WATER POLLUTION CONTROL RESEARCH SERIES • 12020 EEQ 10/71
12020EEQ1071
Treatment of Wastewater
From The
Production of Polyhydric Organics
EP 1.16
12020EEQ10/71
U.S. ENVIRONMENTAL PROTECTION AGENCY
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes
the results and progress in the control and abatement
of pollution in our Nation's waters. They provide a
central source of information on the research, develop-
ment, and demonstration activities in the Environmental
Protection Agency, through inhouse research and grants
and contracts with Federal, State, and local agencies,
research institutions, and industrial organizations.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Chief, Publications
Branch, Research Information Division, Research and
Monitoring, Environmental Protection Agency, Washington,
D. C. 20460.
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TREATMENT OF WASTEWATER
FROM THE PRODUCTION OF POLYHYDRIC ORGANICS
The Dow Chemical Company
Texas Division
Freeport, Texas 775^1
for the
OFFICE OF RESEARCH AND MONITORING
ENVIRONMENTAL PROTECTION AGENCY
Project No. 12020-EEQ
October., 1971
For sale by the Superintendent of Documents, U S. Oovernment Printing Office, Washington, D.C. 20402 - Price $1.75
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EPA Review Notice
This report has been reviewed by the Environmental Protec-
tion Agency and approved for publication. Approval does
not signify that the contents necessarily reflect the views
and policies of the Environmental Protection Agency, nor
does mention of trade names or commercial products consti-
tute endorsement or recommendation for use.
11
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ABSTRACT
A number of extremely useful and widely produced compounds
are produced by the alkaline hydrolysis of chlorohydrins.
Ethylene and propylene glycols and glycerin are produced
in this manner.
The brine wastewater resulting from the production of the
glycols is characterized by a high salt content (8-10$ NaCl),
excess alkalinity, and the presence of several organic
compounds.
Several processes were examined in the laboratory to deter-
mine the usefulness for the treatment of the brine wastewater.
Solvent extraction of the glycol wastewater with secondary or
tertiary amines produces a raffinate that is salt-saturated
and low in glycol and a product enriched in the glycol and
nearly free of salt. The required large solvent-to-feed
ratio, the requirement for near-freezing temperatures, and
the high reflux to produce a pure product, make solvent ex-
traction, as a treatment method, uneconomical.
Adsorption of glycols on activated carbon was found to be
unfeasible because of the low capacity of carbon for the
glycols. Commercially available cellulose acetate membranes
with low salt rejection were found to exhibit a high pore flow
of propylene glycol and were therefore unable to significantly
separate the salt and the glycol.
Biological oxidation of propylene glycol wastewater in batch
and continuous laboratory units gave a total oxygen demand
(TOD) removal efficiency of 86 to 88$ at a residence time of
12 hours.
An activated sludge pilot plant with a feed rate of 0.5 gpm
was constructed and successfully operated as a completely
mixed aerator on an equalized propylene glycol wastewater.
Removal efficiencies of over 90$ at a retention time of 8.0
hours at loadings of 2.0 to 3-0 pounds total oxygen demand
(TOD) per pound of mixed liquor volatile suspended solids
(MLVSS) per day were obtained. The effluent quality was
improved by operation at recycle ratios of 24 to 40$.
The operational and design parameters determined from the
pilot plant operation were used to design an activated
sludge plant to treat 6 MGD of wastewater resulting from the
production of 1.2 million pounds per day of propylene glycol
at an estimated operating cost of 3-3 cents per pound of TOD
removed or less than 0.2 cent per pound of propylene glycol
produced. The total fixed captial requirement for a 6-MGD
plant was estimated to be 1.4 million dollars.
ii i
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TABLE OF CONTENTS
Section Page
I. Conclusions 1
II. Recommendations 5
III. Introduction 7
IV. Characterization of the Wastewaters 11
V. Renovation and Purification Processes 25
A. Solvent Extraction With Secondary
and Tertiary Amines 25
B. Carbon Adsorption 37
C. Membrane Separations 46
VI. Biological Treatment 49
A. Biodegradability of Glycols in Saline
Waters 49
B. Treatability Studies 50
C. Batch Kinetics 56
D. Bench Scale Continuous Units 66
VII. Activated Sludge Pilot Plant 71
A. Plant Description and Operation 71
B. Evaluation of the Roughing Column 7^
C. Results of Different Modes of Operation 80
D. Operational and Design Parameters S6
E. Polishing of the Biotreatment Plant
Effluent With Activated Carbon 111
VIII. Conceptual Design of a 6-MGD Activated Sludge
Waste Treatment Plant 115
A. Process Description and Plant Design 115
B. Cost Estimate and Economic Evaluation 125
IX. Acknowledgments
X. References 135
XI. Appendices 137
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LIST OF FIGURES
Number Page
III-l Production of Propylene Glycol by the
Chlorohydrin Process 8
IV-1 Biological Oxidation of Ethylene and
Propylene Glycols 20
IV-2 Biological Oxidation of Ethylene and
Propylene Oxides 21
IV-3 Biological Oxidation of Organic Components
of the Ethylene Glycol Waste (Acclimated Seed) 23
V-l Schematic Diagram of the Solvent Extraction
Process 27
V-2 Solubility Diagram - Di-isopropylamine
Water NaCl System 28
V-3 Phase Diagram of Extraction Results -
Stage Calculation for Sodium Chloride
(Solvent - Methyl Diethyl Amine) 35
V-4 Adsorption of Glycols on Witco Carbon
20 x 40 Mesh ' 38
V-5 Effect of pH on Uptake of Propylene Glycoi
by Witco Carbon 20-40 Mesh (Co = 2000 ppm) 39
V-6 Fixed Bed Adsorption of Propylene Glycol on
Witco Carbon "^
V-7 Fixed Bed Adsorption of Ethylene Glycol on
Activated Carbon 43
VI-1 Biotreatability Tests, Loading-Removal Curve
for Propylene Glycol Waste (NaCl 9-10-5$)
(Acclimated Mixed Culture) 52
VI-2 Biotreatability Tests, Effluent-Loading Curve
for Propylene Glycol Waste (Acclimated Mixed
Culture) 53
VI-3 Biotreatability Tests, Loading-Removal Curves -
Propylene and Ethylene Glycol Wastes
(Bacterium No. 52) 54
v
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List of Figures (Cont'd)
Number
VI -4
VI-5
VI-6
VI-7
VI-8
VI-9
VI-10
VI-11
VI-12
VI-13
VI-14
VII-1
VII-2
VII-3
VII-4
VII-5
Biotreatability Tests, Effluent-Loading
Curve for Propylene Glycol Waste
(Bacterium No. 52)
Batch Kinetics, Propylene Glycol - 10% NaCl ,
Acclimated Mixed Culture
Batch Kinetics, Propylene Glycol - 10$ NaCl,
Acclimated Mixed Culture
Batch Kinetics, Propylene Glycol Wastewater,
Acclimated Mixed Culture
Batch Kinetics, Ethylene Glycol Wastewater,
Acclimated Mixed Culture
Batch Kinetics, Propylene Glycol - ~LQ% NaCl,
Bacterium No. 52
Biological Reaction Rate of Propylene Glycol
Complete Mixing Kinetics in a Single Basin
Calculated Treatment Efficiency of Propylene
Glycol in a Continuous System
Bench Scale Continuous Bio-oxidation Unit
Loading-Removal Relationship, Bench Scale
Continuous Unit (Bacterium 52 - Propylene
Glycol - 8.5$ Salt)
Activated Sludge Miniplant - Flow Diagram
Aeration Tank
First Settling Tank and Composite Samplers
Flocculation Vessel With pH Control
Pilot Plant Operation - Mixed Propylene and
Pag
55
57
58
59
ol
62
64
65
67
68
70
72
74
75
76
Ethylene Glycols Wastewater (Plug Flow
Operation) 8l
VII-6 Activated Sludge Pilot Plant Operation -
Plug Flow - Mixed Ethylene Glycol and Propylene
Glycol Wastewater 83
VI
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List of Figures (Cont'd)
Number
VII-7
VII-8
VII-9
VII-10
VII-11
VII-12
VII-13
VII-14
Loading-Removal Curve, Plug Flow - Mixed
Ethylene and Propylene Glycol Wastewater
Effluent Loading Curve, Plug Flow - Mixed
Ethylene and Propylene Glycol Wastewater
Pilot Plant Operation - Propylene Glycol
Waste, Completely Mixed Reactor
Pilot Plant Operation - Equalized Propylene
Glycol Waste - Completely Mixed Reactor
Pilot Plant Operation - Equalized Propylene
Glycol Waste
Loading-Removal Curve - Equalized Propylene
Glycol Wastewater
Effect of Temperature on Uptake Rate
Effluent-Loading Curve, Propylene Glycol
Page
84
85
37
83
89
90
92
Equalized Feed - Completely Mixed Aerator 94
VII-15 TOD Removal Rate as Function of Load Ratio -
Propylene Glycol Equalized Feed - Completely
Mixed Reactor 95
VII-16 Continuous Laboratory Unit for Oxygen Uptake
Measurements 96
VII-l? Oxygen Uptake - Propylene Glycol Wastewater -
20°C 98
VII-18 Oxygen Utilization (Temperature 20° to 25°C) 99
VII-19 Effect of Aeration Rate on Oxygen Transfer 102
VII-20 Oxygen Mass Transfer (Non-Steady State Method)l03
VII-21 Gross Solids Formation 104
VII-22 Sludge Settling Paths - Co=900 ppm., SVI=70 106
VII-23 Sludge Settling Paths - Co=1100 ppm., SVI=53 107
VII-24 Sludge Settling Paths - Co=1700 ppm., SVI=42 108
VI 1.
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List of Figures (Cont'd)
Number
VIII-1 Activated Sludge Plant - 6 MGD, Flow
Diagram
VIII-2 Activated Sludge Plant - 6 MGD, Plant
Layout
VIII-3 Activated Sludge Plant - 6 MGD,
Pretreatment and Aeration
VIII-4 Activated Sludge Plant - 6 MGD, Details
of Aeration Basin
VIII-5 Activated Sludge Plant -, 6 MGD, Sludge
Handling
XI-1 Precision Control Chart - TOD Analysis
XI-2 Precision Control Chart - Glycol VPC
Analysis
Page
117
1 1 £
126
12?
VI11
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LIST OF TABLES
Number Page
1-1 Activated Sludge Treatment of Glycol Waste
Brines - Operational and Design Parameters 4
IV-1 Ethylene System Wastewater (Composite Analyses) 12
IV-2 Propylene System Wastewater (Composite
Analyses) 13
IV-;5 Organics in Ethylene System Wastewater 15
IV-4 Organics in Propylene System Wastewater 16
rv-5 Biological and Chemical Oxygen Demand of
Wastewater From Propylene System 18
IV-6 Correlation of Chemical and Biological Oxygen
Demand - Propylene Glycol Wastewater 19
IV-7 Trace Elements in Typical Glycol Wastes 24
V-l Equilibrium of Diisopropyl Amine-Saturated
NaCl Solution - Glycol 29
V-2 Equilibrium of Methyl Diethyl Amine-Saturated
NaCl Solution - Ethylene Glycol 32
V-3 Equilibrium of Methyl Diethyl Amine - 10$ NaCl
Solution - Ethylene Glycol 34
V-4 Fixed Bed Adsorption of Propylene Glycol on
Witco Carbon 4l
V-5 Fixed Bed Adsorption of Propylene Glycol on
Activated Carbon 45
V-6 Evaluation of Cellulose Membranes for the
Separation of Propylene Glycol and Salt 47
VI-1 Batch Kinetics of Bio-oxidation of Ethylene
and Propylene Wastewaters 63
VII-1 Operation of the Roughing Column With Forced
Draft Air 79
VII-2 Carbon and Oxygen Balance of the Activated
Sludge Process 110
IX
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List of Tables (Cont'd)
Number Page
VII-3 Summary - Glycol Waste Treatment, Activated
Sludge Design Parameters 112
VIII-1 Design Feed, 6 MGD Activated Sludge Waste-
water Treatment Plant 116
VIII-2 Major Equipment - 6 MGD Activated Sludge
Wastewater Treatment Plant 119
VIII-3 Major Instrumentation - 6 MGD Activated
Sludge Wastewater Treatment Plant 121
VIII-4 6 MGD Activated Sludge Waste Treatment Plant -
Estimate of Direct Capital Cost 129
VIII-5 6 MGD Activated Sludge Waste Treatment Plant -
Computation of Fixed Capital 131
VIII-6 6 MGD Activated Sludge Waste Treatment Plant -
Estimate of Operating Cost 132
XI-1 Determination of Suspended Solids - Comparison
of Methods
XI-2 Pilot Plant Operation, Mixed PG and EG Waste-
waters - Plug Flow Reactor 146
XI-3 Pilot Plant Operation, Propylene Glycol Waste -
Completely Mixed Reactor 150
XI-4 Pilot Plant Operation, Equalized Propylene
Glycol Waste - Completely Mixed Reactor 154
XI-5 Pilot Plant Operation, Equalized Propylene
Glycol Waste - Completely Mixed Reactor 157
XI-6 Biochemical Test Reactions for Gram Negative
Rod Bacteria From the Activated Sludge 162
XI-7 Biochemical Test Reactions for Gram Positive
Bacteria From the Activated Sludge 164
x
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SECTION I
CONCLUSIONS
The following conclusions are based on the study of several
alternate processes for the treatment of the saline waste-
water resulting from the production of polyhydric organic
compounds by the chlorohydrin process and on the successful
operation of a biological oxidation pilot plant.
The conclusions are:
1. The wastewater resulting from the production of ethylene
or propylene glycol is characterized by a high salt content
(8 to 10$ NaCl), a pH of 11.0 to 12.0, and the presence of
relatively high concentration of the glycol, (500-1000 ppm.).
Other organics present in concentrations less than 100 ppm. are
the oxide, the dichloride, the chlorohydrin and a chlorinated
ether. A propylene glycol wastewater may also contain
appreciable concentrations of acetol and acetic acid, both of
which are oxidation products of propylene glycol.
2. Instrumental methods that determine total organic carbon
(TOC) and the total oxygen demand (TOD) were found to be con-
siderably more effective than biological oxygen demand (BOD),
and chemical oxygen demand (COD) in the correlation of the
laboratory and pilot plant data. The total oxygen demand
determination and the chromotographic analysis of the organic
components in solution were adopted during this study as the
principal measures of the organic content of the raw and
processed wastewaters.
3. Solvent extraction of the glycol wastewater with secondary
or tertiary amines produces a salt saturated raffinate, low in
glycol, and a product enriched in the glycol and nearly free
of salt. The necessity for high reflux to produce a pure
product and the cost of solvent recovery from both the
raffinate and product, added to the required large solvent
inventory, and the low temperature operation (0°C.) make
solvent extraction uneconomical for the treatment of waste-
water from glycol production.
4. Carbon adsorption is not feasible because of the low
capacity of the activated carbons for the glycols that is
further reduced by the competitive adsorption of the chlori-
nated organics present in the wastewater. Regeneration of
the activated carbon with methanol in fixed bed operation
produces a glycol solution free of salt, but the washing of
the methanol is inefficient resulting in appreciable solvent
losses.
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5. Commercially available cellulose acetate membranes with
low salt rejection exhibit a high pore flow of propylene
glycol and thus produce no significant separation of the salt
and the glycol.
6. All the organic components of glycol wastewater are bio-
degradable by well acclimated cultures, except the chlorinated
ethers. These seem to be poisonous at high concentrations
(over 100 ppm.) or in a batch system, but can be tolerated in
continuous flow reactors.
7. A rather long acclimation period (6-8 weeks) is required
to develop a mixed culture activated sludge that tolerates
the high salt and utilizes the glycols as the only carbon
source.
8. Biological oxidation of propylene glycol wastewater in
batch fill and draw aerators has a reaction rate of 0.48
hour"1 based on the removal of the total oxygen demand (TOD).
Calculated treatment efficiency in a continuous system is 86$
for a residence time of 12 hours.
9. Continuous laboratory biotreatment units removed 88$ of
the incoming TOD from propylene glycol waste at a residence
time of 12 hours. The effluent from the laboratory units
was turbid and contained about 300 ppm. TOD, almost entirely
metabolites and cell fragments. These could be reduced to
100-150 ppm. by chemical flocculation.
10. Tertiary treatment of the effluent from the activated
sludge process, with activated carbon, produces a salt
solution containing less than 10 mg./l. of organic carbon,
which can be recycled as feed to the chlorine cells. The
economics of carbon adsorption is not attractive due to the
low capacity of the carbon and the cost of thermal regeneration,
11. The operation of a 0.5 gpm. activated sludge pilot plant
(aeration volume ^.250 gallons) as a plug flow reactor on a
mixed ethylene and propylene glycol wastewaters produced an
average removal efficiency of 84$ at a residence time of 12
to 14 hours. An effluent quality below 200 ppm. TOD can be
obtained at loadings of up to 2.0 Ibs. TOD/lb. MLVSS-day.
12. The completely mixed mode of operation of the pilot plant
with equalized feed is advantageous. Removal efficiencies of
over '90$ were obtained at retention time of 8.0 to 9-0 hours,
and at loadings of 2.0 to 3-0 Ibs. TOD/lb. MLVSS-day. The
effluent quality is improved by operating at a recycle ratio
of 25-40$, and the chemical flocculant requirements for
clarification is reduced.
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13- The operational and design parameters of the activated
sludge process for the treatment of equalized glycol brine
waste are shown in Table 1-1.
