-
z
L J
z
-J
C,
C,,
U-
U
-J
z
U)
C,
L
U-
0
0
z
z
0 7 14 21 28 35
TIME (DAYS)
FIGURE 10—103 Initial activated slud2e acclimation
to chlorobenzene and reacclimation after a 14—day
interruption in toxics addition to the influent during
t e au1ti—so1t activated slud e study.
MULTI—SOLUTE STUDY
ACCLIMATION PERIODS
CHLOROBENZENE
0 INfllAi.. ACCLJMATION
AFTER 14 DAYS W1 HOUT TOX)CS (Day 76)
-I
272
-------
1,2—dichlorobenzene and 1,2,4—trichlorobenzene. Influent, effluent, and
off—gas concentrations and N,’N 0 values recorded for each con ound during
this operaing period are plotted in Fi ures 10—104 through 10—108.
Influent concentrations of benzene, ethylbenzene, and chlorobenzene
were increased from 150 ugh to over 3000 ugh for a period cf five days
beginning on Day 84. Influent concentrations were increased again to
approximately 9000 ugh fo two days, Days 90 and 91, before being
returned to the 100 to 150 ugh ran :e. The objective of this portion of
the study was to evaluate what effect extremely large influent loadings
of selected roxic co ounds would have on the biodegradation of bertzene,
totuene, ethylbenzene, o—xylerie, and chlorobenzene. The highest
concentrations u9ed were slightly greater than maxi’mm concentrations
reported in influents of r iinicipal wastewaters (2,3).
The increased tox.ics loadings in general had no effect on the
acti . Led sludge’s ability to degrade enzene. During the operatIng
period of high influent concentrations, Days 84—91, benzene removal due
to biodegradation averaged 91Z co ared to 86Z observed during the
steady—state toxics loading period of Days 16 to 45. The maximum
effluent henzene concentration recorded was 12.5 ugh (see Figure
10—104) which corresponded to the largest influent concentration of
11500 ug/Q. An effluent concentration of 532 ag/i . would be predicted
by the air—stripping ‘. odc1. to occur if the activated sludge micro—
otganisms were not capa lc of degrading benzene.
Tk8LE 10—52
COMPARISON OF INITIAL ACatMATto A! D REACCL1MATP )N
AFTER 14 DAYS WITHOUT T ICS ADDED TO THE INFLUENT
Overall Removal(Z) Acclimation Period(da s)
Compound Sre3dy—State Days 80—84 Initial Reaccltnation
Benzene 86 90 16-20 3—4
Toluene 81 88 162J 34
Ethylbenzene 79 90 16—20 3—4
o—xylene 78 81 21—24 3—4
Chlorobenzene 81 8b 16—20 34
273
-------
-J
0
w
-J
IL
z
-J
0
IL .
U-
U i
—I
0
z
(I )
0
L
U-
0
0
z
z
C).
C)
0 10
FIGURE 10—104. Effect of spike to ics leadings on benzene
effluent and off-gas concentraticflS and fractiortal recoveries,
1/No, durinz the multi—solute study.
ACTWATED SLUDGE BIOREACTOR
MULTI—SOJJTE STUDY
BENZENE
C)
C)
C)
C)
C)
C)
C)
A
U,
20 30 40 50 60 70 80 90 100
TIME (DAYS)
274
-------
-j
—
-J
z
C-,
q
C ,,
c
I ’,
a
0 8 %7 25 33 42 50 58 67
TIME (DAYS)
83 92 oo
FtGURC 10— 105 . Effect of spike rox±cs 1 .oadin2s on
ethylbenzene effluent and off—ga3 concentrations and fractional
recoveries, N/No, during the multi—solute activated sludge study.
ACTIVATED SLUDGE BIOREACTOR
MULTI—SOLUTE STUDY
ET HYLBENZENE
A
, rk fl
-J
(;3
L.
LL
w
a
a
a
a
a
U?
a
a
a
It)
-J
0
z
(I,
LL.
0
0
z
z
275
-------
a
a
a
__% c 1
a
-J
LL
a
- I-
Li
Li
6 4 I 3 3 I
i—aD D- O-OO- t O r )
- I I I I 6 4
I
$ I
&ee
0 10 20 30 40 50 60 70 80 50 100
TIME (DAYS)
FIGURE 10—106. Effect of spike toxics loadings on
chlorobenzene efflu nr and off—gas concentrations and fractional
recoveries, N/No, during the multi—solute activated sludge
study.
ACTWATED SLUDGE BIOREACTOR
MULTI—SOLUTE STUDY
CHLOROBENZENE
a
a
a
a
a
C ,)
a
a
( “I
a
a
a
-i
z
(I )
U-
0
0
z
z
a
276
-------
0
z
U
-J
1i
z
—
jCO
O’r
LI-
LL
—S
-j
0
z
L
LI-
0
0
z
z
0 10 20 30 40 50 60 70 80 90 IO U
TIME (DAYS)
FIGURE 10—107. Effect of spike toxics loadings on touene
effluent and off—gds cc’ncentradcns ano fractional recoveries.
NIN . during the toulti—solute activated sludge study.
277
-------
0
z ig,
z
—. i t I I t I
-e I
0 10 20 30 40 50 60
70 80 90 100
TIME (DAYS)
FIGURE 10—108. Effect of spike toxics loadings on o—rvler e
effluent and off—gas concentraticns and fractional recover:es,
N/No, during the multi—solute activated sluoge study.
ACTIVATED SLUDGE BIOREACTOR
MULTI—SOLUTE STUDY
o—XYLENE
“4
Co
-J
0
w
-J
LL
z
-J
Lj
w
-J
z
0
L
Li.
0
Co
Co
0
278
-------
Results presented by Figure 10—105 indicate that in general the
increased toxjcs concentrations did not adversely affect the
micruorganis ns’ ability to degrade ethylbenzene, as evidenced by the
relatively constant N/N 0 values. Overall ethylbenzene removal averaged
86% during high toxlcs loading period, Day 84—91, compared to 80% during
the steady—state loading periua Day 16 to 45. Maximum effluent and
off—gas concentrations of 27.7 pg/f and 13700 ng/L, respecti ly, were
measured on Day 90 when he largest influenc echylbenzene concentration,
6760 pg/f, was recorded. A decrease in the amount of ethylbenzene
biodegraded Era’s 90 to 8G% was observed to coincide with the Largest
spike loadIng on Day 90. Overall ethylbcnzene re oval Immediately
.ncreased dqrlng the fo1l . ing two days to its steady—state level of
nearly 90%.
A two day period during which time no ethylbenzene was added to the
influent, Day 85 to 87, had no impact upon ethylbertzene biodegrddatiol-.
Overall removals neasur. d before and after the ethylbenzene interruptthn
period were 87 and 92%, respectively.
The chLorobenzene resuits reported by Figure 10—106 sh , slLghtly
greater variations in biode, radattve removal during the high toxics
loading period than was observed for either benzene or ethyibenzene.
Overall chlorobenzene removal averaged 82.6% durIng Days 84 to 91
compared to 81.2% during Days 16 to 45, when the ir.fluent toxics
concentrations averaged epproxi:nateiy 100 ig/Z. Effluent concencracicns
rose from less t’ an 1 pg/f to almost 18 ugh in response to an increase
in influent chlorobenzene concentratjoi from 150 to 2900 pg/f. The
largest effluent concentration measured was 157 pg/i which ocurred on
Day 90 when the Lnfluent concentration was 9560 ug/g. In the r.bsence of
chlorobenzene biodegradation the effluent concentration wculd have been
approximately 68C ugh.
The decrease in the amount of chlorobe,uene removed by
biodegradation from 89 to 67% on Day 90 coincided with the perioa of the
highest infiuertt toxics conc ntrations. Thougn the influent
concentrations of all of the tox.ics were the same c.n Days 90 and 91,
effluent and off—gas chlorobenzene concentrations dropped signiftca. tly
between Days 90 and 91 due to an increase in microbial degradation. An
efflt.ent concentration and an o rall removal of 37 ugh and 83:. were
recorded on Day 91, indicating a raptd return to steau::—state
levels.
Overall removal of toluene was largely unaffected by the high
influent loadings of benzene, ethylbenzene, and chlorobenzene as
evidenced by the constant N/N 0 values In Figure 10—107. The amount of
toluene biodegraded averaged 8(,% during the steady—state loading period
of Days 16 to 45. The only significant variation In biodegradative
removal oLcairred on Day 90 when the overall removal decreased to 7iZ.
As observed br chiorobearene. the r ooval of toluene Increased to
approximately steady—state levets by the next sampling period on Day 91
even though irifluent concentrat Ions were the same on Day 9land Day 90.
279
-------
An appro cimate four day period between Days 84 and 88 during which
time no toluene was added to the influenc had no impact on the
biodegradat Ion of toluene. Ovetall removals before and after the
interruption in toluene addition to the bioreactor were 86 and 92%,
respectively.
Th results for o—xylene were sigrificantly different than those
observed for the other four biodegradable cortpounds. As shc n by FigurA
10—lOS, the measurable decrease in overall o—xylene removal on Day 84
coincided with tncreases tn benzene, ethylbenzene, and chloroben7ene
influent c ncentrat1ons. The amount of o—’cylene biodegraded decreass’
from 847. on Day 83 when r e influent toxic concentrations were a1
approx.ia ately 150 pg/i to 507. on ay 84. Folbuing a four day pert d
when o—xylene was omitted from the irafluent, the overall o—xylene
removal increased to 857..
The biodegradation of o—xylene was reduced on Days 90 and
91, corresponding to the highest influent toxics concentrations.
Overall o—Kyiene removal decreased from 77% on Day 89 to only 41 on Day
90. The amount of o—xylene biodegraded increased to . 8Z on T)ay 91.
Although the influent toxi g concentrations were the same on Day 90 and
91, effluent toxics concentrations, especially chlorobenzerte, .xhihited
significant reductions betw,’cn Day °O and 91. Influenc and effluent
o—’cy .ene concentrations on Day 90 were &44 and 28 jg t, respectively.
While the Influent concentration droppc slightly on Day 91 to 52 ) pg/i,
the effluent concentration decreased by over 60% to 10 pg/i as a result
of the increased o—’cylene biodegradation.
The influer’t toxict c ‘ncentrations were adjustel a fLtal time on
Day 92 to the range .sed during the initial sevea weeks of the
mulct—solute study, 85 to 120 ugh. 0. urall removals of benzene,
toluene, ethylben7ene, o—xvlene, and chlorobenzene were approxamately
the same as observed during the st.eady—state biodegradacton period
between Days 21 an 46. As shcMn by th. plots in Figures 1O l0 through
L0—l , biodegradation effected overa.l removals from nearly 90% for
benzene and toluene to 85 for ethylben ene and o—xyiene.
Results from the multi—solute study provided valuable lnsigt’.t into
the behavior of trace levels of to-4c organic con ounds during act tvated
sludge treatment. The initial objective of the study was to compare the
biodegradation of benzene, toluene, ethylbenzene, o—xylene, a d
chiorobeozene in an a ttvated sludge system receiving a variety of toxic
organic compounds in the inuluent to the biodegradation of each compound
in a system recelvtng on’ y one toxic organic compound. The comparison
of results from single solute studies to res ..lts from the multi—solute
230
-------
study demonscrsced that there was no significant difference in the
amount of each compound removed by biodegradation in the two systeis.
Steady—state biodegradation rate coefficients and acclimation phases for
individual compounds in the multi—solute study were the same as those
observed in single—solute studies. There were no apparent competitive
interactions among the biodegradable compounds that favored biodegrada-
tion of one compound over the others.
The multi—solute study provided an excellent opportunity to observe
and contrast the fate and behavior i f rhe c , p unds Lnder identical
operating conditions. The cort.,istently high recovery of
1,2,!s—trachlorobenzene (ger,erally >90Z) served is an internal control to
continually validate the experimental procedure . used to develop mass
balances on all of the compounds. In general t e overall removals of
the compounds were in the order predicted to occur based on results of
single—solute activated sludge studies. Though ot planned, the
pH—upset episodes provided the opportunity to monitor the removal of
each compound during an activated sludge upset period. tlith the
exception of o—xylene, the oiodegradable compo’ nds experienced a
significant, bst temporary reduction in biodegradation. Witriin 24 to 36
hoi.rs overall removals returned to steady—statu levels. The effect on
o—cylene biodegradation lasted for a much longer time. in general, the
biodegradation of o—xylene appeared less stable than the other four
readily biodegradable compounds and more sensitive to changes in
bioreactor operating conditions.
The reaccilmation phase following two weeks during whicn time no
to,d.cs were added to the influen yes only two to three days compared
with the initial 14 to 21 day accl’mation per od at the begirtr.ing of the
study. Thus, once the activated sludge had a c1irnated to a compourd the
microorganisms retained the ability to degrade it during extended
periods when that compc.und was not found in the influent.
Increasing nfluent concentrations of eItzena, ethyihensene, and
chioroberizene to the 8000 to 12000 ug/L range initially resulzed in
increased effluent concentrations of each compound and small redtccions
it. the biodegradation of these three compounds. Reductions also
ocoirred in the overall removal of roluene and o—xylene, which were
added to the iifluer’t at 500 to 700 ugh. Within 36 to 8 hours after
the adjustment in influent concentrations to the largest levels tested,
the overall removal of all compounds except o-xylene approached
steady—state levels. Though not studied in detail, the results
si gesred that the percent of each compound, except o—xylene,
btodegraded increased as influc’it concentrations were increased from 100
to greater than 1000 ugh.
L0.7 EFFECT OF INFLUENT TOXICS coNcENTRAT1o : ON 8I0DEGRADAT10
Activated sludge bicre..ctor studies were conducted to evaluate the
effect of the influenc tox.lcs concentration on overall removals of four
biodegradable to,dcs; benzene, ethylbenzene, chlorobenzenc, and
nit benzene. St dies involving the volatile compounds benzene,
ethylberzene, aid chlorobenzene were conductee itt bioreactors LO which
all three compounds were added simultaneously to the influenc.
281
-------
Activated sludge studies wth nitrobenzene were conducted in hioreactors
receiving only nitrobenzen-.
The impetus for this study came from observations in the
multi—solute study that overalL removals and b’odegradation rate
coefficients generally increased as influent concentrations were
increased front 100 pg/i to the 5C0—1000 pg/i range.
10.7.1 Benzcne, Eth 1benzene , and Ctlorobenzene
An activated sludge bioreactor study was conducted for a totai of
18 weeks to examine the impact of influeit concentration on the fate of
three volatile, biedegradabLe compounds: benzene, ethylbenzene, and
chlorebenzene. The 18—week study can be aivided into four different
operating periods, as indicated by rable 1(J—5 3, based upon the influent
concentrations of the three compounds. T .iring the first nine weeks of
the study influent toxics concentrations were maintained between 15 and
30 pg/i, concentrations t pical of nany municipal wastewaters. During
the next seven weeks the influent concentrations were first increased to
between 100 and 200 pg/f and then to between 500 and 700 pg/i. The
influent concentrations were returned to the 100 to 150 ugh range
during the final two weeks.
Influent, effLuent, artd off—gas concentrations of each toxic
organic compound were measured every two to three days during the 116
days of the study. Also monitored on a regular basis were the
traditional activated sludge parameters: Influent and effluent soluble
organic carbon (TOC), rrnxed liquor suspended soLids (‘ LSS) and mixed
liquor p1!. Table 10—54 sunmarizes the TOC, MLSS, and pH data. The mean
solids retention time and the hydraulic retention time were fixed at 6
days and 5.5 hours, respectively.
The fate of benzene during the first 63 dayt. of the activated
sludge study is given in Figures 10—109 and 10—110. Figure 10—109
provides measured influent, effluent, and off—gas benzene concentrations
and N/ 1 0 values representing the fraction of the influenc mass flux
measured leaving tne bioreactor in the effluent and off—gas cOmbined.
The coi centracion data in Figure 10—109 wercconverted to nass flux values
and plotted in ‘igure 10-flU. The dashed line representing the anount of
benzene biodegraded by the activated sludge was calculated from the mass
balance equation for a C 1F reactor. As sh in by Figure 10—109 , the
effluent concentration remained less than 1.0 pg/i during the 63 days
when the influent concentration averaged 22.7 pg/i. A significant
difference between this study and activated sludge studies conducted
with influent concentrations in the 100 to 200 ugh range was the
absence of a distinct 14 to 21 day acclimation period characterized by a
gradual decrease in N/ 0 values from approximately 0.5 to less than
0.20. Results from this study were plotted ith results from art
activated sludge bioreactor study with a mean influent concentration of
118 pg/i in Figure 10—111. A stsnrnary of results from both studies is
given by Table 10—55. For comparative purposes, the results from the
282
-------
TABLE 10—53
BIOREACTOR OPERATING PERIODS IN THE ACTIVATED
SLUDGE T(2(ICS’ INFLUENT CONCENTRATION ST .
t ratins Pericd Length (days) Influent Concentraci.,ns
1. Days 0 to 63 63 15 — 30 hg/f
2. Days 64 to 71 14 100 — 230 ‘ ig/L
3. Days 7B to 112 35 500 — 700 ug/L
4. Days 113 to 116 14 100 — 150 ig/t
lower influent concentration study betw . en days 21 and 63 were used in
TabLe 10—55 because they represented the period of the largest benzene
biodegradaticn. The smaller N/N 0 values trom the higher influent
concentration study indicated that the fraction of the influenc benzene
measured in the effluent and off—gas combined as less than in the low
concentration study. Therefore, the percent of benzere biodegraded by
the activated sludge was greater in the bioreactor vith the larger
influenc concen,.racjon, as shown by Figure 10—111. The calculated
bi. Jegradation rate coefficient was significantly larger in the reactor
operated with the higher influent concentration.
An interesting feature of the results given in Figure 10—1 11 and
Table [ 0—55 were the similarities of the effluent concentrations. While
mean iiifiuenc concentrations differed by a factor of five, effluent
concantrations were approximately the same, 0.5 g/2. in the low influent
concentracior. unit and 0.8 ig/V. in the higher tnfluent concentration
reactor. Based solely upon effluent concentrations the performance of
the two bioreactors with respect to the amount of benzene discharged was
approxLmarely the same. Of f—ga. concentrations, tho gh not idencical,
dlffer d by less than a factor of three.
The resui recorded for chiorobenterte during the first four weeks
of the low influent concentration study were similar to those for
benzene. thlorobenzene influeric, effluent, and off—gas concentritions
have been plotted in Figure 10—112; nass fb. xes into and out of .he
bioreartor are shown In Figure 10—113. Effluent, off—gas, and N,’N 0
values were relatively unchanged during the f .rst four weeKs of the
study. Alter Day 28 the fractional recovery, N/N 0 , decreased indica (
an increase in tne amount of chlorobenzei e removed by hiodegradat ion.
CorrespondIng to the increased biodegradaci.ve removal was a reduction in
the amount cf chlorot enzene lea rtng the bioreactor in the effluent and
off—gas. The bioreactor performance with respect to overall
chlorobenzene removaL after Day 35 was sitnil ir to that obserw d in
acci.ated sludge studies with influent chlorobenzene conrertcrations in
283
-------
TABLE 10—54
OP .RATtNG CONDITIONS FCR THE BIOREACIOR STUDY
EVALUATING THE EFFECr O INFLUENT TOXICS
CONCENTRATIONS ON BIODEGRADATION
Paranieter an Value
InfI.uent TOC (mg/P.) 104
Effluent TOC (mg/P.) 17
TOC Removal (%) 84
MLSS (mg/P.) 3100—3400
pEt
SRT (days) 6
HRT (hours) 5.5
Aeration Race (P.1mm) 4.1
k (min ), benzene 0.076
k (nan ), ethylbenzene 0.086
k (min t ), chlorobenzene 0.050
284
-------
ACTVATED SLUDGE BIOREACTOR
6—Day SRI
OENZENE
0 7 14 21 28 35 42 49 56
TIME (DAYS)
FIGtRE 10—109. 3enzene infl’ient, effluent and off—gas
concentrations and fractlon3l recoveries, N/’ o, measured
during an activateo sludge study with an average influent
benzene concentration of 23 ugh.
285
-------
0
—S
z
>(
-J
LLO
U,
C /,
0
0
0
0
0
>(-
-J
LL 0
TIME (DAYs)
FIGURE 10-110. Ben ene influent, effluent, and off—gas
mass fluxes and at ounts rernoved by biodegradation during the
activated sludge study with an average influent ber.zene
concentration of 23 ugh.
7
14
21
28
35 42
49
56
63
7 14 21 28 35 42 49 56 63
286
-------
-J
Li
-J
U-
2
Li
-i
‘N
C.,
z
U)
(j
LL
0
0
z
‘N
z
TIME (DAYS)
FIGLRE 10—111. Comparison of ben ene effluent and off—gas
concencrat ons and fractional recoveries, Nf o , measured duri 2
activated sludge studies. ‘ ith average influent benzene
concentrations of 23 ugh and 118 ugh
C’,
C)
c
C)
C)
(0
C,
C.,
C)
C)
C..’
BENZENE
ACT WA1 ED SLUDCE STUDIES
AVG IN LUEN4T = 22.7 ug/I
AVG INFLIJENT = fl3 ug/
q
U,
C)
0 7 14 21 28 35 42 49 56 3 70 7
287
-------
TABLE 10-55
COMPARISON OF BENZENE REMOVALS IN BIOREACTORS
OPERATED WITH DIFFEkENT INE’LUENT BENZENE CONCENTRATIONS
Low Concentration 100 pg/i Influent
Study ConceritratLoti
Parameter ( Days 21—63) ( Drys 18—77 )
Influent (pg/I) 2 .7 118
Effluent (pg/i) 0.5 0.8
Off—Gas (na/I) 58.1 142
N/N 0 0.383 0.169
Overall. Removal (1) 61.7 83.1
Reduction in Aqueous 97.8 99.3
Concentration (%)
k 5 , calculated (aln’) 0.124 0.507
288
-------
-______
ACTIV8JEO SLUDCE BIOREACTOR
6—Dcy SRI
CHLOROBENZENE
I
21 28 35 9 56
TIME (DAYS)
FiGURE 10—112. Cbioroben:ene influent, effluent, and off-
2as c3ncentracions an? fractional rec veri€ s, / 4n, eacured
durins an activated s .udge study ‘ic i an average in luent
chlorobenzene concentrati n at 28 u Il.
289
-------
C
0
c l
CNLOROeENZENE (Low Concentration Study)
INFLUENT
X EFFLUENT
0 OFF—GA3
BIODECRADED
$ 1 1’ Th 1 ) A -v.
0 7 14 21 28 35 42 49 56 63
0
0
0
0
0
0
0
(0
0
0
C 4
0
TIME (DAYS)
FIGI E 10—113. Ch1crnbenz ’,e influent, €fquent, and off—gas
mass fluxes and amounts removed by hic deerad tion during t e
activiced sludgp study with an average influent chlorobenzene
concentration of 28 ugh.
z
0
-J
U)
U)
x
—I
L&.
I-
z
Li
-J
L I-
z
0
Li
0
Li
0
0 7 14 21 28 35 42 49 56 63
290
-------
the 100 to 200 pg/i range, as shown by the comparison in Figure l0—i14.
Table 10—56 s nnrnartzes and compares the results from the chlorobenzerie
studies Lompared in Figure 10—114. Results from the lower concentration
study tabulated in the first colu nn of Table 10—56 were obtaxne from
data collected during the operating period which corresponded to the
largest chlorobenzene biodegradative removal, Days 35 to 63. The values
in the second column were calculated from data for the same operating
period, but data collected from Da/s 44 to 46 were omitted. The
bioreactor experienced a slight u set which caused a temporaty reduction
in chlorobenzene re’noval between Days 44 to 66. Omitting this period
resulted .n a slight lncrea,e in the average overall chiorobeniene
removal and biodegradation rate coefficient.
The fate of ethyl.benzene during the low influent concentration
study is described by Figures 10—115 and 10—116 which present influent,
effluent, and off—gas concentration nd mass flux data, respectively.
During the first eleven days the fractional recovery, N/N 0 , aecreased
from 0.80 to approximately 0.50 where it remained fur almost three
weeks. The mass flux data in Figure 10—116 shows tt at the amount of
e:hylbenzene biodegraded increased substantlall) during the first two
week3, the primarj result of which was a decrease in the amount leaving
the bioreactor in the off—gas. The period of greatest biodegradation
ocm.irrea from Day 35 to 63 when an average of 68Z of the ethylbenzene
entering the bioreactor could not be found in the effluen. and
off—gases combined.
Results from t e low concentratior study have been plotted in
Figure 10—117 with results from an activated sludge study with an
influent ethylbenzene concentration In the 100 to 150 pg/f range. The
fractional recovery of ethylbenzene from the bioreactor with the larger
influent concentration was lower :naci that from the low influecit
concentration unit. This result indicated that a larger percent of the
influent ethylbenzene was subject to biodegradative removal in the unit
with an influent concentration between 100 and 150 pg/f. The stznmary of
the two studies in Table 10—5;’ shows that, like benzene, the
ethylbenzene biodegradation rate coefticient, and hence overall removal,
was greater in the bior actor eceiving the larger Influent
concentration. The effluent cincentrations observed in the two studies
were similar; averaging 0.3 and 0.6 pg/i for the 23 and 120 pg/f
influent concentration bioreactors, respectively. For comparative
purposes the period of greatest ethylbenzerie biodegradation, Days 35 to
63, was used to compute the values in Table 10—57.
Influent, effluent, and off—gas concentrations and N/N 0 values have
been compared for the following combinations o the three toxic
compounds in Figure 10—I 18 through 10—120: benzene and ethylber.zene,
benzene and chlor,benzene, and ethylbenzene and chlorobenzene, respective-
ly. A summary of results for each compound during the last four weeks of
the lo , concentration study, 6ay 35 to 63, is given in Table 10—38.
Durii.g the nine weecs of the low influent concentration period, chloro—
berizene e\f ’erlenced the lar est overall removal due to biodegracatton as
291
-------
N
-j
C.,
w
-J
I L
z
-J
C. ,
IL
IL
w
-J
C -,
z
U,
(p
IL
IL
0
0
z
z
TIME (DAYS)
FIGURE 10—114. Comparison of chlcrob nzene effluent and
off—gas concentrations and fractional recoveries, N/So,
measured during activated sludge studies vith average
influent concentrations of 28 ugh and 130 ugh.
N
a
c
U,
a
a
a
]
I I I
CHLORO B ENZ E F J E
ACTh/ATED SLUDGE STUDIES
AVG NFLLJE 1T = 28.3 uQ/i
0 AVG INFLU NT = 1 3O ug,’I
a
a
(0
0 7 l 21 28 35 42 49 56 63
292
-------
rABI.E 10—56
CtlI.0RobE LEuE REMOVAL IN ACTL AIEI SLu6CE BIOREACIoRS
Activated Sludge Study
lOt) JJZ/& fnf1ui iir
Low Concesitrjt Ion Low Couc. Days 35—63 ConcenLraL Ion
Parameter Days 35—6i (C nLt Days 44—46) (Days 16—56)
Influent (i g/ ) 26.6 26.3 lii
Effluent (iglZ) 0.4 0.2 1.1
Off—Gas (ng/i) 40.4 J5.6 192
N/N 0 0.243 0.200 0.180
Overall Removal (2) 75./ l L0 82.0
Reduction in Aqueous
Concentration (2) 98.5 99.2 99.2
kb. calculated (min 1 ) 0.167 0.215 0.245
-------
I. ,
0 •7 14 21 28 35 42 49 56 63
TIME (DAYS)
FIGURE 1O—11 .. Ethvlbenzene influent. effluent. aid off—
gas concentrations and fraction . recoveries, N/No, ea ured
during an crivatec sludge study with en average influent
echyl nzene concentration of 23 ugh.
—S
-J
U
-J
L&
z
ACTIVATED SLUDGE BIOREACTOR
6—Day SRT
ETHYLOENZENE
ee—
-J
C,
Ij
U
-J
z
C-,
L
I L .
0
0
z
z
a’
U,
294
-------
0
z
(. e’i
-J
Cr ,
Cr,
0
C
0
0
><-
-J
L. 0
_J ‘
z
0
L J
0
L J
-0
(DAYS)
FIGURE 10—116. Ethvlbenzene Influent, effluent, amd off—
as mass fluxes and amoun re oved by b ode radation dur .n
the accivatec sludge study with an average etnvlbenz ne influe tt
concentration of 23 ugh.
0 7 14 21 28 35 42 49 56 63
TIME
295
-------
C ’) I I I I -I
TIME (DAYS)
63
FIGURE 10—117. Cotnparisnn of ethvlbeuzene effluent and
off—gas concentratio ’S and fractional recoveries, N/No,
neasured during activated s]udte studies vith average influer.t
concentrations of 23 ugh and 119 urhl.
-J
0
w
-J
z
(0
C,
)
ETHY LB E. NZ EN E
ACTIVATED SLUDGE STUDIES
AVG INFLUENT = 23 4 ugh
0 AVG INFLUEN1 11 ug/I
a
C,
-J
c i
z
u )
Cf
LL
0
0
z
z
a
U,
a
0 7 14 21 28 35 42 49 56
296
-------
TABLE 10—57
ETHYL3ENZE: E RFMOVAL IN ACTIVATED SLUDGE BIOREACTORS WITH
DIFFERENT INFLUENT TOXICS’ CONCENTRATIONS
Parameter Low concentration 100 ugh Influent
Study Concentration Study
Days 35-63 Days 21—63
Influent (pg/i) 23.4 (6.5) 119 (14
Effluent (pg/i) 0.3 (0.1) 0.6 (0.2)
Off—Gas (ng/i) 46.7 (12.9) 166 (43)
N/N 0 0.321 (0.06) 0.19 (0.04)
Overall Ramoval (Z) 67.9 81.0
kb, calculated (min ) 0.192 0.387
Standard Deviation
297
-------
C,
w
-J
U-
z
-J
C,
-
U-
U-
( 4
—S
-J
C,
z
v)
L
U-
0
0
z
z
63
TIME (DAYS)
FGURE 10—118. Comparison of 1’enzene and ethylbenaene
inf1 ent, effluent. ;nd off—gas conc-entrations and fractional
recoveries. N/No, measured during the activated sludge stuuv with
low influent toxics concenLrations.
LOW• INFLUENT CONCENTRATION STUDY
ACTIVATED SLUDGE B OREACTOR
0 BENZENE
ETHYLBENZENE
I I I I ——
U)
0 7 14 21 28 35 42 49 56
298
-------
-J
0
L J
-J
z
-J
0
z
(I )
L
0
0
z
In
)
-J
C-,
L .
TIME (DAYS)
iIGtYRE 10—119. Comparison of ben7eqe and chlorobenzene
influen:, effluent, and off—gas concentrations and fract’ onal
recoveries, N/No, measured during the activated sludge study
with low influent toxic concentrations.
63
LOW INFLIJENT CONCENTRATION STUDY
ACTIVATED SLUDGE BIOREACTOR
O 6ENZEN
O CHLOF?OSENZENE
C
C
U,
0 7 14 21 28 35 42 49 56
299
-------
( 1
‘ -I
L J
-J
z
0
LL
Li
-J
0
z
U)
9
0
0
z
z
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
FIG1 RE 10—120. Cotn arison of ethylbenzene and chlorobenzene
influent, effluent, and off—gas concentrations and fractional
recoveries, X/ o, measured during the accivate sludge study
with low influent roxics concentrations.
LOW 1NFLUENT CONCENT RATION STUDY
ACTIVATED SLUDGE BIOREACTOR
0 ETHYL8ENZEN
0 CHLORO8ENZENE
300
-------
TABLE 10-58
COMPARISON OF BNZENE, ETHYLBENZEME, AND CHLOROBENZENE
REMOVALS IN THE LOW TOXICS’ INFLUENT CONCENTRATIOM
BIOR .EAcTOR DURING DAYS 35—63
Paraneter Benzene Ethylbenzene thioroberizene
Influent (pg/P.) 22.7 23.4 26.6
Effluent (pg/P.) 0.5 0.3 0.4
Off—Gas (ng/L) 58.7 ‘ 6.7 40.4
0.383 0.321 0.243
overall Removal (7.) 61.7 67.9 75.7
Reduction in Aqueous
Conc. (%) 97.S 98.6 98.5
kb. calculated (mtn ) 0.124 0.192 0.167
k (min ) 0.0763 0.O 78 0.0508
301
-------
shown by the comparisons in Figure 10—121. Overall removal of
chlorobenzene averaged nearly 76% from Day 35 to 63 compared with 62%
and 68Z for benzene and ethylbenzene, respectively. As shown in Table
10—59 the overall removals of benzene, ethylbenzene, and chlor)benzene
in activated sludge studies with average ,.nflucnt concentrations in the
100 to 150 ‘.jg/R. were similar to each other and exceeded 80%. While
biodegradation rate coefficient; for the three compounds listed in Table
10—59 were different from each other when rh influent concentrations
w re between 100 and 150 pg/i, they were approximately the same when
influenc concentrations were In the 15 ta 30 pg/i range, as reported in
Table 10—58.
Overall removals were calculated ftom N/N 0 values which can be
related to the volatilization ard biodegradation rate coefficients as
fo 1 lows:
N CeQe + CgQg 1 + k t
N 0 C 1 Qj t(kb+kv) 1
For a constant vaLue of k 0 , as k increases the value N/N 0 increases and
approaches a maximum of 1.0 which would indicate no disappearance due to
biodegradatIon. if the values of kb for benzene, ethylbenzene, and
chlorobenzene were appro amately equal, as was observed during the low
concentracion study, the compound with the lowest volatIlity should
experience the greatest overall removal due to biodegradation. The mean
values of k for benzene, ethylbenzene, and chlorobenzene during Days 35
to 63 of the low concentration study were 0.076 , 0.088 and 0.OS1
min5 respectively. Thus chlorobenzene would be predicted to have t .e
greatest overall removal and lowest fractional recovery.