14. An activated sludge plant designed for the treatment of
6 MGD of propylene glycol wastewater, resulting from the
production of about 1.2 million pounds per day of the glycol,
would include the following sequential steps:
a. A cooling and equalization pond.
b. Neutralization to pH below 9.0 with 38^ HC1.
c. Addition of nutrients as phosphoric acid and
ammonia and the addition of dilution water to
replace the evaporation losses in the pond.
d. An aeration basin with the required surface
aerators.
e. A clarifier and sludge recycle to the aeration
basin.
f. A thickener and centrifuges to concentrate the
excess sludge to lQ-20fo solids before transport
to landfill.
The total fixed capital required is estimated at 1.4 million
dollars. The total operating cost is 775*000 $/year, in-
cluding the $4^0,000 cost of the acid required for the
neutralization.
The cost per pound TOD removed is 3-23 cents, and is less
than 0.2 cents per pound of propylene glycol produced.
15. As a result of this investigation, an activated sludge
plant is being built by The Dow Chemical Company at Freeport,
Texas, to treat up to 300 gallons per minute of propylene
glycol wastewater. The plant utilizes one 50 H.P. surface
aerator in the aeration basin, comprising a single, full-
scale element of a larger plant.
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TABLE 1-1
ACTIVATED SLUDGE TREATMENT OF GLYCOL WASTE BRINES
OPERATIONAL AND DESIGN PARAMETERS
Removal efficiency:
Optimum temperature:
Allowable temperature range:
Nutrient requirements:
TOD:N:P = "500:10:1
hemoval rate:
TODj - TODR
t x TODp
MLVSS
Oxygen utilization: Lbs. O.C./day = 0.256 (Lbs. TOD removed
/day)' t- 0.13 (Ibs. MLVSS)
Oxygen transfer:
a = 1.2
Sludge production: Lbs. VSS formed/day =-- 0.133 (Ibs.
TOD removed/day) - O.C21 (Ibs. MLVSS)
The symbols used are defined in Table VII-3-
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SECTION II
RECOMMENDATIONS
Based upon the operating and engineering experience gained
during this investigation, the following recommendations for
improving the technology of wastewater treatment in the petro-
chemical industries are made:
1. Particular emphasis should be given to the chemical and
biological characterization of the waste streams. This in-
cludes the detection of the specific organic components in
the wastewater and their biological oxidation rates.
2. Instrumental methods that determine total organic carbon
(TOG) and total oxygen demand (TOD) should be substituted for
the BOD5 and COD tests, for the reliable interpretation of
behavior and fate of the organics in the wastewaters and for
the evaluation of treatment processes.
3- Batch biological treatability tests should be limited to
a period of acclimation that may extend to several months and
could be used to determine the approximate process kinetics.
However, continuous pilot systems should be used to determine
the design parameters of a treatment facility.
4. An equalization basin to dampen the fluctuations of the
organics in the wastewater resulting from petrochemical
operations is a necessity and should be provided. The basin
can also act as a cooling pond if the waste stream is released
at a temperature too high for proper operation of the biological
treatment unit.
5. There is a critical need for the development of control
systems so that an activated sludge process can be operated
as efficiently as chemical processes. The performance of an
activated sludge process is greatly improved and its reli-
ability increased under steady state conditions. This can
only be achieved by instrumentation to control the food to
bacteria ratio in the aeration basin, the nitrogen and phos-
phorous requirement and the treatment temperature. A
biological toxin detector to detect and eliminate a toxic
substance before it can enter the aeration basin is greatly
needed.
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SECTION III
INTRODUCTION
A number of extremely useful and wide.!/ produce :
are manufactured by the alKaline hydrolysis of er: j - M-
Both ethylene and propylene glycol: as well as •/'•>'• -.-
produced in this manner.
A flow sheet of the chlorohydrin proceoS for the nr.'
of polyhydric compounds, exemplified by TO rop fieri.' / I
shown in Figure TII-1. The caustic hydrolysis of U
hydrin to the oxide takes place in the aqueous pb:js>-
molecule of sodium chloride Is produced ro>" u'icr •-•K;1
oxide formed:
(propylene chlorohydrin)
The hydrolyzer is a separation column in which the :>verhea i
product is the oxide and the bottoms contain the urrcac'-<-:i
chlorohydrin, any excess caustic, the produced so.Hum
chloride, and several organic, materials at low eo^cen 1.1 aj : :>i
The largest in concentration is the glycol which r<. ~'j_ut:- :'>-•
the overlap in the rates of the several reaction.".
A typical propylene glycol plant produces about "•".•-. gal • cns
of wastewater for each pound of propylene glycoi.
amount of the wastewater and its high salinity ma:
particularly difficult waste to handle by cor.ver: i':,••'' 1
techniques.
The overall objective of this program, un-ier t'•" • ^rani, ;V
the Environmental Protection Agency, was tc S]/s:,.----at '•.<:;, ;
characterize the physical, chemical, and biological ,"at; r-
the brine waste resulting from the production of polvhyir:
organic compounds and to develop a method of tre-i t>v- ,-•/ .
specifically, the objective was to examine Severn: -,>t'. >v"
treatment methods and tc determine the technical , er •':•.
and economic feasibility of each. The processor if :,-. •
were:
1. Biological Treatment - The objective was to d--Y-'-:!.or a
biological oxidation process that would require -'. mLinim. .••.
of dilution of the brine waste or that exhibited a maxi-i;'
tolerance of salinity at hi gh purification rates. Th.'"
microbial metabolism of ethylene and uropylene glyc-i-S '.r.
the presence of soli urn chloride \vas the sub fr-ct of a sub.C;'
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by the Texas A. and M. Research Foundation. Organisms were
to be sought in areas exposed to glycol and glycerin wastes,
from hyper-saline soils, from known cultures, and from other
saline sources including seawater and naturally saline lakes
and enclosed bays.
2. Solvent Extraction With Secondary and Tertiary Amines -
The solvent extraction process as developed for the recla-
mation of saline water, if applicable to the glycol waste-
water, could enable recovery of the glycol in a relatively
pure water product. The raffinate would be a saturated
salt solution low in organics that could be used as feed
to chlorine cells for the production of the caustic required
in the hydrolysis. This would then represent a completely
closed cycle with no waste to be discharged.
3. Adsorption and Recovery of the Glycol - The adsorptive
capacity of activated charcoal for ethylene and propylene
glycols was known to be low, but investigations of several
regeneration methods that would result in the recovery of
the glycol as a product were part of this program. The use
of activated carbon as a pretreatment for an activated
sludge process, or as a tertiary treatment to polish the
biologically treated waste were also to be investigated.
4. Membrane Separation - Many potential chemical and
physical processes for the removal and recovery of glycols
from the hydrolyzer effluent are inoperable because of the
presence of the large amounts of salt. Membranes that would
allow selective separation of the salt and the glycol would
allow these other processes to be employed. The screening
of potential membranes highly permeable to NaCl but rejecting
propylene glycol was done by the Gulf South Research Institute
in New Orleans, Louisiana, as a part of a separate R. and D.
grant (Project No. 12020DQC) awarded to the State of Louisiana
Department of Commerce and Industry by the Environmental
Protection Agency.
The final objective was to develop sufficient pilot plant
information, based on the most economically attractive of
the processes examined, for the conceptual design of a waste
treatment facility. Hopefully, the process developed and
engineered would then be applicable to other organically
contaminated waste brines.
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SECTION IV
CHARACTERIZATION OF THE WASTEWATERS
The characterization of a wastewater stream from an Industrial
process includes determination of the physical, chemical, and
biological properties of the effluent in sufficient detail to
allow the engineering of treatment processes. A survey of the
wastewater from several of the hydrolyzer trains, operating
on ethylene and propylene feed stock, was made to determine
the properties. This survey was conducted so that the effects
of the operating conditions on the quality of the waste sr.ream
were reflected. A description of the analytical methods used
in this study and of the quality control techniques applied,
are given in Appendix A.
Sampling and Analyses
Composite samples were collected from several of the operating
plants over 24-hour periods during the week and 72-hour periods
during the weekend. The sampling period extended from July I
to September 12, 1969.
The measured analyses of the wastewater from those plants
producing ethylene glycol are given in Table IV-1, and from
those plants producing propylene glycol in Table IV-2. The
results are tabulated to show the number of samples from each
plant and the range and average values for each parameter.
The variation of the organic matter concentration in the
effluents is rather wide, while the pH, % NaCl, and total
dissolved solids (TDS) vary very little since they are easier
to control in the process. The pH of the wastewater is 11.2
to 11.5* while the excess alkalinity, as sodium hydroxide.
varies from 0.05$ to 0.45$.
The principal organic materials in the ethylene system waste-
water are glycol (averaging over 1000 ppm.) and dichloroethyl
ether (averaging 29 ppm.). Ethylene oxide, dichloride, and
chlorohydrin are not detected in most of the samples, and,
when found, are in very low concentration.
In all the samples collected in the propylene system, the
wastewater was found to contain the glycol, the oxide, and
the epichlorohydrin. The high concentrations of organics in
the wastewater from Plant (X), which is an experimental
train, are reflected by the changes being made in the plant
operation to study methods for reducing total organic losses.
The ranges of concentrations found in the wastewater from
Plant (Y) reflect normal operating conditions at full pro-
duction capacity.
11
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TABLE IV-1
ETHYLENE SYSTEM WASTEWATER
(COMPOSITE ANALYSES)
No. of
Samples Minimum Maximum Average
% NaC
TDS,
Sp.Gr
COD,
TOD,
E.G. j
E . 0 . ,
EDC,
ECH,
DCEE ,
{B; -
(A) -
E.G.
E.O.
EDC
1
%
. /30 ° C
ppm.
ppm.
ppm.
ppm.
ppm.
ppm.
ppm.
• First
• Second
(B)
(A)
(B)
(A)
(B)
(A)
(B)
(A)
(B)
(A)
(B)
(A)
ethylene
ethylene
37
14
28
9
37
9
37
13
24
13
37
14
12
7
23
47
system.
system.
- Ethylene Glycol
- Ethylene Oxide
- Ethylene Bichloride
9-2
12.3
9.36
12.87
1.062
1.084
1120
1160
1310
1110
680
720
30
(nil in 39
5
(nil in 44
5
(nil in 28
10
11.46
13-40
11.87
13-81
1.077
1.089
2240
3200
2480
3000
1470
2300
100
samples )
50
samples )
30
samples )
90
10.72
12.90
11.12
13.30
1.072
1.087
1630
1850
1730
1920
1003
1306
60
16
15
29
ECH - Ethylene Chlorohydrin
DCEE - Dichloroethyl Ether
12
-------
TABLE IV-2
PROPYLENE SYSTEM WASTEWATER
(COMPOSITE ANALYSES)
No. of
Samples Minimum
Maximum Average
% NaCl
TDS, %
Sp.Gr./X>°C
COD, pprn.
TOD , pprn .
PG , pprn .
PO, ppm.
EPCH, pprn.
PJH, ppm.
PDC )
DCIPE)
(X)
(Y;
(X)
(YJ
(X)
(Y)
(X)
(Y)
(X)
(Y)
(X)
(Y)
(X)
(Y)
(X)
(Y)
41 8.5 10 .,7
14 9.8 10.6
28 9.51 10.82
9 10.20 11.04
no 1.064? 1.069
9 1.0682 l.ov?
?7 H7-6 8160
14 1550 ;528o
27 1910 71-0
14 1590 3J'50
14 756 1620
30 1.0 3 'X;
14 10 '70
^7 38 MQO
^ 1 ,-^ - -' - '
14 o 3c
16 13 /'O
(nil in 36 samples)
(nil in all samples)
(X) - First propylene system.
(Y; - Second propylene system.
10.65
PG - Propylene Glycol
PO - Propylene Oxide
EPCH - Epichlorohydrin
PCH - Propylene Chlorohydrin
(two isomers)
PDC - Propylene Dichloride
DCIPE - Dichloroisopropyl Ether
-------
The analyses of the organic components in the wastewaters
did not always account for the high values of COD and TOD.
The gas chromatographic results were checked against a
periodate oxidation method able to detect the oxide, the
glycol and the chlorohydrin.
For the ethylene system (Table IV-3), the periodate and gas
chromatographic results checked very well for the analysis
of the glycol. The periodate method yielded higher values
for the oxide and the chlorohydrin. As an example, the
theoretical oxygen demand of the organic compounds detected
in the first sample was calculated as follows:
Analysis, ppm.
Periodate
1033
20
28
5
lan
.6
.2
d,
X
X
X
X
1
1
1
1
.288
.23
.093
.819
ppm.
- 1330
= 25
- 31
= 9
1395
Gas Chromatographic
1100
20
10
5.2
x 1
x 1
X 1
X 1
.288
.23
.093
.819
- 1420
= 25
11
= 9
1465
EG
DCEE
ECH
EO
Theoretical 0-
Both the COD and TOD of this sample were 1600 ppm., thus the
organics detected account for 91-5$ of the COD of the sample.
In the case of the propylene system (Table IV-4), the periodate
method always yielded higher values for the glycol concen-
tration than those determined by gas chromatography. A
sample from the propylene wastewater had a theoretical oxygen
demand of 2744 ppm. based on the periodate analysis, which
accounts for 93-2^ of the TOD of 2950 ppm.
Some of the wastewater samples from the propylene system
contained other organics that were not detected by the
developed VPC method. These other materials were separated
on a modified column after acidifying the sample and were
identified as acetol and acetic acid. The amount of these
components varied with the age of the sample and are believed
to be oxidation products of the major organic components of
the wastewater.
Biological Oxidation of Organics in the Wastewater
A standard 5-day biological oxygen demand (BOD5) test was
run on several of the composite samples collected during the
period extending from July to September, 1969. The seed
used in the BOD bottles was a raw sewage sludge acclimated
for a period of at least three days to the diluted waste
stream.
14
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The results obtained for the wastewater from the propylene
system are given in Table IV-5. The BOD5 varied from 22%
to 43.6$ of the COD of the samples analyzed. The BOD5
represents a fraction (0-5 to 0.8) of the calculated theo-
retical oxygen demand of the propylene glycol present in
the sample. If it is assumed that the other organic com-
ponents of the wastewater samples are not biodegradable,
then the BOD5 of the propylene glycol is 0-5 to 0.8 of its
COD value. Several more samples of the propylene glycol
wastewater were analyzed for BOD5 during the operation of an
activated sludge pilot plant. The correlation of the chemical
and biological oxygen demands is shown in Table IV-6 to be:
BOD5 = 0.36 (TOD) + 5
The BOD5 tests on several ethylene wastewater samples gave
no response indicating that either a biological retardant
or a poison is present in the wastes from the ethylene system.
The biological oxidation curve over a 10-day period was then
determined with solutions of the organic components known to
be present in the ethylene and propylene glycol wastes.
Solutions containing about 100 parts per million of each
compound were prepared and diluted 15 times in the BOD
bottles, and 1 milliliter of an acclimated 0 days) sewage
sludge seed was added to each bottle.
The results obtained with both ethylene glycol and propylene
glycol are plotted in Figure IV-1. The 10-day BOD value
represents 63.4$ removal of ethylene glycol and 64.4$ re-
moval of propylene glycol.
The oxidation rates of ethylene oxide and propylene oxide
are plotted in Figure VI-2. The 10-day BOD value represents
a 30.8$ oxidation of the ethylene oxide and only 12.4$
oxidation of the propylene oxide. These values may be low
due to the loss of the oxide by evaporation during the
start of the test since the oxides have a low boiling point
and are very volatile.
Ethylene dichloride, ethylene chlorohydrin, and the dichloro-
ethyl ether gave negative BOD values as compared to the blank
while the propylene dichloride, the epichlorohydrin, and the
propylene chlorohydrin (l-chloro-2-propanol) yielded small
positive BOD values over a 10-day period representing an
oxidation of 3-5$ to 7-5$ of the theoretical oxygen demand.
A seed that has been acclimated to the ethylene glycol waste
over a period of two months was used in the BOD bottles to
determine the biological oxidation of the organic components
in an ethylene glycol waste. Starting with the same concen-
tration of each of the components, the ethylene glycol
17
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-------
TABLE IV-6
CORRELATION OF CHEMICAL AND BIOLOGICAL OXYGEN DEMAND
PROPYLENE GLYCOL WASTEWATER
TOD or COD BOD5
ppm ppm
1580 560
2320 680
4000 1450
1256 658
1360 503
2020 1000
2300 814
1170 377
1470 475
1370 317
BOD5 = 0.36 (TOD) + 5
(correlation coefficient, r = 0.91;
<99-95$ significant)
19
-------
Figure IV-T
BIOLOGICAL OXIDATION OF ETHYLENE AND
PROPYLENE GLYCOLS
no
100
90
80
70
^ 60
•
o
S 50
40
30
20
10
0
OEthyiene Glycol
• Propylene Glycol
I
3
5
Time, days
INITIAL. CONCENTRATION
10
100 ppm
20
-------
Figure IV-2
BIOLOGICAL OXIDATION OF ETHYLENE AND
PROPYLENE OXIDES
o
o
m
100
90
80
70
60
50
40
30
20
10
0
OEthylene Oxide
• Propylene Oxide
INITIAL CONCENTRATION - 100 ppm
-------
consumed practically all of the oxygen during the first day
of the test. The results are plotted in Figure IV-3 over a
period of 10 days. It Ls evident that ethylene chlorohydrin
is biodegradable while the ethylene dichloride can be
tolerated by the well acclimated culture and is partially
oxidized. The dichloroethyl ether seems to be a poison.