The influent concentration of eaci compound was increased from the
15 to 30 pg/i range to the 100 to 200 pg/i range on Day 64 and
n intained at that level for aporoximately two weeks. On Day 78 the
influent concentrations were further iicreased to between 600 and 700
iig/t where they remained for three weeks. I iring the last two weeks of
the study the influent concentrations ware reduced to approximately 100
pg/i.
The results for benzene, shown by FIgure 10—122, indicated that the
decrease in fractional recovery, N/N 0 , coincided with the operating
period of increased ipfluent ccncentrations. The mean N/N 0 value
decreased from 0.32, averaged during the low influent phase between Days
35 and 63, to 0.08 for the operating period from Day 79 to 101
indicating that the biodegradation rate had increased. Table 10-60
gives mean values for influent, effluent, and off—gas concentrations and
overall removals recorded during periods of low, 22.7 pg/i, and high,
601 pg/i, influent concentrations. A significant finding was that
only a small increase in the effluent concentration resulted from thc
increased influent concentration. The largest effluent corcentratlon
-------
0
0
0
‘ ‘0
-J
F-’ 0
‘-J CD
Li
c o
0
TIME (DAYS)
F I CUR K 10— 1 7 I . Conipa r Isini of hen cne • etliy Ibenzeiie, aid ch1orobcn enc overall
remuvals iliw to bindegrnldt. kin during tI’e activated sludge study fth low Influent
coucent rat 1(11 15.
LOW INFLUENT CONCENTRATION STUDY
ACTIVATED SLUDGE BIOREACTOR
0 BENZENE
O ETHYLOENZENE
* CHLOROBENZENE
7 14 21 28 35 42 49 56 63
-------
TABLE 10—59
CO ARISON OF STEADY—STATE REMOVALS OF BENZENE, ETUYLBENZENE,
AND CHLORO8ENZ NE IN SINGLE SOLUTE ACTtVATEI) SLUDGE STUD!ES
Paraxi’eter Benzene Echylbenzene CTdorobenzene
Influent ( g/ ) 118 119 133
Effluent (pg/Z) 0.8 0.6 1.1
0ff—Gas (ng/Q) 142 1b5 192
N/N 0 0.169 0.190 0.180
Overall Removal (Z) 83.1 ei.0 82.0
ReJuction in Aqueous
Conc. ) 99.3 99.5 99.2
kb, calc ilated ( nin 1 ) 0.51 0.387 0.245
304
-------
-J
-J
L&
z
1
-j
‘-.. ( ‘.8
U-
L I-
-J
C,
z
C’,
‘I.’ =
Ic• . 8
U-
0
C,
zu,
z
0 14 28 42 56 70 84 98 112 126
TIME (DAYS)
FIG!.RE 10—122. Effect on effluent and off—gas concentraclons
and fractional recoveries, N/\’o. of 10 to 30—fold increases in
ir.fluent benzene concentrat ofl t the activated sludge b .orea:tor
receiving a 23 Llg/l avera e influent benzene concentration.
• I
ACTh’ATED SLUDGE BIQR ACTOR
S—Cay S T
BCNZENE
r
305
-------
TABLE 10—60
EFFECT OF INFLUENT CONCENTRATION ON THE RENIOVAL
OF BENZENE FR1 1 AN ACTIVATED SLUDGE BIOREACT)R
Pa tame tar
InfI.uent (ug/t)
Effluent (pg/f)
Of f—Gas (nglf)
N/ N 0
Overall Removal (Z)
Reduction in Aque s Conc. (Z)
kb (min )
Days 35—6:v
22.7
0.5
58.7
0.383
61 .7
97.8
0.12’.
Days 79—1O1
601 (64.6)
1.0 (0.7)
323 60.6)
0.081 (0.011)
91.9
99.8
0.9 19
+ Values averaged from 9 samples collected over 28 days
++ Values averaged from 8 samoles collected over 22 days
( ) Numbers in parentheses are standard deviatior&s
306
-------
recorded was less than 2.5 ig/i. and it occurred one day after the
influent concentration was increased from 20() to 650 g/9.. An
interesctng feature of the results in Figure 10—122 was the variation in
both effluent and off—gas concentrations et een Days 64 and 77. While
the influenc concencrar ion during that operating period was relatively
constant with an average value of 12u ig/t. the effluent and off—gas
concentrations decreased significantly. The calculated biodegradation
rate coefficient increased from less than 0.20 to greater than 0.90
mtn during this period.
The greatest overall removal of benzene during the 18 weeks of the
study occurred during the period of the h1 hesc influent concerrracion,
Days 31 to lOt. Overall b nzene removal due to biodegradation aweraged
92Z during chat period coWared with only 62Z during Days 35 to 63 of
the low influenc concentration period.
Ethyiber zene behaved in a manner similar to benzene as shown by the
results in Figure 10—123. A decrease in the mean fractional recovery of
ethyiben2ene from 0.33 to 0.08 coincided uitn he period of increased
inhluent concentrations. While Little variation in the steady—state
effluent concencrac ions occurred as a result of the change in influenc
concentration, off—gas concentrations increased measurably.
The cthylben2ene results in Figure 10—123 between r ays 64 and 77
e,thibjced the same trend as observec for benzene. Following initial
increases on Day 64 caused by the change in influent concentration, the
effluent and off—gas concentrations decrea 0 ed by a factor of four over
the next two weeks. The corresponding reduction in fractional
recoveries indicated a f .rther acclimation of the activated sludge to
echylbenzene and an increased biodegradation rate. Table 10—61
suamarizes mean influent, effluent, and off—gas concentrations, overall
removals, and biodegradation rate coefficients recorded during the low
and high influent concentration periods.
The fractional recovery of chlorobenzene decreased from a mean
value of 0.24 recorded during the operating period Day 35 to 63 to 0.07
for the period of highest influent toxics concenercions, Days 79 to 101
as shown by the re u1rs presented ta Figure 10—124 and suamartzed by
Table 10—62.
Effluent concentrations showed initial increases coinciaing with
the increased influent concentrations, but then decreased to approxicate
steady state levels .iichin ten days. The increase in influenc
chlorobeazene concentration on Day 64 produced a five fold increase in
off—gas concentration. While the Influent concentration averaged
approximately 140 ig/& for the operating period Days 64 to 77. the
oft—gas concentration decreased by over SOZ as the chlorobenzene
biodegradation rate increased.
307
-------
(0
-J
0
z
c- f l
4:
IC . , ’
o
0 14 28 42 56 ?O 84 ‘ee fl2 126
TIME (DAYS)
FIGCRE 10—123. Effect on effluent and off—gas concen:ratio
and fractional recoveries. s/No, of 10 to 30—fold increases in
influent ethvlbenzene concentration to the activated sludge
bloreactor receiving a 23 ugh average ethylbenzene conceitration.
.— (p
-J
0
p
308
-------
TABLE 10—61
EFFECT OF INFLUENT C0NCENTSAT1O ON T! E RE )VAL
OF ETHYLEENZENE FRO 4 AN ACTIVATED SLUDGE BIOREACTOR
Parameter Days 35—63 Days 79—101
tntli ent (iig/t) 20.7 61J (69.7)
Effluent ( ‘g/ ) 0.3 0.7 (0.6)
OU—Gas (ngI ) 48.1 331 (44.1)
N/N 0 0.332 0.079 (O.Ot)
Overall emova1 (Z) 66.8 92.1
Reductioit in Aqueous Conc. (Z) 98.6 99.9
kb (miif 1 ) 0.183 1.081
Standard Devxat .on
309
-------
-J
C,
-j
z
-J
0
L.
IL ________ _____________________
w
-J
0
z
(-I - ,
IL
I L
C
0
z
z
0 14 28 42 56 70 84 98 112 126
TIME (DAYS)
FIGERE 10—12 ’. Effect on effluent and off—gas concentrations
and fractional recoveries. N/Nc. of 10 to 30—fold increases in
influent chlorobenzene concentrations to the activated sludge
bioreactcr receiving 28 ugh average influent chlorobenzene
concentration.
— I- I I I I
ACTIVATED SLUDGE BIOPEACIOR
6—Day SRI
CHLORO6E NZEN E
TTJG
I I I I
C 4
310
-------
TABLE 10—62
EFFECT OF LNiL1J NT C0NCE TRATI0N ON THE REMOVAL
OF CHLOROBENZENE FROM AN ACTIVATED SLUDGE BIOREACTOR
Pa raxneter
Influent (ijg/L)
Effluent (ugh)
Of f—Gas (n F4)
N/N 0
Overall Re noval ( )
Reduction in Aqueous Conc. (Z)
kb, calculated (ain 1 )
Days 35—63
26.6
0.4
40 • 4
0.243
75.7
98.5
0.167
Days 79—101
673 (41.6)
1.3 (1.3)
331 (43.9)
0.071 (0.013)
92.9
99.8
0.719
( ) Standard DeviatLon
311
-------
Overall removals of benzene, ethylbenzen , and chlorobenzene
attrj ted to biodegradation have been plotted in Ftg’ire 10—125 for the
18 weeks of the bioreactor study. The results show the signińcant
increase in removals measured during the first 63 days when influent
concentrations ranged from 15 to 30 tig/& compared to Chose measured
between Days 79 and 112 when influent concentrations ranged from 600 to
650 ugh. Average overall remova .s during the low conceniration period
here largest for chlorobenzene, 757, compared to approximately 66% rot
both benzene and ethylbenzene. Overall removals of each compound were
equivalent for the three compounds and averaged 92% during the ooerating
period when intLient Loncentrations averaged greater than 600 hg/i. The
relatively horizontal lines describing removal between Day 79 and 112
indicated a larger degree of stability with resptct to toxics
biodegradation than was observed during the preceding period of low
influent concentrations.
An important finding of this study was the activated sludge
microorganisms’ ability Co degrade the three organic compounds to low
part—per—billion levels. Influent concentrations in the 15 to 30 ug/
range represent typical levels of organic priority pollutants that
occjr in municipal wastewacers. The bacteria exhibited an ability
to oegrada the compounds even though the concentration to wnich they
were exposed, the effluent concentration in a CMF reactor, never
exceeded aoproximatel ’ 1.5 ugh. Effluent or mixed liquor concentra-
tions typically were less than 1.0 ug/9. throughout the low concen ra—
period. Even though influent concentrations were increased by a
factor of nearly 20 during the course of the 18—week study, steady-
state effluent concentrations were essentially unchanged.
10. 7.2 Nitrobenzene
Activated sludge bioreactor studies with nitrobenzene demonstrated
that biodegradatinri effected removals greater rhan 90% under
steady—state conditions. The influent cancentration in those studies
was maintained in the 90 to 130 pg/i range, and under steady—state
operating conditions the effluent concentration varied between 2 and 5
pg/i. This study was designed to evaluate the cffect of nicroberizene
concentrations ranging from 100 pg/i to nearly 25,000 pg/i on th2
removal of nitrobeizene and the overall performance of the activated
sludge unit as measured by TOC removal.
312
-------
0
0
0
0
0
“0
C.’
-J
C)
Sd
w
1
-J
Li
F I CURE 10— I 2 S . (‘oniparl son of I)CUZCflL, ctliy II)enicIu • anti clii orolictizcne overall
remov iIs due to biodegradation during periods ol low (IS to 30 ugh) and high
(600 to 750 ugh) infitient t.ixlts cimccntrations to an actlv.ited sludge hioreactor.
I3ENZENE
W ETH’YLBENZENE
CHLOROBEN7ENE
0
0
0
0
0
0
0
I . .’
I-
INFLUENT CONCENTRATION STUDY
AC1 WAlED SLUDGE BIOREACTOR
14 28 42 56 70 84 98 112
TIME (DAYS)
126
-------
Influent nitrobenzene concentrations were mAintained between 90 and
[ 20 pg/i for the first four weeks to achieve steady—state nitrobenzene
removals. Effluent concentrations decreased from appoximately 85 pg/i
on Day I to 3 ug/R. on Day 13, and then remained in tl e 2 to 4 pg/i
range. The intluent nitrobenzene concentration was increased on Day 30
from 110 to 250 p r/i and remained at that level for approximately one
week. There was essentially no change in steady-state effluent
nitrobenzene concentration; it reaained in the 2 to 4 pg/’. coriceitration
range. the influent concei.tration ar further increased to between 500
and 600 pg/i on Day 41 of the bioreactor study. After a small, inlti3L
increase, the effluent concentration returned to its previous
steady—state level. T. le 0—63 lists a sLrwary of results from the
nitrobenzene bioreactor study. The most interesting aspect of the data
presented tn Table 10—03 was the finding that steady—state effluent
concentrations were essentially t ’e same even though influeqt
concentrations ranged from 100 to nearly 550 pg/i. Ihe increasing
nitrooenzene concentrations had no effect upon overall organics removal
as measured by soluble TOC.
Another activated sludge study with nitrobenzene was conducted to
evaluate nitrobenzene removal at influent concentrations in the low
milligram—per—liter concentration range. The bioreactor initially was
acclimated to an L fluenL nirrobenzene concentration cf between 90 and
120 pg/i. As in the previously describe I study, there was an
approximate two week acclimation period followed by steady—state
effluent concentrations of 3 to 4 pg/i. After two weeks of steady—state
nitrobenzene degradation the influent concentration was increased to
between 1200 and 1300 pg/i. The effluent nitrobenzene concentration
TABLE 10—63
STEADY—STATE RESULTS FROM NITROBENZENE
ACTIVATED SLUDGE STUDY WITH INCREASING
INFLUENT CONCENTRATIONS
Influent EUluent Removal
( pg/i) ( u&I ) ( % )
116 2.6 98
265 2.4 99
541 3.2 >99
314
-------
initially rose from 3 to nearly 600 ugh as a result of the increase in
influenc concer.tration from 100 to over 1200 ugh. Within a week the
effluent concentration had decreased to between 1 and 4 ugh, the sa ne
level that occurred when the influenc was 100 ugh. The bioreactor was
operated for approxi.m.ately two weeks with an influent nicrobenzene
concentration berween 1200 and 1300 ugh. 1 iring that time the
steady—state effluent concentration averaged approxlaia e1y 2.5 ugh.
The i &fiuenc nitrobenzene concentration was increased a second Lime
from 1200 ug/2. to nearly 25,000 ugh. The effluent concentration
Locreased from 3 ug/P. to approximately 20,000 ug/L and remained at that
leveL for the ten days that 25,000 ugh of nitrobenzene was added to the
influent. S seline studies indicated that an approximate 20% reduction
in aqueous aicrobenzene concentration occurred due to air—stripping in
bioreactors without a tivated sludge. The 20% reduction in aqueous
concentration recorded during the 25,000 ugh nitrobeozene influenc
concentration caused a reduction in soluble TOC removal from
aoprox.imacely 85% to 40% as effluent TOC concentrations rose from 15
ag/i to nearly 60 mg/L. The high irifluent nitrobeozene concentration
apparently had an inhibitory effect on the microbial activity in the
activated sludge that resulted in a reduction in the microorganisms’
abiLity to degrade the organic con ounds co rising the synthetic
wastewater. A batch TOC degradation study was conducted to measure the
effect of the nitrobeezene on the TOC biodegradation rate coefficient.
Results of the study given in Figure 10—126 and suomarizea by Table
fl)—64 confir d that the high nitrobenrene :oncentration effected a
reduction in the TOC biodegradation rate coefficient.
FolL ing the 10 day 25,000 ugh influent concentration operating
period the Lnfluent concentration was reduced to its original level of
approximately LO0 ug/) . . ithin two weeks nitrobenzene removal returned
to the 97—98Z range as the effluent concentration dropped to between 2
and 4 ugh. The TOC removal also returned to its previous steady—st..ite
level of nearly 85%.
The inhibitory effect caused by the 25,000 ug/2. influent
concentration was only temporary. It is possible that the activated
sludge would have eventually acclimated to the high nfluent
nitrobeozene concentration. Gotnolka ana Gomolka (59) reported that
activated sludge acclimated to nicrobenzene influent concentrations up to
400 mg/i. Only at the highest concentration evaluated, 430 mg/i, did they
find an inhibitory effect on the biodegradation of overall organics.
The purpose of this study was: 1) to measure nit-obenzene degradation
at the microgram—per—liter concentrations likely to be in municipal
vastewater, and 2) to evaluate the effect of sudden increases in
influent concentratio i representing a spike loading situation that would
be of short duration. The results suggest that no adverse affect in
steady—state removal occurred up to influent concentrations of 1200 to
l300ug/Z. A steady—state effluent concentration of between 2 and 4 ug/P.
was recorded for influent concentrations ranging from 100 to 1300 ugh.
An almost complete inhibitior’ in nitrobenzene renoval occurred at an
315
-------
FIGURE 10—126. Effect of a 25,000 ugh influent
riitrobenzene con:entration on activated sludge degradation
of synthetic wastewacer 5olubie bC. (TOG degradacioi
rate studies conducted in the 10—liter bioreactor being
used for the nitrobenzene activated sludge study.)
ICC BIODE t 5RADATION RATE S11J 1ES
10-LITER BIOREACTOR (BATCH FIDDE)
—J
C D
z
w
C-)
z
0
C-)
L)
Influenc Nitrobenzene Concentration:
25,000 ug/l
( . I
0
10 20 30 40 50 60
TIME ((1INUTES)
316
-------
influent concentration of 25 mg/i. There was rto sign of microbial
reacclieacion after 10 days of operation at the 25 mg/P. level. Once
the influent concentration decreased to appro dr.ately 100 pg/i the
removal of nitrobenzene i ’nmed ately i icreased, reaching steady—state
levels of 987. witriin i wo weeks.
[ 0.8. TRANSIENT LOADING STUDIES
The results presented thus far were obtained from bioreactorS
receiving a continuous input of toxic organic compounds i,n the influent
flows. While SUCh steady—state loadings were necessary for quantifying
the, behavior of idividual compounds in activated sludge SyStemS, they
m y not bu representative of actual treat ’nent conditions. Rather it is
sore likely : Iac trace organic priority pollutants are present in
influents on a transient basis. An important question is how such
transient loading conditions affect the removal of volatile and
non—vol3tile biodegradable compounds for which distinct acclimation
periods exist.
The removal of trace toxic organic compounds under transienr
loadi g conditinns was studied using th 10—liter bioreactors operated
in continuous flow modes. Three volatile compounds, benzene,
ethylbenzene, a. d chlorobenzene, and one non—volatile compound,
nitrobenze .e, were chosen for the study. The three volatile compounds
were added simultaneously to an activated sludge bioreactor operated
with a 6—day solids retengion time. A transiunt loading study with
nitrobenzene was studied in a separate unit also operated at a 6—day
solids retention time. Transient loading conditions were obtained by
operating the oloreactors on a cycle of two days during which the test
organic solutes were added cc the influeTits followed by three Co six
days during which time the tox.tc oiganic compounds were not added to the
activated sludge units. All other bioreactor operating conditions were
maintained constant.
10.8.1. Benzene, Ethylbenzene, and C lorobenzene Results
The activated sludge bioreactor receiving benzene, echylbenzene,
and chlorobenzene was operated for a total ef 18 weeks. A mean solids
reter.tion time ana hydraulic residence time of 6 days and 5.5 hours,
respertively, were used during the study. The influent TOC ranged
between 90 and 120 ugh and the influent concentrations of the
individual toxic organic compounds were maintained between 100 and 150
ugh. Table 10—65 sunmarizes five operating periods, with respect to
toxics ddttion to the influ nt, into which the [ 8 weeks can be
divided.
Influont, effluent, and off—gas concentrations and fractional
recoveries, N/N 3 , of benzene, ethylbenze’ e, and chlorobenzene measured
during the 18 week transient loading study have b en plotted in Figures
10—127, 10—128, and 10—129, respectively. Dashed lines indicate periods
of transient toxics loadings while solid lines represent operating
periods during which time the toxics were added continuously to the
inf)uent. Day 0 represents the initiation of the toxics addition to the
317
-------
TABLE 10—64
EFFECT OF INFLUENT NITROBENZENE CONCENTRaTION
ON SOLUBLE TUC RE4OVAL
Influent Nitrobenzene TOC Biodegradation +
Corcentration ( gf _ Rate Coefficient (min 1 )
100 0.015
25000 0.007
+ From Figure 10—126
TABLE 10—65
BIOREAcTIJR OPERATP4G PERIODS WITI’ RESPECT TO TOXICS
ADDITION DURING THE TRANSIENT LOADING ACTIVATED
SLUDGE STUDY
Bioreactor Operating
Time Period Length (days) Conditions
1. Days 0—56 56 Toxics ndded on a cycle of 2
days present in influer t
fo11c ied by 3 days not ptesent
2. Days 57—65 9 Toxics added continuously
3. Days 66—14 9 Toxics not present for 6 days
then added for 2 days
4. Days 75—9i 19 Toxics not present in infiuent
5. Days 94—125 32 Toxics added on a cycle of 2
days present in influent
foll .ied by 6 days not present
318
-------
TABLE IO—öô
COMPARISON OF OVERALL REMOVALS AND 8IOOEGRADAT [ ON
RATE COEFF [ C [ E’ Ts ‘IEASURED ON DAY 1 AND DAYS 52—53
OF TUE TRANSIENT LOADING STUDY
Biodegradac1on ”’
Overall P mova1 (Z1 4 Rate Coefficient(cniri t )
ound Day t Days 52—53 j y 1 Days 52—53
Serizene 39 88 0.05 0.48
EthyLbenzene 17 77 0.02 0.26
Cn loroberizene 27 85 0.02 0.26
* Overall Removal 1 01—N/N 0 )
i + Calculated by aquacton 10—9
319
-------
-J
C.,
w
-J
LL
z
-J
C-,
U-
U-
U i
C-,
z
(1,
9
11
IL
0
0
-7
z
TIME (DAYS)
FIGURE 10—127. Benzene influent. effluent, and off—gas
concentrations and fractional recoveries, N/so, measured
during the acttvated sludge study with transIent loadings of
benzene, thylbenzene, and chlorcbeflzefle.
U)
4 _
‘
‘
a).
•
a)
I
I I
SI
II
Is
I I
I I
‘.
6
I
0
‘
w
%
‘
‘
%
•
‘ -
I
R
I
a)
$
--- - -
0 14 28 42 56 70 84 98 112 126
I I
TRANSiENT LOADING STUDY
B(NZENE
O ADDED 2 DAYS/OFF 3 DAYS (days 0—57)
* COU1 N1IOUSLY ADDED (dnys 57—65)
OADflED 2 DAYS/OFF 6 DAYS (doys Q4—’25)
I I
.
320
-------
—1--
TRANSIENT LOADING STUDY
EThYLBENZENE
“
0 ADDED 2 DAYS/OFF 3 DAYS
CONTI JUOUSLY ADDED (days
0 ADDED 2 DAYS/OFF 6 DAYS
(days 0—57)
57—65)
(days 94—125)
-J
C,
Li
‘—S
L
LL
LaJ
‘ -S
-J
(5
z
5 1
C’,
(j?
0
0
z
z
TtME (DAYS)
FIGURE 10—123. Ethylbenzene in luent, effluent, and off—
as concentrations and fractional recoveries, N/’o, neasured
during the activated sludge studs vith transient 1oadi ngs of
henzene, ethyLbenzene. and chlorcbenzene.
a
m
4
I
w
‘
0 ___ -. -.t
I I
I
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J,I
l
I
I,
0
I
I 4
El
(D
I
II
‘
,00
,
\
I I I
w
I
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UJI i
I
I
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I
I
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— — I
I —s
I
I
.
I
I
I
U,
0 14 28 42 56 70 84 28 112 126
321
-------
TRANSIENT LOAD NC STUDY•
w
CHLOROBENZENE
I
I
[ T
.._-W
‘i I
,
S
t
0 ADDED 2 DAYS/OFF 3 DAYS
CONTINUOUSLY ADDED (days
(days 0—57)
57—65)
0 ADDED 2 DAYS/OFF 6 DAYS
(days
94—12
5)
a ,cv
.rn ® / (I
:‘
% --cfl
/
II
- , II
II $
t S S
II
It
& I,
I g S
I I
.. S
\J
I I S
Ii
I
..
%
‘
‘
$
‘a’-
%
$
,.
%
‘9
I
TIME (DAYS)
FIGURF 10—129. ChlorobenzQne influer,t, effluent, and off—
gas concentrations and fractional recov r es, N/No. neasure ’
during the activated sludge study i:h tr nsie.it 1oadinz ef
of benzene, ethvlbenzene, nd ch1or Den. ucu .
c 4
-
a
C , , ’
-J
w
-J
Li
z
-J
C.,
L.
Li
-J
0
z
C /)
Li-
0
0
z
z
a
It,
a
0 14 28 42 56 70 84 88 112 126
322
-------
influent. Prior to the addition of the three test compounds o the
influent the bioreactor was operated f r nearly three weeks to acclimate
the i.icroor anisrnS to the synthetic wastewatar. Activated sludge used
to seed the bioreactor was obtained from the Ann Arbor wasteslater
treatment facility. The addition of the three organic compounds on Day
0 had no observable effeLt on bioreactor performance as aeasured by
traditional operating parameters such as TOC removal, 1LSS, and effluent
susper.ded solids.
The results pt sented by Figures 10—127, 10—128, and 10—129, indicated
that the overall removal of each compound due o biodegradation was
characterized by an acclimation phase e cending from Day 0 to
approxlmat ly Day 52. As shewn b Table 10—66, a significant increase
in the overall removal of each compound occurred bet. een Day I and Day
52.
In general the removal of ben eae due to biodegradation was the
largest follewed by chlorobertzene and ethylbenzene I. .-. decreasing order,
as s”ewn by the comparison of results for all three compounds between
Days 0 and 70 in Figure 10—130. The same order ‘.zas jbserved in sin le
and reultt—iolute activated sludge studies conducted with continuous
toxics loadings.
A sudden increased recovery of each compound on Day 46 was observed
to coincide with a drop in the n1.e liquor pH from approximately
7.2 to 6.2. The- pH decreased due to tu5ing tatigue in tne
teed p p sup 4ying tap water co,itaintng NaHCO 3 buffer t the influent
flew. Within a maxiiiurn ot twelve hours the pH had been adjusted to its
original level of 7.2. Samples collected one day later, Day 47, shewed
that both effluent and off—gas concentraC ons had decreased
significantly from values recorded on Day 46 as a result of increasad
biodegradation of each compound. While the pM—induced upset episode
effected significant reductions in the biodegradation i the three toxic
organic compounds, the effect was only temporary. Within 24 to 36 hoi.rs
after the p11 had been adjusted to its original level, the system had
returned to its previous levels of bicdegradative removal. Similar
results were observed for benzene, et,ylbenzcr.e, and chloroben2ene in
other activated sludge stjdies. The magni:ud’ of the reductions in
biodegradation were larger during the transient loading study, but the
length of the effects was similar to that observed in other a tivaCed
sludge bioreactor studies.
T.nfluent, effluent, anJ off—gas coicentrations and N/N 0 values for
benzene, ethylbenzene, and chlorobe zene from Days 0—74 of the cransie t
loading study have been compared with results from steady—state loading
studies in Figures 10—131. 10—132 , and 10—133, respectivaly. In each
case the l/N 0 values measured on Day I were approx1matel the same for
each compound in both continuous and transient loading stud e indicating
that initia . biodegradation rate coeffic:ents were similar. The results
for benzene in Figure l0—l3 show that removal of benzene by activated
sludge in the stedy—state and transient studies was approximately the
same with the exception of the pu—induced upset epi’ode on day 46.
323
-------
0
0
o 6 I
TRANSIENT LOADING STUDY
ACT ATED SLUDGE --
.—- ° — - ‘ — —
— — — ID — — — — , i — — —
S
. —
. I
——
S I It •II j.
ç — — ! ‘ ,_, . 0 -, I
% I I
o G---c %,. •‘
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0 s I •• 3 \
. • I I
.. I I t I
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I
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t!J ‘ S ti ll
ci
I
O8ENZENE
t . 0 ET fYLBENZENE
>
o 3K CHLOROBENZENE
0
o I —..--——- I
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FICURE 10—110 fle,i en , erhyibcnzene, and cIi1orohenzc’ e overall removals due to
uloclegradation during the Initial 66 (lays of the activated iiidge study with
transient toxics loadIn . (Toxics added to tile Influent for 2 days and then omitted
for 3 days during days 0—56.)
-------
C,
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C.,
U
-J
z
C3
-J o
L .
U
-J
C.,
z
U -)
I
I L.
0
I I 4 4 I 4 4 1 4
o I’
z’ a
0 7 14 21 28 35 42 4 56 63 70 77
TIME (DAYS)
FIG RE 1O-1 i. Ccmparison of benzene effluent and off—
gas concentrations and fractional recoveries, N/No. measured
urin2 activated s1ud e studies with transient (2 days addedl
3 days omitted for days 0—56) and steady—state tcxics loadings.
BENZENE (Activated Sludge)
fl TRANSIENT LOADING
C STEADY—STATE LOADING
a
I,
..
C ,
0•
325
-------
-J
(5
Li
-J
z
-.J(O
Lz _____
L&
Li
-J
C-,
z
U,
1 L
l.L
0
0
z
z
FIGURE 10—132. Comparison of ethylbenzefle effluent and
off—gas concentrations and fractional recoveries, NI o.
me. sured during activated sludge studies .ith transient
(2 days added/3 days omitted for days 0—56) and steady—state
toxics Loadings.
ETHYLBENZENE (Activated Sludge)
O TRANSIENT LOADING
O STEAD’1 _ STATE LOADING
- - - 4 I
$ I I - I I I I I —
—2? ‘I
_____ 4
$1)
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
70 71
326
-------
C•’d
C ’,
‘
CHLOROBENZENE (Activcted Sludge)
I
LOADING
• TRANSIENT
I STEADY—STATE LOADING
6 I 4 I 4 4 I 4 4
I I I I I I I I
s ?.
I•
I
S
a
L 4 — —4 1 I
FIGURE 10—133. Conparison of chlorobenzene effluent and
off-gas cc’ncentratioflS anc fractional recoveries. N/No,
measured dur n acr .vaced sludge studies with trans!e t
(2 days addt d/3 days oraicced for days 0—56) and stead>-state
toxics loadings.
-J
C,
Li
-J
U-
z
—I
C,
U-
U-
Li
-J
C ,
z
(I)
Cf
1L
1L
0
—
4
0
z
z
0 7 H 21 28 35 42 49 56 63 ?0 77
TIME (DAYS)
327
-------
difference in effluent or off—gas concentrations between the rwo
studies after Day 35. During the acclimation period, however, the
overall, removal of benzene in the steady—state loading bicreactor was
slightLy greater as indicated by the smaller N/N 0 values.
The comparison of results fcr thlbenzene under steady—state and
transient loading conditions in Figure 10-132 indicates that the removal
of ethylbenzene during the acclimation period, Days 0— 8, was slighLly
better in the bioreactor with the steady—state loadings. The length of
the acclimation periods in both studies was between 21 and 28 days.
With the exception of the results from the transient study collected
between Days 42 and 49, the overall removals after acclimation were
approximately the same. The transient lo. 3 d ng bioreactor experienced
an upset between Dr’s 42 and 49, therefore the data collected during
that period was likely to be unrepresentative of the removals under
steady—state bioreactor conditions.
The coL2arison of results [ or .hlorobenzene from steady—state and
transient loading studies, plotted in Figure 10—133, indicated greater
overall removal due to biodegradation occurred during thL acclimation
phase of the steady—state loading reactor. The results after Day 49
were approximately the same for the two loading sludies.
While exact effluent and off—gas concentrations and overall toxic
removaLs observed during acclimation periods were found to vary from
study tA study, an interesting trend was obrerved during the transient
study. Two reactor samples were generally collected during the period
when toxics were added to the influent, the first between 18 and 24
hours and the second between 36 and 48 hours a€cer the to dcs addition
was begun. The amount of each compound biodegraded by the activated
sludge as lar cr on the secnd lay than on the firsi day oz each tox ics
addition period. The greatar amount of degradation on the second day is
evidenced in the N/N 0 values for the second data point in ea:h pair of
points repre enting samples collected during the toxics addition
periods. The removal of each cou ound during the 2—day period when
toxics were added was more thoroughly investigated on two occasions by
sampling the bioreactor every four to eight hours during this period.
The first detai1 . d sampling was conductc.d from Days 42 to 43, and
tne results for benzene, ethylbenzene, and chlorobenzene are given by
Figure 10—134. The overall removal of each con ,aund due to
biodegradation increased during the sampling period as sh n by the
decreasing trend in fractional recoveries, N/N 0 . The order of removal
was the same as observed to occur throughout the 176 days of the
transient study
benzene ) chlorobenzene > ethyibenzane
Table 10—67 provides a comparison of measured overall removals and
calculated first—order biodegradation rate coefficients at the beginning
and end of the 38—hour study.
328
-------
TRANZLENT LO AD NG STUDY (Days 42 — 4i)
ACTWATED SLUDGE CIOREACTOR
—
BENZEN(
—J ETHYLBENZENE
CHLOROBENZENE
—
p i.
O 1’2 18 24 30 36 42 48
TIME (HOURS)
FIGURE 1O—13 . Changes in benzene, ethylbenzene, and
chlorobenze e effluent and off—gas concentrations and
fractional recoveries, N/No, due to incr!ased microbial
degradation during tne 2-day toxics addition period,
Days 42 to 43.
329
-------
The second sampling period was conductea on Day 57; influent,
effluent, and off—gas cor centrations and N/N 0 values are given by
Figure 10—135. The same relative order of removals was observed:
benzene > chlorobenzene > ehtylbenzene
Uverdil removals of each compound increased during the 24 hours sampling
period with the largest increase occurring for e hylbenzene. A
comparison of overall removals and biodegradation rate cc.effictents
measured 2 and 24 hours after toxics addition to the influent was begun
on Day 57 is given in Table 10—68.
TABLE 10—67
CONPA ISON OF OVERALL REMOVAL AND BIODEGRADATION
RATE COEFFICI .NTS AT 2 AND 38 HOURS GUttING
THE ro cIcs ADDITION PERIO [ ) DAYS 42—43
Biodegradation
Over .dl Remova1( ) Race Coefficent(mi 1 )
Compound 2hL. 38 hr. 2 r. 38 hr .
Benzew 61 85 0.13 0.44
Ethylbenzenu 9 57 0.01 0.1.
Chlorobenzene 41 79 0.04 0.20
TABLE 1O—6i.
COMPARISON OF OVERALL REMOVAL AND BICDEGRAL•6TION
RATE COEFFICIENTS AT 2 AND 24 HOURS DURING THE
T (1CS ADDITION PERIOD OF DAY 57
8iodegrad t ion
Overall Removal(Z) Rare Coefficient(rnin— 1 )
pound 2 hr. 24 hr. 2 hr .
Benzene 75 81 0.22 0.33
Ethylbenzene 20 66 0.02 0.19
Chlurrh nzene 2 74 0.08
330
-------
-J
0
Li
-J
LL
z
-J
L
IL
U i
c i .
(c
C)
c i
c i
ci
ci
C-
-J
-v ci
U)
- E
I
I
4
I I
I
4
ci
— — 4
_
% c i :-- - _____
c i
0 6 12 18 24 30 3 — 42 48
TIME (HOURS)
F!”4R :(-135. Chanees in ethylbenzene, and
ch1oroben- ne effluent and off— 6 as . ent:atj i and
fractiot , ecoverles, N/No, due to . c’- b a1
deg:adaci’ a during the 1 -day toxics addi io”
Day 5
TRANSIENT LOADING STUDY (Coy 57)
ACTIVATED SLUDGE BIOREACTOR
O BENZENE
O ETHYLBENZENE
* CHLORCBENZENE
3M
-------
Results for benzene from the two sa npling periods, Days 42—43 and
Day 57, were nerrly identical, as sha n by Figure 10—135. Results for
ch],orobenzerte given by Figure [ 0—137, indicated that the overall
removal decreased slightly faster during the second in—depth sampling
period. The ata for ethylbenzene given by Figure 10—138 showed that
the approach to steady—state biodegradation was significantly more rapid
during the study conducted on Dz y 57, as evidenced by the reductions in
N/N , values. The results from the LWO studies indicated that during
each two—day period to ics addi’ Lon there was an increase in the
amount of each compound biodegraded. I iring the acclimation phase of
the study that increase likely continued throughout the two days the
toxics were added to the influent. Once the system had fully acclii ated
to the three compounds overall removals increased during the first 24
hours to their respective steady—state levels.
The significant finding of the in—depth sampling periods was that
during transient toxics loading conditions the overall removal of the
three compounds went through a short reaccilmation phase rather tha’
continuing at the level that existed when to’cics addition was
discontinued. When fully acclimated this reacclimation phase was short
and the system returned t steaay—state toxics biodegradation within 24
hours.
After the overall removal of each compound in the transient loading
bioreactor reached the approximate steady—state levels observed in
previous activated sludge srudie , tne three orCanic compounds were
added continuously to the influent for 8 days beginning on Day 57.
There was an increase in the removals of ethylbenzene, and, to a lesser
extent, chlorobcnzene, during that time such that by Day 65
approximately 85% of each compound was biodegraded ny the activated
sludge. No increase in berizene removal occurred.
Following the con’iruous addition period the toxics were amitted
from the influent for 6 days, Days 66 to 72; then added for two days.
The 6 day interruption had the most significant impact art et’ ylbtnzene
e nova1 causing it to decrease fvom 85% on Day 65 to 63% on Day 73.
Aftar the :econd day of toxics addition, Day 74, the overall
etIylbe zene -emoval returned to 83%, approximately the same level
observed on l v .,5. The 6—day Łnterrupcion had a mi ttma1 effect on
benzer.e an chiorobeozene removals. Both compounds experienced only
sitght reductions in removals on Daj 73 and then by Day 74 returned to
the appxoximate levels cotc’ed ‘ n Day 65.
In a . effort to evaluate t i ,. .ffect of an extended period of toxics
interruption on the biodegrad ive removal of benzene, ethy1b nzene, and
chi ;obenzeae toxics addition to the transient loading bioreactor was
after the reactor samole on Day 74. When the tox.ics were added
to the Influent again 19 days later, Day 93, the overaU remava1 of
a ’ ” r o’id had decre ed s gnificancly. The N/N 0 values iteasured n
Day 94 sp ro x iii:.. l. - “e same as measured on flay 1 of the transient
loadings study indicating t ’ e activated sludge’s ability t degrade the
toxics had decreased to the level observea at he beginning of the
Study.
332
-------
-J
w
-j
z
a
I - ’
-J
0. i.
a
Lija
-J
C.)
z
C’,
4:
(i
LL
0
TIME (HOURS)
F1 URE 10—136. Cornparison ‘f t!io reductions in benzene
eI 1uent .,nd off—gas concentrat ns d f’.. r, 4 reco’:er s
N/No. iieasured during wo to ics ad 1it1on ‘e
TRANSIENT LOADING STUDY
. 6ENZENE (Activoted Sludge)
—
0 DAYS 42 — 43
DAY 57
4 I I I
I I •
a
a
w
a
a
a
a
c•.J
a
a
U,
a
a
a
I I
I I -I
I I I I I —l
z
0 6 12 18 24 30 42 48
-------
-J
0
L*
-J
c i
z
V)
0
L
0
0
z
$ I I I
TRANSIENT LOADING STUDY
CHLOROBENZEN (Activoted Sludge)
0 DAYS 42 — 43
DAY 57
(0
eq.
0
0
0
( 0
U)
0
TIME (HouRs)
FICIRE 10- i 3 . Co—’arison of the reductions in c h1 :o-
benzer.e effluent nd f f—gas concentrations and fractjon.,1
&ec.. eries, INo, rnt- ’ured d rin tvo toxics addition
periods.
I —
z
w
-J
LL
— —ga —_.
—
—e - _ ._
I • I I I I
. I
0
C.)
0
%e
- I -I
I I I I I I I
‘ — -Te.
0 6
12 16 24 30 36 42 49
334
-------
C,
0 6 12 18 24 30 36 42 48
TIME (HOURS)
FIGURE 1O—1.s8. Ct’u par son cf the reduc:ions in ethyl—
benzene effluenr and off—z c ncentra ions and fractional
recDveries, N/No, during cwc toxics dditin periods.
TRANSIENT LOADING STUDY
ETI YL8EN2ENE (Activated Sludge)
DAYS42—43
I DAY 57
w
C,
335
-------
Following the 19—day period when coxIc, were not added to the
influent the toxics addition cycle was changed to a two day addition
period followed by a si . day interruption peciod. This cycle approximates
a situation in which the activated sludge is e osed to the toxic
organic compounds for only two days out of the six days co..prising one
mean solids residence time. Comparisons of the initial acclimation
(Days 0—42) and reaecllrnatton periods for benzene, ethyloenzene, and
chloroben.zene are given in Figures 10—i 39, O—l40, and 10—141. The
results were approximately the same indicating the longer period without
toxics. si c days compared with three days, had little impact upon the
activated sludge’s ability to acclimate to the three organic compounds.
Typically the sample collected on the second day of the addition period
indicated a greater removal of each compound had occurred than was
measured on the first day of that pertod. As occurred during toe frst
part of the transient toxics loading study, benzene removal was
typically the largest, followed by chlorobenzene and ethylbenzene in
that order. A co arison of the data for the three compounds is
preseiited by Figure 10—142.
336
-------
c . I
-J
(5
Li
-J
LL
z
C,.’
-J
(.5
z
(P1
1
0
0
z
FIGURE 10—139. Co parison of benzene effi nt and off—
gas concentra icns and fractlc’tal recQverie . N/Nc. measured
durin2 toxlcs icading cycles of 2 days addedl3 days omitted and
2 days added/s days om tced.
TR, NSiENT LOADING STUDY
_-&-- -- _•..1 - # #-
BENZENE (Activated Sludge)
TOXICS ON 2 DAYS/OFF 3 DAYS
1OXJ S ON 2 DAYS/OFF 6 DAYS (day 0 day 94
4 I I I
l
.
r ! ’
,4 ..
+c’
6
I E
‘
I I
n
S I
SI
I,
‘I
S I
S I
S I
S
,
-- .
1
- ‘ ‘ ® .‘
U,
0 7 14 21 28 35 42 49 56
T!ME (DA’i’S)
63
337
-------
I - .
a
_jCO
0.
a
LL
Wa
1
I I I I
a
c
— I I I •
. I I I
TIME (DAYS)
FIGURE 10—140. Comparison of
gas concentr3tions and fractional
during toxics loathng cycles of 2
2 days added/6 days omitted.
cthylbenzene ‘effluent and off •
recoveries, N/No, measured
days added/3 days omitted and
-J
0
U
-j
L
z
TRANSIENT LOADING STUDY
-
ETHYL6ENZENE (Activated Sludge)
OTOXICS ON 2 DAYS/OFT 3 DAYS
R TOXICS ON 2 DAYS/OFF 6 DAYS (day 0 = day 94
I ’
-J
0
z
1/)
LL
L.
0
0
z
z
0 7 14 21 28 35 42 43 56 63
3 3
-------
TRANSIENT LOADING STUDY
-
CHLOROBENZENE (Activcted Sludge)
0 TOXIC5 ON 2 DAYS/OFF 3 DAYS
TOXICS ON 2 DAYS,’OFF 6 DAYS (day 0 = day 94
(0
.
c
c
c
___-4
.
1
-
‘%
S
5’
. .
I
I
.f
I
I ’
a’
,•
I .
I ll
,
;i
- ‘
S ——
S ‘ _
S
‘
I I I
I,
‘I
z
SI
‘ I
I’
S
I ®
‘SD,
I I
TIME (DAYS)
FIGURE 10—141. Comparison of
gas concentrations and fractional
during toxics loading cycles of 2
2 days added/6 days omitted.
chlorobenzene effluent and off-
recoveries. N/’ o, measured
days added/3 days omitted ano
-J
0
Li
-J
z
-J
0
5 —
U
-J
0
z
U,
9
L
LL
0
0
z
z
0 7 4 21 28 35 42 49 56 63
339
-------
o
0
— p
PTh
-
‘—. 0 9—— ‘
U — — . —
*_ # __ ,_._ U I
— — S
L!1’ —— W
d :
10 -E
Li c i
0
TRANSIENT LOADING STUDY
ACTIVATED SLUDGE BIOREACTOR
0 BENZEI’JE
0 CTHYLGENZEF4E
o CHLOROBENZENE
0.1
0 I -.
56 63 70 77 84 91 98 105 112 119 126
TIME (DAYS)
FT CU RE 10— 142 . Compari son of benzene, ethylbenzene, anti ch oroben cne overAll
removals due to biodegradation during the final 70 days of the transient toxics loading
activated sludgc study.
-------
SECTION 11
RES JLTS: INTEGRATED ACTIVATED SLUDCE/CAR ON
ADSORPTION BIOREACTOR STJDIE
The remove]. of each to c organic comound by integ:aeed powdered
activated carbon/activated sludge treatment was studied in the LO—licer
e qerjacntal bioreactors operated in continuous flow nodes. Control
activated sludge units n t receiving powdered activated carbon (PAC)
were operated in parallel with the PAC units. liioreaccor operating
conditions were similar to those reported for thc activated sludge
studies in Section 10. the majority of the s: &dies were con&icted in
bioreactors operated wtch a 5.5 hour hydraulic retention time ar4 a
6—day s ,lids retention time. Bioreector influents were co’posed of t ie
synthetic wastewacer detailed in Table 5—3, ?oxics organic sOlution, and
either slurried PAC or tap water. Additional PAC iorea tor studies
with lindane were con icted with primary effluent from tha Ann Arbor
wastewater treao. ent facility as the source of influent wastewater.
Results from PAC bloreactor studies presented in Sec.ion Li are
divided into four different types of studie
1. Effect of Influent PAC Dose . Bioreactot studies were conducted
with each co o mdco evaluate the effect of influent PAC dose upon
o seral ]. removals. These studies typically were conducted ii bioreactnrs
receiving only one to,d.c organic conpound.
2. Effect of Solids F etention Time . PAC bioreactor studies were
conducted at a constant PAC dose to deter -utne whether the solids
retention ti e affected to,d.cs removals.
3. PAC—Interrupelon Stu oreac .or studies were conducted to
evaluat the effect of i. terrt pting PAC ddition upon th removal of
both biodegradable and non—biodegradabLe to’ic organic coWounds.
. Transient Loading Stu z The effect of transient to cs
loadings r the rernova . of a combination of toxic organic coWounds in a
PAC bicreactor was evaluated.
-------
11.1 BLOREACTOR OPERATING CONDITIONS
The removal of to d.c organic co ounds it’. integrated powdered
activated carbon/activated sludge sysce was studied in the 10—liter
e q,erimental bioreacLors operated .n cOntinuoUs flow nodes. Control
acti ated sludge units not receiving PAC were operated n parallel with
each PAC unit during the initial phases of the study. During later
e çeriwents evaluating the effect of additional PAC influent doses,
control bioreactors were not always used to allow more PAC studies to be
conducted.
Bioreaccor operating conditions were similar to those reported for
the activated sludge studies. The majority of me studies were
conducted with a 5.5—hour hydraulic retention tine and a 6—day solids
retentton time. Except for a fec, studies with lindane the synthetic
wastewater detailed in Table —3 was used. A summary of pertinent
bioreactor operating conditions is given in Table 11--I.
11.2 PAC ADSORPTION STUDIES
Equilibrium adsorption studies were conducted :o eo pare the
adsorptive capacities of the various adsorbeats for each of the to d.c
organic cr .r ounds. Initial isotherm studies were conducted with lindane,
l,2—dichlorobenzene and nitrobenzerte to select a principal PAC to
be used in the PAC bioreactor stud3.es. The initial isotherms were
conducted in various background solutions including deionized—distilled
water, b±oreactor influertt, effluent from a control activated sludge
unit, and b oreacter mixed liquor whi .ch included n.x .xed liquor
suspended solids. Results from these studies have been braphically
oresented in linearized form in Figures li—i through 11—5. The
Freundlich isotherm equation was used t model the adsorption of
each of the toxic organic compounds. The Treundlich isotherm is
described by
qe Kf Ce 1
which can be written in linearized form as
log q log Kf + (ho) log Ce
where C (ugIL) is the equilibrium solution concentration, q (pg g) is
the amount adsorbed per unit of wctight of activated carbon and Kf and
1/n are Preuctdlich isotherm constants.
In general the experimental, high surface area powtered activated
carbon, PX—21, e chibited the large t capacity to adsorb Lincane and
1,2—dichlorobec Zene at a given equilibrium solution concentration.
Results obtained with the two commercial powdered acdvaced carbons
Hydrodarco C and SA—iS were quite similar. Based upon its similar
performance to the other powdered activated carbon and recon!IEnded usage
by the manufacturer for fu 1—scale PACTS treatment facilities,
Hydrodarco C was selected as the principal PAC to be used in the
PAC—addition to activated sludge studies.
342
-------
EQUILIBRIUM SOLUTION CONCENTRATION (UG/L)
I4IO
I ’!CiiHF Il—I. Fxperimental data and best—fit flues describing the adsorption of tintiane
by tIir e pI)wIIcr d act I vdt ed carho’ s: Ilytiroda r.o C, SA— IS, and PX—2 I.
C-)
. ,;
C-)
IJ
Co
0
C,-)
0
‘1Z
N
— a-,
In
I b I D 2
-------
N I
I _____________ ____________________
SOLUTE: LINDANE
j SOLUflON BOREACTOR EFFLUENT
0 { ‘ RO ARCO C
• 0 NUC AR SA—15
AMOCO PX—21
C,
0
LU
(I)
C-
I—
z
0
— i i —t.’s’,I i i i I tiii
S I 5 5 5
I I 1C 2
EQUILIBRIUM SOLUTION CONCENTRATION (UG/L)
FT CUR F I I — 2 1.xpcrfrnontal d,itn and bect— fit I Jncs dese riI)lng the adsorption of
1 I iiilan. f rum art I vat vd si tudge b toreac r or eli I u nt by tI roe I)0wt 1c red act I vated
a rI ’iis Ilyd rv(I I rc C • SA— I , anti rX—2 1
-------
. 1
•1
I 14 1&
—‘ ‘‘‘‘I I I I I
S S
EQUILIBRIUM SOLUTION CONCENTRATION (UG/L)
F IGtJRE 1 1—3. Experimentdl Iar and best—fit 1 Ines describing the adsorption of
I • 2—d I c l i I orl)b1 .nzt n( f roni de 1(1111 4 0(1—tI 1st Il led w,it r by van oi ls act I vatetl ca 11)0115.
SOLUTE. 1.2—DICHLO OOENZENE
SOLUTOft DEIONIZED DISTILLED WATER
O CALCON F—400
O HYDRODARCO C
M MJCHAR SA—15
AMOCO PX—21
td)
U,
CD
(3
-
0
L 1 J
a)
a:
0
U)
a
I—
z
0
0
9
. 5
0
-------
I . .1 . . I
• a • •i • .•. .••. I
SOLUTE: 1.2—DICHLOROBENZEIIE
SOLUTION: SYNTHETIC WASTEWATER (TOC 200 mg/I)
o CALCON F—400
O t-(YD’ ODARCO C
X NUCRkR SA—15
AMOCO PX—21
• • - ,- • -
S
a I D 3
EQUILIBRIUM SOLUTION CONCENTRATION (UG/L)
S
In.
C)
0
a
w
Cr)
a:
0
(.1)
0
I ---—
a
F i (:1, P F I I 4 E p’ r I rnt ii t I d t Iilld h st — f I t I I nes tI qc rib I n F lie ndsorpt ien of
I • 2—dlclitnriil’tnzeuit• I r m byfltlleL tc WaSt ewater by varll)11 •icL Ivated cai hons.
-------
•1
l. 3l b ID 3
I —I I I I - I I i—t—-f-4d 1
SOLUTC: NITRO6ENZENE
SOLuT:Oft DEIONIZED DISTILLED WATER
C) CA CON F—403
o I-IYCROOARCO C
( tWCHAR SA— 5 -
* AMOCO PX—21
0
—I
4 .
0
I J
I3
C.
S.
c/
D
F-
z
0
V)
In
EQUILIBRIUM SOLUTION CONCENTRATION (UG/L)
S
F I CllKI I 1—5. Fxpt rInicnt u i d.it a ni,J I’e F— 1(t 1 Iuit titacriiilsig the ntIs rpr IcIn of
1)1 I rUi,eu14.IiI I r.,n, ik Ion I LI II—II I st I II t• wat r by va I I 1 ) 115 81 I I v.it I ra rhuitis
-------
TABLE U—I
PERTINENT OPERATING CONDITIONS USED
DURING THE PAC/ACTIVATED S!UDGE BIORF.ACTOR STUDIES
Influent Iow 29—31 mi/mm.
Hvdraulmc retentmon mme 5.4—5.6 hours
Aeration rate 3.8—4.4 1/rain.
tnfluent TOC 95-110 mg/ I
Effluent TOC 10—20 mg/I
1L3S (3—day SRI) 1800—2400 mg/I
LSS (6—day SR ) 3 O0—42OO rag/ 9
MLSS (12—day SRT) 7500—6200 mg/ I
Influent toxicS 100—200 ug/Z
IABLE 11—2
FREUNDLICH ISOTHERN PARAMETERS
FOR APSORPTION OF TOXIC G G NICS
BY HYDRODARCO C FR(\M CONIROL ACTIVATED SLUDGE
BIOREACTOR EFFLUENT
Compound 1/a
Benzcne 0.5 0.46
L ’o luene 1.2 0.47
Ethvibenzene 1.6 0.39
o—X’ 1ene 1.1 0.37
Ch lorobenzefle 1.8 0.40
1,2 —Dich lorobenzefle 3.2 0.41
1,2,4 _Tcich lorobenZene 6.2 O. 4
Lind ..ne 4.0 0.39
Nitrobenzene 3.2 0.35
348
-------
Results fron equilibrLu adsorpc on isoche m 3cud es conducted ¶11th
the re .a .n1ng toxic orgacu.c coctpour.ds have been presented in Figures
11—6 through 11—8. 5u.aries c the Freur.d1 ch isothpr paranecers for
each ciocund i acc wared Judge effluent are given in Table li—a.
Equi1ibriu isocher studies were conducted to aode]. the adsorptIon
o wastewacer TOC by Evdrcdarco C. Results presented is Figures 11—9 to
11—li and su tarI:ed by Table 11—3 shcwed that the crganic const Ituents
of the wascawatar were nor readily ad orbeo b the powdered act vaced carbons.
Carbon adsorption race studies werL conducted to evaluate bow rapIdly
the t0x.c organic conpounds were adsorbed by powdered activaced carbon.
Results f:o represen:ae .ve rate studies v ch liOdAne and Eydrodarco C are
given by Figures 11—12 through 11—14. As indicated by data in Figure 11—12,
the adsoc-pr .on of the 1Lnda te was chara...ter zed by a rapia reduct .on is
aqueous concencrat .on within the first 30 to 60 n.i ices. Greater than 90Z
of the coral amount adsorbed at e uiibriu was adsoroed within 1 to 2 hcurs.
EcuiUbr u conditIons were attained after 4 to 5 hours. Resuit shown by
Figure l! -14 de nn straced that the rare of lindane adsorption in the exper .-
encal bioreactors was the sane as occurred in a weU— i ed batch reactor.
11. 3 EFTECT OF PA —AD ITIOW ON OVERALL LOC R OVAL
FIgure 11—15 cc paren data fron the synthetic waste ater soluble TOC
adsorpc:on race stu :es conducted with powdered carbon doses of 100, 1000,
and 2000 n /L to soluble TCC deg d tIon by actIvated sludge. Each of the
scudiss wa.s conducted in a 3.0- i:er 3 reactor. The carbon adsorptIon
studIes were n ec at 300 rpm and conpressad air was adoed. to the TOC
degranarlon scud7 to na .nraan aerobic condItions. The data demonstrate
that a :er 60 n .nures the greatest ancunt of TOC removal occnrred in the
blodegracaclon scucy A powdered actIvated carbon done of 2Z0O mg/I
was renuired to e f en: a TOC removal race during the inItial 30 m nutes
comnaraole to that which occurred due to biodegradatIon. The adsorption
rare study with 100 ig/Z powoered carnon produced very little TOC removal
ccmoared to biodegradation. The largest powdered carbon dose used in the
integrated studies was 200 mg/i. On the basis of these studies, as well
a.3 the wascewacer TCC adsorpc c . isocherns, the covde:ed caroon coses
used in t e con uous flow bioreacror studies would appear to nc .c sIg’- .ifi—
camrly increase TOC removal over that observed is the conr cL a, ri.vared
sludge umis.
Previous invescngacior.s have shown tOa one of the benefits to
accrue from the addit.on uf the P lC to activated sludge is enhanced
removal of overall organ2.cs as measured by BOO, COD, or TCL. ‘. ny of
the studIes reporting enhanced 100 removal by integrated activated
sludzefcarooc treatment systems . re conducted with industrial wastewacers
whIch are cyp cal1y less baodegradaole and more readily adsorbed by
activated carbons c an the synchec.c wastewacer used in this stuny to
repra cen: un cLpa1 wascewater.
3 9
-------
2
0
-J
c
w
U::
0
(I)
‘I .
0
0
2
FTGURE 11-6. Ex erfmeu taI data and 1)est—fit ilnes describing Freundlich Isothcrrns for
In. adsorp t Ion of benzene to Itiene, e thy) beuzene, o—xylene, ond chi oroljenzene from
activated sludge hioreactor ef1Iiicn by Ilydrodarco C.
w
I .-
EQUILIBRIUM SOLUTION CONCENTRATION (UC/L)
4 5 8 1Q81
bdO 1
3 4 5818
-------
— -.I
- - -1’
EQUILIBRIUM SOLUTION CONcENTRATION (uG/L)
F! GEl RE I I—i. Experimentn I data an ’! best—fl t I foes describing Fretinil 1db adsorption Isoiherms
for • lie adsorli t I on ii f nit riil ionzeuic • I • 2—ti! ci . In rotunzene , I I nd..ne , ni .! I ,2,4 —t ri ci . Iot-obenzcne
Iron. jet. Iv. .tid HI .Iti) c I.Iorc.it tor (Ii Iiitiit I Ilyilitniort () C.
—4--
ADSOROENT: I-fYDP .ODARCO C
SOLIfl ION: BIOR [ ACTOR EFFLUENT
O NIL robenzerte
0 1 ,2-Dich1oroben ene
A I.indane
o 1 • 2 .4-Trich1orobenzenC
dJ
‘I
U-..
0 )
I-
(0
0
0
L .J
0
‘p
C)
z
-s
-------
I I I 4111
I . I I I I I I I
SOLUTE: LINDANE
U ! ‘ i ‘ ‘ ‘ ‘ u
ADSOF
-------
I I 1 I iiiiil I - I I
—
L)
1-
7:
C)—
Lii
m ” o
U)
C) °
a:
I— -.
0
1:
—— t I 111111 I I tI$III t IIIIII•
2 3 4 56789 2 3 4 5 6189 2 3 4 56789
I 1x 10 2
EQUILIBRIUM SOLUTION CONCENTRPTION (MC TOC/L)
V I ( IP RE I I — 9 . Exper I ux nt a I data and hi. t— ft t line tic6c r I I) I ng the adse rp t Ion of
Anii Arbor wa t ew ite r t reatnient p t auit I Inn 1 elf I ilent so I iiI le 1OC Lj iivdroiia rcu C.
-------
r J I __
1 I I I I I I
2 3 4 56 89 2
lxW’
EOUILIBRIUII SOLUTION
0
‘ I J iiiiJ--
ADSO I3Ei1T: IIYDROCARCO C
SOLUTE: SOLUBLE TOC
o Synthetic wastew iLer
o t3 orcactor effluent
_J I I_Il II I I I I I III
4
Jxi 2
CONCENTRATION
(fIG
j
TOC/L)
FTGURI I I—SO. Expertmi ntaI data nd l,est—fLt lici s for adsorpt.i on of
‘wnthctic wa tew3ter nnd bloreartor effluent by Ilvdrndnrco C.
soJ.t b1e ‘roc [ rum
a
4
—
I .-
If)
N
C-)
cD
I—
Li 9
( .3 I . —
‘ -4
-------
I tt ii1— I I I I (III ’
— I 111111 I I 1111111 - -
2 3 4 58789 2 3 4 5 6 1891 2 3 4 56 i69
1x 102 1x10 3
EOUILIBRIUM SOLUTION CONCENTR RTION (MG TOC/L)
i.1 i:Iiiii: I I—Il. F cpi’rIinisiI ;iI 1 1311 -I ntl Ifl -st —i h I usc’ sIt -si rililuig hit’ asIs.srp Ion i ii L u1iloflF
snl sib 1s 1(X F rim .5 l’A(—hlors ’artor u - u I ul uig a 100 mgi I tot I u-ut l’A( iIo 4L, by lIyLIr(oJare() C.
-------
TABLE 11-3
FREUNDLICH ?ARA ETZRS FOR
WASTEWATER SOLU3LE TOC ADSORPTION
BY HYDRODARCO C +
1 /i’.
synthetic astew ter 0.005 2.57
activated sludge
effluent 0.175 2.12
A n Arbor efflueit 1.1 1.56
Ef 1uent from 100
mg/i PAC bioreactor 0.092 2.74
+ Freundlich constants calculated for C in
mg/i and q in mg/g e
356
-------
SOLUTE : LUIDANE
* ADsor BENT : HYDRODARCO C
* C 01 lJ ) SAL’JTI’ PI DFIflPJI7ED-
DISTILLED WATER
‘-4
i-_ j!I ‘C 0 100uG/L
crd ®® 0
1— 0 0
w 10 MG/L
C-)
cjd
C-)
w
25 IIG/L
-J
U i
0 50M 0/L
9
0 60 120 160 240 300
TIME (MINUTES)
F I . lIRE I I — 1Z lyp lea I ri sII I t s I rum I i nlanc .Id8orpl Ion r.I t e S L ml Ps onilmim. tcd in
— ii irr immimiiIt.IIy—nmI til haicli ((Ml ) rc .i tur..
-------
c i
C-)
d L1UI) E RATE S11JDY
X) MG/L CARBO I
0
I—I 3 3 LITER GIB REACTOR
1C)
0 SOLuTE: BIOREACTOR EFFLUENT
Ck
I— (1) SOLUTE: BIOREACTOR MIXED LIQWR
uJ
C-)
Lu 0
>
cr
-J
Lu
0000
d
0 60 120 ? 0 240 300
TIME (MINUTES)
F i (; lIRE I I — I 3 . (:ntnp u r I Holl (if rv i, It m I rrim I I nhI,9,le ndHorp t (Ill ru e Hr sd I em l’cnsdIIe Lcd
in 3 ()—I ILcr roniplvtely—uil xed h.ircls tt.s uir wit Ii hatk riii,ntI Hl)Islt 10519 iii .IrtIvdtcd
s I inige hI n reit t or C If lien r and a t I u.i t 4 .I si iuigc mixed I quo r . (Adserhent 50 rug/I of
I Ivd I 1)11. 1 ri . C)
-------
U )
(T I . • • $ • p . a •
LINDANE RATE STUDY
m 25 flG/L CARBON
IN DISTILLED LJATER
I C!J 10.0 LITtER REACTOR(4.0 L/tl AIR FLOU)
i * 3.0 LITER cria RERCTOR 300 RPt1)
1 .-I
I—
c
I- .
w
I S
‘ -p
2 :.-
cD
C—.)
0 60 120 1130 2 0 300 360 420 480 540
TIME (MINUTES)
F1CIJRI I I — 14. C i p irlsi,n of r tuI Is from I ImuI,m .lds$rp l hum r mI & stuuul lm.s ct$flduIctcLI
Iii 3.0—I I I cr cuunuplcte ly—uuul tuI b.ii li ri•,Irtor (nuIxm uI ,it too rpm) amid a lO—Ilter blurcat-tor
wi Iii mm 6.0 II Iur/unIu, it•—.mt hum, rnlm (lualel , nioult.)
-------
120
0’ 00
E
z
8 40
1—
U i
-J
La
-J
0
b
180
TIME (minutes)
FIGURE 11 — 15. Comparison of syntIit tJc wastewater soluble 1CC biod. grndot1on by
activated sludge to r movnI by adsorpi Ion by Hydrodarco C.
Adsorption by tOO mg/I Hydrodarco C
Ad3orption by 1000 mg/I Hydrodorco C
Bodegrodation by
Activated Sludge
Adsorption by 2000 mg/I Hydrodarco C
0 20 40 60 80 100 120 140 160
-------
Influent and effluent TOC samples were typically taken every
three to five days during steady—state bioreactor operating conditions.
Typical TOC removals ranged between O and 90% for all of the PAC
btoreactor studies conducted with influent PAC concentrations ft)m 25 to
100 mg/i. Results from PAC studies with influent P ’.C doses up to IJO mgI .
showed nn s gntficant increase in TOC removal coinp .red to control studies
without PAC.
I 1.4 RE k)VAL OF N0r4-BIODEGRADABLE T( 1C 0 ANIC COMPOUNDS
integrated activated sludge/carbon adsorption bioreactor studies to
be described in this section incLude the non—biodegradable compounds
lindane and 1,2,4—trichloroben ene and tne poorly hiodegraded compound
L,2—dichlorobenzene. Resu .ts from the activated slodge studies
pres . nced in Section 8 indicated that lindane and 1,2,4—tticnlorobeniene
were not biodegradable in the experimental activat .d sludge system.
While nearly complete recoveries of both compounds from the activated
sludge units were possible, their fate “as quite different. Very little
reductioh in the aqueous concentration of Lindane occurred during
activated sLudge treatment. Typically, effluent concentrations averaged
93 tc. 957. of the influent value. Results for 1,2,4—trichlorobenzene
were quite different, h iever; effluent concentrations averaged only 10
to 12% of the influent value. The approximate 90% :eduction in ct e
aqueous 1,2,4—trichlorobenzene concentration that occurred diring
activated sludge treatment was cue to volatilization from the activated
sludge bioreactors. Baseline atudie demonstrated that near complete
recovery of the anount of 1,2,4—trichlorobenzene volatilized was
possible. Although l,2—d chlorobenzene was found to be partially
removed by biodegradation in activated sludge studies, its behavior
in the PAC bioreactor studies was more similar to 1,2 4—trichloro—
benzene than the readily bL degradable ccnpounas.
11.4.1 Non—volatile Comoound
Lindane wag used as a model non—voLatile, non—bicdegradable
compound for the PAC hioreacror studies. Results from activated sludge
studies shc ed only small (—5%) reductior.s in aqueous cor.centration
ocoirred due to sorption of lindane by the activated sludge biomass.
integrated activated sludge/carbon absorption studies were conducted
under two different bioreactor operating conditions. ln ttal bioreacter
studies utilt ed the 13—liter experimental bioreactors which ecei ed
the synthetic wostewater solution. A second set of continuous flew
studies were conducted in 3—liter bioreactors, described in Section 5,
which received primary effluent from the ?,nn Arbor wastawater treatment
facility.
[ 1.4.1.1 Synthetic Wastewater Studies; 10—liter Bioreactors
The effect of influent PAC concentration on the removal of lindane
in the 10—liter bio:eactors receiving synthetic wastecjatet was evaluated
at influent Hydroarco C concentrations of 12.5, 25, and 50 mg/f and
361
-------
influent SA—L3 concentrations of 25 and 50 mg/i. The bioreactors were
operated with 3 day solids retention times and 5.5 hour hydraulic
retention times.
Results from the PAC studies with Hydrodarco C have beei compared
with results from control activated sludge studies in Figures li—Ib,
11—17 and 11—L8 for influent PAC do es of 12.5, 25, and 50 mg/P.,
respectively. Each figure presents inuluent arid effluent concentrations
and c/c 1 values representing the ratio of effluent concentration to
influent concentration. Day Zero in each figure represents the
initiation of both the lindane and PAC slurry flows to the influent.