Trace Elements in Waste Streams
Composite samples of the propylene and ethylene glycol
wastewaters were analyzed for the trace elements that are
important for the metabolism of bacteria and that may be
toxic if present in high concentrations. An average analysis
of these elements using emission spectroscopy is given in
Table IV-7- It is concluded that the glycol waste streams
do not contain any toxic quantities of trace metal ions and
that the only required ingredients for bacterial growth in
the waste media are the N and P nutrients.
22
-------
Figure IV-3
BIOLOGICAL OXIDATION OF ORGANIC COMPONENTS
OF THE ETHYLENE GLYCOL WASTE (Acclimated Seed)
100 r-
O
O
CD
I I I I I
INITIAL CONCENTRATION OF EACH COMPONENT - 100 ppm
-------
TABLE IV-7
TMCE ELEMENTS IN TYPICAL GLYGOL WASTES
Concentration
Element ppm
Magnesium (Mg) 7.0
Calcium (Ca) 16.0
Iron (Fe) 1.0
Copper (Cu) 0.4
Zinc (Zn) <2.0
Manganese (Mn) <0.1
Molybdenum (Mo) <0.1
-------
SECTION V
RENOVATION AND PURIFICATION PROCESSES
The high salt content of the wastewaters from the production
of polyhydric compounds makes it difficult to treat these
waters by conventional methods. It has been believed that
the wastewater must be diluted by a ratio of 1 to 6 to reduce
the chloride concentration to below 10,000 ppm. in order for
biological treatment to be possible. It has been previously
recommended (Ford,, 1971) , that physical or chemical methods
of treatment should be considered when the ratio of
biological to chemical oxygen demand of the waste is in the
range of 0.1 to 0.4. This ratio (BOD5/COD) was found to be
about 0.4 for the propylene glycol wastewater.
Several physical and chemical processes have been evaluated
for the treatment of saline organic containing wastes.
Chemical oxidation by the use of chlorine has been found to
be technically unfeasible. Direct oxidation with ozone Is
able to affect a 90$ reduction of COD In the waste, but at
a prohibitively high cost. Extraction with conventional
solvents has failed tj allow separation of the glycol from
the salt at the levels present in the waste streams and acti-
vated charcoal was found to have a very low capacity for glycol
adsorption. Any wastewater renovation method that results
in the separation of the sodium chloride from the main
organic component, glycol, and at the same time yields a
recoverable product is likely to be more attractive economically
than those processes that eliminate or destroy the organic
content.
Solvent extraction, adsorption and membrane separations were
chosen as processes to be further studied for the treatment
of the glycol wastewater and for possible further recovery of
a usable product.
A. Solvent Extraction With Secondary and Tertiary Amines
Trie solvent extraction process as developed for the reclamation
of saline water (Davison, 1960) and for the treatment of
secondary sewage effluents (Zeitoun, 1964), operates on the
principle that certain solvents which contain strong elec-
tronegative atoms within the molecule are partially miscible
with water to an extent dependent on both the temperature
and the salt content of the water. Secondary and tertiary
amines of 5 and 6 total carbon atoms have been found to have,
by far, the best solvent properties, (Davison, 1960).
-------
Figure V-l schematically shows the three major steps: ex-
traction, separation, and solvent recovery. The solvent
containing 8$ water, as shown in Figure V-2, enters the
bottom of the column and dissolves water as it rises counter-
currently to the descending water phase. As the solvent
leaves, it approaches equilibrium with the feed stream. The
extract from the top of the column is heated to cause phase
separation, and the solvent and water are decanted. The
solvent is cooled and recycled, and the water goes to solvent
recovery where the small amount of dissolved amine is re-
covered completely by steam stripping.
In Figure V-2, the solubility curve of diisopropylamine (DIPA)
is shown. In this curve, the weight percent of water in the
solvent is plotted against temperature for different salt
concentrations. If one chooses an extraction temperature of
32 °C, the solvent will dissolve approximately ~5Q% water from
the 1% salt solution. Heating the DIPA to 55°C will cause
all but 8fo of the water to phase out. After separation of
the phases, recycling of the solvent makes the process con-
tinuous .
Solvent extraction, if applied to the wastewater from glycol
production, could extractively separate both the glycol and
water from the salt. The wastewater would then be concen-
trated to salt saturation and the glycol recovered in the
low salt product water.
An engineering assessment could not be made because data were
not available at these high salt concentration levels and
the selectivity for glycol was not known. A laboratory in-
vestigation was undertaken to obtain the necessary equilibrium
data to allow stage calculations.
Diisopropyl Amlne-Saturated NaCl Solution-Glycol System
Diisopropyl amine was equilibrated with a nearly saturated
salt solution containing a known concentration of ethylene
or propylene glycol. The solvent-salt mixture was well
mixed in a water bath at a regulated temperature for at
least four hours. The phases were separated, weighed, and
analyzed for amine content, salt content, and glycol con-
centration. The salt and glycol concentrations in the
feed, raffinate and product water are given in Table V-l
for propylene glycol and ethylene glycol at different tem-
peratures .
The low temperatures used in these tests were necessary to
enable the DIPA to pick up enough water at the high salt
concentration. In every run except No. 6, salt precipita-
tion was noticed, indicating that the aqueous phase became
saturated.
26
-------
Figur* V-l
SCHEMATIC DIAGRAM OF THE SOLVENT EXTRACTION PROCESS
Waste
Water
Extract
—>
Solvent
Raffinate
Concentrated Waste
Heating
Cooling
Separator
Solvent
Recovery
• Product Water
-------
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28
-------
TABLE V-l
EQUILIBRIUM OF
DIISOPROPYL AMINE-SATURATED Nad SOLUTION-GLYCOL
Peed Raffinate Product( K
Run No. 1, (0°G)
$ NaCl 22.9
Propylene Glycol, ppm 1640
1.1
nil
8500
7
Run No. 2, (-5°C)
°/o NaCl 23.1 26.0
Propylene Glycol, ppm 1770 550
9.64
5300
0.3
Run No. 3, (0°G)
% NaCl
Propylene Glycol, ppm
1700
26.6
260
5.78
8600
Run No. 4, (-5°G)
% NaCl
Propylene Glycol, ppm
1700
27.1
170
6000
0.4
35
Run No. 5,
1o NaCl
Ethylene Glycol, ppm
Run No. 6 , (-5°C)
% NaCl
Ethylene Glycol, ppm
Run No. 7 , (10°C)
°/0 NaCl
Ethylene Glycol, ppm
21.0 2^.7
2400 500
22.9 2^.4
2400 550
22.9 24.9
2400 1010
7.1
«300
10 . ^
7100
7.2
21,300
0
16
0
12
0
21
.29
.6
• 39
.9
• 29
29
-------
Table V-l (Continued)
Feed Raffinate Product (a) K
Run No. B, (0°C)
°/o NaCl 22.9 27.1 S.2 0.30
Ethylene Glycol, ppm 2400 620 12,300 20
(a)
Product obtained by distilling the amine from the extract.
(b) K; equilibrium constant for NaCl and the glycol is the
ratio of concentration in the product to that in the
raffinate calculated on solvent-free basis.
-------
These results show that a high selectivity for the glycol
in the solvent phase exists at the salt saturation stage
of the extraction with no adverse effect on the salt
selectivity. The raffinate, a saturated salt solution,
would contain a very low concentration of glycol and thus
may be directly usable as feed to chlorine cells. The
product water separated from the extract by heating would
have higher glycol concentrations and low salt concentra-
tions and could be recycled to the glycol production plant,
thus enabling recovery of the glycol from the waste stream.
Methyl Diethyl Amine-Saturated NaCl Solution - Ethylene
Glycol System
Methyl Diethyl Amine (MDEA) is a tertiary amine with equivalent
water - NaCl mixtures higher on the temperature scale than
diisopropyl amine (DIPA). Therefore, MDEA can be used at
higher temperatures to dissolve the same amount of water
from a saturated NaCl solution than DIPA.
A sample of MDEA was obtained, purified and distilled, then
used for the extraction of ethylene glycol from salt
solutions. The MDEA was equilibrated with a nearly saturated
salt solution containing a known concentration of ethylene
glycol at 10° or 1^°C. The raffinate was separated, then the
extract was heated to 55-6o°C to separate a product. The re-
maining solvent phase was then distilled to recover the rest
of the glycol.
Table V-2 shows the results of three runs at 10° and 15°C.
The material balance on the ethylene glycol shows about 25$
of the glycol remaining in the raffinate. The glycol con-
centration in the product is two to three times the concen-
tration in the raffinate, while the recycle solvent contained
a high concentration of glycol calculated on solvent free
basis.
This indicates that a lower equilibrium ratio for glycol in
the product and raffinate exists than that obtained for
diisopropyl amine, because the product in the previous ex-
periments with DIPA was separated by distillation. The
glycol will thus tend to accumulate in the solvent phase
after a product separation which would require distillation
of part of the flow of the solvent recycle.
Methyl Diethyl Amine - 10$ NaCl Solution - Ethylene Glycol
System
Another important equilibrium stage is that at the top of a
column where the feed would be a 10$ NaCl solution. The
solvent phase would have a high concentration of glycol and
a lower salt concentration.
-------
TABLE V-2
EQUILIBRIUM OF
METHYL DIETHYL AMINE-SATURATED NaCl SOLUTION-ETHYLENE GLYCOL
Feed Raffinate Product(a) Solvent(b)
Run No. 1, 10 °C
Wt . , grams
% NaCl
Ethylene Glycol, ppm
Run No . 2 , 10 ° C
Wt. , grams
% NaCl
22.36
22. 9
2150
22.007
24.7
17.195
28.6
650
16.86
29-4
3.166
6.2
1300
1.368
6.9
2.005
-
14, 800
3.27
-
Cthylene Glycol, ppm 2190
1000
3100
8000
Run No. 3, 15°C
Wt., grams 22.667 17.98
% NaCl 22.9 27-2
Ethylene Glycol, ppm 2150 590
4.496
2.7
1300
0.191
169,000
(a)
(b)
Product separated from extract by heating to 55-6o°C.
Water separated from solvent by distillation.
Note: All concentrations are calculated on solvent-free basis
-------
A large volume of 10$ NaCl solution containing a high con-
centration of ethylene glycol (-4400 ppm.) was equilibrated
with a samll volume of methyl diethyl amine (MDEA) at
temperatures of 22° to 25°C. The results are given in
Table V-3- The glycol concentration in the product remains
higher than that in the raffinate, with some accumulation in
the solvent phase. This indicates that in an extraction
column the equilibrium with the feed at the top of the
column results in a product with very low salt concentration
and a relatively higher glycol concentration, and that the
glycol will not tend to recycle in the extraction process
since it keeps favoring the solvent phase at the top stage.
Solvent Extraction Design
Stagewise calculations were made for the extraction of
ethylene glycol from the waste stream using methyl diethyl
amine as the solvent. The extraction calculations were
initially made considering salt as the solute to obtain flow
rates and number of stages. Then, using equilibrium values
for ethylene glycol, tray-by-tray calculations were made.
Assuming operating conditions corresponding to the obtained
experimental data, (i.e., 25°C at the feed end and 10°C at
the raffinate end and concentrating the brine to saturation),
five theoretical stages were calculated to be required. A
solvent-to-feed ratio of 5.?^ was required and a saturated
raffinate and a product water containing 2.5$ NaCl and
2489 ppm. glycol were produced.
The resulting brine contained 860 ppm. glycol, using recycled
solvent resulting from the phase separation at 6o°G. Under
these conditions the solvent contains appreciable glycol.
With a lower glycol content in the solvent, a lower raffinate
glycol content would be obtained.
Figure V-3 shows the stage calculation for sodium chloride
using a coordinate system in which the X axis is:
Salt
salt + water
and the Y axis is:
solvent
salt + water
Because of the small amount of solvent in the water phase,
the water phase lies almost on the X axis. The solvent curve
was averaged from the data. K values versus the Y axis were
obtained from the data. Similar data were plotted for ethylene
glycol. It is realized that for ethylene glycol, this plot is
not exact, since K is a function of temperature, but since the
operating temperatures are assumed to correspond to the data,
this should not matter.
-------
TABLE V-3
EQUILIBRIUM OF
METHYL DIETHYL AMINE-10^ NaCl SOLUTION-ETHYLENE GLYCOL
Feed Raffinate Product(a'Solvent(b)
Run No. 1, 25°C
Wt. , grams
% NaCl
Ethylene Glycol, ppm
Run No. 2, 25°C
Wt. , grams
% NaCl
Ethylene Glycol, ppm
Run No. 5, 22 °C
Wt. , grams
-------
(J8JBM * »|eS)/!U8A|OS
-------
Five stages were obtained for sodium chloride. This gives
an extract nearly in equilibrium with the feed. From the
flow rates obtained in this way, a trial and error stagewise
calculation was made on ethylene glycol until the system was
in close material balance. The overall material balance is:
Flow Glycol,
Stream (Solvent-Free) Salt ppm.
Feed 1 10$ 2000
Extract 1.16 2400
Product .7 2.5$ 2489
Solvent .46 2265
Raffinate -3 28$ 839
On a total flow basis, based on an extract containing 18$
warmer and a solvent 8$ water:
Product _ v
~ • f
Feed
Solvent
Product
Solvent
Feed
= 8.2
= 5-74
The solvent flow rate could be greatly reduced by operating
at a higher extract water content (lower temperature). It
is uncertain how this would affect equilibrium. The only
comparison is the 10°C and 15°C data at 27 to 29$ salt and
the 25° and 22°C data at 10$ salt. In each case, the K's
are of the same order of magnitude. The effect of lowering
temperature more than offsets the water effect, confirmed by
low K's at separation, so much lower solvent rates could be
obtained only by dropping the temperature. The effect on
salt content in the product of lowering the temperature will
be adverse, and it appears likely that some extract reflux
will be necessary.
Solvent extraction seems to be technically feasible but would
be uneconomic due principally to the high solvent-to-feed
ratio required to produce a Nad-saturated raffinate.
Operation at low temperatures, close to 0°C, represents an
appreciable increase in the difficulty and cost of the ex-
traction process. The necessity of high reflux to produce
a pure product and the cost of solvent recovery from both
the raffinate and product, added to the required large solvent
36
-------
inyentory, and the low temperature operation make solvent
extraction uneconomical for the treatment of wastewater
from glycol production.
B. Carbon Adsorption
Preliminary laboratory tests of glycol adsorption on acti-
vated carbons resulted in the selection of Witco carbon
(20-40 mesh) as the best adsorbent available. Although the
adsorptive capacity of carbon for ethylene or propylene glycol
appeared to be too small for economical operation, further
studies of the kinetics of glycol adsorption in batch and
column operation were conducted with the hope that a simple
regeneration procedure could be found that would result in
the recovery of a product, thus improving the economics of
the process.
Ethylene and propylene glycol solutions of two different con-
centration levels were prepared with and without 10$ salt.
A volume of 200 milliliters of each solution was dispensed
into 250-ml. glass stoppered bottles. About 5 grams of
carbon were weighed accurately and added to each bottle. The
bottles were then tightly stoppered and placed in an
oscillating shaker for three days. Samples of all solutions
were collected at intervals of from 1 to 72 hours and
analyzed for glycol by gas chromatography. Batch carbon
adsorption tests were also conducted with both ethylene and
propylene glycol solutions in 10$ NaCl, at pH' s ranging from
2 to 12.
In Figure V-4 is plotted the ratio of glycol concentration
remaining in solution to the original concentration (C-t/Co)
as a function of time. The initial rate of adsorption of
propylene glycol is higher than that for ethylene glycol,
and equilibrium seems to be reached in a shorter time.
The equilibrium capacity of carbon for propylene glycol from
a 10$ NaCl solution is 263 mg/gram of carbon while that for
ethylene glycol is 118 mg/gram of carbon. The presence of
10$ NaCl in the glycol caused a slight increase in the
adsorptive capacity.
In Figure V-5, the ratio of propylene glycol concentration
remaining in solution to the original concentration, Ct/Co,
is plotted as a function of time at different pH's. The up-
take of both glycols increases with increasing pH's. An
increase in pH quite probably results in an increase of the
negative charges at the surface of the carbon, thus enhancing
the adsorption of the positively charged glycols which are
known to be hydrogen bonded with the water molecules.
-------
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Figure V-5
EFFECT OF pH ON UPTAKE OF PROPYLENE GLYCOL
BY WITCO .CARBON 20-40 MESH. (Co = 2000 ppm)
o
^
o
Time, hours
-------
Fixed-Bed Column Adsorption of Glycols
The column adsorption of ethylene and propylene glycols from
10$ NaCl solutions of pH 11.0 on 20 x 40 mesh Witco carbon
was also studied. Methanol was used to regenerate the ex-
hausted carbon and the glycol was recovered by distilling the
methanol.
Propylene Glycol
A 7/8 inch i.d. column was packed with 18 inches (73 grams)
of carbon. The propylene glycol solution was then passed
through the column under constant pressure at a flow rate
of 1.26 gal./min./ft.2.
Samples of the effluent were collected periodically and
analyzed. After saturation of the carbon with glycol, as
determined by the breakthrough curves, the carbon was
regenerated with two bed volumes of methanol at a flow rate
of 0.57 gal./min./ft.2. The carbon was then washed with
several bed volumes of distilled water and another adsorption
run repeated.
The results of eight adsorption regeneration cycles are
given in Table V-4. Figure V-6 is a plot of the break-
through of propylene glycol for the first and second ad-
sorptions .