Each study was conthct d for a total of four to eight weeks.
The results given in Figures 11—16 through 11—18 Indicate that the
removal ef linjane due to .rdsorption by the activated carbon increased
with increasing inLluent PAC concontration. A significant finding was
that a PAC dose as smoalt ae 12.5 mg/i effected an approximate 68Z
reductjr,n in eFfluent lindane concentration. Mean influent and effluent
concentrations for the 12.5 mg/i PAC study were 104 and 34 ig/t,
respectively. Increasing the influent PAC dose to 25 mg/P. resulted in
an b3Z reduction of Li-idane as influent and effluent concentrations
averaged 98.2 md 15.2 i /P respectively. Greater than a 90% lindane
removal .‘as recorded when an influent PAC concentration of 50 mg/i was
used. The effluent concentration in 50 mg/i PAC study averaged 8.2 ugh
while the influent concentration averaged 101 jg/i. Figure 11—19
provides a coe arison of overall lindane removals for the three PAC
bioroactor studies with Hydrodarco C. Summartes of mean influent and
effluent concentrations are given in Table 11—4.
Results from the PAC bloreactor studies with SA—15 have been
compared to results from control activated mludge studies in Figures
11—20 and 11—21 for influent PAC doses of 25 and 50 mg/i, respectively.
Lindane removals averaged 83.4 and 91.LZ dur!ng the 25 and 5fl mg/I PAC
studies, respectively, coripared with 3.5% during the control activated
sludge study. Figure 11—22 provides a conparison of cverall removals
observed during the two SA—iS bioreactor studies. Summaries of mean
influent and effluent concentrations for the control, 25 and 50 mg/P.
SA—15 bioreactor studies were tncluded in Table 11—4.
Equilibrium adsorption isotherm studies conducted with lindane In
btoreactor effluent indicated that for a given aqueous concentration
more linda,ie was adsorbed by SA—15 than Hydrodarco C. Results from the
ClIP PAC bioreactor studies demonstrated, hci ever, that there were no
significant differences in lindane removal between biorsators recaiving
SA—15 and Hydrodarco C. Figures 11—43 anc, 11—24 provide coriparisosts of
efflucrit lindane concentrations and C/C 0 values from bioreactor studies
with 25 and 50 mg/i, respectively, of SA—15 and Hydrodarco C. For a
given PAC dose, SA—15 and Hydrodarco C effected the same level of
lindane removal. The plot of per.ent removal versus PAC dose in
Figure 11—25 show-p the similarity in performances of the :wo
ccrmmercial powdered activated carbons Hydrodarco C and SA-IS,
and the su er1or performance of the experime9tal high surf ce
362
-------
LINDANE (3—day SRI)
D 12.5 mg/I KYDRODARCO C
Z 0 CONTROL ACTIVATED SLUDGE
0 I I
0 4 8 12 15 20 24 28
0
I I I I I
‘- ‘I
3 4 8 24 29
___ ________ I- — -
ov,.
0
4 8 12 16 20 24 28
TIME (DAYS)
FIGURE 11—16. Effect of a 12.5 gI1 .nf1uenc Hydrodarco C
dose on the eff1uen lindane concentration fron a 10—Liter
bioreactor.
363
-------
r i
C,
C.’
c
LINDANE (3—day SRT)
25 mg/I I-WDRODARCO C
0 CONTROL ACTWATED SLUDGE
0 6 12 18 24 30 36 42 48 54
0 6 12 18 24 30 36 42 48 54
ou,
6 12 18 24 30 36 42 48 54
TIME (DAYS)
FIGURE 11—17. Effect of a 25 g/1 i.’fluent Hydrodarco C
dose o the effluent lindane concentration from a 10—liter
bioreactor.
C,
C,
(D
C,
-J
0
I—
z
-J
Li
z
-J
0
z
L J
-J
U-
U-
Li
364
-------
LU\ DANE (3—dcy SRI)
50 mo/I 1-fYDRODARCO C
z 0 CONTROL ACTIVATED SLUDGE
3-
O 6 12 18 24 30 36 42 48 54
I I I I I I I 1
b
O 6 12 18 24 30 36 42 48 54
2
Qu ,
a,
C-)
-a - --&--
6 12 18 24 30 36 42 48 54
TIME (DAYS)
FIGURE 11—18. Effect of a 50 g/l thfluent l4ydrodarco C
dose cm the effluent lindane concentration from a 1 )—liter
bioreactor.
365
-------
—---.
-J
>
0
I d
-j
-J
I d
>
0
0
8
0
g
0
0
0
0
-4
0
0
N
0
0
0
__ Q
I . . )
0 ’
a’
LU’JDANE BOREACTOR S1UDIES
3—DAY SRI
CONTROL ACTIV. 1 ED SLUDGE
O 12.5 mg/I I-fl’DPCDARCO C
) 25 mr/I F& )ROOARCO C
O 53 mg/I I-ftORODARCO C
28 35 42 49
7 14 21
TIME (DAYS)
FI((JRE 11-19. Con par1snn of lindanc removals measured during a control activated
si tidge stti.Iy and PAC—hior •actor studies i tI infhienr llydroddrco C doses of 12.5,
25, .md 51) nu / I
-------
TAUI.E 11-4
EFFFCT OF INFI.UENT PM FX)SE OW FFFI.LJFtFI’ I.INUAtJF CONCENTRAJIONS
flOW to— i ri i i i i oRt :Ac ious w riti I—DAY SHE’S
Int’lueut Inf luent Cone. (Ihg/1) Ft I luent Corn.. (iig/L) Removal (Z)
Carbon Dose (nig/ ) t iean S.D. Mean S.D. Mean
I1YDROI)ARCO C
o ioo 4.2 96.9 3.6 3.3
12.5 104 6.4 33.7 2.7 67.6
25 98.2 8.8 15.2 4.8 84.5
50 101 5.7 8.2 1.4 91.8
SA—iS
o 93.9 4.1 90.o 3.6 3.5
25 89.0 7.0 15.0 2.3 83.2
50 97.2 4.1 8.1 2.0 91.7
PX—21
15 96.8 6.3 13.2 3.4 86.1
30 96.1 7.1 4.7 2.1 95.1
-------
Ut’4DANE (3—doy SRI)
0 25 mg/I SA—iS
Z 0 CONTROL ACTIVM D SLUOCE
I p
0 7 14 21 28 35 42
35 42
2 ___
0 /u,
0 37l4 21 29 3542
TIME (DAYS)
FIGURE 11—20. Effect of a 25 c’g/l influent SA—IS dose
on the effluent lindane concentration from a 10—liter
bioreactor. -
368
-------
(N
UNDANE (3—day SRT)
50 mg/I SA—15
Z CONTROL ACTiVATED SLUDGE
I 1- I
0 7 21 29 35 42
W .
2
o
14 21 28 35 42
TIME (DAYS)
FIGtRE 11—21. Effect nf a 50 naJl thfluent SA—15 dose
on the eft1uen lindane concentration from IO— .iter
bioreactor
369
-------
0
0
,—..
L’ O
• —• * —*
-J
>0
Co
1 J
( 0 LINDANE BIOREACTOR STUDIES
0
3—DAY SRT
-J
C) CONTROL ACT /ATCD SLUDGE
° 25 mg/I SA—15
LU C!] 50 mg/I SA—15
>
0
0 - _____
a ‘ — — - — 4 • — -
0 14 28 35 42 49
I
TIME (DAYS)
FIGURE 11—72. (‘ompartson of itndnnc removals measured during a control activated
sludge blorcacror stuiiy and I’AC—b loreactor studies with iniluent SA—IS doses of
25 ond SO mg/i.
-------
(N
I - ’
0
z
LLJ
-J
Li
z
-J
0
z
w
-J
1L
uJ
to
LINDANE (3—doy SRI)
o 25 mq/I SA—15
O 25 mg/I l-iYDRCDARCO C
I I 4 I 4
U,
6 12 18 24 30 3 42 48 5
TIME (DAYS)
FIGURE 11—23. Comparison of lindane ef 1uenr concen—
trat ens frrnn PAC—1,iore c or studies irh 25 m !1 inf].uent
PAC doses of Hydrodarcc C and SA—15.
(N
0
6
12
18
24
30
36
(.4
42
48
54
(N
0 6 12 18 24 30 36 42 48 54
C)
0
C.)
371
-------
-j
0
I-
z
I d
-J
LL
z
-J
0
I-
z
Li
-J
LL
LI
eu,.
C)
3 54
TIME (DAYS)
FIGURE l1—2 . Cc parison of lindane effluent concen-
trations from PAC-bioreactor studies with 50 mg/i influent
PAC doses of Hydrodarco C and SA—15.
LINDANE (3—day SRI)
50 mc/I SA—15
0 50 mg/I HYDROcARCO C
a
6
12
C,
16
24
30
36
42
40
54
( ‘4
a,
0 6
12 18 24 30 36 42 48 54
372
-------
0
-4
0
,— d
c i
0
‘0
I-
LU
-J
LU.
0
0
FIGURE 11—25. Effect of influent PAC doses of Hydrodarco C,
SA—15, and PX—21 on lindane effluent concentraricin acd
overall removals
0
0
0
-j
>
0
Li
-J
-J
Li
>
0
INFLUENT PAC DOSE (MC/L)
373
-------
area PAC, PX—21. Figure 11—25 also shows that the incremental
improvement in lindane removal decreased with increasing PAC dose.
While the total amount of 1indn e removed from solution increased xth
increasing PAC dose, the amount adsorbed per unit weight of activated
carbon decreased. As shown by Table 11—5, the amount of lindarie
removed increased from approximately 70 pg/P. to over 90 pg/P. with
an increase in PAC dose from 12.5 mg/i to 50 mgI P.. The amount of
lindane adsorbed per ullit weight of activated carbon decreased from
5.6 g adsorbed/mg PAC to less than 2. i pg/mg. Thus, the larger the
PhC dose for a given influent lindane concentration, the less
effectively the adsorptive capacity for lindane con be utilized.
Such a result is expected in a C 1F reactor. A larger PAC dose
produces a smaller steady state aqueous mixed liquor or effluent
concentration. As the aqueous concentration decreases, the driving
force for ndsurption by the activated carbo.i decreases, resulting
in a smaller amount adsorbed per unit, weight of cc rbon.
11.4.1.2. Ann Arbor Primary Effluent Wastewater
Powdered activatea carbon bioreactor studies with Ann Arbor
primary effluent were conducted in 3—liter reactora with Hydrodarco C,
SA—l5, and PX—21. The reactor condiLian were as outlined in
Table 11—1 with a 6—day SRT. Influent PAC concentrations of
15 and 30 mg/i of Hydrodarco C, 30 m /Z of SA—15, arid 15 and 10 mg/P.
of PX—21 were examined in the 3—liter units. A su ary of results
from the 3—liter PAC bioreactor stuiies wit ’ Ann Arbor wastewater
is given by Table 11—6. At a given PAC dose effluents from bior2actors
receiving Hydrodarco C ana SA—l5 were tne same, while the effluent
from the btoreactor receiving the experimental, high surface area
PAC, PX—2l. was consistently lower. An influent PAC dose of 15 mg/P.
PX—21 effected an average lindane removal of 98% compared with 73% for
Hydrodarco C.
TABLE 11—5
EFFECT OF PAC DOSE ON LINDANE
ADSORPTION PER WEIGHT
OF ACTIVATED CARBON (IJg/mg)
PAC Dose Hydrodarco C SA—iS
( mg/P.) pg/P.. pg/mg pg/P. pg/mg
12.5 70 5.6
25 83 3.3 74 30
50 93 1.9 39 1:8
374
-------
-j
0
z
L U
-j
L&
LU
• - 0
-J
>0
tJJ
0
_j•q
10 20 30 4°
INFLUENT PAC DOSE (Mc/L)
FIGURE 11—26. Effect of jnflue t ydrodarc3 C dose on
1 dar e eff1ue conce rac on a d overall rernoval rneasured
during PAC—b oreac:or scudies vi .th 3—1: er and 1O—1 er
b .oreactors.
0
-l
0
C
S
C
0
0
0
A5TZ ATZ A D ry or oRz c
o Sy hecio waste acer; IO4ite:
A t Arbor as:e’ a:er; 3 —ilta:
o Sy c ec c as e ’ater: 3—liter
375
-------
The removal of lindane was s gnificant1y better in the 3—liter
bioreaccars than in the 10-liter units as shown oy the results plotted
in Figure 11—26. Greater than 95Z lindane removal was achieved in the
smaller units at an influent h’ydrodarco C dose of 30 mg/i while
50 mg/i Hydr darco effected a 922 reduction in the 10—liter unit.
In an effort t determint the reacon for the differences in periorm3nce,
a 3—liter bioreactor was operated .ith synthetic wastewater and a
30 mg/I Hydrodarco C influent dose. There was nc difference in
performance betweefl 3—liter bioreaccors operated with synthetic
wastet.ac r and 3—l .ter biorcareors operated with Ann Arbor primary
cffluent. Average lindane removals were 96 and 962 for reactors with
Ann Arbor primary effluent and synthetic wasteuater, r spective1y.
Differences in the nature and composition of the wastewater did nor
affec: lir.dane reiioval by the powd’ red activated carbon.
11.6.2. Volatile Comüounds
l1.A.2.l. l,2,4—Trirhlorcbenzenc
The effect of PAC additicn on the overall removal of 1,2,4—
trichlorooenzene was evaluated at influent Hydrodarco C doses of
25, 50, 100 and 200 mg/i in biorcaccors operated with 6—day souls
retention rimes. A suaurary of per:fne’lt reactor conditions is outlined
in Table 11—1. Bioreacror influents were composed of the synthetic
wastewater detailed in Section 5—3, a l,2,4—crichlorobenzene solution,
and either slurri ’ad PAC or tap water. ResulcL from the 25, 50, and
100 mg/i PAC bioreaccor studies ‘ava been compared to results from
control ac iva:ed sludge studies in Figures 11—27, 11—28, and 11—29,
respectively. Lnflue t, effluent, and off—gas concentrations for
eacn stud: are shown along with N/N 0 values representing the fraction
of the influenc mass fluxes measured leaving t e bioreaccors in
effluents and oft—gases combined. The addition of l,2,4—cric J .orobenzene
and slerr ed P C to toe influents was begun on Day Zero in each study
represented by Figures 11—27 tnrough 11—29.
The addition of 25 mg/i PAC to tne influent effected signifi anr
reductions in both effluent and off—gas l,2, 4 —rrichlorohenzene
concentrations. Adsorption of 1,2, 4 —trichicrobenzene by the P. C
effected reductions in effluent and off—gas concentrations of 72 and
69, respectively. As sh n by Figure 11—27, the mean effluent
concentration was reduced from 12.0 to 3.3 ugh, and the mean off—gas
value dropped froc approximately 70S Co 225 ng/L for average influer.r.
L,2,4—trtchlorobenzene conccntrations of 113 pg/f. The fractional
recovery of 1,2,4—trichioroberizene averaged 0.31 in the 25 mg/i ?AC
bioreactor indicating that the addition or 25 ugIL PAC to the influenc
effected an overall removal of approxi,iateiy 70:.
Effluent and off—gas concer.crations were reduced further by the
addition of 50 mg/i PAC, as shc n by the results given in Figure 1 .1—25.
The overall t,2,4—trichloroben.zene removal averaged 772 during the seven
week 50 mg/i PAC bioreactor study. an effluent and off—gas
376
-------
TABLE 11—h
I.; NI)ANE KEMOVAI. IN 3— I. I TEN B IORE C IONS RECEIVING
ANN ARBOR PKLM Ri EFILUENT
Influenc PAC Influ nt Concentrutlon Effluent Concentration Remo’iaJ
Dc.se ( I.JgIR.) (%)
15 mg/& Hydrodarco C 100 + 20 27 ± 3 73
30 mg/P. Hydrodarco C 100 + 20 4 ± 96
30 mg/P. SA—15 100 - 20 4 ± 2 96
-J
- .4
15 mg/P. PX—21 100 ± 20 2 ± 1 98
30 mg/P. PX—21 100 ± 20 2 + 1 98
-------
i,2 1 4—TRICHLOROBENZENE
25 mg/I PAC BIOREACTOR
0 CONTROL ACTWATED LUDCE
I I I I
3—e- -
I — -I
0 14 21 28 35 42 49 56
TIME (DAYS)
FIGURE 11—2 7. Effect of a 25 mg/i influent PAC dose on
1,2.4—trichlr rcbenzene effluent and off—gas concentrations and
fractional recoveries, N/No.
378
-------
i
1 2,4—TR;CHLOROBENZENE
50 mg/t PAC EIOREACTOR
0 CONTROL ACTWATED SLUOG
Li I I 4
I I 4
-J
U,. I 0 _____
o 7142128354248 56
TIME (DAYS)
FIGURE 11—28. Effect of a 50 ‘ g/1 infiLent PAC dose on
1,2,4_tr1ch1or’ e.,v...e e e1ue t end oF— a ccnc tratio’,s
and fractional recoveries, N/No.
379
-------
-J
( 5
I-
z
U
-J
U-
z
-J
(5
C D
U-
LJ
-j
C :,
z
rj)
U-
U-
0
0
z
0 7 14 21 28 35 42 49 56
TIME (DAYS)
FIGURE 11—29. Effect of a 100 ng/1 influent PAC dose on
1.2 ,4—trich1 ’robenzene effluQnt and off—gas concentrations
and fraceion 1 recoveries, /NQ.
2
a,
-
rq 23— --9•----
____ - r ,. m m - - -
380
-------
concentrations uere 2.1 pg/i and 145 ng/L, respectively, compared to
values of 12 pg/i and 706 ugh observed i.’ the control unit. The
influenc concentration averaged 103 pg/P.. &dsorption of
1,2,4—tri h1orobenzene by the PAC in the 50 mg/P. bioreactor effected
percent reductions in effluent aed off—gas concentrations that were
approximately the same and averaged 80 and 77 , respectively.
Fagurec 11—30 and 11—31 provide indication of relative effects of PAC
addition a ci biodegradation on c e removal of a volatile non—biodegradable
compou’ d, L,2,4—trlchlorObenZene, and a volatile biodegradable compound,
benaene. A comparison of performance suggests that a PAC dose between
50 ng/ and 100 mg/ 1 is required to e .fect a comparable overall removal
of the biologically resistant l,2,4 —trichlorobenZene.
Influenc PAC concent rations of 100 mg/i produced overall
1,2,4—crictilorobenzene removals in excess of 907., as shc en by results
from the 100 mg/i PAC bioreactor study in Figure 11—29. The intluent
concentration averaged 109 pg/i. during the eight—week stumy while
effluent and oft—gas concentrations averaged 0.7 ig/ 2 and 63
ng/i, respectively. Reductions in effluent ar.d off—gas concentrations
both averaged nearly 947. when measured values were compared to
concentratiins predicted to occur by the air—stripping model if no PAC
was added to tne bioreactor. Of the total flux of non—adsorbed
1,2,4—trichlorooenzene out of the 100 rag/P. PAC bioreactor, the
dirtrtbutlon between the effluent and off—gas was similar to that
observed in the control activated sledge unit wich approximately
10% in the effluent and 90% i the off—gas.
Overall 1,2,4—trichloroberizene removals calculated from the N/N 0
values presented in Figures 11—27 thro& gh 11—29 have been plotted in
Figure 11—32. Overall removal increased with increasing influe t PAC
concentration over the range of 25 to 100 mg/i. An influent PAC
conceitration of 25 ag/S. produced overall removals of nearly 70% while
100 mg/i effected overall removaLs of approximately 957.. Overall
removal has been defined as (1—N/N 0 )xlOO and includes reductions in the
mass flux out of the oioreactor in effluents and off—gases combined.
Although not sh n in Figure 11—32, the addition of 200 mg/i PAC to the
influent produced ?pproxiraately the same results as the .00 mg/i doss.
Complete sunmartes of results from control and 25, 50, 100 and 200
mg/i PAC bioreact”r tud _e nr iven by Table 11—’. Table 11—7
presents influent, effliient aid off—gas concentrations and overall
removals predicted from measured effluent concentrations by Equations
10—Il and 10—12. In general, this method .hicn does not require off—gas
analyses to facilitate a mass balance provided accurate estimates of
off—gas concentrations and overall 1,2,4—trichlorobenzene removals due
to PAC adsorption. Similar find1ng. were de.monstrated tor activated
sludge bioreactors in Section 10.
Table 11—8 sunm3rizes the fate of 1,2,4—trichlorobenzerte in each
PAC bioreactor study by comparing the amount leaving the bioreactors in
effluents and off—ganes to the amount adsorbed by the activatea carbon.
The amount adsorbed in each case was calculated from a reactor mass
balance approach and not measured by extracting the PAC in the waste
351
-------
0 7 14 21 28 35 42 49 56 63 70 77
TIME (DAYS)
FIGURE 11—30. Conparison of eff1u nt and off—gas concen—
trati r.s and fractional recoveries, N/No, from a benzene
ontro1 activated sludge study and a 1,2,!.—trichlorobenzene
PAC-bioreactor study with an inf].uent P C dose of 50 ng/1.
ACTI\/ATED SLUDGE STUDIES
0 BENZENE: ACTWATED SLUDGE
1.2.4—TRICHL0R0BCNZ NE: 50 mg/I PAC
-J
0
I—
z
U
-j
U-
z
-J
U-
U-
Li
-J
0
z
U-
IL
0
0
z
z
0
C ”
382
-------
-J
0
I—
z
Li
-J
L I-
z
-J
C,
Li-
Li
-J
C,
z
(I )
Li-
Li.
0
0
z
0 7 14 21 28 35 42 43 56 53 70 7
TIME (DAYS)
PIGURE I. 1-3 1. Comp3rlson of effluent and off—gas concen-
trations and fract .ona1 recover es. N/’ o 1 from a benzcn
conrrcl activated sludRe scu iy and a 1,2 —crich1orobenzene
PAC—bloreacLor stuay with an influent FAG dose of 100 mg/i.
383
-------
q
0
0
r.
- - p 0
1,2,4—TRICHLOROBENZENE
0 CONTROL ACTWATED SLUDGE
0 25 mg/I PAC BIOREACTOR
0 50 mg/I PAC BIOREACTOR
0 X 100 mg/I PAC BIOREACTOR
0
7 i 1 28 35 42 49
TIME (DAYS)
FIGURE 11—32. Compar!3on of l,2,4—trichlorobcnzciie overall remov ils measured during
a control activated sluilge study nd PAC—hloreuctor studies with In fluent PAC doses
of 25, 50, and 100 mg/I of ilydrodarco C.
-------
TABLE 11—7
EFFECI OF INFLUENT PAC DOSE ON EFFLUENT AND OFF—GAS
1 ,2,4—TRICHLOROBENZENE CONCENTRATIONS
PAC Dose lofluent (iig/t) Effluenr ( g/Z) Off—Gas (ng/ ) W/N 0 ( ra11 Removal
(mg/L) Mean S.D. Mean S.D. Mean S.D. Mean S.D. (%)
MEASURED
Control 117 11.8 12.0 1.8 706 112 0.94 0.05 6
25 113 13.7 3.3 0.6 226 40 0.31 0.04 69
sO 103 12.6 2.1 0.5 145 39 0.23 0.06 77
.1
100 109 22.7 O 7 0.2 43 18 0.06 0.02 94
200 106 8.2 0.6 0.2 44 14 0.06 0.01 94
PREDiCTED FROM EFFLUENT
Control 756 0.99 1
25 208 0.28 72
50 132 0.20 80
100 44 0.06 94
200 38 0.06 94
-------
TABLE 11—8
EFFECT OF PAC DOSE ON THE FATE OF l,2,4—TRICI-ILOROBENZENE
DUK I N(; PAC /Acr IVATED SLUDGE TREATMENT
* Percent of Non—adsorbed
PAC Dose Percent of Influent Flux Flux Out of Bloreactor
(mg/P .) Effluent 0ff—Gas AJsorbed Effluent Off—Gas
Control 10 90 <1 10 90
25 3 28 69 9 91
50 2 2]. 77 9 91
100 <1 6 94 1]. 89
200 <1 6 94 9 91
* j 0 degradat ipn assumed = 0%
-------
sludge. rtempts to extract the P C yielded incomplete and highly
variable recoveries; therefore, data obta .ned from t’ e extractiorte were
not ised in - ass balance fornu.il tions. Table 11—8 also provides a
comparison of the disrri ition betweon offluents and off—gases of the
non—adsorbed 1,2,4—trichlorobenzene flux out of the bioreactors. tn
each bioreaccor study, including the control. activated sludge unit,
appro’umatel/ 90Z of the non—adsorbed l,2,4—trichlorober.zene left the
units in the off—gases and only IUZ left in the effluents. As shown in
Table 11—8, this ratio was constant and not affected by the PAC dose.
Results sisomarized by Table 11—8 show that adsorotion onto the
activat. d carbon effected approximately the saute oerrent reduction in
effluent and off—gat concentrations at a gi;en influent PAC oose.
Percent reductions were calculated by comparing measured values to
conce’ rations predicted to occur in a control activated sludge unIt
receiving the tdenti aL i fluenc 1 ,2,4—trichlorobenzene concencratior’s
and operated under identical operating conditions. Equations 10—’J and
10—12 cre used to predict effluent and off—gas concentrations which
essentially represented steady—state partitioning of
1,2,4—tr chlorobenzerte between the two phases.
The effect of increasing the PAC dose to a given bioreactor on the
removal of I,2,4—trichlorobenzene was examined in the hioreector
receiving the smallest PAC dose, 25 mg/f.. Day 62 of thn 25 ag/f. PAC
bioreactor study the influent PAC dose was increased frcm 5 to 200
by adjusting the concentration of the slurried PAC feed solution.
Results from Day 42 through Day 96, presented in Figure l1—L, show the
effect of increasing tLe influent P C concentration. The increase in
influent PAC dose produced an immediate docrease in steady—state
effluent and off—gas concentrations. Within 26 hours effluent and
off—gas concentrations dccteased to approxun eely 0.5 pg/i and hO ng/t,
respectively. Af proximately four ,eeks were required for t ’e mixed
liquor PAC concentration to increase from 500 to 600 mg/f. to a ncw
steady—state level of 4400 to 5000 mg/i. The incre .se in
L,2,4—trichlorobenzene removal was a function of influent PAC dose anti
not mixed liquor PA conce’.tratlon.
The 25/200 mg/i PAC bioreactor study was used to examine tht effect
of spike influent 1,2,4—trichlorobenzene concenttatlons on effluent and
of f—gas concentrations nd overall removals, t iring tl e 25 mg/i PAC
dose portion of the study the influent concentration 0 f
1,2,4—trichlorobenzene was approximately doubludon Oay 58. Results
shown by Figure [ 1—33 indicate tbar. while the off—gas concentratinn
increased, the effluent concentration remained unchanged. There was no
significant variation in overall % removal on Duy 58. The influent
concentration during the 200 mg/i PAC dose operating period was
Increased on two occasions, to 243 pg/i on Day 68 and to rtcarly 290 pg/P.
on Day 74. The Increased l,2,4—trichlorobenzene luading caused only a
small increase in off—gas concentrations but had no effect on effluent
concentrations. Since overall Z removals remained essentially constant
during the spike loading periods the mass (pg/mm) of
1,2,4—trlchlorobenzene adcorbed by the PAC increased with increasing
387
-------
1 1 2,4—TRICHLOROBENZENE
PAC B OREACTOR STUDY
TtME (DAYS)
FIGURE 11—33. Effect of Increasing the Influent PAC dose
from 25 to 200 m /1 on the 1,2,4-trichlorobenzene effl enc and
off—gas concentration and fractional recovery, N/No.
388
-------
influent concentration. As sh .’n by Figure 11—34, there was a linear
relationship between tle amount adsorbed and the influenc
l,2,4—trichlorobenze e loading daring both the 25 and 200 mg/i doses.
Slopes and regression coefficiEnr ehicr were forced through the origin
were 0.69 and 0.999, respectively, for the 25 mg/i PAC oose and 0.95 and
0.999, respectively (or the 200 mg/I dose. The amount of
1,2,4—trichlorobenzene adsorbed, aeasured in ug/min, was larger when the
influent PAC dose was 200 mg/i cor ared to 25 mg/i as sh n in Figure 11—34.
Steacy—state data from the PAC studies (Table 11—7) was used to
calculate the relationship plotted in Figure 11—35, ‘,hich Indicates less
efficient adsorption of l,2,4—trici 1orobe zene with increasing dosage of
PAC, consistent w th results presented for indane in Section 11.4.1.
11.4.2.2. 1,2—Dichlorobenzene
The effect of PAC addition to activat d sludge reactors on the
removal of 1,2—dichl”robenzene was evaluated at influent Hydrodarco C
doseo of 25, 50, 100 and 200 mg/P. in bioreactors oneraced with 6—day
solids retention times. asults from the 25. 50. and 100 mg/P. P. C
studies have been corrg ared with results from control activated sludge
studies in Figures 11—36 through 11—38. respectively. Each figure
includes plots of influent, effluent, and off—gas concentrations along
with /‘4 values representing the fraction of influent mass fluxes
leaving the bioreactors in effluents and off—gases combined. The
addition of 1,2—dichlorobenzene and slurried PAC to the influencs was
begun on Day Zero in each study represented by Figures 11—36 to 11—38.
The addition of 25 mg/ I. of Hydrodarco C to the influent produced
measurable reductions in both effluent and off—gas concentrations
corçared to concentrations measured in a control activated sludge unit,
as sh , n by Figure 11—36. The mean effluent and off—gas concentrations
were reduced from 7.8 to 4.3 ig/i and from 477 to 298 ng/&,
respectively. Mean influent concentrations in both control . .ad 25 mg/P.
PAC bioreactor studies were appro i aateLy 110 pg/i. The addition of 25
mg/i PAC to the influent effected an irr’provement in the overall
L,2—dichlorobenzene removal from the 36 observed in the contr3l unit
to 61 .
The overall removal or L,2—dichlorobenzene averaged approvimately
714 during eight weeks of steady—state operation in a 6—day SRT
bioreactor receiving 50 mg/i PAC. Mean effluent and off—gas --
concentrations during the eight week study were 2.9 pg/i and 201 ng/i,
respectively. Percent reductions in effluent and off—gas concentrations
during the 50 mg/i PAC biore’ctor study were similar and averaged 63 nd
58%, respectively. Since the off—gas wa., the principal exit route of
1,2—dichlorobenzene out of the bioreactors, the reduction in mass flux
measured in pg/mm was significantly larger for thL off—gas ( [ .10
pg/mm) than the effluent (0.1 . in general, the off—gas flux
represented approdmately 907. of the total non—adsorbed
[ ,2—dlchlorobenzene flux out of the bioreactors while the effluent
flux represented only 10%.
389
-------
C
C
0
0 60 80
I FLUE T ICB MASS FLUX (UG/MIN)
FIGURF 11—3 . Relationsht between he anourt of
1 2,A—trich1orobenzeiie adsor cd h\ the ?AC and the jnf1i nt ss
f1u cf 1,2. —tricn1orobenzene durLng the 5/20() ugh PAC
bioreactor st’idv.
1,2, -Trich orobenzerte (TCB)
PAC Bicreactcr zudv
o 25 r /1 PAC
‘ 20(1 /i PAC
20
10.0 12 0
390
-------
0•
uJ
(1
=
0 50 100 150 200
II1FLIJE 1T PAC DOSE (MG/L)
FIGURF 11—35. Effect of influent PAC dose on the amount of
1,2, —tric 11oroben7ene adsorbed during PAC—bioreactor stu ies.
C
0
0
I I I
C
391
-------
z
L i i
-J
z
-J
C,
L
L i i
-j
C,
z
U,
I.’ —
It,,
L
LL
C
— I I I I
.
— —I------ I — I I —
o 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 11—36. Effect of a 25 ng/1 inflient PAC dose on
1,2—dichlozobenzen effluent and off—gas concentrations and
fractiona! recoveries, N/No.
1,2—DICHLOROBENZENE
r == -
O 25 mg/I PAC BIOREACTOR
O CONTROL ACTWATED SLUDGE
Co
a)
392
-------
—S
z
1 J
-J
z
a
0
U,
a
0 14 2 28 35 42 49 56 63 70
TIME (DAYS)
PICLRE 11—37. Effect of a 50 t g!1 influent PAC dose on
1,2—dichioroberizene effluent and off—gas concentrations n ’
fractional recoveries, N/No.
1,2—D CHLOROBENZENE
50 mg/I PAC B OREACTOR
e CONTROL ACTWATEO SLUDGZ
a
a
0 )
-J
0
U-
U-
w
-J
C D
z
(I ,
1 ’
Li.
Li.
0
a
a
Co
a
0
z
z
393
-------
Ca
r-’- ’
,_pp o-p - -- n
0 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 11—38. Effect of a 100 gf1 influent PAC dose on
1,2—dichlorobenzene effluent and off—gas concentrations and
fractional recoveries, s/No.
1 .2—DICHLORO8ENZENE
100 mg/I PAC BIOR A T0R
0 CONIROL ACTWATED SLUDGE
-J
C)
I-
z
LIJ
=
-J
IL
z
-J
C,
I L
U-
w
-J
C,
z
IL
0
a,
- rr - - =
Ca
C ’,
0
z
z
394
-------
Additional improvement in bioreactor performance with respect to
1,2—dichiorob-’nzene removal was accomplished with an influenc FAG dose
of 100 mg/i. The overall removal averaged nearly 93% during the seven
week 100 mg/i PAC bioreactor study. Mean influenc, effluent and off—gas
concentrations were 94 pg/i, 0.7 pg/i, and 44 ng/t, respectively.
Compared to renults from the control activated sludge unit, these
concLntrationS represented reductions in effluent and off—gas
concentrations in excess of 90% in each case.