The capacity of carbon for propylene glycol was 66 milli-
grams of propylene glycol per gram of carbon for the first
cycle, reduced by about 13$ for the second run, then re-
maining constant at about 53 milligrams of propylene glycol
per gram of carbon for the 8 runs reported in Table V-4.
The exhaustion point remained the same—around 18 bed
volumes—while a change in the position of the break point
was observed. This may be due to incomplete regeneration.
At room temperature, at least two bed volumes of methanol
were required to recover the adsorbed glycol. At tempera-
tures of 40° to 50°C, only one bed volume of methanol was
sufficient to recover over 90$ of the glycol.
Ethylene Glycol
The adsorption breakthrough curve for ethylene glycol from a
column similar to that described for propylene glycol is
given in Figure V-7 (I)•
Because of the slow adsorption of ethylene glycol, another
column was built with a carbon depth of 7^ inches and an
inside diameter of 1/2 inch. The ethylene glycol solution
was passed through the column at a rate of 0.97 gal./min./ft.2
40
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FIXED BED ADSORPTION OF PROPYLENE GLYCOL ON WITCO CARBON
l.Or-
o
o
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0.5
• 1st adsorption
O 2nd adsorption
100
Time, minutes
Column: 7/8" i.d. depth = 18" Wt. carbon = 73 grams
Flow Rate: 1.26 gal/ltVmin.
200
-------
Figure V-7
•
FIXED BED ADSORPTION OF ETHYLENE GLYCOL
ON ACTIVATED CARBON
1.0
o
o
o
0.5
I
100
200
Time, minutes
I- Column: 7/8" i.d. 18" deep, Wt carbon = 73 grams, flow rate = 1.26 gal/ltVmin
IT- Column: 1/2" i.d. 74" deep, Wt carbon = 97 grams, flow rate = 0.97 gal/1tz/min
-------
The breakthrough curve obtained with this column is shown
in Figure V-7
The total capacity of the carbon for ethylene glycol was cal-
culated to be 14 . 9 mg/gram carbon, much smaller than the
capacity obtained for propylene glycol. The capacity of
activated carbon for ethylene glycol remained about the
same through seven cycles --an average of 15 milligrams of
ethylene glycol per gram of carbon, (Table V-5) . The re-
generation of the carbon with methanol required about one
bed volume at ambient temperature, and over 90$ of the
adsorbed glycol was recovered.
Competitive Adsorption of the Chlorinated Hydrocarbons
A solution of 1200 parts per million ethylene glycol and 30
parts per million ethylene chlorohydrin (ECH) was passed
through the 74 -inch carbon column. The glycol breakthrough
occurred after 3 bed volumes. No ECH was detected in the
column effluent after 170 bed volumes. The ECH concentration
was increased to 60 ppm. , and after 26o bed volumes, it still
had not broken through the column.
A solution of 1200 ppm. propylene glycol and 100 ppm. epi-
chlorohydrin (EPCH) was passed through the 18-inch carbon
column at a rate of 1.26 gallons per minute per square foot.
The propylene glycol broke through at about 7 bed volumes
while EPCH was retained through 273 bed volumes. At this
point the flow rate was increased to 4 . 1 gallons per minute
per square foot, and the EPCH broke through after 23 bed
volumes .
The capacity of activated carbon for ECH and EPCH is very
high compared to the glycols. Similar tests with dichloro-
ethylether and dichlorodiisopropylether showed a very high
capacity of the carbon for the ethers over the glycols.
The high adsorptive capacities found may be useful in removing
the low concentrations of chlorinated hydrocarbons, that may
be toxic, as a pretreatment before the activated sludge
process .
Glycol Wastewater Treatment by Carbon Adsorption
Actual propylene glycol wastewater was fed to the 18-inch
carbon column, packed with virgin Witco activated carbon.
On the first pass 6.3 liters of propylene glycol waste was
passes through the column before saturation with propylene
glycol was obtained and 34.4 milligrams of propylene glycol
was adsorbed per gram of carbon. The column was heated to
60 °C and regenerated with hot methanol. Only 82^ of the
44
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propylene glycol was recovered. On the second run 6.5 liters
of propylene glycol were passed "before the column was
saturated and 27.5 mg of propylene glycol was adsorbed per
gram of carbon. On regeneration of the bed, 89$ of the
adsorbed propylene glycol was recovered.
From 5 "to 7 bed volumes of water were required to remove the
regeneration methanol from the bed. The capacity of carbon
for propylene glycol from the wastewater feed is about half
of its capacity when a synthetic propylene glycol solution
is fed under the same operating conditions. This lower
capacity is partly due to the lower propylene glycol concen-
tration in the wastewater, and partly because of the com-
petitive adsorption of the chlorinated organics in the waste
stream.
Carbon adsorption is not considered to be economically
feasible because of the low adsorptive capacity under the
actual conditions and because of the inefficient regeneration
and of the loss of solvent, if one is required.
C. Membrane Separations
During the period of the present grant, the State of Louisiana
Department of Commerce and Industry, also had an R. and D.
grant (Porject No. 12020 DQ,C) for the investigation of
Polymeric Materials for Treatment and Recovery of Petro-
chemical Wastes". Their results have been published by EPA,
Report 12020 DQC-03/71. The objective of the reverse
osmosis work conducted by their research contractor, Gulf
South Research Institute, was to screen membranes that have
a small reflection coefficient for NaCl, and to evaluate
them for the rejection of the glycols and other organic
components in the glycol waste stream.
Commerically available membranes having a small rejection
coefficient for NaCl were evaluated with a synthetic solution
containing:
NaCl, % 9-3-10.4
Propylene glycol, ppm. 500 - 2000
Propylene chlorohydrin, ppm. 20 - 70
Propylene oxide, ppm. 100 - 500
Samples from the tests conducted by GSRI were forwarded to
us and analyzed for glycol content in our laboratories in
Freeport, Texas. A summary of the results obtained from the
screening tests on a flat plate cell are given in Table V-6.
Most of these membranes were of Eastman cellulose acetate
with low salt rejection.
46
-------
TABLE V-6
EVALUATION OF CELLULOSE MEMBRANES FOR THE
SEPARATION OF PROPYLENE GLYCOL AND SALT
Membrane
Number
B112
B112
G16
G17
G19
G20
G21
G22
G2J
G24
G25
Operating
Pressure
p. s . i .
600
600
800
800
800
800
800
800
800
800
800
Flux
GFD
7.
V
1 •
54.
35-
29-
91.
21.
23.
10.
35-
12.
5
5
5
1
c,
I
1
5
C;
^
0
4
Rejection, %
Nad
9-
9.
5.
15-
20.
13.
21.
20
35-
17.
55-
5
7
5
4
7
6
0
6
8
i
Organic s
5-
11.
0
0
20
6.
0
-i.
13.
12.
41
5
3
-7
1
2
5
Note: Data from Gulf South Research Institute EPA Report
12020DQC 03/71.
47
-------
The results of this limited screening tests indicate the
lack of rejection of the low molecular weight organic com-
ponents. This may be due to the fact that when a membrane
is selected to give a low enough NaCl rejection to reduce the
osmotic effect to an acceptable level, pore flow becomes a
dominant mode of transfer, therefore, very little separation
of solutes is observed. Tt was concluded that membranes
with low salt rejection exhibit a high pore flow of propylene
glycol and thus offer no significant separation of the salt
and the glycol.
-------
SECTION VI
BIOLOGICAL TREATMENT
Since the glycol wastewater contains a large amount of salt,
any organism that would be useful in biological treatment
must be able to metabolize glycol in the presence of the
high salinity. Dr. W. A. Taber of Texas A. and M. University
isolated organisms from natural saline environments and from
the waste carrying ditches and canals in the Dow plants, and
screened them for their capacity to utilize glycols in the
presence of high concentrations of salt. The results of this
investigation are reported separately in Appendix E. The
acclimation of mixed cultures to the glycol wastewater in
both batch and continuous reactors was accomplished in the
Dow laboratories at Freeport.
A. Biodegradability of Glycols in Saline Waters
The biodegradability of glycols, using an acclimated acti-
vated sludge seed, has been reported in the literature to
vary from 35 to 85$ (Mills, 1954 and Hatfield, 1957). A
96$ oxidation of ethylene glycol and 39% oxidation of glycerol
was obtained using a pure culture of Alcaligenes Faecalis
(Marian, 1963)• An activated sludge seed, under treatment
plant conditions, was reported to oxidize 75$ of the glycol
present and 28$ of the glycerol (Placak, 1947).
Activated sludges in a conventional biological system has
been found to be much more tolerant to high salinities than
an anaerobic digestion system. Operation of an activated
sludge was found to be possible with salinities up to the
equivalent of 2.% NaCl (Ludzack, 1965). It has been found
previously, however, that significant microbial population
variety and activity changes occur at high salinities. The
presence of sustained high chlorides generally depresses
respiration, but periodic operation at low chlorides was
found to improve the tolerance of activated sludge to high
chlorides.
No information was found in the literature on the utilization
of halophilic bacteria for the biological oxidation of
organic contaminants in brine wastes, although numerous
bacterial species living in very high salt concentrations
have been investigated.
"Halobacterium", isolated from the Dead Sea, has an optimum
NaCl concentration between 17-5 to 20.5$ with a generation
time of 4 hours. "H. salinarium", obtained from Norway, has
an optimum NaCl concentration of 20 to 23$. A unicellular
49
-------
halophilic algae, "Dunaliella parva", was found to grow
optimally in 6 to 9% NaCl with a generation time of one day.
The requirement for NaCl does not appear to be entirely an
osmotic phenomenon, since the bacteria were unable to
tolerate the presence of sucrose instead of sodium chloride.
B. Treatability Studies
The biological treatability of wastewaters from ethylene and
propylene glycol production plants was determined by the fill
and draw procedure (Symons, 1960). A unit containing ten
compartments, 2 inches wide by 5 inches deep by 18 inches
high, was constructed of Plexiglas. The drawdown nozzles
were at the 500 ml. level, and a mark was located at the
1500 ml. level. Each compartment was equipped with an
aeration frit located near the bottom. The supply of oil
free air, at reduced pressure, was manually adjusted to
deliver about 0.55 liter of air per minute to each compart-
ment.
Two cultures were acclimated to the glycol-sodium chloride
solutions and the actual wastewater from the ethylene and
propylene systems. In each set of test solutions, one com-
partment was not inoculated with bacteria and was used as a
control.
Mixed Culture Acclimation
The starting culture was a mixture of sewage sludge and slimes
obtained from the ditches and holding ponds exposed to the
wastewaters from glycol production plants. The acclimation
of this culture to glycol-sodium chloride solutions and
diluted wastewater was begun at a salt concentration of
about 3$ which was raised gradually over a period of 6 weeks
to the concentration of the full strength waste, about 10$
salt. The feeding solution contained glycol as the main
carbon source. Nutrients were added in the form of ammonium
sulfate (0.25 gm/1.), and potassium hydrogen phosphate (0.25-
0.375 gm/1.).
The wastewater-bacteria mixture was aerated for 23 hours, then
the suspended solids were settled for 1 hour, and the
supernatant drained to the 500 ml. level. Each compartment
was then fed with 1,050 ml. of the prepared solution or
diluted waste, with nutrients added and the pH controlled
at 7-0. Aeration was then resumed and a sample collected
within 5 minutes after pH adjustment. At the end of 23 hours
of aeration, another sample was collected before the air was
cut off. All samples were analyzed for pH, % NaCl, glycol
and other organics, total oxygen demand, and volatile sus-
pended solids.
50
-------
During the acclimation period, the salt content was increased
gradually up to the full strength waste, but the glycol con-
centration was kept the same as that in the waste. The daily
composition of the treated waste and the rate of bacterial
growth in each of the compartments dictated the rate at which
changes in conditions were made.
The results obtained in the acclimations when full strength
propylene glycol waste was fed are presented in Figures VI-1
and VI-2. A mixed liquor volatile suspended solids (MLVSS)
of over 1000 ppm. could be maintained and settled quickly
leaving a fairly clear supernatant. The loading-removal
curve for propylene glycol waste (Figure VI-1) shows that
biodegradation was accomplished with an efficiency of 91
by the well-acclimated mixed culture. A treated effluent of
less than 200 ppm. TOD was produced at a loading of 1.0 to
2.0 pounds of TOD per pound of MLVSS per day (Figure VI-2).
Bacterium No. 32
This culture was isolated from mud-water samples from the
Great Salt Lake, during the screening of microbes for
tolerance to high salt content and glycol metabolism.
Since this culture had already been acclimated to the full
strength waste streams, no gradual acclimation to the salt
was necessary. Bacterium No. 52 exhibited a dispersed phase
growth with no appreciable settling when aeration was stopped,
therefore, the fill and draw procedure used with the accli-
mated mixed culture had to be modified. Sufficient feeding
solution was added to the testing compartments to replace
the samples removed, but was enriched with glycol to replace
the substrate oxidized. Near the end of these tests, it
was found that reduction of the nutrient concentrations to
less than half resulted in some improved settling of
Bacterium No. 52. The supernatant was always very turbid.
The results obtained with ethylene and propylene glycol
wastes are presented in Figures VI-3 and VI-4. A mixed liquor
volatile suspended solids (MLVSS) of 1500 ppm. to 2500 ppm.
could be maintained, but the filtered treated effluent had a
high TOD concentration even when it contained no unreacted
glycol.
Bacterium No. 52 showed a lower efficiency of TOD removal
(88$) from propylene glycol waste and even lower (70$) from
ethylene glycol waste (Figure VI-3) than the mixed culture.
At a loading of 1.0 to 1-5 pounds TOD per pound MLVSS per
day, the treated effluent contained over 300 ppm. TOD
(Figure VI-4).
-------
Figure VI-1
BIOTREATABILITY TESTS
LOADING - REMOVAL CURVE FOR PROPYLENE GLYCOL
WASTE (NaCI 9-10.5%)
(Acclimated Mixed Culture]
4.0
Slope =0.912
3.0
Q
C5
2.0
O
o>
cc.
1.0
I
I
1.0 2.0 3.0
Loading - IDS T.O.D./lb MLVSS.Day
4.0
-------
Figur* VI-2
BIOTREATABILITY TESTS
EFFLUENT LOADING CURVE FOR PROPYLENE GLYCOI
WASTE (Nad 9-10.5%)
^Acclimated Mixed CultureJ
300
200
o
o
s 100
O
O
E = 40L +70
I
I
1.0 2.0 3.0
Loading - Ibs T.O.D./lb MLVSS.Oay (L)
4.0
-------
Figur. VI-3
BIOTREATABILITY TESTS
LOADING - REMOVAL CURVES
O Propylene Glycol Waste (NaCI 10-12%)
• Ethylene Glycol Waste (NaCI 11-13.5%)
Q Bacterium No. 52J
2.50
2.00
«9
O
1.50
- i.oo
"to
>
O
§
0.50
Slope = 0.705
I
0.50 1.00 1.50
Loading- Ibs T.O.D./lb MLVSS.Day
2.00
lope 0,
2.50
-------
Fi«w« VI-4
BIOTREATABILITY TESTS
EFFLUENT LOADING CURVE FOR PROPYLENE GLYCOL WASTE
(NaCI 10-12%)
[^Bacterium No. 52]]
a
o
K
g
600
500
400
300
200
100
E = 70 L + 238
I
I
I
0.50 1.00 1.50
Loading - Ibs T.O.D./lb MLVSS.Day (L)
2.00
2.50
-------
C. Batch Kinetics
The rates of bio-oxidation of ethylene and propylene glycols
in synthetic sodium chloride solutions and in actual glycol
wastewaters was followed by measuring the decrease in glycol
and TOD concentrations with time in the fill-and draw com-
partments used for the biotreatability tests.
The TOD removal from a propylene glycol-10% NaCl solution
at a loading of 0-94 pounds TOD per pound MLVSS is shown in
Figure VI-5- The method of calculating the rate of removal
is illustrated in this figure, where r is defined by:
r =
where
r = rate of removal, 1/hr.
Lj_ = initial TOD concentration, ppm.
Le - TOD concentration at equilibrium, ppm.
te = time to reach equilibrium, hr.
The equilibrium is established between the oxidation and
synthesis reactions in which TOD is removed and the endogenous
reactions where the end products of cell lysis return to the
substrate. This model of TOD transfer rate in a batch bio-
logical oxidation system is adopted from Bhatla et. al.
(1966) .
In Figure VI-6 is shown a plot of the concentration of propylene
glycol and an unknown metabolite as a function of time. The
unknown metabolite that peaks around 5 to 6 hours after the
propylene glycol feed is added , elutes from the VPC column
at the same spot as epichlorohydrin.
The batch kinetics of a propylene glycol waste containing
epichlorohydrin is given in Figure VI -7- The sum of the
intermediate metabolite of the propylene glycol plus the
epichlorohydrin is plotted in the lower curve. This
metabolite has been identified by mass spectroscopy and gas
chromatography as acetol. Traces of acetic acid were also
detected in some of the intermediate samples. Acetol appears
to be the first oxidation product of propylene glycol:
CH3CH-CH2 - ~ - > CH3-C-CH2OH
OH OH 0
Propylene glycol Acetol
-------
1200
Figure VI-5
BATCH KINETICS
PROPYLENE GLYCOL-10% Nad
ACCLIMATED MIXED CULTURE
Loading = 0.94 Ibs TOD per Ib MLVSS
'" "cOMShr1
10 12 14
Reaction Time, Hours
16
18
20
22
24
-------
Figure VI-6
BATCH KINETICS
PROPYLENE GLYCOL-10% Nad
ACCLIMATED MIXED CULTURE
1000
Loading = 3.13 Ibs TOD per Ib MLVSS
10 12 14 16
Reaction Time, Hours
18
20
22
-------
Figur. VI-7
BATCH KINETICS
PROPYLENE GLYCOL WASTEWATER, ACCLIMATED MIXED CULTURE
1200
Loading = 1.32 Ibs TOD per Ib MLVSS
Epichlorohydrin + Metabolite
10 12 14
Reaction Time, hours
-------
The bio-oxidation rate of an ethylene glycol wastewater is
shown in Figure VT-8, at a loading of 0.37 Pounds TOD per
pound MLVSS per day. The reaction rate of ethylene glycol
is much slower than that found for propylene glycol.