The largest influent PAC dose examined was 200 mg/i. Results from
this bioreactor study were not significantly diffarent from those
o er”ed in the 100 mg/i PAC ‘ -.ioreactor study. The overall
l,2—dichlorobenzene removal averaged 947.. Mean effluent and off—gas
concentrations of 0.6 pg/i and 56 ng/L, respectively, were approximately
the same as measured in 100 mg/i PAC dose study. The results indicated
that there was no increased benefit from using a 200 mg/i compared to a
100 mg/i dose for relatively constant influent 1,2—dichiorobenzene
concentrations used n the PAC bioreaccor studies. A complete summary of
results for l,2—dicnlorobenzene is given in Table 11—9.
The overall removals of 1,2—dichlorobenzene observed during the
control activated sludge,25 mg/i, 50 mg/i, and [ 00 mg/i PAC bioreactor
studies have oeert compared n Figure 1 [ —39. The incremental increase in
overall removal decreased with increasing PAC dose such that there was
no significant difference between results obtained from PAC reactors
rect ivtng influent doses of 100 and 200 mg/i.
A significant feature of the results in Figures 11—36 through
11—39 was the immediate establishment of steady—state removals of
l,2—dichlorobenzene. While the control activated sludge unit
experienced an acclimariun period of 14 da s prlcr 10 steady—si te
1,2—dichiorobertzene removal, the PAC units reached steady—state removals
within 24 hours after the addition of PAC to the influer’t.
The effect of increasing the i&ifluent PAC dose on the removal of
1,2—dichlorobenzene was studied in the 25 mg/ i PAC bioreactor previousl
escribed. After 63 days of operation with the initial 25 mg/i PAC
oose, the Influent PAC concentration was increased to 200 mg/i. Results
in Figure 11—40 sho i that effluent and off—gas concentrations decreased
to new steady—state levels within 24 hours after the change in influent
PAC concentration.
During this study the effect of spike l, 2 —dichlorobenzene
londings on effluent and off—gas concentrations and overall remova s
were evaluated. The first spike loading test was conducted during
the 25 mg/i influent PAC operating period. Effluent and off—gas
ccmcentratj ens increased on Day 52 in response to an Increase in the
influent concentration frau 100 to ne irly 400 pg/i. While the
overall l,2—dichlorobenezone removal remained constant at 62%, the
effluent concentration rose fran 5 to 15 pg/i.
The bioreactor was dosed with a second spike loading between Days
72 and 80 when the influent PAC dose waa 200 mg/i. Effluent and off—gas
concentration increased ly slightly as shcMn by Figure 11—40, even
395
-------
0
0
____
..—*. 0
-J
4:
>
0
LiJ
ct q
0
-J
4:
/ * C0 R0L ACTWATED SLUDGE
c
> / t 25 mg/I PAC BIOREACTOR
0 D 50 mg/I PAC BIOREACTOR
• 100 rç,g/I PA( BIOREA 1 CTOR ,
o 7 14 21 28 35 42 49 56 63 70
TIME (DAYS)
FIGURE 11—i 9 . Comparison of 1,2—dichiorobenzene overall removal9 measured during
a control activsted sludge 8tUdy and PAC—bioreactor studies with influent PAC doses
of 25, 50, and 100 mg/i of hlydrodarco C.
-------
TABLE 11—9
SUMMARY OF PAC BIOREACTOR RESULTS
LOR 1,2—DICIILOROBENLENE
PAC Dose Influenc (pg/ 2 .) Effluent ( g/ ) tiff—Gas (ng/ 2 ) N/N 0 Overall Removal
Mean S.D. Mean s.D. Mean S.D. Mean S.D. ( )
MEASURED
Control 110 13.3 7.8 1.2 477 93 0.64 0.05 36
75 lii 6.6 4.3 0.9 298 44 0.39 0.04 61
50 115 13.1 2.9 0.6 201 46 0.29 0.06 71
100 94 28.0 0.7 0.2 44 16 0.07 0.01 93
200 118 10.0 0.6 0.2 58 17 0.06 0.01 94
I-RZDICTEI) FROM EFFLUENT
Control 483 0.65 35
276 0.38 62
50 186 0.25 75
100 45 0.07 93
200 38 0.05 95
-------
w
-J
C,
Li
-j
Li.
z
(:1
Li
‘-S
-J
C,
z
(I )
(P
U-
U-
0
1,2— DICHLORO B ENZENE
PAC B!OREACTOR STUDY
O 25 mg/I PAC
O 200 mg/I PAC
0
z
z
TIME (DAYS)
FIGURE 11—1 .0. Effect of increasing the influent PAC dose
from 25 to 200 mg/i on the 1,2—dichiDrobenzene eff.uent and
off—gas concentration and fractional recovery, N/No.
42 49 56 63 70 77 84
=
U,
U,
II )
L i)
( -.4
I -4
a o—G- -e \ ___ c -rG —----4 -!
-------
though the intluent concentration rose to alnost 700 ugh. The effluent
and off—gas concentrations during this spike loading period were less
than the values recorded for the steady—slate operating period with a 25
mg/i PAC dose. The 200 mg/i PAC dose acted as a buffer in th system to
dampen the effect of significant increases in the influent cncentratior,
on measured effluent and off—gas values.
11. 5 REMOVAL OF BIODEGRADABLE COu1POIJNDS
Powdered activated carbon/activated sludge bioreactor studies were
conducted wIth the biodegradable conpounds: ! enzene, toluene,
ethylbenzene, o—xylene, chl.-’robenzene, and nitrobenzene. Influent PAC
concentracic s ranging fror ’ 25 to 200 mg/i ware studied in bioreactors
operated at a 6—day SRT.
There was a significant difference between the results from
PAC/activated slLdge bioreactor studies with the biodegradable conpounds
and those with the poorly and non—biodegradable conpounds. While
influent PAC doses of 25 ‘ng/P. to 100 tog/i produced significant
improvements in overall removals of lindane, 1,2—dichlorobenzene and
1,2,4—trichiorobeozene, compared to control bioreactors such influent
PAC doses had Little effect on the overall removals of the biodegradable
compounds compared to removals measured in control activated sludge
reactors.
11.5.1 son- volatile Compound
Baseline volatil zarion studies arid activated sludge bioreactor
studies showed that n itroben ene was a highly biodegradable compound of
relatively bc ., volatility. PAC bioreactor studies were conducted with
influent P C .loses of 50 and 100 mg/i Hydrodarco C, SO mg/P. SA—15 and 50
mg/i PX—21. The bi.reactor studies were conducted under the operating
conditions listed in Table 11—1 with a six day SRT.
Results from the 50 and 100 mg/i PAC bioreactor studies with
Hydroda:cu C have been graphicalLy compared to results from a control
activated sludge unit in Figures 11—41 and 11—42, respectively. The effect
of PAC addition can be divided i.nto two categories: auring the two—week
acclimation phase and during the steady—state biodegradation phase. In
each study, the effluent concentration from the unt: receiving PAC
reached approximate steady—state levels within 24 hours after both
slurried PAC and nitrobenzene were initially added to the bioreactors.
During the first two weeks the effluent nitrobenz . ne concentrations in
the 50 and 100 mg/f. PAC units were significantly lower than observed in
control activated siudge reactors, as sho.zn by Figures 11—41 and 11-42
Once the control activated sludge bioreactors attained a steady—state
level of nitrobenzene biodegradation, thcre was s:entially no
difference in nitrobenzene removal between the control and 50 mg/P. PAC
bioreactors. The effluent concentration from the 100 tog/i PAC
bioreactor averaged slightly 1 ss than the control activated sludge
unit. As shown Uj Figure 11—43, the effluent concentration of Lhe 100
rug/i PAC bioreactor as consistently less than that of the 50 tog/i PAC
bioreactor throughc’ut the nine weeks of the studies. Complete starnaries
of the two stucies have been p esented in Table 11—10.
399
-------
It,
-J
1-
z
LI
—J
z
a
-J
CD
=
I—
I— Q
z
uJ
-J
L
L.
w
NITROBENZENE (6—day SRI)
50 mg/I Hydrodarco C
0 CONTROL AcTr ’ATED SLUDGE
7 14 21 28 3S 42 49 56 63
FIGCRE 11—41. Effect of a 50 mg/i PAC concentr;.tion
on the effluent nitrobenzene concentratic’ .
CN
CN
0 7 14
21
28
42
49
56
63
0
0
C
7 14 21 28 35 42 43 56 63
TIME (DAYS)
400
-------
-J
C)
I—
z
Li
z
-J
0
z
Li
-J
U-
Li
L I,
U,
FIGURE 11—42.
concentration on
tration.
Effect of a 100 mg/i PAC influent
the nitrobenzene effluent concen—
NITROBENZENE (6—day SRI)
OO mg/P Hydrod rco C
0 CONTi OL ACTIVATED SLUDGE
0 7 14 21 28 35 42 43 56 63
(0
0
0
U )
21 28 35 42
TIME (DAYS)
401
-------
L I ,
‘I,
U,
.
c
7 14 21 23 35 42
TIME (DAYS)
49 56 63
FIGURE 1 —43. Comparison of effluent nitrobenzene
concentrations from ?AC—b ,oreactor studies with influent
PAC doses of 50 and 100 mg/i.
NITROBENZENE (6—day SRI)
100 mg/I Hydrodorco C
0 50 mg/I Hydrodorco C
a
-j
C)
I-
.7
LaJ
-J
z
-J
C)
z
Lii
-J
L
L i i
-‘ 14 21 28 35 42 49 56 63
7 14 21 28 35 42 48 56
C)
0
63
402
-------
N.esults from a five week 50 mg/i SA—15 bioreactor study were not
significantly different than those obtained for 50 mg/i Hydrodarco C.
Nitrobenzene removals in both studies averaged approx.tmately 96Z.
Effluent concentrations from the 50 mg/i PX— I bioreaccer were
approximately equal to the concentrations measured in the effluer from
the 100 r ug/i Hydrodarco C bioreactor. Nitrobeozene removal in those two
studies averaged 98%.
Summaries of the SA-15 and PX—21 bioreactor studies have been given
in Table 11—10.
TABLE 11—10
CFFCCT OF PAC ADDITION TO ACTIVATED SLUDGE ON REMOVAL
OF NITROBENZENE
PAC Dose(mgfi) iniluent (ugh) Effluent (ugh) Kenoval (%
Control 121 4.1 97
KYDRODARCO C
50 112 3.7 97
[ GO 138 1.5 99
S A— I 5
50 102 4.6 96
P K- 2 1
50 98 2.0 98
11.5.2 Volatile Compounds
Integrated activated sludge/carbon adsorption bioreactor studies
were conducted with the vo1 . tile biodegradable compot nds benzene,
toluene, ethylbenzene, o—xylene, and chlorobenzene. All of the studies
presented n this section were conducted in bioreactors operated with
6—day soLds retention time. Influent PAC doses ranged frr, 25 to 200
mg/i, and the mediuia activity PAC Hvdrodarco C was used in all of
the studies iith the volatile, biodegradable compour.is. Aerati3n rates
ranged from 3.6 to 4.4 i/ruin, and the hydraulic retei ..ion time was set
at 5.5 hours.
403
-------
11.5.2.1 Bcnzene
The effect of adding powdered activated carbon to acr vatcd sludga
bioreaccors on cne overall removal of benzene was evaluated at iniiuent
PAC doses of 25, 50, 100, and 200 mg/i. Riisults from bioreactor studies
conducted with influent PAC doses of 25, 50, and 100 mg/i have 1’een
plotted with results from the control activated sludge unit in igures
11—4/., 11—45, and 11—46. respectively. Each fIgure includes influent,
effluent, and off—gas concentratIons and N/N 3 values representing the
fraction of the influent fluxes measured in effluerca and off—gases
combined.
No significant improvement in overall benzene removal orcu:red in
reactors receiving PAC doses of 25, 50 md 100 mg/i compared to the
control unit, as shown by the coiiparisort in Figures 1 1—44 through
11—46. Overall benzerte removals in control and 25, 50, and 100 mg/i PAC
unuls were approximately the same, averaging 83%, 797., 84%, and 867.,
respectively. Even the addition of 100 mg/i had little effect upon effluent
aria off—gas concentrations which averaged a ’roidmately 0.6 jig/i and
less than 150—ng/2., respectiveLy, In both control and 00 mg/i PAC
bi,reactors. The influent PAC concentration to the bioreactor receiv .ng
25 mg/i powdered activated carbon was ir .crease ’ to 200 mg/i on Day 74.
As the resuLts in Figure 11—47 illustrate, the eight—told increase
in influerut PAC concentration did not significantly improve the overall
removal of benzene. Overall benzene removals measured in the 25, 50,
and 100 mg/i PAC bioreaccors have beer. graphically coirçared with the
overall removals observed in the control activated sludge unit in Figure
11—48. Table 11—11 gives the average values for influent, effluent, and
off—gas concer.trations and overall removals observed for the various P C
bioreactor studies.
A 10—liter bioreactor without activated slud o wa operated in a
continuous flow mode jith an influent composed of synthetic .zastewater
spiked with benzene and slurried PAC, to determiae the maximum benzene
removal attribjtable solely to adsorption. No influent FAC
concentratIons were considered, 50 and 100 mg/i. P sults froa these two
studies have been coripared with results obtained from the 50 and 100
rag/i PAC sludge bioreactor studies in Figure 11—49 an.! Table 11—12.
Overall benzene removal due solely to adsorption in th PAC units
without activated sludge biomasses averaged only 19Z and 26 for
influent PAC auses of 50 and 100 mg/i, respectively. Overall removals
in activated sludge units recei;ing 50 and 100 mg/I of PAC were sisnif —
candy larger,averaging 84 and 86%, respectively. Biodegradation of benzene
in the control activated sludge unit averaged 837.. Thi’ set of results
s gects that the dom.nant removul mechanism in the activated sludge
units teceiving slurried PAC was biodegradation by the activated sludge
microorganisms rather than PAC adsorption.
11.5.2.2. Ethylbenzene
Powdered activated carbonfactivated sludge studies with
ethylberizene were conducted with influent PAC concentrations anging
404
-------
-J
z
w
-J
U-
z
-J
C.,
U-
LJ
-J
z
U,
U-
U-
0
C
z
z
0- 7 14 21 28 35 42 49 56 63 73 77
TIME (DAYS)
FIGURE 1 1—44 Effect of a 25 ng/1 irifluent PAC dose on
benzene effluent and off-gas concentrations and fractional
recoveries, N/No.
BENZENE ACTh’ATED SLUDGE STUDIES
25 mg/I PAC BIOREACTOR
CONTROL A T1VATED SLUDGE
U.,
405
-------
-J
jC d
w
-J
z
-J
U-
U-
U i
—J
C ,,
4:
C)
‘-, c
Ic d
U-
0
a
0I
z n.
0 7 14 21 2U 35 42 49 EG 63 70 77
TiME (DAYS)
FIGURE 1 1— 5 . Effect --f a 50 rn /l influe”t PAC dose on
benzcne effluent and cff—gas concentrations and fractional
recoveijes. N/No.
8ENZENE ACTIVATED SLUDCE STUDIES
r3 ’\
-J
0 50 rnc/l PAC ORCACTOR
C CO J1 CL ACT J\TED SLuDGE
1 4 * I I 1 —.——- i i I —
a
10
I : ,
C,
406
-------
1 BENZENE ACTIVATED SLUDGE STUDIES
100 mg/I PAC BIOREACTOR
0 CONTROL ACTMATED SLUDGE
, I - t -t I I I
I 4— 4 4 I 4 4- 4 1
Li I 4- t I I t I
I I -$ I I- I I —4—---— 4 I
-j
I 14II’4
e 4
0 7 14 21 26 35 42 49 56 63 70 77
TiME (DAYS)
FIGURE 11—46. Effect of a 100 ng/1 nf1uent PAC dose on
benzene effluent and off—gas concentrations and fractional
recoveries, N/No.
407
-------
-J
-J
L
z
U-
U
C -,
z
(I )
U-
0
0
z
z _______
56 63 70 77 84 91 98
TIME (DAYS)
FIGURE 11—67. Effect of increasing the influent PAC dose
from 25 tc 200 mg/i on the benzene effluent and off—gas con—
centraric’n and fractional recovery, N/No.
c 4
408
-------
p
0
0
p - s
—0
t0
-J
• IZ
00
Li
0
Li e
0
0
0
TIME (DAYS)
FICURE 11—68. Compar Ison of hen ene overall removal3 due to biodegradation and
PAC adsorption measured during a c- itrol activated sludge study and PAC—bioreactor
studies wIth Inficient PAC closes of 25, 50, and 100 mg/I of II’idrodarco C.
7 14 21 28 35 42 49 56 63 70 77
-------
TABLE 11—11
EFFECT OF INFLUEI T PAC DOSE ON STEADY—STATE BENZENE RENOVAL IN
10—LITER BIOREACTORS OFERATED WIT!! 6-DAY SRT’s
+ Overall Removal (l—N/N 0 )xl OO
( ) Standard Deviation
0
Influent PAC
Dose (mg/R )
Control
118
Influet t
(Dg/J )
(8.4)
Effluent
(pg/I)
0.8(0.4)
Off—Gas
(ng/ I)
142(40)
Overall Removal+
(%)
83.1 (5.2)
25
110
(11.1)
0.6(0.1)
112 (13)
79.0 (4.4)
50
106
(8.3)
0.7(0.3)
119(21)
83.7 (2.4)
100
100
(7.4)
0.6(0.1)
92(2 )
86.4 (3.2)
200
123
(21.4)
0.4(0.1)
119(42)
85.9
-------
cD
C
C —
cc
C)
Li
C) —
u _ I
—
C) tf C i
U
C) >
> (I
— —
—I C)
+
<1
0
U U
-4
C — _
C C
In t. —
C
0
0—
F1rURE 11—1.9. C ’er 1 hei :ene reninvals measured
cont nuc us floc’ 10—liter binreactor studies with activated
slud e. Hydrodarco C PAC without activated sludgc, and
acrivat d sludce with PAC.
411
-------
TABLE 11—12
BENZENE RE 1OVALS MEASURED IN CONTINUOUS FLOW 10—LITER
BIOREACTOR STUDIES WITH ACTIVATED SLUDGE, PAC
WITHOUT ACTIVATED SLUflCE, AND ACTIVATED SLUDGE WITH PAC
OPERATINO CONDITIONS
Paralleter SW 1 S .4 & A/S 2 SW & PAC 3 SW. A/S & ____
50 . /f PAC
Influent (pg/f) 94 113 105 106
Effluenc ( jgI2L) 3.4 0.8 2.4 0.7
Off—Gas (ng/ ) 652 142 660 119
N/N 0 0.96 0.17 0.81 0.16
Overall Re ova1 (Z) 83 19 84
100 tr g/2. PAC
Influent (pg/f) 111 100
Effluent (pg/f) 3.2 0.6
Off—Gas (‘ g!t) 593 92
N/N 0 0.74 0.14
Overall Renoval (‘ ) 26 86
1. Base1ir . studies without activated sludge or PAC in the bioreactor
2. Control activated sludge bioreactor (no PAC—addition)
3. Bioreactor without activated sludge receiving slurried PAC
4. Bioreactor with activated sludge receiving slurried PAC
412
-------
from 25 to 200 mg/i in bioreactors operated at 6—day SRT’s. The PAC
used in the ethylbenzene studies was Uydrodarco C. Results from
bioreactors receiving 25, 50 and lOu mg/i PAC have been compared with
results from contr d activated sludge studies in Figures 11—50, ii si,
and [ 1—52, respectively. Each figure includes measured influent,
effluc.it, and off—gas concentrations and N/N 0 values representing the
fraction of the Influen- fluxes measured in effluents and off—gases
combined.
There was no difference in ethylbenzene removal in control and 25
mg/P. bioreactors as indicated by the similarities of the N/N 0 curves in
Figure 11—50. Both reactors experienced an approximate 14—day
acclimation period preceding steady-state ethylbenzene removal. The
comparison of N/N 0 values measured during the acclimation phase and
under steady—state conditions given in Table 11—13 shows that comparable
increases in overall removals occurred in both the control activated
sludge and 25 mg/i PAC bioreactors.
The results for the 50 mg/P. PAC bioreactor presented in Figure
11—5lhave been compared to a parallcl control reactor. As
noted in the discussion of results from activated bioreactor studies in
Section 10, bioreactor performance with respect to toxics removal during
the acclimation period from replicate s..udies have varied siightly, but
steady—state removals typically yielded comparable results.
Ethylbenzene addition to the 50 mg/P. PAC bioreactor was begun on Day
zero while slurried PAC addition was initiated on Day 7. Prior to PAC
addition ethylbenzene removal in the two reactors was nearly identical,
as evidenced by the similarities in the N/N 0 curves. The overall
removal of ethylbenzene increased from approximately 30 to 60% within 24
hours after the 50 mg/P. PAC addi ton was begun, while the removal ifl the
control unit remained at 30%. Both control activated sludge and 50 mg/P.
PAC b oreactors exhibited a significant increase in tne overall
ethylbenzene removal on Day 14, and steady—state rerroval was achieved by
Day 21. Results from the 50 mg/i PAC unit demonstrated that PAC
addition during the acclimation phase effected decreases in effluent and
off—gas concentrations, and hence an increase in overall ethylbenzene
removal. Ad interesting feature of the results from the 50 mg/P. AC
bioreactor was the continued acclimation of the activatad sludge
microorganisma to ethylbenzene atter PAC addition was begun. The
greatest benefit to accrue from the 50 mg/P. PAC dose occurred between
Days 7 and 15, before the activated sludge bioreactor units
became fully acclimated. After Day 18 the overall ethylbenzene removal
was only slightly larger in the PAC unit, averaging 84% compared to 80%
in the control activated sludge bioreactor.
The addition of a 100 mg/ I. influent PAC dose produced a significant
improvement in ethylbenzene removal during the initial two to three week
phase, as shown in Figure 11—52 . Additions of both ethylbenzene and
slurried PAC to the activated sludge and (00 mg/i PAC bioreac-tor
influents were begun on Day 0. After the first 14 dsys differences in
effluent and off—gas concentrations and overall removals were
considerably reduced, but the average overall ethylbenzene removal
remained slightly larger in the PAC unit throughout the length of the
413
-------
2
C ,)
-J
z
L i
-J
z
-J
Li
-J
0
z
U,
0
0
z
z
0 7 14 21 28 35 42 49 56 63 10
TIME (DAYS)
FIGURE 11-50. Effect of a 25 mg/i influent AC dose on
eth lbenzene effluent and off—gas concentrations and
fractional recoveries, N/No.
I .I I I- t I I t r
414
-------
c. I
0 7 14 21 28 35 42 49 56 63
TIME (DAYS)
FIGURE !l-j j Effect cf a 50 -zig/i influent PAC dose on
ethvlbenzene effluert and off—gas concentrations and
fractioru 1 recoveri.es, N/” o.
-J
C,
I-.
z
U
-J
U-
z
ET -fYLBENZENE
0 50 mg/I PAC BIOREACTOR
CONTROL ACTWATED SLUDGE
‘-S
-J
C,
5
U-
U
( ‘4
‘ -S
1
‘N
C,
z
‘-I
La
0
C
z
‘N
z
U,
413
-------
(N
a
- J
(I)
0
L
LL
0
0
z
z ______
0 1 14 21 28 5 42 49 55 63
TIME (DAYS)
FIGURE 11—52. Effect of a 100 rn /l inf]uent PAC do5e or!
cthylbenzene effluent and off-gas concentrations and
fracr onal reccveries. “/ro.
-J
0
C.- (N
U-
L i i
U,
a
__ ___
416
-------
TABLE 11—13
COMPARISON OF ETI{YLBENZENE N/N 0 VALVES FROM ACCLIMATION
PERIODS AND STEADY—STATE CONDITIONS IN
CONTROL AND 25 rng/ PAC BIOREACTORS
Acclimation Period
Bioreactor Steady—state ( average )
Control 0.72 0.43 0.19
25 mg/i 0.61 0.42 0.19
TARLE 11—15
CO .1P6.RISON OF N/N 0 DATk FROM CONTROL AND
PAC BIOREACTORS FOR CHLOROBENZENE
Bioreactor Steady—stare (a ierage )
Control 0.53 0.45 0.19
25 mg/i 0.29 0.25 0.19
50 mg/i 0.21 0.22 0.17
100 mg/i 0.18 0.15 0.10
417
-------
study. Results from the 100 mg/i PAC reactor showed no acclimation
period as was observed for the other ethylbenzene studies. The PAC
added to tne nfluent had sufficient adsorption capacity to prevent
significant discharges of ethylbcnzene in the efLluent and of f—gas
during the early stages of th acclimation period when the amount
biodegraded in the control. uflit was small.
Results from t.ontrol and 23, 50 and 100 ugh PAC bioreactors have
been compared in Figure 11—53. Influent, effluent and off—gas
concentrations averaged during periods of steady—state ethylbenzene
r oval are s*znmarized by Table 11—14.
Thc effect of an eight—fold increase n infiuent PAC
concentration on ethylbenzene removal was studied by increasing the PAC
dose from 25 to 200 ‘ ag/i. On Day 75 of the 25 mg/i PAC bioreactor
study. the influent Hydrodarco C dose was increased to 200 mg/i by
adjusting the concentration of the PAC slurry. The change in PAC dose
effected only a slight increase in overall ethylbenzene removal, as
evtdenced by the N/ curve in Figure 11— 4. Overall ethylbenzene
removal averaged during the 25 rag/i PAC dosing period compared t
87% during the 200 r ug/i PAC dosing period.
11.5.2.3. Q iorobenzene
Powdered activated carbon/activated sludge studies were conducted
with chlorobenzene at influent PAC doses ranging from 25 to 200 mg/i in
hioreactors operated at 6—day SRT’s. The PAC used in these studies was
Hydrodarco C. Influent, effluent and off—gas concentrations measured in
PAC bireactor studies with 25, 50, and 100 mg/f PAC have been netted
in Figures 11—55, 11—56, and 11—57, respectively, with values from the
control activated sludge unit. Also included in each figure are NIN 0
“ lees representing the fractton of the influent fluxes measured in
efflueots and off—gases combined. Oilorobenzer.e and slurried PAC
additions to the influents were initiated on Day zero.
Results from the PAC bioreactor studies shc .ied that the addition of
PAC produced the most significant improvements in overall chlorobe ’izene
removaLs, compared to control reactors, dvring the first 7 to t4 days
after the initial additions of PAC and c lorobenzene to the influents.
This time period corresponded to the microbial acclimation phase
observed for all of the bicdegradable compounds in control activated
sludge stud 4 es. The co. varison of data from control and PAC reactors on
Days I and 3 given in Table 11—15 shows that enhanced rerno’a1 was most
significant at the beginning of the studies. After the accilmation
period the results from the control ac:iva:ed sludge and PAC bioreactors
receiving 25 and 50 mg/i influent PAC were nearly identical.
Steady—state overall re iovals averaged 81%, 81%, and 83% an control
activated sludge and 25 and 50 rug/9. PAC bioreartors, respectiveiy.
The overall removal of chlorobenzene in the 100 mg/i PAC unit . as
cor.sistently better than that obse vcd in the contro) reactor as showi by
Figure 11—57. The improvement in chlorobenzene removal waq most
significant during the acclimat on period. Under steady—state
conditions me differences in effluent and otf—gas concentrations
418
-------
0
0
0
-j
>0
1 ic
hi
— 0
0
-J
<0
L c’
0
0
0
0 7
TIME (DAYS)
F I CUR K I 1—5 3. (‘tmp.irison of etI ylIwnzt ne r nu vals due to biodegradation and
PAC adsorption measured during a rcintrnl actfvate(I sludge study 39d I’AC—bioreactor
t nil es wi iii I nfl unl I’AC dosl,H iii 25, O, ,uid IO U un / I of Il”drod,i rco C.
14 21 28 35 42 49 56 63
-------
TAHI.E I I— 14
EFFECT OF 1NFLUEN1 PAC DOSE ON STCADY-S1ATE ETIIYLflFNZENL REMOVAL IN
10—I HER BFOUEACTORS WITH 6—I)AY SRI’S
+ Ovetall Renioval = (I —N/N) c 100
0
Influeni I’AC
Inf liieiit
Fff liieut
L )
Of f—Cas
!L
Oucral I Rcrnoval+
Control
119 (14.4)
0.6 (0.2)
166 (43)
81 (4.0)
25
109 (L2)
0.6 (0.1)
165 (11)
78.5 (2.0)
50
94 (11.2)
0.4 (0.1)
98 (25)
84.7 (3.5)
100
92 (17.’))
0.3 (0.1)
79 (31)
87.2 (6.5)
200
118 (20.5)
0.2 (0.1)
)8 (213
87.4 (2.8)
( ) Standard c ev1ation
-------
I D
ETEfY LBENZEt JE
PAC BIOREACTOR STUDY
0 25 mg/I PAC
Q 200 mg/I PAC
0
z
-
58 63 70 77 84 81 88
TIME (DAYS)
FIGL’RE 1I—S . Effect of increasino the influent PAC do c
from 25 to 200 ig/1 on the ethvlbenzene effluent and off—gas
concentration and fractional recovery, N/No.
C ’.
‘4
-J
0
Li
-J
z
-J
0
LL
Li
-J
0
z
C ))
0
L
0
I 4 I I
U,
421
-------
-J
I-
z
U
-J
L&
z
-J
LJ
-J
z, 7
U,
Li
0
4
TIME (DAYS)
FIGURE 1I—5 . Effect of a 25 rn /1 influent PAC dose on
chlorobe’,zene effluent and off—gas concentrations and
fractional recoveries, N/No.
422
-------
-J
0
I —
z
L i
1
z
0
Li
-J
C,
z
( -I )
L
0
0
z
z ______
0
0 7 14 21 28 35 42 48 56
TIME (DAYS)
FIGURE 11—56. Effect of a 50mg/i influent PAC dose o
chlorobenzene effluent and off—gas concentrations and
fractional recovedes, INo.
C.- LORO6ENZENE
50 mg/I PAC BIOREACTOR
0 CONTROL ACTWATI 0 SLUDGE
C I
C,
C,
423
-------
1
-J
0
Li
-J
z
-J
0
U-
Li
-J
0
z
(I ,
0
0
zu,
z
0 7 14 21 29 35 42 49 56
TIME (DAYS)
FIGURE 11—57. Effect of a 100 mg/i influent PAC dose on
chiorobenzene effluent and off—gas concentrations and
frac tional recoveries. N/No.
c 1
q
424
-------
between the control and 100 mg/i I’AC reactors were considerably rečjced.
The results recorded during the 100 mg/P. PAC study show the absence of
an acclimation period during the initial two woeLs of operation.
effluent and off—gas concentratiOns observed on Day 1 were approximately
the sa as those eeasi.red throughout the study.
A comparison of overall chlorobenzene removal from control and 25,
50 and 100 mg/P. PAC bioreactors has been provide 1 in Figure 1 1— 8
Summaries of influent, effluent nnd off—gas concentrations and overall
removals averaged from steady—state roxics remeval periods are given by
Table 11—16.
The effect of an eight—fold change in influent PAC
concentration on chlorobenzene removal was exaniined by increasing the
PAC dose from 25 to 200 mg/i. On Day /4 of the 25 mg/i PAC study
previously described, the influent concentration of Hydrt iarco C was
increased to 200 mg/i by adjusting th concentration of the PAC slurry.
As the results in Figure 11—59 indicate, there was only a slight
decrease in the fractional recovery, ‘ /N 0 , of chlorobenzene. Overall
chlorubenzene removal averaged 82% during the 25 mg/i PAC period compared
to 90% during the 230 mg/i influent PAC dose. The results for
chlorobenzene during the two influent PAC concentrations have been
sunmarized in T.’bie 11—1g. Benzene, erhylbenzer.e, and chlorobenzene,
all three biodegradable conpounds, exhibited only slight changes
in overall removals attributable to the 8— fold increase in
influent PAC dose. In general, the greater the amount of a compound
removed by biodegradation, the less was the effect of increasing the
influent PAC dose.
11.5.2.4. Toluene
A single—solute PAC—bioreactor study with tcluene was conducted at
cn influent Hy.rodarco C concentration cf 200 mg/P.. Results from this
study are compared to results from a parallel operated contro 1 activated
reactor in Figure 11—63. Toluene and slurried PAC were initially added
to the influents on Day 0.
The results in Figure 11—60 show that the greatest improvement in
toluene removal ocoirrel during the 14 to 21 day acclimation phase.
After Day 21 differences itt fractional recovery values measured in the
control and PAC bioreactor decreased. As shown by the comparison of
average overall removals in Table 11—17, the reactor receiving 200 mg/i
PAC yielded lower effluent and off—gas concentrations, and hence better
overall toluene removal. A significant finding was that the magnitude
of the differences between control and PAC reactors was relatively
small for such a large influenc PAC dose. The results were consistent
with the observation chat the benefit of PAC—addirion for enhanced
to’dcs removal decreased as biodegradation increased.
425
-------
0
a
a
r.
‘ 0
Co
-J
‘ 0
‘- Co
w
Q o
0
—4
a’
<0
>
0
0
0
TIME (DAYS)
FIGURE 11-58. Comparison of clilorobenzene overall removals due to biodegradation
and PAC adsorption measured during a ontro1 activated s1 dge study and PAC—bioreactor
studies with influcnt PAC doses of 25 50, aiid )00 mg/i of Hydrndarco C.
7 14 21 26 3 i 42 49 56
-------
TARI.1 11—16
EFFECT CF INFI UFN’ PAC DOSE (IN STE 1 J)Y-SIMt C1ILOROBENZENE
REMOVAL 1l J 10-111 ER BIOREACI’ORS WITh 6—DAY SRT t S
+ Overall Removal (i—N/N) x 100
( ) Staiulard deviation
-J
Infjuenr PAC
i _( . IJJ
inuluent
. (‘! ‘ . it ).