The biological oxidation of a propylene glycol-10$ NaCl
solution with Bacterium No. 52 is presented in Figure VI-9-
These results show a fast rate of propylene glycol removal,
but the remaining TOD is high, a characteristic of the well
dispersed Bacterium No. 52.
Effect of Dilution on Reaction Rates
Several runs were made using the acclimated mixed culture
and Bacterium No. 52, at various dilutions of propylene glycol
waste with river water, to observe the effect of lower
sodium chloride concentrations on TOD removal rates. These
dilutions were:
River Water (6-6.5$ NaCl)
River Water (7-7-5$ NaCl)
River Water (8-8.5$ NaCl)
The rates of TOD removal at various loadings and dilutions
are given in Table VI-1 for both the acclimated mixed culture
and Bacterium No. 52. Dilution of the propylene glycol waste-
water to a salt content of 6 to 8$ appears to increase the
rate of TOD removal appreciably, for either of the two
bacterial cultures used.
Calculation of Removal Efficiency in a Continuous Treatment
From Batch Kinetic Data
The model used to calculate a rate constant at the equilibrium
point is based on the assumption that the substrate equilibrium
curve follows a first order relationship:
Wastewater -
75$ Wastewater - 2
7o Wastewater -
The rate constant, r = 0.48 hr."1, for the propylene glycol
system was used to calculate the degree of completion of the
reaction, D = 1 - (1-r)*, as shown in Figure VI-10.
To translate the batch reaction data to a continuous system,
mixing kinetics in a continuous system must be utilized. A
curve for complete mixing kinetics in a single basin is shown
in Figure VI-11.
60
-------
Figure VI-8
BATCH KINETICS
ETHYLENE GLYCOL WASTEWATER;ACCLIMATED MIXED CULTURE
Loading: 0.37 Ibs TOD per Ib MLVSS
16 18 20 22
26
Reaction Time, hours
-------
1700
Figure VI-9
BATCH KINETICS
PROPYLENE GLYCOL- 10% NaCI, BACTERIUM No. 52
Loading = 0.33 Ib TOD per Ib MLVSS
8 10 12 14
Reaction Time, hours
16 18 20 22
24
b2
-------
TABLE VI-1
BATCH KINETICS OF BIO-OXIDATION OF ETHYLENE
AND PROPYLENE WASTEWATERS
Wastewater
Ethylene Glycol
Ethylene Glycol
NaCl Sludge
Loading Rate of TOD
Lbs. TOD/ Removal
Lb. MLVSS
10 Mixed Culture 1.21
10 Mixed Culture 0.37
Propylene Glycol 10 Mixed Culture 1.32
Propylene Glycol 10 Mixed Culture 0.94
Propylene Glycol 10 Bacterium 52
Propylene Glycol
0.33
1.3 Mixed Culture 0.30
Propylene Glycol 6.1 Mixed Culture 0.43
Propylene Glycol 8.1 Bacterium 52 0.34
Propylene Glycol 7-5 Bacterium 52 0.34
T, hr.
0.058
0.138
0.130
0.48
0.44
1.06
0.8o
0.72
0.76
-------
Figure VI-10
BIOLOGICAL REACTION RATE OF
PROPYLENE GLYCOL
1.0
0>
ea
§
I
a.
o
S
D = 1 - (1 - r
r=0.48hr1,
I
4 5 6
Treatment Time, Hours
10
-------
00
UJ
o
o
o>
00
CD
IO
O
A 'Ja3uo| jo }
MOIJ jo UOIJDEJJ
65
-------
The performance of a continuous system at a residence time
of 6 and 12 hours is determined by integrating the values of
degree of completion of reaction and the mixing theory data.
This is accomplished graphically as shown in Figure VI-12,
where the area under the curve, as a fraction of the total
area, is a prediction of the efficiency of a. continuous system
which has the specified retention time.
The results for propylene glycol wastewater treatment, shown
in Figure VI-12 predict a removal efficiency of 86^ of the
TOD at a residence time of 12 hours in a completely mixed
single basin. The design of the bench scale continuous
units and the pilot plant was based on this information as
a starting operating condition.
D. Bench Scale Continuous Units
Two bench scale units were built to determine the removal
efficiency of a continuous system. The unit, shown in
Figure VI-13, was based on a design adopted from Busch (1963).
Operation was difficult and continuous sampling proved to be
impractical. The bench scale continuous units were not
operated long enough to obtain equilibrium values or to allow
measurement of any design parameters.
The units were operated on a neutralized propylene glycol
waste diluted with river water to a 6f0 NaCl concentration.
One unit was seeded with the acclimated mixed culture and
the other with Bacterium No. 52. Sampling was done by
collecting one liter samples, homogenizing, and returning
the unused portion of the sample. The total volume of the
substrate, in each unit, was 5.5 liters. The dilution water
was gradually reduced until the feed was at full strength.
The residence time (to) in the continuous unit can be cal-
culated by the following equation:
t _ V ._ Cp - Ct
U/-\ — ^~
where
Q, ,-dC)
dt'ctMt
V = aeration volume
Q = rate of flow
C0 = initial TOD
Ct = effluent TOD
-------
Figur. VI-12
CALCULATED TREATMENT EFFICIENCY OF PROPYLENE GLYCOL
IN A CONTINUOUS SYSTEM
o
"w
I
'J3
2
u.
0.4 -
0.2 -
0.2
(A)
(B)
Residence Time
t, (hours)
6
12
0.4
0.6
0.8
I-Y
Fraction of Effluent Held Time t or less
Treatment
Efficiency
%
75
86
1.0
-------
Figure VI-13
BENCH SCALE CONTINUOUS BIO-OXIDATION UNIT
2-5 ml./min.
To Aspirator
Feed
Reservoir
Mixed Liquo
Sample
68
-------
(—)
dt C-^Mt - overall reaction rate
Mt = active mass at time t (MLVSS)
The loading-removal data is plotted in Figure VI-14. At a
residence time of 12 hours, a TOD removal of 88$ and a
filtered effluent quality of 150 ppm. TOD was obtained. The
results also indicate, in general, that the loading should
be kept below 1.0 pound TOD per pound MLVSS per day, in order
to produce an effluent quality of less than 200 ppm. TOD.
The TOD concentration in the turbid effluent from the con-
tinuous units averaged about 300 ppm., although it contained
no residual organics present in the feed. Preliminary tests
indicated that the TOD concentration could be reduced to
100-150 ppm. by chemical flocculation. A chemical flocculation
step was, therefore, included in the design of the pilot plant.
69
-------
Figur. VI-14
LOADING-REMOVAL RELATIONSHIP, BENCH SCALE CONTINUOUS UNIT
(Bacterium 52-Propylene glycol-8.5% salt)
o
I—
o
MLVSS = 3000
Loading-lbs T.O.D./lb MLVSS.Day
70
-------
SECTION VII
ACTIVATED SLUDGE PILOT PLANT
The preliminary batch tests and the limited tests on "bench
scale continuous units indicated that glycol waste brines
containing up to 10$ salt could be successfully biodegraded.
The efficiency of TOD removal varied between 85 to 92$ and a
product of less than 200 ppm. TOD was obtained both from
synthetic solutions and samples from the actual wastewater
streams. Larger scale testing was required to study the
operation under continuous feeding from the production
plant, to measure the process parameters under varying con-
ditions of operation, and to obtain accurate engineering
design information for economic appraisal. To meet these
requirements, an activated sludge pilot plant similar to
that described by Mulbarger (1966) was designed and con-
structed for an average waste flow rate of 0.5 gallons per
minute.
A. Plant Description and Operation
A flow diagram of the plant is shown in Figure VII-1. The
plant contains the following major components:
1. A cooling tower with a recirculating pump. The basin of
the tower has a capacity of 28 gallons.
2. A river water supply line to the cooling tower with a
density-controlled automatic valve.
3- An acid tank feeding into the suction line of the re-
circulating pump through a pH controlled automatic valve.
4. A nutrient solution tank supplying nutrients to the feed
through a metering pump.
5- A packed Plexiglas roughing column, 18 inches in
diameter by 96 inches tall, with its recirculating
pump.
6. A 280-gallon aerator tank made of Plexiglas with six
removable partitions. Diffused air is introduced into
the bottom of each compartment and controlled by needle
valves on rotameters.
7- Two 50-gallon Plexiglas settlers, each with an adjustable
overflow weir and an airlift to pump the settled solids
from the bottom.
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8. A 5-gallon glass battc-ry ,jar with a stirrer and two
metering pumps for Plocculant mixing.
9- Various composite t L Tie-operated samplers.
All components except the cooling tower and the feed lines
are mounted on a portable structural steel frame. Figure
VII-2 is a photograph showing the aeration tank and the
rotameters on the inlets to the air diffusers in the bottom
of each compartment. The aeration tank is covered and vented
by suction to a water ccrubber.
Figure VII-3 shows the first settling tank where the biofloc
settles and the two samplers that periodically sample the
feed to the aeration tanx as well as the overflow from the
settling tank. Figure VII-4 shows the flocculation vessel,
the metering pumps, and the pH control. This vessel is fed
by gravity from the first settler and flows by gravity to the
second settler where the alum flocculant is settled.
Plant Operation
The waste stream from the glycol production plant was cooled
from 140°F. to a temperature below 100°F. in the cooling
tower. The circulation rate over the natural draft spray
tower was 25 to 30 gallons per minute. Part of the stream
to the tower spray nozzle was diverted to a jet below the
liquid level in the tower basin to thoroughly mix the basin
contents with the raw feed as it enters. The suction line
to the pump operated under a vacuum of 15 to 20 inches of
mercury, which lends itself conveniently to the addition and
mixing of the nutrients and acid.
Good mixing, both in the basin and in the pump, has been
found to be necessary for good pH control, since the
alkalinity of the feed varies between 0.05 and 0. ^$ sodium
hydroxide. The neutralization of the feed to a pH of- around
7-8 with either a 10$ H2S04 solution or, later, with a 38$
HC1 solution, was controlled by an apparatus that measures
and records the pH of the discharge stream from the cooling
tower circulating pump. The pH control circuit shuts off the
feed to the activated sludge aeration tanks If the pH goes
above 8.5 or below 5-5 units.
The nutrient solution, 3.17$ (NH4)2SC4 and 0.73$ K2HP04, Is
fed into the circulation pump suction line by a Model 2M1
Moyno pump. The rate of addition is controlled to result
in the required concentrations of nitrogen and phosphorus
in the feed.
-------
-------
Figure VII-3, First Settling Tank and Composite Samplers
J
75
-------
76
-------
Any entrained air had to be separated from the treated feed
stream to enable proper functioning of the flow recorders
and the density control apparatus. This was achieved by
forwarding the circulating pump discharge to an elevated
Plexiglas vessel with an 8-inch high dividing plate. The
outlet side of the vessel had an overflow near the top,
piped to the cooling tower basin, and a port near the bottom
from which the treated feed was drawn.
Provision was made for the addition of fresh water to the in-
coming glycol effluent at the cooling tower during those
times when the NaCl content increases excessively beyond 10$--
either due to evaporation or to operational changes. The
salt concentration was controlled by the density of the feed.
A sample stream from the air separator vessel was piped into
the bottom end of a 2-inch vertical pipe 10 feet tall, flanged
at its lower end to a 2-inch tee. The stream rose through
the pipe and overflowed at a constant level into a plastic
pan and drained into the cooling tower. The pressure at
the bottom of the column varied with the density of the
fluid and was measured by a differential pressure transmitter
and recorded as density. The sensitivity of the signal from
the transmitter was improved by balancing the column pressure
against a fixed column of mercury while the unit was filled
with pure water. The transmitter signal is also applied to
a pneumatic relay which controls a diaphragm valve on the
fresh water supply line to the top of the cooling tower.
The pre-treated feed was forwarded from the air separator either
to the roughing tower or to the aeration tank by a metering
gear pump (Model 1L2 Moyno) which is adjusted for flow rates
from 0.2 to 0.6 gpm.
The roughing column was packed with 5 feet of porcelain Berl
saddles. A recycle pump was adjusted to give a rate of recycle
five to ten times that of the feed flow rate. The column was
started by recycling about 15 gallons of acclimated culture
and feeding with glycol daily for a period of two weeks to
build up the bacteria on the packing. Then the column was
switched onto the continuous feed. The overflow of the
column basin flowed by gravity to the aeration tank.
Prior to start up, a batch of 400 gallons of the mixed
culture was acclimated to the glycol effluent in a glass
tank equipped with air diffusers. This batch-grown culture
was used to fill the aeration tank and was kept growing by
a fill-and-draw procedure as a standby bacterial supply.
The diffused air to the aeration tank was supplied from a
header, at 8 psig, at a rate of 1.5 cfm to each of seven
diffusers. The total air supply, 10-5 cfm, was about 0-33
cfm per cubic foot of aerator volume.
77
-------
The mixed liquor overflowing from the aerator entered the
first settling tank through an inlet port about 15 inches
above the bottom. The settled sludge was returned to the
feed end of the aerator by means of an air lift pump operated
by a timer adjusted to keep the same concentration of sus-
pended solids in the aeration tank. The overflow from the
first settler was usually slightly turbid. It flows into
the flocculator where alum and caustic solutions are added,
then to the second settling tank.
Automatic composite samplers were used to collect samples
from the treated feed before and after the roughing column
and from the overflow of the first and second settling
tanks. The timer-operated samplers collect 1 to 2 milli-
liters at 15-minute intervals. Samples of the wastes,
after the biological treatment, were collected in bottles
kept cool in dry ice to prevent any further biological
action. The 24-hour composite samples were analyzed daily
for TOD, glycols and other components, percent NaCl, pH
and nutrients. A sample of the mixed liquor in the aeration
tank was collected daily for determination of the suspended
solids.
B. Evaluation of the Roughing Column
A film of bacterial growth was built up on the surface of
the packing in the roughing column by batch feeding the
column with propylene glycol. During the period when the
plant operation was operating on a mixed ethylene and propylene
glycol waste, the feed was directed through the roughing column,
Composite samples before and after the column were analyzed
daily.
The results of two weeks of operation were erratic. The
non-filtered samples from the roughing treatment showed an
increase in TOD value, but the initial dissolved organics,
ethylene and propylene glycol were always reduced.
The operation of the packed column without additional air was
found to be oxygen limited and the bacterial film became
anaerobic as the bacteria increased on the packing. The
packing turned black in less than ten days of operation. A
diffuser was installed at the bottom of the column, and air
was supplied, under a pressure of about 2 atmosphere, at a
rate of 2 cubic feed per minute. The column was then
successfully operated for a period of three weeks, with no
indication of anaerobic conditions developing. The flow rate
of 0.4 gpm corresponds to about a 1 hour residence time in
the column at a recycle ratio of 1:20. The results are pre-
sented in Table VII-1. A TOD removal of over J>Q% was obtained
except during period when the air diffuser was plugged.
Cleaning the air diffuser improved the operation of the column
overnight.
78
-------
TABLE VII-1
OPERATION OF THE ROUGHING COLUMN
WITH FORCED DRAFT AIR
Pretreated Feed
Date
11-27
11-28
11-29
11-50
12-1
12-2
12-3
12-4
12-5
12-6
12-7
12-8
12-9
12-10
12-11
12-13
PG
ppm
520
260
300
230
220
650
510
520
500
350
570
470
530
280
560
660
TOD
ppm
1750
1680
1280
1420
1130
1300
1760
1490
1490
126o
1590
128o
1230
1240
1220
1200
Effluent from Column
PG
ppm
150
-
-
-
-
360
310
190
180
l4o
260
290
330
250
270
420
TOD
ppm
1040
1120
830
870
930
1040
1640
1030
1290
950
1170
1090
710
1030
510
750
TOD
Removal
%
40.6
33-4
35-1
38.7
17.7
20.0
6.81
30.8
13. 41
24.6
26.4
14. 91
42.2
17. o1
58.0
37-5
Flow Rate
gals./min.
0.32
0.32
0.32
0.32
0.36
0.36
0.40
0.40
0.40
0.40
0.40
0.40
0.40
0.40
0.40
0.40
1 Air diffuser at bottom of column was plugged with a fine
material that does not resemble the bacteria. When cleaned,
the removal of TOD improved overnight.
7Q
-------
C. Results of Different Modes_ of_ 0_peration
The operation of the pilot plant as a plug flow reactor and
a completely mixed single basin with a feed composition as
obtained from the glycol production plant constituted the
modes of operation studied. The objective was to determine
the minimum residence t;.ne required for the complete oxidation
of the organics components of the feed under the varying con-
ditions of loading. The results obtained under the several
modes of operation are presented and discussed under the
following subsections. The detailed daily records of the
plant operation are presented in Appendix B.