Elfluer 1 t
Off—Cas
(ne/I)
Overall Remo a1+
Control
133 (21.6)
1.1 (0.3)
192 (57)
82.1
(2.5)
25
Iii (9.1)
0.5 (0.2)
142 (22)
81.7
(1.5)
50
127 (17.2)
0.8 (0.4)
134 (35)
84.3
(2.6)
100
110 (15.3)
0.5 (0.1)
76 (33)
89.7
(4.3)
200
109 (9.8)
(J.i (0.1)
76 (IS)
t JO.0
(2.1)
-------
CHLOROE3ENZENE
PAC BIOREACTOR
Li
25 mg/I PlC
0 200 mg/I PAC
Oc’J
: —O-e-
LJ
4 4-
-J
0
z
=
U)c
4 -4
0
z”)
z -
56 63 70 fl 84 9! 28
T!ME (DAYS)
FIGURE 11-59. Effect of increasLig the influent PAC dose
from 25 to 200 m /l n the effluent and ‘f f—gas chlorobenzene
concent t” ns and fractional recovery, N/No.
428
-------
—
LI
I—
2:
-J
L .
2:
I L
-J
C-,
2:
(J,
CD
U-
Li ___
0
0
2:”
2:
0 7 14 21 28
TIME (DAYS)
FI TRE 11—6’). ffect of a 290 /1 influelt AC dose
on toluene effluent and of —eas concentratlois nd
fractional recoveries. ‘/‘ o.
35 42 43
429,
-------
TABLE 11—17
COMPARISON OF TOLtJENE REMOVALS IN
CONTROL AND 200 mg/I PAC BIOREACTORS
Control 200 iog/& PAC
Paraa ter Average+ Avetage
ITifluent ( ig/L) 76.0 120 (12)+4. 122 132 (46 )
Effluent (i ig/L) 2.1 0.8 (0.2) 0.3 0.3 (0.2)
Off—gas (ng/L) 233 142 (32) 139 82 (33)
0.43 0.16 (0.04) 0.17 0.10 (0.04)
Reduction in 97.2 99.4 (0.2 99.8 99.7 (0.2)
Aqueous Conc (%)
Overall Remo ’al (%) 57 81. (4) 83 90 (4)
+Average values calculated froa data collected after Day 14
+4 1unbers in parentheses are standard deviation values
430
-------
11.5.2.5. 0—Kylerte
Single solute PAC bioreactor studies with o—xylene were conducted
at only one infiuent PAC dose, 50 mg/i. The powdered caroon used was
Hydrodarco C. Results from this study nave been plotted with results
from a parallel control activated sludge study in Figure 11—61. Day
0 marked the beginning of o—xylene addition to the two ui.its and PAC
addition was started on Day 7. Prior o Day 7 results from both
reactors were nearly identical.
Effluent and off—gas on .entrations decreased measurably on Day 8
in response to the addition of 50 mg/i slurried Hydrodarco C. The PAC
bioreactor gave better overall c-xylene removal between Days 7 and 18.
As the results show, the control unit yielded consistent recoveries of
approximately 85% during the ftcst fourteen days. The significant
decrease in efflueni. and off—gas concentrations of the c,ntrol reactor
occurred between the second and third weeks of operation indicating the
activated sludge mitroorganioms had acclimated to o—xylene. Once
acclimation occurred •here wa no signiiicant difference in steady—state
performances betw en t te 50 mg/i PM’. and control activated sludge
bioreactor.
An important finding ‘a ; that the SO mg/i PAC unit appeare’ less
susceptible Co upset conditt ns which resulted i measurably reduced
o—xylene removal in the activated sludge reactor. The control unit
experienced two occasions in whicn o—xylene recoveries suddenly
increased, Day 35 and Day 43, and then decreased to steady—state levels.
During both upset periods o— ylene remov .J in the 50 mg/P. unit remained
relatively constant. In general, the PAC reactor appeared relatively
unaffected by the upset conditions which caused reduced o—,cylene
removals in the control reactor.
ii. 6 EFFECT OF SOLII)S RETENTION TLMi ON OVERALL lOX ICS RE IOVAL
Previous studies evaluating PAC addition to activated sL dge have
reported tt’at combinations of high solids retention times and low PAC
doses provided enhancee removal of overall organics, as measured by TOC,
COD, or BOD. Activated sludge studies, described in Section 10,
evaluatiitg the effect of solids retention time on the biodegradation of
the toxic organic compounds found no variation in overall removal at SRT
values between 3 and 12 days. This study was c . iducted to evaluate the
effect of SRT on the overall removal, hiodcgra .k.tion and/or adsorption,
of both biodegradable and non—biodegradable compounds in PAC bioreactors
receiving influent PAC doses f 25 and 50 mg/i.
11.6.1 Non—biodegradable Compounds
11.6.1.1 Lir.dane
Initial studies evaluating the effect of solids retention ttme o
the overall removal of the toxic organic compcu ds from PI C bioreactors
were conducted with the non—biodegradable, non—vo .atile compound,
431
-------
-.J
C-,
z
w
-J
Lj
z
—
—I
C,
.— —
LL
w
-J
C,
z
V)
9,
L
L&
0
0
z
..%—
z
0
0
0 7 14 21 28 35 42 49 56
TIME (DAYS)
FIGURE 1i— 1. Effect ,f a 50 g/l influei’t PAC duse on
effluent a d off—qa o-xvlene concentrations and fractional
recoveries, N/No.
0
0
0
(0
0
(‘1
0
0
0
C-:,
c i
432
-------
lindane. tnfluent lindane and Hydrodarco C concentrations of 100 ugh
and 25 mg/i, respectively, were added to PAC biorea .tors operated at 3,
6, and 9—day solids retention times. Results given by Figures 11—62 and
1 i—63 demonstrated that no sig’ ifi.cant variation in lindane removal
occurred over the range of SRI’s considered. Lindane removals during
the eight week studies averaged 84Z in the 3—day SRT unit and 83Z in
both the 6 and 9—dey SRT bioreactors. Complete summaries of results
from the three SRI PAC bloreactors are given by Table 11—18.
Steady—state mixed liquor PAC concentrations ranged from nearly 350
irg/& in the 3—day SRI PAC bioreactor to over 950 mg/i in the 9—day SRI
PAC bioreactor. While the amount of PAC in the 3 and 9-day SRI
bioreactors differed by a factor of three, the amount of lindane removed
was identical. Results from this study combined with those detailing
the effect of Influent PAC dose suggest th. t the removal of a
non—volatile, non—biodegradable compound with a relatively constant
influett concentration in an i’itegrated activated sludge/carbon
treatment system was not control]ed by the mixed liquor PAC
concentration, but rather was a function of the iitfluent PAC dose.
Unlike 1 tndane i AC bioreactor studies reported in Section 11.3 in
which lindana and siurried PAC were initially added to the influents at
the same time, lindane was added to influent six to ten days prior to
the slurried PAC in each of the three different SRI units. The Ce/Ci
values were approximately the same in each unit prior to PAC addition
and ranged from 0.93 to 0.97. Day aero in Figures 11—62 and 1l j
represent the initiation of PAC addition to the units. In each case
within 24 hours the Ce/C i and effluent values dropped to approximately
the same steady—state le l.
The solids retention tires in the 3—day SRT PAC bioreacrior was
increased to 15—days after 31 days of operation. Subsequent samples
collected after the new steady—st ”-e mixed liquor suspended solids
concentration of between 6500 and - J00 mg/i (PAC mixed liquor
concentration of approximately 1500 mg/i) was obtaiaed, sh ed no change
in lindane removal.
A fourth lindane bioreactor receiving 25 rn /t Hydrodarco C was
operated with an aoproximate SRT of 0.25 days. In this unit there was
no solids recycle nd the solids retention time equalled the hydraulic
retention time. The r teady—state mixed liquor PAC concentration was 25
mg/i. Lindane in this unit was nor significantly different t.an that
observed in the other SRT studies. lAiring the eight days the 0.25 day
unit was operated lindane removal averaged nearly 81%. For an influent
lindane concentration that averaged 98.4 ugh, the effluent
concentration ranged from 12.3 to 24 pg/i and averaged 19 pg/i.
11.6.1.2 1,2—Dichlorobenzene and L, ,4—Trichlorobenzene
The effect of solids retention time on the overall removals of the
volatile compounds 1,2—dichlorobenzene and I,2,4—trichiorobenzene was
413
-------
to
0
0
0 6 12 18 24 30 36 42 48 54
TIME (DAYS)
FIGURE 11—62. Fffect of solids retention t1 ne
on effli ent lindane concentratior.s from 10—liter
bioreactors receiving 25 mg/i influent PAC dosLs.
L.INDANE + 25 mg/I HYDRODARCO C
O 3—DAY SRT
O 6—DAY SRI
* 9—DAY SRI-
-j
LU
-j
LU.
z
-j
0
U
-j
L .
Li
4
0 6 12 IC 24 30 36 42 48
54
C , ’
0
6
12
18
24 30 36 42 48 54
434
-------
0
0
.4
0
0
0
0
0
11-
TIME (DAYS)
FICI’Rt I t—63. Effect of oItds retention tine (Sin) on Iindine removal due to
PAC .ithorpt Inn In IO—Ilter hiore,i ‘rs rt1cclv [ ng 25 mfl/I Infiticut PAC doses.
0
C,
0
0
0
a)
0
0
0
‘4
3 -n
-J
>
0
Li
-J
Li
>
0
LINDANE PAC BIOREACTOR STUD:ES
25 mg/I 1-fYDRODARCO C
M 3—DAY SRI OU)REACTOR
O 6—OAY srcr 6IOF EACTOR
O 9—DAY SRI 6IOREACTOR
21
28
42
40
-------
TABLE 11—18
EFFECT (‘F SOLIDS RETENTION TLME ON THE REMOVAL
OF LINDANE FROM BIOREACTORS RECEIVING 25 zig/L HYDRODARCO C
Solids Retenticn Time
Parameter 3—Days 6—Days 9—Days
Influent ( ig/t) 96.9 lOt 106
Effluent (tsg/P.) t 15.2 18.4 18.7
Reuo al (PercentY’ 84.3 82.9 82.6
MLSS (mg/i) 1600 3500 4100
P C Mixed Liquor Conc.
(ragIZ) ’ 320 640 960
+ Values represent averages determined frets 19 dat3 points taken
during seven weeks of bioreactor operation.
+ + Theoretical values; actual concentrations averaged approxintately
902 of the theoretical values.
436
-------
evaluated in PAC bioreactors operated at 0.25, 3, 6, and 12—day SzT’s.
An influent PAC dose of 50 mg/P. Hydrodarco C was used for this group of
S t ud i e s.
Figure 11—64 graphically compares results from control activated
sludge and 50 mg/i PAC bioreactor studies for 1,2,4—trichlorobenzene.
The slurried PAC was legu on Day 9 of the 50 mg/P. PAC bioreactor.
Results presented in Figure 11—64 shc that N/N 0 values recorded for
the two units prior o PAC addition were not ‘ignificantly different
and were greater th.. n 0.94, indicating complete 1,2,4—trichlorobenzene
recovery. Effluent and off—gas concentrations dropped to their new
steady—state levels within 24 hours after PAC addition was begun. As
observed for lindane, the overall removal of 1,2,4—trichloroben- ene
no further increase as PAC accumulated in the bioreactor mixed
liquor. Approxiaately 60 days were t equired for the mixed liquor PAC
concentrations to reach the steady—state concentration of 2000 to 2400
mg/P.. thiring that time effluent and off—gds concentrations remained
relatively constant.
Results from the 1,2,4—trichlorobenrene 50 mg/f PAC bioreactor
studies conducted at 0.25, 6, and 12—day SRT’s surmnarized by Table
1 —L9 show that there was no variation in overall remo al as a function
of solj . retention time. Overall removals obse rved at 0.25—day SRT’s
were, not significantly different from those recorded in the 12—day SRT
study.
Results for 1,2—dichlorobenzene from 50 mg , PAC and control activated
sludge studies conductea at a 12—day SRT have been graph:cally compared
in Figure 11—65. Addition of PAC to the influent began on Day 7. Within
24 houis the effluent and off—gas concentrations had been reduced from
approximately 11 ,ig/2. and 730 ng/l, respectively, to steady—state values
of 2 pg/i and 290 ng/i, respectively. As observed for
l,2,4—trichlorobenzerie, no further decreases in effluent and off—gas
concentratioas were observed to occur as PAC accumulated in the
bioreactor mixed liquor. The overall 1,2—dlchlorobenzene removal
recorded 24 hours after PAC aadition had begun was the same as the level
measured at Day Dwhen the mixed liquor PAC concentration had reached a
steaoy--state level of 1900 to 2400 mg/P.. The mixed liquor PAC
concentration was not important for PAC bioreactors receiving a constant
influent 1,2—dichlorobenzene concentration.
As shown by Figure 11—66 which graphically coi ares results from 50
mg/P. PAC bioreactors operated at 6 and 12—day SRT’5, there was no
difference in bioreactor performance witi respect to 1,2—dichlorobenzene
r irnoval at 6 and 12—day SRT’s. The influents were initially spiked with
1,2—dichlorobenzene on Da zero in both studies while slurried PAC
addition was begun on Day zero In the 6—day SRT unit and Day 7 in the
12—Day SRT unit. Table 11—19 ccmpares results from 0.25, 3, 6, and
[ 2—day SRT bioreactor studies with an influent PAC dose of 50 mg/P.. As
observed for 1,2,4—trlchlorobenzene and lindane, there was no variation
in 1,2—dichlorobenzene removal as a function of SRT over the 0.25 to
12—day range considered by this project.
437
-------
(N
-J
0
U
-J
z
-J
C-,
L I.
LI.
U
—a
C,
z
C,)
9
I.;-
L.
0
0
z
z
0 7 14 21 28 25 42 49 56 63 70 77
TIME (DAYS)
FIGURE 11—6th. Effect of a 50 rn /l influent PAC dose on
1,2,4—trichlorobenzene effluent and off—gas concentrations
and fractional :ecoveries, N/’ o. measurad during 12—day SRT
bioreactur studies. (PAC addition was begun on Day 9)
(N
Co
(N
‘-I -
438
-------
‘IABLE 11—19
EFFECT OF SOLIDS RETENrT0N TIME ON
REMOVAL OF I , 2 ,4—TRICIILOR0BFN °ENE Af41) I , 2—r,IflILORO’IENZEUE
IN 50 m /l PAC 1 I0REACTORS
Solids Retention 1n1Juc ’ t Effluent ()ff—Cas Removal
( J1) (r I_1)_ (Z) --
1,2,4 -TR1ClILORORENZI NE
0.25 73 1.3 110 78.2
6 103 2.1 145 77.0
12 106 2.2 164 76.4
I ,2-II ’IlI.0Il0IlEN7ENE
0.25 1.8 192 76.0
3 101 2.3 180 74.1
6 115 2.9 2 )1 71.0
12 107 2. 1 170 76.5
-------
C)
C.,’
C)
-i-
‘ —C)
IL
LjJ
U,
0 7 14 21 28 35 42 48 56 63 70 77
T M (DAY \
L
FIGURE 11—65. Effect of a 50 mg/i influent PAC dose on
1,2—dichlorobenzene effluent and cff—gar concentrations and
fractional recoveries, N/No. measured during 12-day SRT
bioreactor studies. (PAC—addition was begun on Day 7)
-J
C-,
Li
-J
Li
z
1.2—D cHLoRoeENzENE (12—day SRI)
ACTh’ATED SLUDCE
0 50 mg/I PAC BiOREt 1 T0R
-i
(5
z
(I,
IL
Li
0
0
z
z
c
440
-------
-J
(-5
Li
-J
z
-J
LL
Li
-J
0
z
C,,
(L-
u-
0
0
z
z
C—.,
C . .’
d
1 2—0lCHI.ORO3ENZE ’1E 50 rng/ PAC BICREACTOR
TIME (DAYS)
FIGURE 11—66. Ccmparison of effluent and off—gas concen-
trations and fractional recoveries. ‘c/Nc. reas ired durln2
1,2—dichlorobenzene PAC--b .oreactor stur’ies with 6 and 12—day
solids reter tion tires. (Influenc PAC dase was 50 mg/i.)
O 6—Dc’y SRI B oreactor
O 12—C .y SRI B!D CACTO2
C0
C,
C,
=
0 7 14 ii 2R 35 42 4 56 63 70 77
441
-------
11. 6.2 Biodegradable Con ounds
The effect of SRT on the steady—state overall removals of the two
volatile, biodegradable coapounds benzene and chlorobenzene was
evaluated in bioreactors receiv-ing influent PAC (Hydrodarco C)
concentrations of 50 mg/i. Benzene and chlorobenzene 50 mg/i PAC
bioreactor studies were conducted at two solids reter’tion times, 6 and 12
days.
11.6.2.1 Benzene
Activated sludge bioreactor studies demonstrated that th overall
benzene removal due to biodegradation was not significantly different
over the 6 to 12—day SRT range. Results from a 50 mg/i PAC bioreactor
operated in parallel with a control activated sludge unit, both operated
with 6—day SRT’s, shc zed that the addition of 50 mg/i Hydroda:c- C to
the irifluer ’c did not effect an increase in overall benzene removal
compared to the control bi oreactor. Since SRT had no effect upon
ben2ene degradation and an influent PAC dose of 50 mg/i did not enhance
the overall benzene removal, two hypotheses were for m.dated: I) a 50
mg/I. PAC dose to a 12—day SRT unit would not res”.. .. in increased benzene
removal comoared to a 12—day SRT control activated sludge Lnit; and, 2)
there would be no difterence in overall ben2ene removal in 50 rug/i PAC
units operated at 6 and 12—day SRT’s.
Bioreactor results shown by Figure 11—67 amd able 11—20
cot firmed the above hypotheses. As sh in by Figure 11—67, there were
no differences in effluent and off—gas concentrations from a control
activated sludge and a 50 mg/i PAC bioreactor operated at 12—day solids
retention times. Eacn study was conducted for ten wueks. Slurried PAC
and benzene were first introduced into each unit on Day zero. The
ovetall steady—state benzene removal averaged 84% in the activated
sludge bioreactor and 87% in the 50 mg/i PAC bioreactor, respectively.
There was no significant differenc. In overall henzene removal in
50 Ii P L C units opera ed at6 and 12—days solids retention times. Overall
steady—state benrene removals in the 6 and 12-day SRT unIts receiving 50
mg/i aveiaged 84% and 87%, respeccive y. An overall sunvoary of results
for benzene is presented in Table 11—2).
11.6.2.2 thlorobenzene
Similar races ar ,d extents of chlorobenzene biodegradation wera
observed to occur in activated sludge bioreactors operated at 6 and
12—day SRI’s, as described in Section 10. Results from 6—day SRI
control activated sludge and 50 rug/i PAC b oreactors previously
described ‘ a Jection 11 sh .ied that there was no significant difference
in overall chlorobenzene removal in the two units.
41 2
-------
a
_jc ..1
0
U
:
—J
Ii - .
z
-J
c i
LL
Li
-J
v)
Li
0
0
zu,
z
0 7 14 21 28 35 42 49 56 63 7
TIME (DAYS)
FIGURE 11—67. Effect of a 50 g/1 influent AC dose on
benzene eff1ue it and rff—: is cencenrr3tjons and fra tiona1
reccwer es , N/No, rneasur J during 12—day SRT bioreactor studies.
BENZENE ( 2—doy SRI)
0 A ATED SLUDGE
0 50 mg/I PAC Bl0RE cT0R
a
C,
C o
643
-------
TARLE 11—20
EFFECT OF SOLIDS RE1ENTION TIME ON THE REMOVAL
OF BCNZENE IN 50 mg/P. PAC BIOREACIORS
PAC Dose Influent Effluent Off—Cds N/N 0 Overall Removal
(mg/P.) ( zg/ P .) ( ig/Z) (ng/ ) (2)
6-DAY SRi’
*
Control 118(8) 0.8(0.4) 141(40) 0.169(0.052) 83 (5)
50 106(b) 0.7(0.3) 119(21) 0.163(0.024) o4 (2)
‘2—DAY SRI
Control 113(24) 0.5(0.2) 116(41) 0.164(0.041) 84 (4)
50 123(18) 0.5(0.1) 108(15) 0 126(0.021) 87 (2)
() is standard deviation
-------
A SO rag/i PAC bioreactor was operated at a 2—day solids retention
time for a total of ten weeks. ResuLts from this study have been
plotted with results from the 12—day SRT control activated sludge “itt
in Figure 11—68. th units experkericed an approximate two week
accl.tnatjor phase preceding steady—state chl.orobenzene removal. Overall
steady—state chlorobenzer.e removals averaged 82Z and 87 in the
activated -1iIL1 e and 50 mg/i PAC units, respectively.
Th ’re were no significant differe ee U i bto eactor petforinance
with respect to chlorobenzene removal in 50 nJ/i ?AC bioreaccors
operated at 6 and 12—day solids retention times, as chu..jri l’ ’ Figure
11—6g. Steady—state effluent and off—gas concentrations aver.sged 0.8
ug/2. and 134 ng/2 ., re ,pecttvely, in the 6—day SiT study coa ared to 0.4
‘.ig/9. and 104 ngJt, respectively, in the 12—day SiT study. Overall
chlorohe’i’eui. c. nova1 recorled for the SO mg/i PAC units including
biodegradation and ikorpr on by the PAC, averaged 841 in the 6—day SiT
bioreactor coit are 1 to 1 7’ tn the 12—day SkT bioreactor. Th].s small
difference in overall emival ltd -iot represent a significant increase
in cMorobenzeae removal.
445
-------
-J
0
w
-J
L&
z
-J
w
.1
z
(1
0
L
( .
z
z
0 7 14 21 70
TIME (DAYS)
FTC URE 11—68. Effect of a 50 g/1 in luent PAC dose on
ch1orol’enz ne effluent and off—gas Concentrations and
fractional rec ver1es, N/No, rnea ured during 12—day SRT
bioreactor studies.
C.
U)
a
28 35 42 49 56 63
446
-------
c 1
L U
-J
LL
z
-j
( ‘4
I L
L&J
0 7 14 21 28
TiME
3S 42 42 6 63 70
(DAYS)
FTGURE 11—69. Cc ’npari on of chlorobenzene effluent and
off-gas concentrations and fractional recoveries. N/No,
measured during 50 mg/i PAC—bioreacror studies conducted with
6 and 12—day sc’lids retention tines (SRT).
2
Ca
Ca
I i )
-J
0
z
U)
L
I
I
C)
z
tI)
0•
447
-------
1 1.7 EFFECT OF INTERRUPTING PAC-ADDITION ON TOXICS REMOVALS
Two studies were designed to evaluate the effect of interruptIng
PAC-addition to activated sludge bioreactors on the overall removals
of selected biodegradable and non-biodegradable toxic organic
compounds. One study was conducted in an activated sludge bioreactor
receiving an influent spiked with five volatile compounds: benzene,
ethyibenzene, chiorobenrene, l,2-d chlorobenzene, and 1,2,4-
trichiorobenzene. The second study evaluated the effect of at
interruption in the addition of 25 mg/I PAC to en activated sludge
bioreactor receiving lindane.
11.7.1 Five Volatile Corrpound Study
A 100 mg/i PAC dose of hydrodarco C was added to a bioreactor
receiving synthetic wastewater influent spiked with three
biodegradao le compounds, benzetie, ethylbe-zene, and chiorobeozene; a
poorly btodegradable compound, i,2-dichiorobenzene; and a non-
biodegradable conpoLnd, l, 2 , 4 -trichlorobenzene. Influent, effluent,
and off-gas concentrations of each volatile compound were monitored cn
a regular basis during the 84-day study. The 100 mg/I influent PAC
dose was adeed continuously to the bioreactor for the initial 48 days
of the s-uay. After appropriate bioreactor samples were collected on
Day 48, the siurried PAC feed soluUon w ,is stopped and replaced with
tap water to maintain the 5.5-hour hydraulic retention time. Powdered
activated carbon was not added to the influent for four weeks, Day4S
to 77, resulting in a drop in the mixed liquor PAC concentration from
greater than 1000 mg/i to less than 100 mg/i. On Day 77 PAC addition
wag continued at the original influent dose of 100 mg/i. A summary of
the bioreactor operating periods is provided by Table 11-21.
TABLE 11-21
OPERATING PERIODS FOR ThE 100 mg/1 PAC
INTERR’ PTION STUDY WITh A 6—DAY SRT
Op rating Period Length Conditions
1. Days 0 to 4-8 48 100 mg/i PAC added continuously
2. Days 48 to 77 29 No PAC added
3. Days 77 to 84 7 100 mg/i PAC added continuously
Influent, effluent, and off-gas concentrations recorded for each
compound durIng the 84-day study have b€ n plotted in Figures 11-70
through 11-74. Also included in each figure are N/N 0 values
representing the fractton of the influent fluxes measured in effluents
and off-gases combined. Overall removals of the compounds, calculated
as (i-N/N 0 ) x 100, have been compared during the 84 days in Figures
11-75 and 11-76. Average steady-state influent, effluent, and off-gas
concentrations and overall removals of eech compound observed during
the three operating periods are given in Table 11-22. Durh’g the
initial phase of the study when the influent PAC dose was 100 mg/I
overall removals of the five biodegradable compounds were similar to
each other. Steady-state overall removals of the five compounds
averaged from Day 29 to Day 48 were approximately 907., as detailed in
4 ‘48
-------
_J
PAC INTERRUPTION STUDY
C,
BENZENF
]1OO/C
LJ
-J
I I
I I
C-,
I I
C,
LI
o I
a’ I I I I
1 I I I
0
zu,.
:
28 35 42 49 56 63 70 77 84
TIME (DAYS)
FIGURE 11—70. Effect of interruoting the addition of
100 mg/I PAC to ac.t vated sludge on benzene effluent and off—
gas concentrations and fractional recoveries, N/No.
449
-------
-J
‘N
C,
LU
-J
Lj
z
La
LU ___
-J
N
C,
z
C / )
L&
0
FIGuRE 11:7 1. Effect of interrupcing the addition of
100 mg/i PAC to activated sludge on thy1benzene effluent
and off—gas concentrations and fractional recoveries, N/No.
C,
(‘4
— I I I I I
PAC INTERRUPI ION STUDY
ETHYL BENZENE
100 rn,,g/I PAC
AC (Days 48 — 77)
i L
I I I •i
I I I I I
- --- -
C,
C,
( ‘ 4
0
z
0
I I I
U)
C,
28 35 42 49 56 63 70 17 84
TIME (DAYS)
( ‘50
-------
PAC INTE1 RUPTION STUDY
CHLOROSENZENE
2.. fflOOrnq/IPAC
I I 0 mc I 1 PAC (Ocys 48 — 77)
-J
28 35 42 49 56 63 70 77 84
TIME (DAYS)
FIGURE 11—72. Effect of interrupting the addition of
100 a /l PAC to activated sludge on chlorobenzene effluent and
off—gas concentrations and fractional recoveries, N/No.
451
-------
I
U
z
—
-J-
Li
Lid
C,
z
V)
L .
I i-
0
0
z
TIME (DAYS)
FIGURE 11—73. Effect of interrupting the addition of
100 tag/i PAC to activated sludge on 1,2—dlchlorobenzene
effluent and off—gas concentrations and fractional recoveries,
N/N 0 .
PAC INTERRUPTION STUDY
1.2—DICHLORQBENZENE
100 mg/I PAC
0 0 mg/I PAC (Day8 48 —
77)
28 35 42 49 56 63 70 77 84
452
-------
TIME (DAYS)
FIGURE 11—74. Effect of interrupting the addition of
100 mg/i PAC to activated sludge on l,2, 4 —trichlorober.zene
effluent and oft—gas concentrations and fractional recoveries,
N/No.
1,2,4—’RIC HLORO B ENZ ENE
O 0 mg/I PAC (Doys 48 — 77)
ICO mg/I PAC (Doy! — 48 & 77 — 84)
0
0
28 35 42 49 56 63 70 77 84
453
-------
0
0
o PAC INTERRUPTION STUDY
100 mg/I PAC BIOREACTOR
0 mg/I PAC Days 4 s — 77
0 BEt4ZCNE
Li ETF{YLAENZENC
0 CHLOROBEtJZENE
0
d 4
28 42 49 56 83 70 77 84
TIME (DAYS)
FtCURE I 1—75. Comp .rison of hcnzene, ethylbenzene, and chlnrohenzcne
overal 1 removals due to biodc rad lou and adsorption nlc?aHured lur1ng the
PAC Interruption study.
-------
0
0
0
- C)
cO
-J
>0
F-’ 0
_d O
I d
0
_J
LIJ c”i
>
0
0
0
28
TIME (DAYS)
FIGIJR F I 1—76. Con pLIrlcnn of hcnzt’in , 1, 2—dI clii orohcnzeiw • nd 1 ,2, /i -t rIch1orobenz n ’
nyc r’ I 1 removals dup to Ii Iiid grada t Ion ii,d adsnrp I Ion nea Iu re(I tIii r in tIit P C
nterrupt Ion StiI(IV
PAC INTERRUPTION STUDY
100 mg/I PAC 8IOREACTO
0 mg/I PAC Days 48 — 77
BENZEt E
O 1.2—DlCHLOROBEuZE ’iE
O 1.2 ,4—TNICHL0F OAENZENE
35 42 49 56 63 70 77 84
-------
TABLE 11—22
STEADY-STATE TOXICS REHOVALS MEASURED DURING TIlE THREE
OPERATING PERIODS OF THE PAC INTERRUPTIOt 1 STbDY
Influent Effluent Off-Gas Overall Removal 4- +
Operating Perlod+ jug/1)_ _( ) (n / ) _______(Z)_______
B EN ZEN E
1. Days 29—48 104 (20.2) 0.6 (0.1) 74 (24) 89 (4)
2. Days 53-76 123 (27.8) 0.6 (0.1) 95 (21) 89 (1)
3. Days 77—84 lL4 (14.3) 0.3 (0.1) 64 <5) 92 (1)
ETHYLBEN7.ENE
1. Days 29-48 106 (13.0) 0.3 (o .iF 54 (20) 94 (3)
2. Days 53-76 lO S (30.5) 0.4 (0.1) 114 (42) 06 (2)
3. Days 77-84 110 (6).3) 0.3 (0.1) 53 (6) 94 (1)
CHLOROBENZENE
1. Days 29-48 103 (16.)) 0.3 (0.1) 43 (24) 94 (2)
2. Days 53-76 108 (30.5) [ .0 (0.6) 115 (39) 85 (3)
3. Days 77-84 108 (3.2)) 0.3 (0.1) 38 (8) 95 (1)
1, 2-D1CHLOROBENZEHE
1. Days 29-48 104 (13.6) o.oTio 3) 40 (16) 94 (2)
2. Days 53-7( 120 (13.1) 9.3 (1.2) 570 (105) 32 (8)
3. Days 77-64 115 (13.3) 1.0 (0.4) 56 (17) 93 (1)
1 • 2, 4-TR ICHLOROBENZENE
1. Days 29-48 118 (20.1) — 0.8 (0.3) 50 (18) 94 (2)
2. D ya 53-76 L i i. (15.3) 11.3 <1.6) 664 (82)) 9 (5)
3. Days 77-84 112 (3.5) 1.0 (0.4) 56 (9) 93 (1)
+ Days 29-48 100 mg/I PAC
Days 53-76 0 mg/i PAC
Days 77-84 100 mg/i PAC
+4-Overall Removal ‘. ( 1 —N/N 0 ) x 100
( ) Standard Dt v1at1on
-------
Table 11—22. SimIlar levels of overall renova.s were observed for
each compo .ind in single solute PAC bioreact r studies conducted with
influent P C doses of 00 mg/i. as rc ported in TaSle 11-23. These
results indicate that the removal of each toxic organic compound was
not adversely affected by the presence of the other compounds for the
experimental conditions considered.
TABLF 11-23
STEADY-STATE RZ!1O LS OF TOXIC. ORC NIC COMPOUNDS
FROM BIOREACTORS RECEIVING 100 mg/i PAC DOSES
Overall Removal (%)
Single Solute PAC Interruotion Study
Compound Studies Days 2? 4
Benzene 89
Ethylbenzene 90 93
Ch lorobenzene 92 94
l,2-Dich lorooenzene 94 94
l,2,4-Trichorabenzene 94 93
After the steady—state overall removals of each compound were
e tabli .hed and prior to the four week interruption in the 100 mg/i
PAC drse, the influent concentration of each compound except 1,2,4-
trichlorobenzer ’e was increased from 100 ug/l to between 400 and 600
ugll. The objective of increasing the influent concentrations was to
evaluate the effect of sptkc loadings of toxic organic compounds on
the overall removals of each compound. The increased toxics loading
period occurred ber :ecn Day 35 and ‘)ay /2. As reoults
presented by Figures 11-70 through 11-74 and Table 11-24 show, the
spike loadings ca ’ sed only small increases in effluent and off-gas
concentrations of benzene, ethylbenzene, chlorobenzene, and 1,2-
dichlorobenzene. The increased influent concentrations of the four
compounds had no measurable effect on eithrr effluent and off-gas
concentrations or overall removals of 1,2,4—trichioroberizene. An
interesting observation for the highly biodegradable compounds
benzene, ethylbenzene, and chlorobenzene was the reduction in effluent
and off-gas concentrations that occurred on the second sampling day of
the spike loading period. In the care of benzene the effluenr and off-
gas concentrations decreased from 1.8 ugh and 310 ng/l, respectively,
to 0.5 ugh and 94 nz/l, respectively, within two days while inuluent
concentration as between 400 and 600 g/i . Similar results were
observed for ethylbenzene and chlorobertzene.