Mixed Ethylene and Propylene Glycol Wastewaters Plug Flow
Operation
The activated sludge pilot plant was started with a bacterial
culture grown batchwise in a 300 gallon glass tank filled
daily with pretreated glycol wastewater. During the period
of operation, from June 2J4 to August 26, 1970, partitions
were placed in the aeration tank. A dye study snowed that
the configuration of the aeration tank was that of a plug
flow reactor with seven completely mixed reactors in series.
The feed was a mixture containing about one third ethylene
glycol and two thirds propylene glycol. The TOD of the feed
varied between 1200 to 2000 ppm. The flow rate of the feed
was brought up gradually to 0.3 gpm, corresponding to a
residence time of 14 hours in the aeration tank. The re-
moval of TOD varied between 86 to 95$ at this flow rate,
yielding a product quality between 100 and 23C ppm. TOD.
When the feed was switched over to propylene glycol waste
for a period of five days (July 31 to August J4) , a higher
percent removal, 90 to 95$., and a product of less than a
100 ppm. TOD was obtaired. Due to mechanical difficulties
with the feed pump, the feed was then sv. itched back to the
mixed waste stream,
A plot of the TOD, in ?jid out, and the concentration of MLVSS
in the aeration tank over this operating period, is shown in
Figure VII-5. A complete daily record of the analyses is
given in Table XI-2 of Appendix B.
On August 22 the feed rate was increased to O.1'- gpm (giving
a residence time of about 10 hours). Good operation was
maintained for three days at this higher flow rate, with TOD
removal of 88 to 91$. As the TOD concentration in the feed
increased, residual glycol and higher TOD were produced in
the treated waste. The sludge settling became less efficient
and it became difficult to maintain a MLSS over 100 ppm.
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During the interruptions of the operation (A, B, C and D in
Figure VII-5) the aeration tank was either fed propylene
glycol or secondary culture was added before startup.
Usually the batch grown bacteria suffered a decrease in con-
centration when exposed to continuous flow conditions, followed
by a culture increase and better settling characteristics, as
the bacteria became acclimated to the flow conditions.
A schematic of the operation showing the range of the results
obtained during ten days of continuous operation at a flow
rate of 0.3 gpm is shown in Figure VII-6. During this period
the roughing column was in operation most of the time. The
loading-removal relationship obtained during this period is
shown in Figure VII-7. The indicated slope of 0.834 corres-
ponds very well with the calculated value from batch tests
for a residence time of 12 hours. The effluent-loading re-
lationship is presented in Figure VII-8. An effluent quality
below 200 ppm. TOD can be obtained at a loading of up to 2.0
pounds TOD per pound MLVSS per day in this mode of operation.
Propylene Glycol Waste - Completely Mixed Reactor
The partitions were removed from the aeration tank, and the
feed was switched to wastes containing only propylene glycol.
A hydrochloric acid (38$) rubber lined tank was installed and
HC1 used for neutralization.
The feed to the completely mixed aeration tanks was started
on July 9> at a rate of 0.325 gpm (12.8 hours residence time).
For the first week of operation the MLVSS remained low and the
feed had a high TOD concentration. This high loading resulted
in only 70 to 77$ removal of TOD with the product containing
higher concentrations of TOD and propylene glycol. From
September 24 to October 2, a TOD removal of over 90$ was
obtained and the MLVSS was building up, while the TOD in the
feed varied from 1940 to 2400 ppm.
On October 3> the temperature of the feed rose to 46°C, due
to the plugging of the spray nozzle in the cooling tower.
This was accompanied by an increase of TOD in the feed to
3240 ppm. The bacteria were killed, anaerobic conditions
developed, and the bacteria were lost by floating and carry-
over. For a period of two weeks following this incident,
it was difficult to build up the concentration of the bacteria.
The settling of the sludge was very inferior and most of the
bacteria were filamentous in nature.
From October 20 to October 27, 88$ to 94$ TOD removal was
obtained and the sludge settling improved as the bacterial
concentration built up to l66o ppm. The TOD in the feed then
began to fluctuate to very high concentrations, again
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-------
accompanied by a loss of the bacterial concentration. It was
decided to install a 3000-gallon tank in the feed system to
equalize the organic loading to the activated sludge plant,
to maintain a near steady state operation. The results of
this period of operation are plotted in Figure VII-9. The
complete daily analyses are given in Table XI-3 of Appendix B.
Equalized Propylene Glycol Waste Completely Mixed Reactor
The feed was switched to a propylene glycol waste stream
collected from several production trains and was equalized
in a 3000-gallon tank before feeding to the pilot plant. A
residence time of about 3.5 days in the equalizing tank after
neutralization resulted in considerable dampening of the
fluctuations in the TOD concentrations. The nutrients were
added to the feed after equalization. Addition of the
nutrients prior to the tank resulted in the development of
anaerobic activity inside the tank. The pilot plant results
during November and December, 1970 are plotted in Figure VII-10
The daily analyses are shown in Table XI-4 of Appendix B. The
initial flow rate of the feed was 0.32 gpm. It was increased
to 0.4 gpm (10-5 hours residence time) in two weeks. Removal
efficiencies of over 80$ and a product of less than 300 ppm.
TOD was obtained during most of this time. Lower removal
efficiencies were experienced during this period due to the
lowered waste temperatures (60 to 70°F.). Heating the feed to
85°F. resulted in increased activity.
The operation of the activated sludge pilot plant continued
through January and February under steady state conditions
using equalized feed. The obtained results are given in
Table XI-5, Appendix B, and in Figure VII-11. The feed rate
was increased to 0.45 gpm on January 26, giving a residence
time of 8.25 hours in the aeration basin. The loading and
removal relationship is plotted in Figure VII-12, for the
period from January 15 to February 22. A removal efficiency
of 92$ was obtained for loadings between 1.5 to 3.0 pounds
TOD per pound of MLVSS per day. The lower end of the loading
was found to be operationally critical. At loadings below
1.5* "the food to bacteria ratio was too low to maintain the
mixed culture in the aeration basin, and resulted in a sudden
loss of the bacterial concentration due to endogenous res-
piration.
D. Operational and Design Parameters
The operation of the activated sludge pilot plant was main-
tained at nearly steady state during the months of January
and February, 1971. The emphasis during this period was on
collection of the data necessary for process design. The
86
-------
MLVSS.ppm
oc
o
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x
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operational and design parameters of the process are best
discussed under the following headings.
Stability of the Biota to Transients
Equalization of the wastewater feed to the aeration basin
was found to be necessary to dampen the fluctuations of the
organic loading of the activated sludge. Loadings below
1-5 pounds TOD per pound MLVSS per day, resulted in a sudden
loss of the bacterial concentration, while at loadings over
4.0 or 5-0 filamentous bacterial growth resulted, with poor
settling properties and a resultant high concentration of
suspended solids in the effluent from the settling tank.
The recommended range of organic loading of this particular
culture is 1.5 to 3-0 pounds of TOD per pound of MLVSS per
day.
The characteristics of the various components in this culture
are given in Appendix C. Biochemical test reactions of forty-
eight isolates from the activated sludge indicated that there
are no more than 3 or 4 species. The most numerous bacterium
is a Gram negative, non-motile, oxidase positive rod.
The growth of this culture is favored at higher temperatures.
Good operation was maintained during the summer months, at
100°F., but difficulties were encountered at temperatures below
65°F., during the period January 7 to January 13, as indicated
in Figure VII-11. The temperature of the aeration basin was
maintained at 85°F. by heating the feed during the period
from January 14 to the end of February.
The temperature limits were determined in the laboratory
continuous unit shown in Figure VII-16. The unit was filled
daily with mixed liquor from the pilot plant and loaded with
pretreated feed at approximately the same rate as the pilot
plant. The temperature of the aeration vessel was varied
between 10°C. and 50°C. The oxygen uptake rate under loading,
the removal efficiency and sludge production were measured
during a 24-hour period.
In Figure VII-1J5, oxygen saturation, oxygen equilibrium con-
centration and oxygen uptake rate are plotted as functions
of temperature. At 11°C. the oxygen uptake rate decreased
to one-third of the value at 20°C., there was no sludge
production and the removal efficiency dropped off and
residual glycol appeared in the effluent. The bacterial
culture formed dense clumps and was difficult to mix with
the feed. At temperatures over 4o°C., some decrease in
oxygen uptake rate was noted, but removal efficiency and
sludge production was not affected. The optimum oxygen up-
take appears to be at a temperature between 30 and 35°C.
(85 to 95°C.).
91
-------
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I—
Q_
2 §
-i UJ
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I -
.1 s
u. o-
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or
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wdd
3>IVldn
92
-------
Substrate Removal Rate_
For the period of operation from November 20, 1970 to
February 28, 1971, the recycle ratio, to the completely
mixed aeration tank, was varied between 15 and 2^fo of the
equalized propylene glycol waste feed rate. In Figure VTI-14
the effluent TOD is plotted as a function of loading. The
initial loading of the aeration tank (TODi) is calculated as
a weight average of the feed and recycle:
= rJQg_f +_(recycle ratio) (TODe)
i ~ 1 + recycle ratio
(a)
where
TODf - Total oxygen demand in the feed.
TODe = Total oxygen demand in the effluent.
The line of best fit of the data is represented by:
TODe = 9-3 •+ 69.7 (-
(b)
x MLVSS'
The same data can also be presented as in Figure VII-15,
where the rate is plotted as a function of a loading ratio.
The correlation Is given by:
- TODe
t x TODe
- 1.3.5 - 0.412
TODj
MLVSS
(c)
The coefficients of correlation for equations (b) and (c) are
0.725 and 0.8l6, respectively. Both relations can be used to
calculate the residence time (t) and the volume of the reaction
basin required.
Oxygen Utilization Rate
The laboratory activated sludge unit, used for oxygen measure-
ments, is shown In Figure VII-16. The aerator (4.1 liters)
was started dally with mixed "Mquor obtained from the pilot
plant, and air was supplied to it at a rate of 600 ml./min.
The stirrer, at 60 rpin, was just enough to keep the suspended
solids mixed when the air was cut off. The temperature of
the aerator was controlled by immersing it in a water bath.
The unit was fed with the same pretreated waste at the same
loading and recycle as in trie pilot plant, then equilibrated
over a period of 20 hours. At this tine, the air was shut
-------
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1
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oo
o
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001 X }
001- !001
-------
cc
O
— LU
=3 LU
x_ OC.
O
O
96
-------
off and the dissolved oxygen concentration measured as a
function of time. The air was then turned back on for 5
minutes, but without any feed or sludge return. The air was
then cut off, and the oxygen uptake recorded under no-loading
conditions .
A typical oxygen uptake measurement is shown in Figure VII-17.
The slope of the oxygen depletion line with respect to time
was found to be the same whether or not a nitrogen blanket
was used on the surface of the aerator. The surface re-
adsorption of oxygen at the mixed liquor interface is
negligible during the first few minutes of the test at the
mixing speed of 60 rpm and the operating level of around
3 ppm. oxygen.
The oxygen uptake was measured at various loading levels.
The oxygen demand (pounds per pound MLVSS per day) is shown
as a function of removal in Figure VII-18. The slope of the
line of best fit represents the oxygen consumed per pound of
TOD removed (a = 0.256). The intercept b =0.13 is the
oxygen demand of the endogenous respiration of the bacteria.
This value checks the measured value very closely. From
Figure VII-17, the rate of oxygen uptake under no loading is
seen to be 0.19 ppm. per minute when the MLVSS averaged 1970
ppm. over a 24-hour period. This corresponds to b = 0.139 in
pounds O.C. per pound MLVSS per day.
The ratio of a/b in this high salt system is about 2. For
fresh water activated sludge the value of a/b is more likely
to be 5 or 6 . This lower ratio of the active oxygen demand
to the endogenous respiration seems to be a characteristic
of the halophilic bacteria, that differentiates it from
fresh water bacteria.
The effect of temperature on the oxygen uptake rate is shown
in Figure VII-13- The relationship can be represented by:
KT = K20° • 1.042 (t'20)
where
= Oxygen uptake rate coefficient at t°C.
K20° = Oxygen uptake rate coefficient at 20 °C.
t = Temperature in °C.
The energy of activation AE as calculated from these tempera-
ture data, is 7250 Cal./mol. which is about half of the value
reported for fresh water activated sludge (Eckenfelder, 1961) .
97
-------
3 -
Q.
Q.
o
d
i r-
Figure VII-17
OXYGEN UPTAKE
PROPYLENE GLYCOL WASTEWATER-20°C
r = 0.19, (NO LOADING)
= 0.82, (LOADING^ 2.1 Lbs TOD per LbMLVSS^Da/)
4 6
TIME, Atinutes
10
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£
SSA1W
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-------
Oxygen Mass Transfer Rate
The oxygen saturation level in the saline wastewater is only
0.4-2 to 0.46 that of tap water, principally because of
the high salt content of the waste. In an activated sludge
system the oxygen transfer rate is given by:
dc/dt = KLa/Cs-C7 - r
where
GS = oxygen saturation in the wastewater
c = equilibrium or operating oxygen concentration
r = oxygen uptake rate.
At steady state dc/dt = o, therefore:
T
In the non-steady state method used to determine KLa, the
oxygen in the water sample was depleted, then the sample re-
aerated and the dissolved oxygen increased with time recorded
By plotting the oxygen deficit (Cs-C) versus time on a semi-
log paper, a straight line is obtained with a slope equal to
KLa' therefore:
v - A In (Cs-C)
KLa - - -
The laboratory activated sludge unit was used to measure the
oxygen mass transfer coefficients KLa for tap water and the
mixed liquor. The ratio of KLa in the waste to KLa in tap
water (a) was found to be very difficult to determine, since
depends on the nature of the wastewater (surface activity) ,
the degree of surface renewal (KLa = KL ==) , and the degree
of turbulence or the mechanics of aeration.
In the laboratory equipment under quiescent conditions, with
air transfer through the surface of the liquid and the mixer
at very low speed, an a value less than 0.5 for the waste-
water feed was obtained. This is due to the high concen-
tration of surface active organics in the wastewater feed,
the presents a barrier for oxygen transfer at the surface.
When KLa was determined for the treated wastewater using a
submerged diffuser, arid applying the steady state method,
the values of a were found to be unreasonably high (over 2.0).
100
-------
The effect of the turbulence created by aeration on the oxygen
transfer rate is shown in Figure VII-19- The higher rate of
surface renewal (A/V) in the wastewater as compared to tap
water, was indicated by a noticable reduction in bubble size,
and is the reason for the determined a values over 1.0. The
determinations of KL^ in tap water and the treated waste at
an aeration rate of 600 c.c./min. are plotted in Figure VII-20,
For aeration rates of 400 to 900 c.c./min. in the 4.1 liter
vessel, the a value remained constant at around 1.2.
Sludge Production Rate
The sludge production over a 24-hour period was measured in
both the laboratory equipment and in the pilot plant during
steady state operation on an equalized feed. Initially the
wasting of settled sludge or mixed liquor was batchwise, but
a pump was then installed to continuously waste a measured
amount of mixed liquor in order to maintain the mixed liquor
volatile suspended solids (MLVSS) in the aeration tank at an
almost constant value over a 24-hour period. The volatile
suspended solids (VSS) formed each day was calculated by
using the following equation:
Lbs. VSS formed/lb. MLVSS-day - VwCW + (CF-C0)VA +
vAGavg.
where
Vw = wasted volume of mixed liquor
VA - volume of aeration tank
VE = volume of effluent
C0 = initial MLVSS in aeration tank
CJP = final MLVSS in aeration tank
Cy = MLVSS in wasted mixed liquor
CE = VSS in treated effluent
cavg. =
-------
Figur. VII-19
EFFECT OF AERATION RATE ON OXYGEN TRANSFER
2000
1500
1000
900
800
700
600
500
400
300
250
200
150
X=tap water
•^treated wastevater
V« reactor volume=4.1 liters
100
I I
I _l I I I I
I
100 15'1 200 250 300 400 5006007008009001000 1500 2000
Aerano.) Rate; Gs,cc/min.
102
-------
Figur* VII-20
OXYGEN MASS TRANSFER
The non-steady state method)
Temperature 20°C
TAP WATER
OC - 1.2
TREATED WASTE
KLa - 0.221
4 6
TIME, Minutts
103
-------
00
>-
<
Q
a.
CD
O
UJ
s
Figure VII-21
GROSS SOLIDS FORMATION
IBS VSS FORMED per DAYi= C(Lbs TOD Retooved per DayHd(MLVSS)
0.32
0.28
0.24
0.20
0.16
0.12
0.08
0.04
0.00
-0.04
-0.08
SLOPE
SLOPE = 0.133 Lbs VSS per
LbTOD
0.111 LbsVSSptr.
LbTCD
• Laboratory Unit
O Batch Wasting From Pilot Plant
Continuous Wasting From Pilot
Plant
LBS TOD REMOVED per DAY per LB MLVSS
104
-------
Liquid-Solid Separation
The sludge formed during most of the pilot plant operation
was found to have a, very low volume index with very good
settling properties.
Air flotation was tried as a method of sludge separation from
the mixed liquor. The sludge particles were broken down to
a very fine suspension that was difficult to handle, since
only part of it floated to the surface. The addition of
organic flocculants to the air flotation unit did not improve
the separation.
The sludge settling properties were determined in a 6 foot
deep test cylinder with sampling points at 2, 4, 5 and 6 foot .
depths. Sludge samples from the aeration tank of the pilot
plant were well mixed and the original suspended solids (Co)
measured. Samples were drawn off at selected time intervals
at 2 , 4 and 5 foot depths. The concentration of suspended
solids was measured at each sampling point and each time. The
amount removed from the initial concentration (Co) was plotted
against the respective depths and times. Curves are then
approximated by connecting points of equal concentrations.