Data collected following the cessation of PAC addition on Day 48
revealed a significant difference between the behavior of the
biodegradable compounds benzene, ethylbenzene, and chlorobenxene and
the poorly biodegradable and non-biodegradable compounds 1,2-
dichlorobenzene and l,2,4-trichlorobenzene, respectively. Results fc r
457
-------
T Bi.E II—2
EFFECT OF SPIKE I.OADIt4G I EKlt)U ON RFHOVALS
OF INDIViDUAL TOXIC ORGANIC COMPOUNDS
Op. rattng ln(Iu ’nt Efluent 0(1-Gas Overall
Period _( )_ Removal (Z)
l13 N2ENE
Steady-State Avg. 104 0.6 74 90
Day 37 514 1.8 310 92
Day 39 403 0 5 94 96
ETllYLI NZ l NE
Steady-State Avg. 107 0.3 54 93
Di 17 449 0.7 219 91
39 365 0. 2 92 97
CHI.OROBENZENE
Steady-State Avg. 103 0.3 43 94
Day 37 640 1.6 234 93
Day 39 362 0.5 75 97
I L2DICIII 0ROBENZENE
Steady-State Avg. 103 0.6 42 94
Day 37 370 2.6 158 94
Day 19 lOS 0.8 53 93
4-TR I CIIL0ROBENZENE
Steady-Staze Avg. tIR 0.8 50 93
Day 37 100 0.7 50 93
Day 39 (05 0.8 45 94
-------
l,2,4-trichlorobenzene given by Figure 11-74 show that after the PAC
was omitted from the influent the PAC in the aeration section retained
its ability to removc some 1,2.4-trichlorobenzene for only four to
five days. During that time overall l,2,4-trichlorobenzene removals
de. reased from greater thati 90% to less than 10% while the mixed
liquor PAC concentration decreased by apprcxieately 50%. The effluent
concentration increased from less than 1.0 ugh to between 12 and 14
ugh and the off-gas concentration increased from less than 100 ‘ g/l
to approximately 700 ng/i as a result of the interruption in PAC
addition. At the time at which no significant removal of 1,2,4-
trichiorobenrene concentration (N/N 0 0.90) was initially observed
the mixed liquor PAC concentration was approximately 500 mg/i. The
ramaining PAC was in apparent equilibtium with the solution 1,2,4-
trichlorobenzene (amproxlmately 12 to 13 ugh) ane therefore not
capable of adsorbing 1,2,4-trichiorobeozene in the influent. Results
for l,2, 4 -trich orobenzene recorded from Day 63 to tiaj 77 were nearly
identical to those observed in control activated sludge bioreactors.
Near complete recovery of i,2,4-trLchlorobenzer e was evidenced by
N/N values between 0.90 and 1.00.
The results for l,2-dichlorobenzene were similar to those
recorded for l,2,4-trichlorobenzene except that 1,2-dichiorobeuzene
recoveries, N/N 0 , rose from approximately 0.10 to an average value
of 0.70, indicatuig some microbial degradation was occurring. The 32
overall removal averaged frcm sauiples collected from Day 53-76
comparable to the 35% removals meas red in control activated sludge
units. Within four days after the PAC flow was stoppedthe effluent
concentration had increased from 1.0 to 8.0 ug/l. During the period
when the reactor was receivlrg a 103 mg/i PAC dose the affluent
concentration rose from 1.0 to only 3.0 ugh in response to the change
in influent concentration from 100 to nearly 400 ug/1. In general the
efflt .ent and off-gas concentrations were extremely sensitive to
changes in the influent PAC dose and relatively insensitive to changes
in the influent 1,2-dichlorobenzene concentrations over the range of
conditions studied.
The data collected for benzene, ethylbenzene, and chlorobenzene
between Days 48 and 77 when no PAC was added were similar for each
compoind a d different from the results for l,2,4—trichlorobenzene and
l,2-dichlorobenzene. The results for benzene presented in Figure 11-
70 show that the small increases in the effluent and off-gas
concentrations which occurred during the first four days after the PkC
addition was stopped were fo1lowe by a decrease in both
concentrations to steady-state levels. Average steady-state beazene
removal during the operating periods when the PAC influent
concentration was 10 mg/I and 0 mg/i were approximately the same.
The results suggest that the activated sludge biornass had
acclimated to benzene during the tine 00 mg/i PAC was added to the
reactor. Prevtous control and PAC bioreactor studies indicated that
an acclimation period of ap roximateIy 14 days was required to achieve
overall benzene removals in the 80% range. The benzene biodegradation
vate coefficient which had been evaluate4 during control activated
sludge studies was measured during the PkC interruption pe..iod on Day
74. The mixed liquor PACconcantraticn was between 100 and 200 mg/i at
459
-------
this point in the bioTeactor study. The biodegradation rate
coefficient was measured in the 10-liter bloreactor being used for the
PAC interruption study with a procedure identical to that detailed in
Section 5 for aerated biodegradation studies. The bloreactor was
temporarily converted to a batch node by stopping influent and sludga
waste flows. An aeration rate of 4.2 1/mm was used for the
biodegradation study.
Results presented In the semi-logarithmic p’ot of co ’centration
versus time in Figure 11-77 and sun iarizeo by Table 11—25 s ow a rapid
removal of benzene due to biodegradation and volatilization. An
overall removal rate coeficient, k 0 , of 0.71 min was measured
with a correlation coef .cjcni (r 2 ) of 0.999. The volatilization
rate coefficient, k,,, corresponding to a 4.2 1/mm aeration rate was
calculated to be 0.078 mind. Tne difference between the overall
removal rate coefficient and the volatilization rate coeffici?nt is
the biodegradation rate coefficient. This value of 0.63 min was
nearly Identical to the calculated value of 0.67 nin based upon a
CMF reactor mass balance using measurcd influent, effluent, and off-
gas concentraticns and assuming first order biodegradation kinetics.
Pertinent informatIon concerning the bioreactor operating :onditions
and measured ben’.ene concentrations the day the biodegrad .tion study
was conducted re given In Table 11-25.
The results recorded for ethylbenzene and chlorobenzene during
the 84—day study in Figures 11—71 and 11-72, respectively, were nearly
identical. Small increases in ef 6 luent and off-gas concentrations of
each conpo nd occurred as a result of the increased influent
concentrations between Days 35 and 42 of the spike loading period.
While influent concentrations Increased from 100 to 500 ugh, effluent
concentrations of etnylbenzene and chlorobenzene rose to only 0.7 and
l. ugh, respectiv ly, from their steady-state levels of
approximately 0.3 ug/l.
Overall removals of both ethylbenzene and chloro e zene decreased
sl ,ht1y during the first four days after the influent PAC
concentration was changed from 100 to 0 mg/I. Ethylbenzene rem .wa1
decreased from 94 to 86% while chlorobenzene decreased from 94 to
85%. The reduction in overall removal is evidenced in Figures 11—71
and 11-72 by the small increase In N/N 0 values between Days 48 and
53. Overall removals of each compound achieved new steady-state
levels within five days after the PAC addition was stopped. Results
for the con-biodegradable compcund l,2,4-trichlorobenzene indicated
that approximately the same length of tine was required for the PAC
remaining in the aeration section of the bioreactor to exhaust its
apabUity to adsorb L,2,4-trichlorobenzene.
One of the most interesting aspects of the PAC Interruption study
was the appaTent acclimation of the activated sludge microorganisms
to benzene, ethylbenzene, and chlorobenzene, and to a lesser extent
1,2-dichiorobenrene, prior to the PAC interruption phase. This
acclimation likely occurred at the beginning of the study within the
two to three weeks after the toxics were added to the influent. If
the system had not acelimated to the biodegradable cou’pounds prior to
the PAC interruption phase there would have been a more significant
decrease in overall removals followed by a gradual two-week incrcsse
460
-------
BENZENE REMOVAL
10—LITER BIOREACTOR —— BATCH MODE
AccUmated Activated S’udge
Aeration Rate 4.2 litera/miri
Run BIO+MR—BZS
I ’
C l
-J
.,...- . —.
20
TIME (MINUTES)
FICL’RE 11—77. ExDeritental data and best-fic line
describing benzene biodegradation by activated sludge
in a comoletelv—mi’ced batch rate study in a
bioreactor vith a 4.2 liter/nin aer rion rate.
461
-------
TABLE 11-25
RESULTS FROM 10-LITER CHB BIODEGRADATION
RATE STUDY ITK AERATION
CMB BrODEGRADkTIOM RESULTS
Solute: Benzene
Run: 810 + AIR - 8Z6
Activated Sludge Source: Acclimated activated s udg from PAC
Interruption Bloreactor, Day 74
k 0 (mind): 0.707
corr. co ff.: 0.999
k (min ): 0.078 4.2 1/mfn)
kb (inin ): C.629
BrOREACTOR OPERATING SUMMARY
Influent (ugh): 167
Effluent (ugh): 0.4
Off—Gas (ng/l): 127
N/N 0 : 0.092
Overall emoval (Z): 90.8
k (ciin ): - 0.065
kh, calculated (mj L) 0.673
MLSS: 3850
— 5.6
= 1/rain)
PREDICTED EFFLUENT, OFF-GAS AND OVERALL TOXICS
REMOVAL USINC Kh MEASURED IN 018 STUDY
Effluent (ugh): 0.7
0ff-Gas (ng/1): 134
0.098
Overall Removal (Z): 93.2
462
-------
to steady-state levels. Instead the steady—state re’novais due to
microbial degradatirn occurred within five days after the PAC-addition
was stopped.
The original iifiuent PAC dose of 100 n’gJl was begun again after
bioreactor sanples for analyses of the toxic organic compounis were
collected on Day 77. Jithin 24 hours effluent and off-gas
concentrations of l,2-dichloro enzene and l,2,4-trichlorobenzerc tied
decreased to the steady—slate levels that existed during he initial
48 days of the study. Overall removals of l,2-dichlorobenzene and
l,2,4-trichlorobenzene increased from 32 t 93Z and from 9 to 93%,
respe:tively. In marked contrast to results for 1,2-dichiorobensene
and l,2,4-trichlorober.zene, no significant change in the overall
beazene removal occurred as a result of the continuation of the 100
mg/i PAC dose. Overall removals of ethylbenzene and chlorobenzene
increased slightly to steady-state levels observed with the initial
100 mg/i PAC dose. A summary of overall removals during the three
operating reriods is provided by Table 11-26.
11. 7.2 Non-Volatile Compound
Two additional bioreactor studies were conducted with lindane to
evaluate the response of the integrated activated sludg ‘arbon system
to PAC interruption. An influent PAC dose of 25 mg/I was used in each
case. Figure 11-78 presents the result.s from an interruption (at Day
0) in PAC feed to a bioreactor operated at a 9-day SRT and receiving
an average influent lindane concentration of 80 ugh. The average
value of Ce/C i for the reactor under steady-state conditions prior to
PAC interruption was 0.16. The mixed liquar PAC continued to adsorb
lindane for an additional six days before becoming exhausted. Twenty-
four hours after the PAC dose was stopped the effluent concentration
increased by only a small amount while after three days the effluent
concentration had increased fro 12 to 2 hen tLe influent
lindane concentration was increased to an average value of 250 ug/l
and the solids retention time reduced to tnree days,effluent
concentrat.o ncre: ,cd r.’ore ra d1y n rc onse to t c ntcrrun on in
PAC addition as shown by Figure 11-79. In both studies the effluent
concentratimdropped to its original steady-state value within 24
hours after PAC-addition was continued.
463
-------
TACI.E 11—26
SUMMARY OF AVERAGI TOXICS REMOVALS FROM ThE 100 mg/i
PAC INTERRUPTION BIOREACTOR S1UDY
100 mg/I Period 0 mg/i PerIod 100 mg/I Period Single Solute Studies
Compound Day 29-48 Day 53-76 Day 77-94 Control 100 mg/I PAC
Benzene 89 89 92 83 89
Ethy lbenzene 94 86 95 81 90
Ch lorobenzene 94 85 95 81 92
0 ’
I,2-Dichlorobenzene 94 32 93 37 94
1,2,4—Trtch lorobenzene 94 9 93 3 94
-------
0
In
0
1 2 3 4 5 8 7 8
TItlE (DAYS)
FIGURE 11—78. Eff t of interrurting the addition
of 25 ng/l PAC to activated sludge or lindane effluent
concentration Eroii a 10—liter bioreaccor with a 9—day SRT.
465
-------
0
-S
N
=11)
LiJ
U
z
U I
>
I—c ,,
-J
cr j
FIGURE 11—79.
of 25 - g/l PAC to
concentrations.
Effect of interrupting the addition
activated sludge on lindane effluent
a,
d
c.o
1,0 2.0 3.0 40 5.0 8.0
TIME (OPIYS)
“66
-------
11.8 TRANSIENT LOADING STUDY
An in tegra ted activated s lt’ ’re/ca rbon tree tn’en t bloreac tot study
was conducted with transient influent lc ’dIngs of three toxic organic
compounds: benzene, ethylbenrene, and chlorobenzene. The bloreactor
received an Influent PAC doPe of O0 mg/i of Hydrodarco C. The three
organic compounds were added on a transient loading cycle consisting
of two days during which time the toxics were added to the influent
followed by three days when the toxics were omitted from the
Influent. The transient loading study was conducted for a total of 88
days. A mean solids retention time and a hydraulic residence time of
6 days and 5.5 hours, respectively, were used throughout the study. The
100 mg/i PAC bioreactor was operated in parallel with the activated
sludge transient loading bioreactor described in Section 10. Influent,
effluent, and off—gas analyses typically were conducted each day of
the two day period when the toxics were aaded to the influent flow.
Influent, ettluent, and oft-gas concentrations and N/N 0 values
five been plotted for the tulI 88 days of the study for benzene,
ethylbeozene, and chlorobenzene in Figures 11-80, 11-81, and 11- ,
respectiveiy. Duting the initial 43 days of the study influent
concentrations were maintained between 100 and 120 t 0 /l. Influent
concentrations up to 600 to 750 ig/L were evaluated in the latter 46
days f the . tudy.
The Influent concentration of benrene, ethylbenzene, and
chlorobenzene averaged between 100 and 120 ug/l during the first 1 3
days of the study. Table 11-27 sumaarizes results for each compcund
from this operating period. Results ‘or benzene presented ii Figure
11-SO show that the fractional recovery, WIN 0 , initially ‘ncreased
from 0.30 to nearly 0.50 di:ting the first week before decreasing to a
steady-state e1ue of 0.16 after app:. cimateiy three weeks. The
overall bencene removal increased, therefore, during the initial three
weeks from between 50 to 707. to a steady-state le”el of 84%.
Decreases In both effluent and off-gas concentrations contributed c’
the observed increase in benzene removal. This increased romoval was
a result of &ncreased microbial degradation of benzene. Similar
acclimation phases were observed in nearly all activated sludge and
PAC bioreactor studies conducted with benzene. PAC biorcactor studies
with non-degradable compounds, lindane and i,2, 4 -trjchiorobenzene,
demonstrrted that toxics’ reriovals due solely to carbon adsorption
reached steady—state levels within 24 hours after initiation of PAC
ddition. Results from the 100 mg/i PAC transient loading study were
not signiiicantly different from those observed in the benzene steady—
state loading study with a 100 mg/I PAC dose, as shown by the
comparison in Figure 11-83. Steady-state benzcne removals in the
steady-state and transient loading studies averaged S6Z and 86%,
respectively. The transient nature of benzene addition to the 100
mg/I PAC bioreactor had no measurable affect on the system’s abil1ty
to remove bensene.
Results recorded for ethylbenzene during the initial 43 days of
the transient load . g study are presented by Figure ll-8L. Steady-
state ethylbenzene removal was achieved within 24 hours after 100 mg/i
of the slurried PAC dose was initially added to the bioreactor.
Effluent and off-gas concentrations averaged 0.8 ugh and 17.8 ng/l,
467
-------
U)
I - .
c i
La,
U)
C d
a
C
C,
U,
:1
TRANSIENT LOADING (oddtd 2 days/off 3 doy8)
100 mrj/I PAC BIOREACTCRp
OENZENE
• I
• I
I I
• I I
I
I - I I
, _ %
: —
I I
‘S
‘I
IS
‘I
I4
m I I
I I
I I
I I
— I-
0 10 20 30 40 50 60 70 80 93
TIME (DAYS)
FIGURE 11—80. Benzene influent, effluent, and off—gas
concentrations and fractional recoveries, N/No, i easured during
a 100 og/i PAC—bioreactor study with transi”nr toxics loadings.
(2 days added to i nfluent/3 days omitted)
If,
-J
z
Li
-J
z
-J
LL
LL
Li
- J
C.,
z
U)
LI
0
0
z
468
-------
- I I —
TRANSIENT LOADING (added 2 days/off 3 days)
100 mg/I PAC O OREACTOR
N EThYLBENZENE
U I
I S
LiJ
S I •
- c.
I I I
.,.__. Lt / ‘ ‘
4’
I I I
-J
(5
z
C ’
( ) S I
(5
I
• 1
L&
LL
S I g
o ‘ -e- - I
I- I
o r 4 —4
ZU,’
z
0 I D 20 30 40 SD 60 70 80 30
TIME (DAYS)
FICURE 11—81. Ethvlbenzene influent, effluent, and off—gas
concentra’i ns nd raction il recoveries, N/’cc , measured during
a 100 m g/ i PAC—bior accor study with transient coxics loadings.
(2 day3 added to influenc/3 days on.1t ed)
469
-------
I.—’ 4 4 4
TRANSIENT LOADING (added 2 days/off .3 days)
100 mg/I PAC B 1OREACTOR
CHLOROBENZENE
/
I J S
U, I
c..d
._J
L
1. 4 4
4 4 4 I 4
U,
I
U..
Li
4 4 4 —+— I I
-J
U)
C.,
I
S
I
I - I I—
0
z
z
0 10 20 30 40 50 60 70 0 90
TIME (DXt’S)
FICJRE 11—82. Chlovcbenzene influent, effluent, and off-
gas concentrations and fractional recoveries. ‘a/No, measured
during a 100 m /1 PAC—bioreactor study with transient coxi.cs
loadings. (2 d..vs addeo/3 days omitted)
470
-------
TARI.E 11—22
RESULTS FOR BI.NZ .NE ETIIYLBLNLENE AND CIILOROBENLENE FROM TIlE 100 mg/9 .
PAC BIOREACTOR O°ERATEI) WIfH RANSIENf INFLIJENT TOXIC ’ LOADINGS (DAYS 21—43)
Parameter
Benzene
Cthylbcnzene Ch lorobenzene
In(luent
Elf Inert
Off—Cas
H/N 0
Overall Reriioval (2)
Reduction in Aqueous Conc. (2)
119 (6.6)
0.6 (0.2)
134 (16.8)
0.164 (0.012)
83.6 (1.2)
99.5 (0.2)
107 (6.8)
0.8 (0.6)
128 ‘20.6)
0. 176 (0.027)
82.4 (2.7)
9 .3 (0.5)
113 (4.91
0.8 (0.5)
77 (13.2)
0.101 (0.009)
89.9 (0.9)
99.3 (0.5)
-------
BE NZE NE
o
g ,‘ -‘
Li 100 mg/I PAC BIOREAC1 OR
0 TE.A0Y—STATE LOADINS
TRANSIENT LOADiNC (added 2 days/off 3 days)
I I I • I
I I I I
I
c Tw
2.
I I -I I
(0
-J
‘I
‘I
U)
0
La
I L .
I I I
I . 1 I I —
0
zig,.
0 7 14 21 2 5 42 49 56
TIME (DAYS)
FIC RE 11—83. Comparison or benzene eff 1 uent and off-gas
concencraticns and fractional recoveries, ‘ /No. neasured during
100 -neIl P. C—bloreactor studies vith steady—state and transient
(added 2 days/omitted 3 days) toxics addition to influen.
472
-------
espectively, during the three week operating period fron Day 21 to
Day 43. An average influent concentration of 107 ugh was recorded
during that time. As shown by the similarities in N/N values in
FIgure 11-84 ,verall ethylbenzene removal in the trans?ent loading
unit was the same as measured in the steady-state loading bioreactor.
Overall steady-stato ethylbenzene remcvals in the steady-state and
transient loading units averaged alter the initial 21 days to ensure
complete accliration by the activated sludge were 87% and 82%,
respectively.
The results for chlorobenzene p1o ted in Figure 11-32 indicate
that despite the transient loading conditions, steady-state
chlorobenzene removal was obtained within 24 hours after surried PAC
ar.d chlorobenzeie were first added to the reactors. Influent,
effluent, and off-gas concentrations averared 118 ug/l, 0.8 ugh,
and 77 ng/1, respectively, during the 2l.- 3 days of the transienr
loading study. These results were not significantly different from
those recorded for the 100 mg/i PAC bioreactor study with a continuous
in luent flux of chlorobeazene, as shown by results from the two
studies plotted in Figure 11-85. Overall chlorobenzene removals
averaged during Days 1 to 43 of the transIent loading study and Days 1
to 56 of the steady-state loading study were both 87..
In summary, tnere was no significant difference in overall
removals me sured in 100 mg/I PAC bioreactors operated under
cor.ditions of Continuous and transient loadings of the three volatile,
biodegradable organic compounds. The following relative order of
overall removal was observed in both continuous and transient oxics
add I ti on:
chlorobenzene > ethylbenzene benzene
This order of toxics renrovar Is evidenced In the comparative plot of
benzene, ethylbenrene, and chiorobeazene overall removals in Figure Il-
8I for the 88 days of the transient loading study.
Results presented for bioreactors receiving continuous additions
of toxic organic c3mpounds indicated that the addition of 100 mg/i PAC
had no significant effect on benzene removal ar.i produced only slight
increases in ethylbenzene and chiorobenrene overall removals compared
to control units with identical operating conditions. One of the
primary objectives of the transient loading study was to determine
whether or not PAC addition to activatcd sludge provided enhanced
removals of biodegradable compovnds under conditions such as transIent
toxics loadings which might adversely affeLt microbial acclimation
and ‘iodegradatic 1 n processes. The effect on toxics removals of PAC-
addition to activated sludge systems receiving transient toxics
1. adings was evaluated by comparing results iron the 100 mg/i PAC
bioreactor to results from the control activatcd sludge unit detailed
in Section 10. The two bioreactors were operated with identical
toxics Ioadtng cycles consisting of two days of toxics addition to the
influent followed by three days during which time no toxics were added
to the influents. Only 0ays 0 to 43 of the 100 nigh PAC study were
used In the comparison because after Day 43 the inuluent concentration
was varied from approximately 30 to 800 pg/iS.
The effect on beazene removal of adding a 100 mg/I PAC dose to
activated sludge is shown by the comparison of data from control and
473
-------
< TETHYLBENZENE
o . 100 mg/I PAC BIOREACTOR
0 STEADY—STATE L0AD NG
TRANSiENT LOADING (added 2 days/off 3 dcys)
I I I
‘2 1
C.,
I__—i ‘
I I I
-J
C,
z
(I , , \
(N I I
‘4. I I 1
O714 28 ;s 42 49 56
TIME (DAYS)
FIGURE 11-84. Conparison of ethvlbenzene effluent and off-
gas concentrations and fracti na1 recoveries, N/No, measured
during LOU g/l PAC—bioreacter studies with steady—state and
transient (added 2 days/emitted 3 days) toxics addition to the
influent.
474
-------
-J
C.,
w
-J
L I-
z __________
-J
C,
— c d
L I
LjJd ______
TIME (DAYS)
FIGURE 11—85. Con parison of chlorobenzene effluent and off—
gas concentrations an fractional recoveries, N/No, measured
during 100 mt/i PAC—bioreactor studies wito steady—state artd
trdnsient (added 2 days/omitted 3 days) tox cs addition to the
iriL 2uent.
I CHLOROBENZENE
100 mg/I PAC BIOREACIOR
O STEADY—STATE LOADING
O TRANSIENT LOADING ( dde 2 d;y3,’ fr 3 dc ys)
)
-J
C-,
z
C,,
LI..
0
0
z
0
U,
I I -
a -
0 7 14 21 28 35 42 49 56
475
-------
0
0
0
.--- 0
>0
1 0
w
(Yo
0
0 ’ _J ,
-J
>
0
0
o
0 10 20 30 43 50 60 70 80 90
TIME (DAYS)
FICLIRE I I —86. Comparison of bc zene, ethylbeuzene, and clulorobenzene overall
removals due ro h1odegr datjon and adsoipt Ion during the 100 mg/I PAC—bloreactor
St iiily I th t rafls I Cult t ( IX I Cs 1 O I(I I ogs
e
TRANS CNT LOADING STUDY
100 mg/I PAC 8IOI EACTOR
TOXICS ADDED 2 DAYS/OMITTED 3 DAYS
O BENZENE
J ETHYL6EN7.ENE
CHLOROBENZENE
-------
100 mg/I bioreactors in Figures 11-87 and 11-88 and Table 11-28.
Influent, effluent, and off-gas benzene concentrations along with
N/N 0 values for the two studies have been plotted in Figure 11-87.
Overall removals have been compared in the piot in Figure 11-Sd. As
the results sjmmarzed in Table 11-28 indicate, during periods of
steady—state benzene removal there was no d:ffc’rence in overall
removals between the control reactor and the u .iit receiving 100 mg/I
PAC. In each unit beozer-’ removal averaged 847. and effluent and off-
as concentrations were approximately 0.5 ugh and 130 ng/i.
respectively.
The addition of 100 mg/I PAC to the transient loading bioreactor
did effect a small increase in benzene removal during the acclimation
phase. The acclimation phase in the 100 mg/I PAC unit was 21 days
compared to nearly 35 days in the control activated sludge
bloreactor. As shown by the results in Figure 11-88. the overall
removal during the acclimation phase in the PAC bioreactor was
consistently greater than that observed during the accI mation phase
in the ectivated sludge unit. When results from the acclimation
phaaes were combined with results from the steady-state periods,
overall beozene removal In the 100 mg/I PAC unit averaged 73% compared
tc 66% in the control activated sludge unit.
Results for ethylbenzene in the 100 mg/I PAC bioreactor have been
compared with those from the activated sludge unit in Figures 11-89
and 11-90. Influent, effluent, and cff-gas concentrations and N/N
v.iues from the two studies are shown in Figure 11-89 while overall
removals are compared in Figure 11-90. The 100 mg/I PAC bioreactor
produced lower effluent and off-gas ethylbenzene concentrations than
the activated sludge unit throug iout the scud,. As illustrated
by Figure 11—39, while overall ethylbc .rerie removals graduallj
increased from less than 20% to nearly 807 in the control
unit during the initial four weeks, the overall removal observed In
the 100 mg/I PAC unit remained relatively constant and averaged nearly
79%. The PAC unit was not subject to the wide variations in
et ’yIbenzene removal that occurred in the activated sludge
bioreactor. Steady-state ethylbenzene removal occurred within 24
hours in the bioreactor receIving 100 mg/i PAC, but was not acnie’-ed
in the activated sludge unit during the time frame studied.
The most significant difference in toxics removal between the 100
ngll PAC bioreactor and the onrrol activated sludge bloreactor was
observed for chlorobenzene. Effluent and off-gas c n er. rations and
N/N values from he two tareactors ha”e been comparrd in Figure 11-
91 and overall removais have been rompared in Figure 11-92. As the
results in Figure 11—91 indicate, effluent and off-gas concentrations
from the biorea’tor receiving 100 mg/I PAC were significantly smaller
than those measured In the activated sludge bioreactor between Days i
and 43. Inf1u nt concentrations from the activated sludge and 100
mg/I PAC unit were approximately the same and averaged 118 ugh ard
120 ug/1, respectively. Overall chlorobenzene removal in the
activated sludge bioreactor began at 25% on Day I and gradually
increased to 75% by Day 43. The addition of a 100 mg/i PAC dose to
activated sludge produced steady-state removels of nearly 90% by Day I
of the study, as shoi. n by Figure 11—92, and averaged 89%.
477
-------
-j
0
w
-J
z
-j
(;1
I&
LU
-J
C,
z
U,
C.,
0
0
z
z
0
TIME (DAYS)
VIGtRE 11—87. Effect of a 100 mg/i influent PAC dose on
benzene effluent and off-gas concentrations and fractional
recoveries, N/No, measured during transient toxics loading
studies.
TRANSIENT LOADING (adoed 2 days/off 3 days)
/
BENZ EN E
100 m /t PAC
0 ACTWATED SLUDGC
‘I
‘I
‘I
I i
I
U,
14 21 28 35 42 49 56
478
-------
0
0
0
‘_ ‘0
-J
>0
0
L) tC
Li
0
-J
liJrs 1
>
0
7 14 21 28 35 42 49 56
TIME (DAYS)
F I f’.U RE II —88. 1f fect of a 100 Intt/ 1 in 11 sient PM dose on boozenc ovoral I
reniova Is ineasti red during transIent t ox! cs loading studies.
D
S
0
( “(I;
‘I
TP ANSlE T LOADU G STUDIES
8ENZENE
T0X CS ADDED 2 DAYS/OMiTTED 3 DAYS
0 ACTIVATED S1.UPCE
100 mg/I PAC BIOREACTOR
-------
fABIJ 11—28
COMPARISON OF BENLENE RFt4OVAL IN CONTROl. ACT! VAfED SLUDGE AND 100 mgR
PAC BIOREACTORS OPERATE!) DER TRANSIENT TOXICS LOADINGS
Activated Sltidgt Bioreactor 100 mg/I PAC Bioreactor
Parameter Days 35—57 I)ays 0-56 Days 21—41 Days 0-43
Influent (ug.’l) 121 (15.4) 119
Effluent (ug/1) 0.5 (0.1) 0.6
Off-Gas (ng/l) 129 (lb.4) 134
N/N 0 0.IbI (0.037) 0.338 (0.18) 0.164 0.266 (0.112)
Overall Removal ( ) 83.9 (3.7) 66.2 (18.0) 83.6 73.4 (11.2)
Reduction in Aqbeous Conc. (%) 99.6 (0.2) 99.5
+ Data from p11—induced upset on Day 47 omitted.
-------
0
U-
W a
. I I I
m
I ,
/ I
I
O -
- , . ss I
S I
a
I • I
-
I I I I I
1D
t, I ,l •
I —
I I I
I
I
_1 --
I
/ - a
‘I
o_-_o-
-
3_
t
— I I I I I
4 I I
0 7 14 21 29 3 42 49 56
TIME (DAYS)
PIC!JRE 11—89. Effect cIf a 100 mg/i Influent PAC dose
on ethv]benzene effluent and cff—gas cor.centrations and frac—
ticnai recrverl.es. N/No, measured during transient toxics
loading studies.
-J
0
-J
z
TRANSIENT LOADING (added 2 dcys/off 3 days)
ETHYLBE NZEN E
0 100 mo/I PAC
ACT IATED SLUDGE
a
—S
-J
5 5
0
U,
Cf
U-
0
0
z
z
U,
48].
-------
0
0
o
.., 0 p-
I..
- I 0%
J I
S • _ # %
I
I
I
I
o
a W
?—_ : 9
a: 0 ,
o a a ‘ I
_.J . - a ‘• ‘ •
— ,. a i a
% I
‘ I
.1
° ?‘ s , TRAtISIENT LOADING STUDIES
0 ElI IYLBENZFJIE
‘I
0 0 ACTIVATED SLUDGE
o 100 mg/I PAC BIOREACTOR
0 7 14 21 28 35 42 49 56
TIME (DAYS)
FICURE I —9O. Effect of n 100 mg/i Infitient [ ‘AC dose on overall ethyihenzene
removals mcnsiara d (IilrIn3 Lrnnslcuit toxic.s loadIng studies.
-------
-J
0
z
V)
0
LL
I L
0
0
z
z
TRANSIENT LOADING (c&cd 2 doys/off 3 days)
CHLGROBENZENE
100 rna/I PAC
ACTIVATED SLUDGE
. I I -
‘I
‘I
c ,
TIME (DAYS)
FIGURE 11—91. EVect of a 100 n /1 influent PAC dose on
ch1orc enz ae effluert arId -1ff—gas concentrations and
fracticnal recoveries. ‘/\ , easured curine transient toxics
loadings studies.
-J
0
w
-J
Li
z
—S
C,
-
IL
I L
L i i
S I — .L1 /
- S S S
J -; :: ’
.
I I
0
0
U,
d
— — ,, ,,,/i’ \I \
‘I
S..- ,
—II I: ‘.
.ae %t s
I I I
t 4 I I
lt __ft2 . /
— — - - — — d
5 eŘ sS S .e
0 7 14 21 :8 35 42 49 56
483
-------
0
0
p —4
-. - - - - - - - - - - - - - - - -
‘ ..- 0 : ‘
I
0
I
0 I
, %
I — 0
j F
F I •
> I —
..
—
ck 0 I
o S _qj
d ‘
o TRANSIENT LOADING STUDIES
Lu
II
CHLOROBENZENE
o 0 ACTWATED SLUDGE
0 100 mg/I PAC BIOREACTOR
4————-— I
0 7 14 21 28 35 42 49 56
TIME (DAYS)
FIGURE 11—92. Effect of a 100 mg/I influent PAC dose on overall chlorobenzene
removals measured dur1n transient toxics loading studies.
-------
The most sigaificant benefit to accrue from the addition of 100
r ’ g/l PAC to an activated sludge system receiving transient toxtcs
loadings was an enhanced removal of chlorobenzene, ethylbenzene, and
to a lesser ex,. nt benrene during the mtrobial acclimation phase.
The impr’ ved removals rcalized on Day ) gradually diminished as
microbial degradation effected increasingly larg r overall removals in
the control activated sludge unit. The difference in bioreactor
performance with respect to toxics removals after the initial four
weeks was significant for only chlorobenzene. While the largest
chloroben ene and ethylbenzene removals in the control reactor
approached the average values recorded for the PAC unit, the duration
of that level of removal in the activated sludge reactor was short.
Chiorobenzene and ethylbenzene removals in the activated sludge
bioreactor never achieved steady-state evels, but instead were
subject to wide fluctuations. Tho removaL of these compounds in the
PAC unit, however, was constant throughout the study and steady-state
levels were achieved within 24 hours. ?horefor . an additional
benefit of PAC addition was increased activated sludge performance
with res ect to toxics removals. In general the less biodegradable
au.i more adsorbable a compound, the greater the benefit of PAC-
additon to activated sludge systems experien .iig transient loadings
of toxic organic compounds.
Following the toxics addition period of ‘) ‘ s 0 to 43. thc’ three
compounds were not added to the infhtent again until av51 , eight nays
later. On Day 31 the influent concentrations of the toxic compounds
were increased from previous steady-state levels uf 120 ugh to
between 610 ug/l and 730 ug/l. During the final 17 days of the
transient loading study, Days 5] t 88, the Influent concentrations
during the toxics addition periods were varied from 35 ugh to 730
ugh, as shown b,r Table 11-29. Three da)s during which time no toxics
were added to the influent separated each t .o day period of toxi s
addition. Influent. effluent, and off-gas concentrations for each
compound from Days 51 to 88 were included in Figurea 11-80 to 1182.
Average iniIuen , effluent, and off-gas concentrations and overall
removals observed during each of the eight toxics addition periods
have beefl tabulated in Tables 11- 30, 11-31, and 11-3 2 for benzene.
ethylbenzene and chlorobenrene, respectively.
Results f r t,enzene given by ?igures 11-80 and 11-86 and Table
11—30 indicated that the increased influeit concentrations did not
ptoduce an adverse impact on overall benzen removal. In general
benzene 7 removals were slighi 1 v greater during the periods of high
toxics loadings (influent concentrations from 630 to 730 ug/l)
compared with removals during perio s of low toxic loadings (influer.t
concentrations 35 to 60 ug, ‘). Removals averaged 88’!. when the
influent concentration wa. between 630 and 730 ug/l end 83% when the
influent benzene level was between 35 and 60 ug/l. As Figure 11-80
shows, effluent and off-gas concentrations, however, were
significantiy larger during the toxics addition periods with the
largest in! luent concentrations. The largest effluent and off-gas
concentrations, 9.0 ug/l and 1160 ng/1, respectively, were measured on
Day 52, approximately 24 hours after the influent concentration was
first increased to the 630 to 730 ugh range. While the influent
485
-------
TABLE 11-29
AVERAGE INFLUENT TOXICS CONCENTRATIONS DURING
DAYS 51 10 88 OF TUE TRANSIENT TOXICS
LOADING 100 mg/Z PAC BIOREACTOR STUDY
Bioreactor Average Influent Concentration (ugh)
Operating Pericd Senzene EtI-v tbenzene Ch loroberzene
Days SI. to 52 730 609 678
53to55 0 0 0
56 to 57 696 570 649
58to61 0 0 0
62vo63 37 40 44
64to66 0 0 0
67 to 68 35 39 44
69 to 71 0 0 0
72 to 73 724 615 687
74to76 0 0 0
77 to 78 628 634 704
79to81 0 0 0
82to83 57 66 70
84to86 0 0 0
87to88 53 63 69
48(.
-------
IABLE It-30
RENIENE RESULTS FROM DAYS 51 TO 88 OF TUE
TRANSIENr TOXICS LOAD1 100 mg/P PAC RIOREACTOR STUDY
Toxics Addition Periods
I 2 3 4 5 6 7 8
Days Days Days Days Days Days Days Days
Paran eter 51—52 56-51 62—63 61—68 72—73 71—78 82—83 87—88
Inftuc’nt (ugh) 730 696 37 15 724 628 57 53
Effluent (ugh) 7.6 4.5 0.7 0.5 3.7 3.3 0.8 0.6
Off—Gas (ng/l) 896 547 38 33 473 448 63 62
Removal (Z) 82 89 83 85 90 89 83 82
Aqueous
Reduction (Z) 99.0 99.4 98.% 98.6 99.5 99.5 98.6 98.9
-------
concentration was maintained within this range for two toxics addition
periods, effluent and off-gas concentrations continually decreased due
to increas.d microbial degrad.-tion of benzene. Mean effluent and off-
gas concentratj ns during the second toxics addition pericd of high
influent concentrations were approxImately 40% lower than those
observed during the first period of high influent concentrations.
Seozene effluent and off-gas concentrations during the final t4o
periods of high influert concentrations, Days 72- 3 and Days 77-78,
ware relati-iely constant and nearly 20% lower than the v lucs observed
during the second period of high influent concentrations, Days 56-57.
Effluent and off-gas concentrations during the periods of low
influent concentrations were consistently lower than the values
observed during the high influent concentration Feriods. During all
four low intuent concentration periods, vecage influent
concentration was 46 ugh, the effluent and off-gas concentrations
were relatively constant, avLragin .- 0.7 ugh and 49 ng/l,
respec tively.
The overall removal of ethylber.zene was relatively unchanged
during the periods of high and low influen concentrarinna as sho in by
results in F 1 gures 11-31 and Il-8b and Table 11-31. 0v rall removals
corresponding to average influent concentration.sof 60’ .g/l (high
loading periods) and 52 ug/l (low loading periods) wete 83% and 867.,
respectively. As was observed for benzene, the effluer. and off-gas
Concentrations during periods of high influent toxics concent:?’i na
were significantly larger than those observed during periods of low
influerit concentrations. Average effluent concentrat. nS during the
high influent periods ranged from 3.4 ug/l to 6.2 ug/l, compared to an
average value of 0.5 ugh recorded during the low influent periods.
Cff-gas concentrations averaged 678 ng/l during the )ugh loading
periods and 4 ng/l during the low loading periods. When off-gas
fluxes were calculated as a percent of the infiuert flux, there was no
significant difference between the high and low toxins loading
periods. In each case the off—gas fluxes represcntei approximately
15% of the influent fluxes. The effluent flux when evaluated as a
percent of the influent flux, likewise, was constan. throughout the
study, varying fro’n 0.5% to only 1.8%.
Overall chlorobenzene removal during the high and low toxics
loading periods was consistently clightly larger than either benzene
or ethylbenzene as shown by Figure 11-86. The influent concentration
in general had little effect on chlorobenzene removal; it averaged 91%
during both high and low toxics loadIng periods. The influent
concentration during the high and low loading periods differed by an
order of magnitude and averaged 683 ug/l and 57 ugh, respectively.
(Table 11—32).
The larger influent concentrations did result in more
chlorobenzene in the effluent and off-gas than occurred when the
influent concentrations were ten times smaller. The largest effluent
and off-gas concentrations of 6.2 ugh and 590 ng/l, respectively were
measured on Day 51, Figure 11-82, 24 hours after the initial increase
in influent concentrations. Effluent concentrations averaged during
the periods of high and the periods of low influent concentrations
were 4.2 ugll and 0.6 ugh, respectively. Off-gas concentrations
during the same operating periods averaged 394 ng/l and 31 ag/ I,
488
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TABLE 11—31
ETIIYLRENZENE RESULTS FROM DAYS 51 TO 88 OF TIlE
TRANSIENT TOXICS U)ADING 100 mg/ 2 PAC BIO8EAC 0R STUDY
Toxics Addition Peri,ds
I 2 3 4 5 6 7 8
Days D]ys Days D -ivs Daya Days Days Days
Parameter 51—52 56-57 62—63 67—68 72—73 77—78 82—81 87—88
Inituent (ugh) 609 570 40 39 615 634 66 63
Effluent (ugh) 6.2 5.6 0.4 0.7 5.1 3.4 0.5 0.3
0ff—Gas (ng/I) 783 810 44 36 608 510 53 57
R!movol (U 80.6 7q 4 83.4 85.2 85.0 87.8 87.6 87.1
Aqueous
Reduction (Z) 99.0 99.0 99.0 98 2 99.2 99.5 99.2 99.5
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TABLE 11-32
CIILOROBFNZI .NE RESULTS FROM DAYS 51 TO 88 OF THE
TRANSIENT TOXICS LOADING 100 rng/Z PAC HIOREACTOR STUDY
Toxics Addition Periods
2 3 9 5 6 7 8
Days I)ays I)ays Days Days Days Days Days
Parameter 51—52 56—57 62—63 67- 8 72—73 77—78 82—83 87—88
_______ ____ -___ —— ____ ____ ____ ____
Q
Influent (ugh) 678 649 44 44 687 704 70 69
Effluent (ugh) 5.9 4.7 0.6 0.8 3.3 3.0 0.6 0.5
0f1—tas (rig/I) 524 445 23 24 310 294 37 39
Removal (2) 88.2 89.7 91.1 90.6 93.1 93.6 91.3 91.6
Aqueous
Reduction (2) 98.9 99.3 98.6 98.2 99.5 99.6 99.1 98.7
-------
respectively. The tenfold differences in average irfluent
concentrations between low and high loading periods resulted in
approximate tenfold differences in both effluent concentrattons and
off-gas concentrations between the two loading pericds. When effluent
and off-gas fluxes were measured as a percent of the influent fluxes
there was ro significant difference 5etween low and high toxics
loading periods. Off-gas fluxes represented approximately 8% of the
influent flux and effluent fluxes were genetally less than 2% of the
influent flux.
491
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S TION i2
SUMMARY
The results from thi . project have provided the firbt detailed
study of the fate and behavior of spec iic to.ic organic pollutants
during activated sludge treath ent and the int ratd activated
sludge/carbon treatment process comnonly referred to as the PACT R
process. This work differed from previous studies of tcaic organic
compounds in waste’ eter treat nt systems for the following reasons:
1. Individual reuxval mechanisms of volatilization,
biodegradation, rnind carbon adsorption (integrated activated
sludge/carbon trea ient studies) were quantified for each
compound.
2. Bioreactor off—gases were n nitor& throughout all bioreactor
studies with volatile compounds to quantify the a unt of eaca
compound stripped to the atmosphere.
3. Quantification of off—gas fluxes e iabled formilation of mass
balances for all compounds and a determination of the arxunts of
each compound biodegraied.
4. Volatilization was sufficiently characterized to enable
predictions of steady—state distributions of the compounds
between aqueous and gaseous phases that would occur in the
absence of biodegradat ion. Comparisons of predicted and measured
effluent and off—gas concentrations showed the effect of
biodegradation on the fate of each compound.
5. Influent concentrations in the 50 to 200 ugh range were
typical of actual influent concentrations for mnnicipal and many
industrial vast t waters
For the purpose of summarizing the results from the project,
Section 12 will address: (1) results from volatilization and
biosorption studies; (2) fate and behdvior of tscic organic compounds
in activated sludge bioreactors; and, (3) effect of PAC—addit ion to
activated sludge on the fate and behavior of the toxic organic
compounds.
492
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12.1 R12 OVAL ME(1HANISMS
Three processes were found tc affect the fate and behavior of
trace concentrations of toxic organic compounds during activated
sludge treatment: (1) volatilization or air—stripping; (2)
hioaorpt ion by activated s1ud e mixed liquor suspended solids; and,
(3) biodegradation by acclimated activated sludge microorganisms. The
addition of PAC provided a fourth removal mechanism, adsorption. Only
one of these mechanisms effects ultimate removal of a compound during
treatment. Volatilization 1 biosorption and carbon adsorption act to
reduce the aqueous conc tration )f compounds by red str .buting them
in the environment, and, therefore. i re not considered as ultimate
removal mechanisms. Biodegradation results in the disappearance of
the parent compound due to its conversion to either a metabolic
intermediate, or CO 2 and water. The term removal mechanism refers to
ar’v process that effects a reduction in the aqueous concentration
of a compound during wastewater treatmer t. Ove all rem va1 or
ulti’nate removal refers ro the disappearance of a conpound due to
biodegradation.
12.1.1 Volatilization
Seven of the nine compounds were found to be read ily transferree
from the aqueous to gaseous phase in the 10—liter bioreactors. The
rate of transfer was modeled as an overall first order process and
found to be a lviear function of the aeration rate used to provide
oxygen to the nicroorganissis and maintain completely—mixed conditions
in the aeration section of the bioreactors. Aeration rates betwten
3.6 and 4.4 i/mi.n were used in the continuous—f mw bioreactor studies.
This level was necessaiy to maintain the mixed liquor suspended solidr
in suspension. The aeration rate used in the bioreactor studies was
larger than that typically used in full—scale treatment facilities and
typically produced D.C. levels ot 5 to 6 mg/I 1 tvo to three times
larger thar maintained in activated sludge aeration basins. This
level of aeiation likely effected a greater degree of volatilization
of the toxic organic compound than occurs at full—scale activated
sludge facilities. The objective of the project as not, however, to
siaa late typical aeration rates, but to achieve complete mixing using
only diffused aeration.
The first order volatilization rate coefficient, k , was
described by the following equation relating it to the aeratio rate
in Section 7:
LQa + ky , 0
In the absence of other removal mechanisms, volatilization resulted in
rapid reductions in the aqueous concentrations of seven compounds.
Table 12—1 compares calculated half—lives for each compound during
batch volatilization studies in 10—liter bioreactors with 4.0 1/mm
aeration rates. The compounds are listed in decreasing otder of
493
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TABLE 12-1
Cc T TED H 4 \LF—LIFT FOR VOLATILE O A IC CO O1JNDS
DURING 3ATCH STRIPPING STUDIES IN 10—LITER BIOREACT S
WITHOUT ACTIVATED LL’DGE
Half—Life due to Volat iizatiofl (nin) +
(4.0 1/enin Aeration)
Ethylbenzene 8.1
Toluene 8.9
Benzene 9.3
o—Xylene 11.8
Chloroberzefle
1,2-Dichlorobenzeflc 2’. 1
1,2 ,4_TrichlorobeflZeT e 27.5
+ — in 0.5 — In 0.5
Half—life = —- k = LQ
V 8 V,O
494
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volatility, and half—lives range from 8 minutes for ethylbenzene to
27.5 minutes for 1,2 ,4—tr ichiorobenzA ne.
Base .tne continuous flow striprnng studies, conducted in 10—liter
bioreactors without acti’,ated sludge, re used to derionstrate the
fo 1 Ic wing:
1. Analytical methodologies were suffu ient to enable greater
than 9O recovery of eath compound.
2. Effluent and off—gas concentrations could be predicted from
batch measured volatilization rate coefficients, k
V
3. Off—gas concentrations could be predicted from measured
effluent concentrations.
4. Studies conducted with a single compound and up to seven
compounds showe I that the number of tozics added to the influent
had no effect upon either air—stripping or percent recovery of
individual compounds.
Volatilization resulted in a 90Z reduction in aqueous concentrations
of all compounds except lindarie and nitrobeozene during the baseline
continuous flow studies in bioreactors operated under conditions
identical to those used in the activated sludge studies.
2.l.2 Biosorption
The three most hydrophobic COWDOUUdS, based upon octanol/water
partition coefficients, ere tested for their ability to accumulate in
the mixed liquor suspended solids: 1,2—dichlorobenzene , 1,2,4—
trichlorobenzene, and lindane. Results from sorption isotherm studies
shovc that biosorption could be described by the linear sorption
model:
o KC
‘e Be
Values of for 1,2—dichlorobenzene, lindane, and 1,2,4—
trichlorobeazeoe re 252, 560, and 1025, respectively. When
incorporated into a C? reactor mass balance that included
volatilization, biosorption did nc’t significantly change the predictea
effluent off—gas concentrations of the two volatile compounds. The
model did predict a slight reduction in the aqueous concentration of
lindane. Measured effluent and off—ga! concentrations were in
agreement with predicted values for all three compounds.
12.2 ACTIVATID SLUDGE CW T3IOREACTOR STUDIES
Completely—mixed flow biorsator studies were conducted in the 10—
liter experimental bioreactors equipped with air—tight lids to
determine the fate of each compound during activated sludge treatment.
495
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Influent, effluent, and off—gas concentrations were measured every
three t3 four days during all activated sludge studies while waste
sludg2 concentrations of selected compounds were measured less
frequently. The use of air—tight lids to enable collection and
analyses of the volatile compounds in bioreactor off—gases was a unique
and important feature of the experimental system. Irifluent, effluent,
and off-gas fluxes were used to develop mass balances fi.r each compound
and determine its fate in the activated sludge system. Baseline
studies conducted in 10—liter bioreactors without activated sludge
desonstrated that recoveries, (effluent flux + off—gas flux)/(influent
flux) x 100, for all compounds, including the st volatile ones,
averaged greater than 90Z.
Biodegradation was identified by comparing the total flux out of
the bioreactors (effiuent and off—gas) to the influent flux. Baseline
studies den nstrated that the ratio of the mass flux leaving a bioreac or to
the mass flux entering it, the fract lanai recovery or N/N 0 , averaged
greater than 0.90. Thus N/N 0 values significantly less than 0.90 were
ev dence of biodegradation. Complete recoveries, N/N 0 values 0.90, of
biodegradable compounds occtnred when sufficient quantties of silver
chloride or concentrated Rd ere added to the influent to inhibit
biological ac ivicy. Batch biodegraiation rate studies were conducted
with activated sludge from acclimated bioreactors to confirm that
biodegreda.. on was occi ring in the continuous flow units.
The activated sludge bioreactor studies were divided into four
phases:
1. Single solute : only one toxic organic compound was
added to a bioreactor influent.
2. Multi—solute : two to seven compounds were added to a
bioreactor influent.
3. Effect of Influent Cot centration : effect on
biodegradation of influent concentrations from 25 to
over 5000 ugh.
4. Transient Londing : effect of transient loading
conditions on biodegradation of trace toxic organics.
Significant results from each phase of the activated sludge studies
have been s aiutarized in the following sections.
12.2.1 Single Solute Studies
1. Table 12—2 gives a si.n mary of the fate of each compound during
activated sludge treatment in the 10—liter bioreactors with
air—tight lids.
2. Based upon at’ unts of each compound r€rioved by biodegradation
the nine compounds can he divided into the folle ing three
496
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TABLE 12—2
FAT! OF TOXIC ORG NICS IN ACCLIMATED ACTIVATED SU?DGE
BIOREACTORS OPERATED UNDER STEADY-STATE CCXDITIONS
Percent. of Influenc.
C ”i pound EffLuent Off—Gas Blosorbed 3iode ’ rade’1
Benzene <1 16 0 84
Toluene <1 17 0 83
Et.hy15 rtzene <1 22 0 78
O—Xylene <1 25 0 75
Ch lorobenzene <1 20 0 80
1, 2—Dic Lorc.—
b nze ne 6 59 0 35
1,2,4—Tr cI oro—
benzerte’ 10 90 <1
Ni troberizene 2 <1 98
Lindane 96 0 4 0
497
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groups. Coniparisons of the amounts of the volatile compounds
degraded during typical activated sludge stut!ies is given by
Figures 12—1 and 12—2.
iodegradabI Poorly—biodegradable Non—biodegradable
(N/N 0 < 0.30) (0.40 < N/N 0 < 0.90) (N/N 0 0.90)
Nitrobeniene 1,2—D ichlorobenz ne 1,2,4—Tricblorobenzene
Senzene Lindane
To luene
Chiorobeozene
Ethy lbenzene
o—Xy lene
3. In general, the amount of a cot pound biodegraded decreased as
me degree of chlorine substitution on the benzene ring
increased, as shown by Figure 12—2.
4. Solids retention tines from 6 to 12 days had no 8ignificaflt
effect on the fate of each compound.
5. Biosorption had no significant effect on the fate of the
campounds, except lindane.
6. Biodegradation resulted in reductions in effluent and off—gas
concentrations. For volatile compounds, the primary effect of
biodegradation was a reduction in off—gas fluxes. Measured as a
percent of the amounts predicted to occur in the absence of
biodegradation, biodegradation caused approximately the same
percent reductions in effluent and off—gas concentrations.
7. Effluent and off—gas concentrations of 1,2,4—Trichlorobenzene
re accurately predicted from independently measured
volatilization rate coefficients.
8. 0ff—gas concentrations of all of the volatile compounds,
biodegradable and non—biodegradable, ere accurately predicted
from measured effluent concentrations.
9. Predicted off—gas and measured effluent concentrations could
be used to determine the amount of each compoi ad removed by
biodegradation.
10. Non—aeration CMB biodegr ation st dies confirmed the
biodegradation observed in CMF 10—liter activated sludge
bioreactors.
11. Approl.inate L’+ to 21 day acclimation periods existed prior
to steady—state biodegradation oc benzene, toluene, ethylbenzene,
o—xylene, uitrobenzecie, and chlorobenzene.
498
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0
0
0
-J
I- 0
w
0
FIGURE 12—1. ComparIson of overall removals of volatile toxic organic compounds
due to biodegradation during eliiglc—solute activated sludge studies.
TIME (DAYS)
-------
I I •
ACTWATED SLUDGE SINGLE SOLUTE STUDIES
TIME (DAYS)
I!J BENZENE
C14LOROLIENZENE
1,2—DICHLOROBENZENE
X 1.2.4—TRICHLCROBENZENE
F I CU K I ? —2 Effect of 1n reased degree of ci lorluallon of benzene on
overall removal due to biodegralat Ion during act ivated sl((I e treatnw.it
>
0
Li
I
Li
>
0
0
0
q
0
0
0
0
0
0
0
0
0
0
7 14 21 28 35 42 49 56 63 70 7_I
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12.2.2 Multi—solute Studies
1. The fate of individual tcacic organic compounds was the sane
in bioreactors receiving up to seven toxic orgnnic compounds as
occurral in biore tors .eceiving only a single toxic organic
compound.
2. Recoveries of benzene, toluene, ethylbenzene, o—xylene and
chiorobeazene a raged bet .een 15 and 25 in t e same bi reactor
in which 1,2,4—trichlorobenzene r overy aver ed in excess of
90%.
12.2.3 Effect of Influent Concentration
1. Influent concentrations between 50 and 750 ugh hal no effect
on the fate of the two non—biodegradable compounds, lindane and
1,2 ,4—trichlor benzene.
2. Biodegradation of the three volatile compounds——beniene,
ethylbenzene, and chlorobenzene——occurred at influent
concentrations as low as 20 and 40 ugh. Overall reaovals
averaged bet en SO and 70%.
3. Perconiagesof influent benzene, atFrJbenzene, and h1orobenze-te
biodegraded .ere greater at inf luent conce trac ions beti.een 500
and 750 ugh than occurrad at influent concentrat:ons between 20
and 40 ug/l.
4. Sitxultaneous spike loadings of beezene, ethylbeuzene, and
chlorobenzene which prcxiuced infl ient concentrations bet een
6,000 and 10,000 ugh hal no effect on overall bioreactor
perfornance or the biodegradation of tolucue and o—zylene,
present at influent conccntrations betweeu 100 and 200 ugh.
Overall ret ovals of benzene, ethylbenzene, nd chiarobenzene
increased slightly during the spike loading periods to
approximately 90%.
5. Spike loadings of biodegradable compounds producing
approximate 10—fold increases in infiuent concentrations from 100
to 1000 ugh resulted in only small, t orary increases in
effluent and off—gas concentrations.
6. Effluent and off—gas concentrations of individual compounds
from bioreactors receiving influent concentrations bet en 100
a d 2000 ugh were not significantly different indicating an
ncreased au unt of biodegradation at the higher concentrat ions.
7. Inhibition of nitrobenzene degradation and Tf removal
occurred at an influent nicrooenzene concentration of
approximately 25 mg/i.
501
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12.2.4 Transient Loading Studies
1. An interruption in toxics addition for 2 to 3 days during
continuous toxics addition studies had no effect upon
biodegradation of benzene, toluene, ethylbenzene, o—xylene,
chlorobenzeae, and nitrobenzene.
2. 14—day interruption in the siriiltaneous addition of
beazene, toluene, ethylbenzene, o—xylene, and chlorobenzene to a
bioreactor influent resulted in reduced rcsnoval due to
biodegradation for 2 to 3 days after toxics addition was resumed.
After that time period steady—state vera1l removals resumed.
3. Addition of benzene, ethylbenzene, and chlorobenzene on a
cyclic basis of 2 days added to the influent followed by 3 days
om ttai from the i.nfluenc had the following effect on
biodegradation:
— Acclimation periods increased from 14 to nearly 42 to 46
days
— Removals of ethylbenzene and chlorobeozene were tess than
those observed during continuous toxics addition studies
— Steady—state removal of benzene approached the sane level
recorded during conti.iuou . ..oxics addition studies.
4. Increasing the time period t ics we.e on tted from the
influent from 3 to 6 days had no additional effect on
biodegradation of benzene, ethylhenzene, and chlorobenzene.
12.3 INTEGRATED ACTIVATED SLUDGI ./CARBON TREATMENT BIOREACTOR STUDIES
Int ratad activated sludge/caroon trea ent studies were
conducted in the lO—liter b oreactors • ith air—tight lids by adding
slurried powdered activated carbon (PAC) to the bioreator. The
effect of PAC—addit ion on overall removals of the toxic organic
compounds was evaluted by comparing results from bioreators receiving
PAC to control activated sludge units that did not receive PAC.
Influent , effluent, and off—gas concentrations were measured every
three to four days during the PAC bioreactor studies. Overall removal
in the PAC bioreactor studies was evaluated by comparing the nass flux
of a compound out of a bioreactor in the effluent and off—gas combined
to inuluent mass flux. Concentrations of compounds adsorbed to PAC in
the mixcd liquor were not measured; therefore, thece was no way to
analytically distinguish between amounts of ccn o n4 recioved by
adsorption and amounts removed by biodegradation. Overall removal in
tne PAC bioreactor studies refers to the disappearance of a compound
due to adsorption and a combination of adsorption and biodegradation
f r biodegradable compounds.
502
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Results from the int rat activatei sludge/carbon treathent
studies have been divided uAto the following sections for the purpose
of summariiing the effects of PAC—addition on the removal of the toxic
rganic Compounds:
1. Iafluent PAC Concentration : effect of influent PAC
concentration on the removal of the toxic organic compounds.
2. Solids Retention rime: solids retention timos were varied to
evaluate the effect of mLxed liquor PAC concentratiou on removal
of toxic organic compounds.
j i—so1ute: two to seven compounds were added
sinultaneously to influents of biore tors receiving 50 to 200
mgI l PAC.
4. Effect of PAC Interruption : effect of an interruption in
PAC—addit ion on overall removals of ron—biodegradable and
biodegradable compounds.
5. Effect of PAC I 2 : comparison of removals of lindane by
three different powdered activated carbons.
6. Effect of Influent Wast ,ater Compositjon : lindane removals
were evaluated in bioreactors receivio synthetic waste ter and
wastevater from the Ann Arbor vastewater trea nent facility.
7. Effect of Influent Concentration : effect on overall removals
of influent tc x1cs concentrations from 100 to over 1000 ugh.
8. Transient Load in s : effect of PAC addition on toxics
removals in a bioreictor under transient toxics loading conditions.
12.3.1 Influent PAC Dose
1. Table 12—3 gives a s rnmary of the effect of i.nfluent PAC
doses on the overall removal, defined as biodegradation + carbon
adsorption, of the nine toxic organic compounds during int rat€d
tteatnient in the IO—liter bioreactors with ai.r—t ght lids.
Results in Table 12—3 were collected during steady—state toxics
remova’ periods.
2. Based on overall removals in Table 12—3 the nine compounds
can be divided ruto the following twe groups based on the
effectiveness of PAC—addition to activated sludge for providing
enhanced toxics removal. These categories represent the effect
of PAC—addition on toxics removal during steady—sta .e toxics
removal periods and do not reflect the effect of PAC—addition
during either acclimation phases or bioreator upset peri .ds.
503
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TABLE 12-3
AVERAGE OVERAlL PLRCENT RINOVALS DUE TO BIODCGRADATION
AND PAC ADSORPTION MEASIIRII) DURING S1NCI E SOLuTE PAC h1OR ACTOR STUI)IES
WITH INF I.UENT IOXIC$ CONCENTRATIONS HETWEEN 100 ANi) 120 ugh
Influent Ilydrodarco C Concentration (mg/i)
Compound Control 12.5 25 50 100 200
NON—B 10 1)ECRADABLE
Lindane 0 68 84 92 NI)
I 2,4—TRieh1orobenz ne 0 NI) 69 77 94 94
0
POORLY BIODFCRADABLF .
1,2—Dlch lorobenzene 36 NI) 61 71 93 94
RI oI)Er;RADARLE
Bcnzcne 83 ND 79 86 86 86
To I ucn .’ 84 NI) NI) ND NI) 90
Etliy lbenzene 81 NI) 79 85 87 87
o—Xyene 78 NI) ND 82 ND ND
C li lorobcnzene 82 NI) 82 85 90 90
Nltrobcnzcnc 97 ND ND 97 99 ND
N Not Determined
-------
P C—Addjt ion Had
PAC—Addition Increased Little or No Effect
Toxjcs Removals on Toxics Remov 1s
Lindane Beozene
1,2 ,4—Tr ichlorobenzene Toluene
1 ,2—Dichlorobeozene Ethylbenrene
o-Xy lene
Ch lorobenzene
Nitrobenzene
3. In general, influent PAC doses between 12.5 and 100 aig/l
significantly increased rhe removals of both volatile and non—
volatile nori—biodegraiaole and poorly biodegradable compounds.
The addition of PAC to activated sludge effected riductwns in
both off—gas and effluent concentrations. Percent reductions in
effluent and off—gas concentrations .cre approximately the same.
4. The incremental improvement in tczcics removal decreased with
increasing PAC dose. There was no significant difference in
l,2,4—Trichlorobenzene recs)val in biore tors receiving 100 and
200 mg/i PAC.
5. Steady—state removals of non— and poorly—biodegradable
compounds was achieved within 24 hours after PAC addition was
begun.
6. Influent PAC doses from 25 to 200 mg/i had no sigt .ificant
effect on steady—state effluent and gas concentrations, and
therefore steady—state overall removals, of both the volatile and
non—vo latile biodegradable compounds.
7. The addition of 50 and 100 mgfl PAC did produce improved
overall removals of nicrobeozene, chlorobenzene, and ethylbenz.ene
during the initial 14 to 21 day- acclimation phases. Improved
overall removals re due to ruiuct ions in both effluent and off—
gas concentrations.
8. Steady—state removals of chiorobeazene and ethylbenzene in
bioreactors receiving a 100 mg/l PAC dose occurr.-d within 24
hours after PAC and the t ics were initially added to the
influent.
12.3.2 Solids Retention L . ( SaT )
1. The infl*4ent PAC concentration controlled the steady—state
overall removal of non— and poorly—biodegradable compounds and
the enhanced removal of sane biodegradable compounds during
acclimation phases.
505
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2. The accumulation of PAC in the mixed liquor had no effrct on
the over lI removal of any of the toxic organic compounds.
3. Solids retention tin s rar thg from 0.25 to 12 days had no
effect on the steady—state removal of 1,2—dichlorobenzene and
l,2,4—trichlorobenzene in biore tors receiving 50mg/i PAC.
Steady—state mixed liquor PAC concentratians ranged from
approximately 50 to 2000 mg/i in biore tors with 0.25 and 12- day
SRT’s, respectively.
4. Solids retention tines from 0.25 to 15 days hal no effect on
the steady—state re!roval of lindane in bioreactors receiving 25
mg/i PAC. Steady—state mixed 1 quor PAC concentrations ranged
from approximately 25 to 1500 tag/i in bioreactors with 0.25 and
15—ay SRT’s, respecti’ ely.
5. So1id’ relentioo tiat s frots 6 to 12 days had no efect on the
steady—sare removal of benzeoe and chlorobenzene in bioreactors
receiving 50 tn?/l PAC.
12.3.3 Multi—Solute Studies
1. Overall removals of individual toxic organic compounds wcre
the same in bioreactors receiving from three to seven to’tic
organic compounds as occtzred in biore tors receiving only a
single toxic organic compound. Influent toxic cOncentrat3Dfls
were in the 100 to 300 ugh range. Multi—solute studies were
conducted at influent PAC doses of 50 to 200 mg/I.
2. Spike loadings of selected biodegradable and non—
biodegradable compounds resulting in 5 to 10—fold increases in
influent concentrations from 100 to 1000 ugh hal no effect o
the removal of toxic organics added to influents of multi—solute
studies.
12.3.4 Effect of PAC Interruption
1. A 4—week interruption in the addition of 100 mg/I ?AC had the
folbwing effects on overall removal of volatile toxic organic
compounds:
— overall ren’val of the non—biodegradable compound 1,2,4—
trichlorobenzene decreased from 90Z to less than 1OZ in 4 to
5 days
— overall rem vals of biodegradable compounds benzene,
ethylbenzene, aud chlorobenzene here not significantly
affected indicating the activatad sludge was acclimated to
these compounds.
506
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2. The continuation of the 100 mg/i PAC dose after the 4—wed
interruption period had the follving effect on overall removals
of the toxic organic compounds:
— overall removal of 1 2,6—trichlorobenzene returned to the
90Z level within 24 hours
— overall removals of ben . ene, ethybenzene, avd
chlorobenzene were unchanged.
3. Removal of lindane in a bior’ tor rccei\’ing a 25 mg/i PAC
dose decreased frem 84% to less than 102. within 6 days after PAC
addit ton was stopped. After 3 days the effluent concentration
increased from 12 to >24 ‘,ic,I indic tinc the mi:
-------
between 1500 and 2000 ugh. Increased removal at the higher
influent concentrati.o’ resulted from increased biodegradatii,n
rates.
4. No significant variations .n steady—state effluent and off—
gas concentratioa of biodegradable compounds re observed for
influent concentrations ranging from approximately IOC ugh to
4000 ugh. The influent PAC dose was 50 mg/i.
12.3.8 Transient Toxics Loadings
1. Interruptions in the addition of poorly biodegradable and
non—biodegradable cocspound to PAC bioreactors had no effect on
effluent and off—gas concentrations, and hence overall removals,
of those compounds.
2. Two to sx day LnterxupLioos in the addition of biode radabie
compounds had no effect on aft iuen and off—gas concentrations,
and hence overall removals, of those compounds measured 24 hours
after the end of the mterniption perwd.
3. Additien of 100 mg/i PAC to a biore tor receiving transients
additions of enzene, ethylbenzene, and chlorobe’tzene c’n a cyclic
basis of 2 d . ys a Ided to the influent followed by 3 days omit tad
from the influent had the follo ’ing effects:
— overall remaval of the compoonds was the sane as observed
in single solute continuous .oxics addition studies with 100
mg/i PAC doses
— overall removal of benzene i s not significantly different
than occurred in a control activated sludge unit operated
under parallel conditions
— overall removal of ethylbenzen and chlorobenzene was
significantly greater in the bioreactor receiving 4 100 mg/i
PAC dose.
508
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