These resultant settling path curves for the sludge of
different original concentrations are shown in Figures
VII-22, VII-23 and VII-24.
The sludge volume index shown on each figure was determined
using the standard method. The final sludge concentration
from the 6 foot tap at the end of each test averaged about
32,000 ppm. for all sludges tested.
With an initial bacterial concentration of over 1100 ppm.,
90$ suspended solids removal was obtained in about 20 minutes.
Sludges with concentrations less than 1000 ppm. took much
longer to settle.
During periods of disturbances in the plant operation,
samples of the sludge had a sludge volume index (SVI) as
high as 100, for which a removal of 70^ required over 100
minutes. Under normal operating conditions, the sludge
volume index varied between 50 and 60, and 90^> of the
sludge settled in less than 20 minutes. These data can be
used, with appropriate scale-up factors, for the design of
settling vessels for the sludges produced in any size acti-
vated sludge plant.
The overflow from the settling tank after the activated
sludge treatment is usually slightly turbid, with a TOD of
200 to 300 ppm., although It contains no residual organics
that are present in the feed. Several flocculants were
tested for clarification of the treated wastewater. Among
105
-------
< fj
0. *.
S °
50
106
-------
0>
o
Figor* VII-23
SLUDGE SETTLING PATHS
Co=1100 ppm, SVI-53
• 35
• 25
10
15
• 99
20
25
Time, min.
107
-------
Figur. VII-24
SLUDGE SETTLING PATHS
Co=1700 ppm, SVU42
£
CL
w
• 0
10
Time, min.
15
20
108
-------
those tested were Puriflocs® (cationic, anionic and nonionic),
alum and ferric salts. The best system examined required
150 to 200 ppm. alum at a pH of 7-5 "to 8.0 (adjusted with
sodium hydroxide). The TOD of the clarified effluent is
usually reduced by 50^ after clarification.
The flocculation step is not felt to be necessary, except
when the treated wastewater is to be reused in other plant
operations, such as a feed to chlorine cells, where the re-
maining TOD is objectionable.
Carbon and 0xygen Balance
A material balance around the organic carbon and oxygen con-
sumed was calculated for l8 days of steady state operation
of the pilot plant. Sample calculations are given in
Table VII-2, for 4 days of operation, showing the ranges of
parameters calculated.
The weight of carbon in the volatile suspended solids (VSS)
formed was calculated as 0.53 of the weight, the ratio of
carbon to the total weight in the bacterial cell formula
(C5H7N02)•
The weight of oxygen consumed for synthesis of the cells was
also calculated as 3?/H3 of the weight of VSS formed. The
carbon oxidized to C02 was calculated by difference The
total organic carbon of bhe homogenized mixed liquor sample
was found experimentally to be about 50$ of the VSS of the
samples, which increased the confidence in using C5H-/N02 as
the formula for the bacterial cells.
Optimization ofJNutrient Requirements
At the start, of the pilot plant operation, t-iie riutr.i ent
solution was added at a rate r.tiat would produce 100 ppm.
nitrogen arid 20 ppm. phosphorus in the feed to the aeration
tank. Ammonia nitrogen, total nitrogen and phosphate were
analyzed in the feed and the treated effluent over a period
of two months and the feed rate adjusted accordingly. As a
result, the rate of nutrient addition, for the range of TOD
values up to 2000 ppm., has been reduced to 50-60 ppm. N
and 10-12 ppm. P, with the treated effluent containing 20-30
ppm. ammonia N and 1-3 ppm. P.
The halophilic bacterial culture requires higher concentrations
of nitrogen and lower concentrations of phosphorus than do
the fresh water cultures reported in the literature. A ratio
of TOD:N:P of 300:10:1 was found to be the optimized value for
the nutrient requirement. For an average of 1500 ppm. TOD in
the propylene glycol wastewater (BOD5 = 540) , 50 ppm., ammonia
109
-------
TABLE VII-2
CARBON AND OXYGEN BALANCE OF THE
ACTIVATED SLUDGE PROCESS
Days of Operation
Feed, GPD. (A)
Effluent, GPD. (B)
TOD removed, ppm. (C)
MLVSS, ppm. (D)
TOC In, ppm. (E)
TOG Out, ppm. (F)
Lbs. VSS formed per Ib.
TOD removed (H)
Lbs. TOD removed
(K = 8.85 AC)
Lbs. VSS formed (L = HK)
Lbs. Carbon In
(M = 8.85 AE x 10~6)
1
650
625.2
1155
1712
257
38
2
650
600
1470
1660
266
23
3
650
599.7
1115
1628
255
31
4
650
602
1060
1312
265
37
0.116 0.089 0.156 0.230
6.64
0.77
1.48
8.47 6.42 6.1
0.755 0.874 1.4
1.53
1.47
Lbs. Carbon Out (N = 8.85
BF x 10~6 +0.53 L)
,M-N
Carbon to C02 (-
M
0.618
x 100)58
65
57
Oxygen Consumed, O.C.
Lbs. O.C./lb. TOD removed
,0.0. ^
(~;
2.52
0.380
2.87
2.49
Average of 18 days of operation:
Lbs. VSS formed/lb. TOD removed
% Carbon oxidized to C02
Lbs. O.C./lb. TOD removed
0.338 0.386
= 0.133
= 0.4
1.
^
0.524 0.627 0.939
2.05
0
• 337
110
-------
N, and 5 ppm. phosphate P fed gave a residual of 8 ppm. N
and 1-2 ppm. P in the effluent.
Summary of Design Parameters
The activated sludge pilot plant was operated both as a plug
flow and as a completely mixed reactor. Results show that
an advantage exists for the completely mixed mode of operation
especially if the feed is equalized to dampen the changes in
organic loading. Removal efficiencies of over 90$ were ob-
tained over a long operational period when the system was
completely mixed, and at retention time of less than 9.0 hours.
The average removal efficiencies of the plug flow operation
were about 84$ for a retention time of 12 hours. The results
of the plug flow operation checks the laboratory batch
results, while the completely mixed mode of operation re-
sulted in higher removal efficiencies at lower residence
times and higher organic loading than can be tolerated in the
plug flow reactor. The measured and calculated design
parameters are summarized in Table VII-3-
E. Polishing of the Biotreatment Plant
Effluent With Activated Carbon
The effluent from the activated sludge treatment does not
contain any of the organic components that were originally
dissolved in the feed wastewater. The effluent, however,
still contains dissolved organics (the degradation products
of the bacterial cells) in concentrations varying from 25 to
50 mg/1 total organic carbon (TOG) or 80 to 150 mg/1 of total
oxygen demand (TOD).
Polishing of the biotreatment plant effluent with activated
carbon to produce a sodium chloride solution suitable for
reuse as feed to the chlorine cells was studied in the
laboratory. An activated carbon, Witco, grade 517, 20-40
mesh, was used in a packed column for the polishing of the
effluent. Several hundred gallons of the polished effluent
were produced containing less than 10 mg/1 of total organic
carbon.
The capacity of the activated carbon for the dissolved
organics averaged about 1-5 pounds per 100 pounds of carbon.
Regeneration with steam at 300°F failed to reactivate the
carbon. Thermal regeneration in a muffle furnace is probably
required.
The polished effluent was saturated with salt, treated with
soda-ash to remove any traces of calcium, and then fed to
two laboratory cells for a period of 10 days. The cell con-
ditions and gas analysis were recorded. No change was noted
111
-------
TABLE VII-3
SUMMARY
GLYCOL WASTE TREATMENT
ACTIVATED SLUDGE DESIGN PARAMETERS
Removal efficiency: 92$
Optimum temperature: 30-35°C.
Allowable temperature range: 17-40°C.
Nutrient requirements: TOD:N:P = 300:10:1
Removal rate: 1 - TODe = 9.3 + 69.7
2 ' R 1 x TODe ~ ^ °'421MLVSV
Oxygen utilization: Ibs. O.C./day = 0.256 (Ibs. TOD
removed/day)
+ 0.13 (Ibs. MLVSS), at 20°C.
Oxygen transfer: $ =0.^7
a - 1.2
Sludge production: Ibs. VSS formed/day = 0.133 (Ibs.
TOD removed/day) -
- 0.021 (Ibs. MLVSS)
TODe = total oxygen demand in effluent.
TODj_ = total oxygen demand in feed plus recycle.
O.C. = oxygen consumed.
VSS = volatile suspended solids
3 = ratio of oxygen saturation in the mixed liquor to that
in tap water.
a = ratio of oxygen transfer rate in the mixed liquor to
that in tap water.
112
-------
in any of the cell operating characteristics. The usual
Orsat analysis of the chlorine showed no increase in C02•
The organic impurities in the feed brine and in the cell
effluent were so low that their presence is not expected to
cause any long-term problems.
The very low capacity of the activated carbon for the dis-
solved organic residues in the effluent from the biotreat-
ment plant, and the need for thermal regeneration of the
carbon rather than an in-situ regeneration with steam,
appears to make the polishing step too expensive to serve
as a reuse process.
Large scale operation of the activated sludge process at an
optimum recycle ratio combined with proper flocculation of
the residual turbidity of the effluent may produce an
effluent quality sufficient for reuse as a feed to chlorine
cells without the need for polishing with activated carbon.
-------
SECTION VIII
CONCEPTUAL DESIGN OF A 6 MGD ACTIVATED
SLUDGE WASTE TREATEMENT PLANT
Based on the results of the successful operation of the pilot
plant for the bio-oxidation of the organics in the glycol
wastewater, a conceptual design of a 6 MGD activated sludge
waste treatment plant has been prepared and the capital re-
quirements and operating cost estimated.
A typical chemical plant producing propylene glycol, by the
ohlorohydrin process, at a rate of about 1.2 million pounds
per day would also produce a wastewater stream of 6 million
gallons per day. This wastewater, resulting from the
hydrolysis of the chlorohydrin to the oxide, is a brine con-
taining dissolved organic components with a pH of 11 to 12
and a temperature of about 190°F. as it leaves the production
plant. The cost estimates and economic evaluation of the
process is based on prices prevailing on the Gulf Coast
during the period 1970-1971.
A. Process Description and Plant Design
The design of the activated sludge plant is based on a feed
of the composition and flow rate as shown in Table VIII-1.
A flow diagram (Figure VIII-1) and a general plant layout
(Figure VIII-2) show the sequence of operations and the
relative positions of the equipment, respectively. The major
equipment and instrumentation is listed in Tables VIII-2 and
VIII-3- Details and design calculations are included in
Appendix D to this report.
Neutralization
The pH of the feed is reduced to about 9.5 by the addition
of hydrochloric acid or sulfuric acid, whichever is most
economically available at the plant site. The acid require-
ment, equivalent to 90$ of the excess caustic in the feed,
is calculated as 14.5 gpm. of J)Q% HC1 or 5 gpm. of 98^ H2S04.
The acid (J>8fo HC1) is pumped from a 30,000 gallon surge tank
Into the feed line before the equalization and cooling pond,
where the pH is controlled at about 9-5 (Figure VIII-3)• It
is expected that during the 2-day retention of the feed in
the cooling pond, the reaction with carbon dioxide from the
atmosphere, will reduce the pH to between 8.0 and 8.5.
Cooling and Equalization
The cooling of the feed from a temperature of l8o°F. to
105°F. during the summer months, when the air maximum daily
115
-------
TABLE VIII-1
DESIGN FEED
6 MGD ACTIVATED SLUDGE WASTEWATER
TREATMENT PLANT
Flow Rate ^200 GPM
(53.2 x 106 Ibs./day)
NaCl 9-<
Sp. Gr./20°C 1.063
NaOH 0.:
Temperature l80°F.
TOD 1400 ppm.
BOD5 510 ppm.
Propylene Glycol 640 ppm.
116
-------
O.*
-------
-------
TABLE VIII-2
MAJOR EQUIPMENT
6 MOD ACTIVATED SLUDGE WASTEWATER
TREATMENT PLANT
D-l 38$ HC1 Surge Tank
EC-1 Equalization and Cooling Ponds
D-2 Ammonia Storage Tank
D-4 Phosphoric Acid Storage Tank
A-6 Aeration Basin
Cl-7 Clarifier
THK-8 Sludge Thickener
CF-9A Centrifuges
CF-9B
P-1A J>8f0 HC1 Acid Pumps
P-1B
P-^A Phosphoric Acid Supply Pumps
P-4B
P-6A Dilution Water Pumps
P-6B
P-7A Sludge Recycle Pumps
P-7B
119
-------
Table VIII-2 (Continued)
P-8A Sludge Pumps
P-8B
P-9A Effluent Return Pumps
P-9B
120
-------
TABLE VIII-3
MAJOR INSTRUMENTATION
6 MGD ACTIVATED SLUDGE WASTEWATER
TREATMENT PLANT
LT-1 Level Control, HC1 Surge Tank
L1C-1
LV-1
LI-1
pHT-1 pH Measurement, Acid Flow Rate Control
pHRC-1
pHV-1
FO-1 Feed Flow Rate Measurement
FE-1
FT-1
FR-1
LT-2 Level Control, Ammonia Storage Tank
L1C-2
LV-2
FO-2 Ammonia Flow Control
FRC-2
FT-2
FV-2
7 rn
-4 Level Control Phosphoric Acid Storage
LI-4
FT-4
121
-------
Table VIII-3 (Continued)
FO-4 Flow Control, Phosphoric Acid
FRC-4
FV-4
AT-5 Dilution Flow Control, Density Measurement
ARC-5
AV-5
FT-5 Parshall Flume Flow Measurement, Aeration
FE-5 Basin
FE-6
pHT-6 pH Measurement, Aeration Basin
pHR-6
TR-1 Temperature Measurements
TR-2
122
-------
1N3A 3A1VA A13JVS a39a3H80S
-------
average temperature is ^5°F., requires a pond containing
254,Q00 square feet of surface area. For a retention time
of 2 days, necessary for the equalization of the concentration
of organics in the feed, the volume of the pond would be
1.6 x 10£l cubic feet. The depth of the pond as designed is
7.35 feet, with a freeboard of 1 foot when full. The pond is
lined with 0.03 inch thick plastic film. The layout and a
cross-section of the pond are shown in Figures VIII-2 and
VITI-3j> respectively.
Nutrient Addition
Nutrients are added to the aeration basin rather than to the
feed in the cooling pond to prevent any anaerobic growth in
the pond. Anhydrous ammonia is pumped from a 10,000 gallon
storage tank at a rate of 0.366 gpm. Phosphoric acid, 75%,
is pumped from a 7^500 gallon storage tank at a rate of
0.05 gp^ The ratio of TOD removed :N:P in the aeration basin
will then be 300:10:1.
Dilution Water
The water lost by evaporation in the cooling pond is replaced
by the addition of river water (or seawater at coastal lo-
cations), to keep the salt content of the feed at about 9^>-
This addition has the added advantage of supplying any trace
elements required for the growth of the bacteria not present
in the glycol wastewater. The requirement for fresh water is
about 355 gpm.; estuarine water of 2.5^ salt content if used
instead should be added at a rate of 480 gpm. Alternatively,
the ammonia and phosphoric acid could be mixed with the
dilution water before addition to the aeration basin, and
the dilution water can also be delivered through foam control
jets placed at the surface of the aeration basin should
foaming become a problem.
Aeration Basin
The aeration basin is designed as a completely mixed reactor,
with a residence time of 8.36 hours based on the feed rate.
The volume of the basin is 300,000 cubic feet with a depth
of 15 feet and a freeboard of 2.5 feet when running full.
The feed flows by gravity from the cooling pond through a
3 foot by 3 foot Parshall flume installed in the common levee
between the two basins (Figures VIII-2 and VIII-3)•
The oxygen required for the removal of 67,200 pounds TOD per
day is calculated as 2070 pounds oxygen per hour. This
oxygen is supplied by nine 75 H.P. floating surface aerators.
The energy delivered is more than that required to keep the
-------
basin completely mixed. The "bottom of the basin is lined
with a 30 mil plastic film and a concrete base is installed
under each surface aerator. Details of the aeration basin
are shown in Figure VIII-4.
The suspended solids would be maintained at 1500 ppm. through-
out the completely mixed basin. The recycle of 25$ of the
feed is more than is required to return an adequate quantity
of the compacted sludge. The designed organic loading in the
basin is 2.28 pounds TOD removed per pound of MLVSS.
Clarifier and Return Sludge
A Dorr-Oliver type clarifier with vacuum pick-up raker arms
is used. The clarifier is 75 feet in diameter with an
effective depth of 6 feet. It is designed for an overflow
rate of 1370 gallons per day per square foot, and a residence
time of 47 minutes. The sludge recycled to the aeration
basin is 25$ of the feed rate, about 1040 gallons per minute
and contains about 7>000 ppm. of suspended solids.
Sludge Thickening and Centrifuging
The excess sludge is pumped from the clarifier at a rate of
92 gpm. to a sludge thickener. The thickener is 18 feet in
diameter and 6 feet deep, designed for an overflow rate of
400 gallons per day per square foot and a residence time of
2 hours. The sludge is compacted by settling to a volume of
20 gallons containing 3-2$ solids, and is pumped to two Dorr-
Oliver type centrifuges (Model 12-L) with 25 H.P. motors.
The thickened sludge is centrifuged to 18$ solids and removed
to land fill. The supernatants from both the thickener and
centrifuges are pumped to the aeration basin. The details of
the sludge handling are shown in Figure VTII-5-
B. Cost Estimate and Economic Evaluation
The activated sludge plant requires a total area of about
11.0 acres. The capital and operating costs estimated are
confined to the block line. Not included are any items that
vary with the location site:
1. Cost of land site, 11.0 acres.
2. Cost of pipeline from glycol production plant to
the block line.
3- Cost of transfer of the treated waste from the block
line to a disposal or reuse point.
4. Cost of disposing of the centrifuged excess sludge
to a land fill location.
125
-------
FIGURE 3ZHI-4
ACTIVATED SLUDGE PLANT-6 MGD
DETAILS OF AERATION BASIN
NINE-75H.P
SURFACE
AERATOR
PLAN
\
JI2.51
— 129' X 119'
179' X 179'
-ft-
-'
6.7'
',••3'
CROSS SECTION
126
-------
o
e>
2
UJ
12?
-------
The capital cost estimated includes installation cost plus
contractor fee and overhead, to which is added 15$ allowances
each for engineering and contingencies. The details of the
derivation of the installed cost of each of the equipment
items and services are given in Appendix D.
A listing of the direct capital equipment is given in Table
VIII-4. Sub-totals are shown for the pretreatment section of
the plant, the aeration and settling section, the sludge
handling section and the general services.
The total direct capital cost would be increased to about
1.39 million dollars after allocation of capital for utilities
and factory expenses as shown in Table VIII-5.
An estimate of the operating cost is shown in Table VIII-6.
The major operating cost item is the acid used to neutralize
the excess alkalinity in the wastewater. A reduction in the
excess alkalinity by better control at the production plant
and a possible lower cost of the acid at the production
facilities could amount to a saving of up to half of the
estimated operating cost.
The unit cost based on the oxygen demand removed from the
wastewater is 3-23 cents per pound of TOD removed. If
based on the glycol production, the cost is less than 0.2
cents per pound of glycol produced.
123
-------
TABLE VIII-4
6 MGD ACTIVATED SLUDGE WASTE TREATMENT PLANT
ESTIMATE OF DIRECT CAPITAL COST
Installed
Items Capital Cost
Pretreatment and Cooling
HC1 Tank $ 27,100
Pumps 6,180
Equalization & Cooling Pond 211,550
Ammonia Storage Tank 40,500
Phosphoric Acid Storage Tank 23,600
Phosphoric Acid Pumps 6,540
Dilution Water Pumps 10,060
Total $ 325,530
2. Aeration and Settling
Aeration Basin & 9, 75 H.P. Surface Aerators $ 214,000
Clarifier 239,980
Sludge Recycle Pumps 21,600
Recycle Pumps from Thickener & Centrifuges 9,930
Total $ 485,510
3- Sludge Handling
Thickener $ 56,400
Sludge Pumps to Centrifuges 3,46o
Centrifuges 141,000
Total $ 200,860
129
-------
Table VIII-4 (Continued)
Installed
Items Capital Cost
4. General Services
Office, Laboratory, Instrument Rm. & Shop $ 109,000
Instrument Air 11,700
Instrumentation (installed) 59^00
Roads and Parking 40,300
Total $ 220,600
TOTAL DIRECT CAPITAL COST $ 1,232,500
-------
TABLE VIII-5
6 MGD ACTIVATED SLUDGE WASTE TREATMENT PLANT
COMPUTATION OF FIXED CAPITAL
Capital
Item Units Units/Year $/Unit/Yr Capital
Direct Capital $1,252,500
Allocated Capital
Electric Power K¥H 6.52 x 10s 0.008 54,000
Riverwater,
untreated MGals 1.9 x 105 0.100 19,000
Factory Expenses
1% of Direct Capital 86,300
TOTAL FIXED CAPITAL $1,391,300
131
-------
TABLE VIII-6
6 MGD ACTIVATED SLUDGE WASTE TREATMENT PLANT
ESTIMATE OF OPERATING COST
Cost Items
Raw Materials
HC1, 38$ solution
H3P04, 75xo solution
Liquid Ammonia
Operating Labor (4 man-yrs.)
Maintenance
Power
Untreated River Water
Factory Expense
Taxes and Insurance
Quantity
Units/Yr.
2.87 x 10
3.47 x 105
9.65 x 105
Units
Lbs .
Lbs .
Lbs.
Cost
$/Unit
0.015
0.0695
0.032
Cost
$/Year
$431,000
24,100
30 , 900
54,000
of Process Equip. Capital 49,800
6.52 x 10s KWH 0.0054 35,200
1.9 x 105 MGals 0.0145 2,800
2.6% of Direct Capital 31,700
1.1$ of Direct Capital 13,400
Depreciation
Site preparation, Ponds
and Buildings
Process Equipment
TOTAL OPERATING COST
$402,500 at 5$ per year
$830,000 at 10$ per year
20,100
83,000
$775,000
TOD removed per year
Cost per pound TOD removed
Propylene glycol production
Cost per pound propylene glycol produced
2.4 x 107 Ibs.
$ 0.0323
4.38 x 108 lba/yr.
$ 0.00177
132
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SECTION IX
ACKNOWLEDGMENTS
The work reported was performed at the Texas Division of The
Dow Chemical Company by Dr. M. A. Zeitoun, the principal in-
vestigator, C. A. Roorda, -I. C. Williams., R. W. Murray, and
W. D. Spears. W. F. Mcllhenny was the Project Director.
Dr. W. A. Taber of Texas A. & M. University was a consultant
on the microbiology and holder of a subgrant.
The project was partially supported by a Class V
Development and Demonstration Grant from the Office of Research
and Monitoring, Environmental Protection Agency. The advice
and assistance of the following personnel connected with the
granting agency is gratefully acknowledged: Lawrence Lively
and Frank Mayhew of the Robert S. Kerr Water Quality Research
Center, Ada, Oklahoma and George Rey and W. J. Lacy of the
Applied Science and Technology Branch, Technology Division,
Washington, D. C.
A special acknowledgment is due to -James A. Horn, the EPA
Project Officer in Ada, Oklahoma, whose advice was invaluable
throughout the project and who reviewed the final manuscript.
133
-------
SECTION X
REFERENCES
Bergey's Manual of Determinative Bacteriology, 7th Edition,
Williams and Wilkins Co., Baltimore.
Bhatla, M. N., V. T. Stack and R. F. Weston. "Design of
Wastewater Treatment Plants from Laboratory Data", JWPCF,
Vol. 38, No. 4, pp. 601-61^. (1966).
Busch, A. W. "Process Kinetics as Design Criteria for Bio-
oxidation of Petrochemical Wastes", J. of Engineering for
Industry. (May 1963).
Davison, R. R., W. H. Smith, Jr. and D. W. Hood. "Structure
and Amine Water Solubility in Desalination by Solvent Extrac-
tion", Jour. Chem. and Eng. Data, Vol. 5, No. 4, p. 420.
(I960).
Dickenson, R. L. and J. L. Giboney. "Stabilization of
Refinery Wastewaters with the Activated Sludge Process;
Determination of Design Parameters", paper presented at
the 25th Purdue Industrial Waste Conference, Lafayette,
Indiana. (May 1970).
Eckenfelder, W. W., Jr. and D. J. O'Connor. "Biological
Waste Treatment", The Macmillan Company, New York. (1961).
Ford, D. L. and W. Jewell. "Preliminary Investigational
Requirements—Petrochemical and Refinery Waste Treatment
Facilities", Report No. 12020 EID 02/71, Environmental
Protection Agency. (January 1971)-
FWPCA, Robert S. Kerr Water Research Center. "Laboratory
Quality Control Manual". (1969).
Hatfield, R. "Biological Oxidation of Some Organic Compounds",
Industrial Engineering Chemistry, Vol. 49, p. 192. (1957).
Ludzack, F. J. and D. K. Noran. "Tolerance of High Salinities
by Conventional Wastewater Treatment Processes", JWPCF,
Vol. 37, No. 10, pp. 1404-1416. (1965).
Marian, C. V. and G. W. Maloney. "The Oxidation of Aliphatic
Compounds by Alcaligenes Faecalis", JWPCF, Vol. 35, p. 1269.
(1963).
135
-------
Mills, E. J. and V. T. Stack. "Biological Oxidation of
Synthetic Organic Chemicals", Proceedings, 8th Industrial
Waste Conference, Purdue University, Extension Series No. Qj>,
p. 492. (1954).
Mulbarger, M. C. and J. A. Castelli. "A Versatile Activated
Sludge Pilot Plant—Its Design, Construction and Operation",
Proceedings, 21st Waste Conference, Purdue University,
Extension Series Wo. 121, pp. 322-337. (1966).
Placak, 0. R. and C. C. Ruchholt. "Studies in Sewage
Purification, XVII. The Utilization of Organic Substrates
by Activated Sludge", Sewage Works Journal, Vol. 19, p. 4-23.
(1947).
Sourirajan, S. and S. Kimura. I.E.G. 6, Proc. Design Develop.,
No. 4, p. 504. (October 1967).
Symons, J. M., R. E. McKinney and H. H. Hassis. JWPCF,
pp. 841-851. (August 19 0).
Yuzaburo Ishida and Tateo Fuji. "isolation of Halophilic and
Halotolerant Bacteria from Solar Salt", Bulletin of the
Japanese Society of Scientific Fisheries, Vol. 36, No. 4.
(1970).
Zeitoun, M. A. and R. R. Davison. "Clean Water by Extraction",
Chem. Eng. Progress, Vol. 60, No. 12, pp. 51-54. (1964).
136
-------
SECTION XI
APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Development of Analytical Methods
Activated Sludge Pilot Plant
Operation
Characteristics of Bacteria From
the Activated Sludge Pilot Plant
Design Calculations and Cost
Estimates of a 6 MGD Activated
Sludge Plant
Microbial Metabolism of Ethylerie
and Propylene Glycols in Presence
of Sodium Chloride. "Abstract" by
Dr. W. A. Taber
137
-------
Appendix A. Development of Analytical Methods
Standard analytical procedures were used for the routine
analyses of % NaCl, total dissolved solids (TDS), pH, excess
alkalinity as NaOH, and specific gravity. Trace metal ions
in a typical waste stream were measured by emission spec-
troscopy. Periodic analyses of added nutrients included
total nitrogen by Kjeldahl, ammonia nitrogen by Nesseri-
zation and total phosphorus by the stannous chloride method.
The analyses of the organic constitutents of petrochemical
wastewaters are more difficult to perform and to interpret.
The characterization of the organic content of the waste-
water resulting from the production of ethylene and propylene
glycols required the development of gas chromatographic
methods to identify the organic components. There are many
limitations of the standard methods of characterizing wastes
such as BOD and GOD. The instrumental methods that determine
total organic carbon (TOG) and total oxygen demand (TOD) were
found to be more effective than BOD and COD for correlation
of the laboratory and pilot plant data.
Chemical Oxygen Demand (CODJ
The standard dichromate COD test was found to be unsuitable
because of the very high concentration of chloride ion in
the waste stream. The 2-hour permanganate COD test was
used instead and yielded values slightly lower than the in-
strumental TOD values.
Biochemical Oxygen Demand (BOD)
The standard 5-day BOD test was conducted on samples of the
waste streams using a sewage seed acclimated for at least
three days to the diluted waste. Biological oxidation over
a 10-day period was determined in BOD bottles with solutions
of the organic components known to be present in the waste
streams. Solutions containing 100 ppm. of each compound were
prepared and diluted 15 times in the BOD bottles and 1 ml. of
an acclimated sewage sludge seed was added to each of 10
bottles for each compound tested. A seed from the treatability
tests that had been acclimated to the actual waste over a period
of two months was also used to determine the 10-day biological
oxidation curve for the organic components of the waste stream.
Total Oxygen Demand (TOD)
A Dow-TOD analyzer was used for the analyses of the total
oxygen demand of the waste samples. A micro sample is in-
jected into a catalytic combustion tube enclosed by an elec-
tric furnace thermostated at 900°C. A carrier gas of nitrogen
15*
-------
containing about 200 ppm. oxygen flows through a caustic
scrubber to an oxygen silver-lead fuel cell. The amount of
oxygen consumed by the sample is directly proportional to
the concentration of the oxygen demanding organics in the
sample. The wastewater from the glycol production contains
no nitrogeneous organics that would interfere. This analytical
method was adopted as the principal measure of the organic
content of the raw and processed wastewaters.
Total Organic Carbon (TOG)
A Dow-Beckman Carbonaceous Analyzer was acquired during the
operation of the activated sludge pilot plant and used for
the analyses of the process streams. The method entails the
injection of a micro sample into a catalytic combustion tube
at 950°C. The carbonaceous material is oxidized to carbon
dioxide in a carrier stream of pure oxygen. The amount of
C02 produced is directly proportional to the amount of car-
bonaceous material in the injected sample and is measured
by a sensitized infrared analyzer. Samples were acidified
and stripped with nitrogen gas blown through to free the
sample from inorganic carbon before injection into the TOG
instrument.
Organic Components by Vapor Phase Chromatography (VPG)
A two-column, two detector, VPC unit was purchased from the
Antek Company of Houston, Texas. The main column used is a
1/8-inch stainless steel thin wall, 36 inches long, packed
with Purapak Q (available from Waters Associates) plus 15$
by weight of E-20,000 (polyethylene glycol, average molecular
weight 20,000). The column temperature is maintained at about
150°C. and the hydrogen-air flame ionization detector at about
l8o°C. Helium is used as the carrier gas at a flow rate of
60 to 80 milliliters per minute.
This column was capable of separating all of the five principal
components in the hydrolyzer wastewater except the ether which
has the longest retention time. Another 24-inch long column
packed with 25$ by weight of the liquid phase E-20,000, and
using a 30 ml./minute carrier gas flow rate, was used to
separate the ether.
The VPC analysis of a mixture of ethylene glycol and propylene
glycol required a more polar column for the separation of the
two glycols. A 5-foot, 1/8-inch column packed with 120-150
mesh Purapak Q, without any liquid phase, was used success-
fully to separate the two glycols and their corresponding
chlorohydrins. The column packing had to be replaced once
a month as it loses its polarity with time.
139
-------
Glycol Analysis by Periodate Oxidation
This method of analysis is specific for glycols having
hydroxyls on adjacent carbons. The oxide and the chlorohydrin
are also detected if hydrolyzed to the glycol in acid solution
prior to the periodate oxidation test.
A 10 ml. aliquot of the diluted sample is reacted with 50 ml.
of 0.4 N sodium periodate (NaI04) solution for 1 hour. The
reaction mixture is diluted with 150 ml. distilled water,
followed by 20 ml. of 20$ sulfuric acid and 40 ml. of J>Q%
potassium iodide solution. The reaction mixture is then
titrated with standardized 0.2 N sodium thiosulfate using
2 ml. of starch solution as a final indicator. A reagent
blank is run concurrently and the percent glycol in the
sample is calculated from the difference between the blank
and the sample titrations.
Total Suspended and Volatile Suspended Matter
The wastewater contains negligible amounts of suspended
matter (less than 10 mg./l.). The mixed liquor suspended
solids (MLSS) and mixed liquor volatile suspended solids
(MLVSS), were determined using a millipore filtering apparatus,
A comparison of the use of a 0.45|_i millipore filter and a
Gooch crucible is given in Table XI-1.
The variation in the MLSS is higher than the MLVSS due to
the error introduced by the washing of the salt content on
the filter paper. The MLVSS values are more reliable, and
duplicates agree better than do the MLSS values.
Dissolved Oxygen
Measurements of dissolved oxygen (DO) in the samples from
the activated sludge mixed liquor were made using a YSI model
51A oxygen analyzer. The instrument was calibrated against
the. azide-alum flocculation modification of the Winkler
analysis and this calibration, at the saturation oxygen con-
centration, was used to apply the corrections for the chloride
ion concentration in the samples.
The temperature calibration of the instrument was checked
daily with distilled water exposed to water-saturated air.
Gentle swirling of the probe was found necessary to obtain
consistent oxygen readings. High readings could be due to
air bubbles sticking on the membrane surface of the probe,
and low readings could result from a liquid film depleted
of oxygen at the membrane surface.
140
-------
TABLE XI-1
DETERMINATION OF SUSPENDED SOLIDS
COMPARISON OF METHODS
Mixed Liquor
Mixed Liquor Volatile
Suspended Solids Suspended Solids
Sample No. Gooch Millipore Gooch Millipore
1 1283 1250 1109 1033
2 2004 1824 1709 1484
3 2374 2452 2150 2193
4 2719 2606 2467 2402
All values in milligrams per liter, triplicate average.
141
-------
Quality Control of Laboratory Analyses
A quality control program was initiated during the first few
months of this investigation. The total oxygen demand (TOD)
and the glycol concentration by gas chromatography were the
two main analyses checked daily against precision charts.
Twenty duplicate pairs of each analysis were used to con-
struct precision control charts (FWPCA-1969). Figures XI-1
and XI-2 show these charts for the TOD and glycol by VPC
analysis, respectively. Based on the initial twenty pairs
of samples, a standard deviation of 27 mg./l. of glycol was
determined for the VPC analysis, and of 40 mg./l. for the
TOD instrument. Results of duplicate samples plotted as
cumulative squared differences indicated more precision than
the original 20 duplicates used to construct the chart.
Accuracy control charts for TOD and glycol by VPC were also
constructed from a set of sixteen standard solutions pre-
pared by the Central Laboratories of the Texas Division of
The Dow Chemical Company. The upper and lower limits of the
accuracy charts are:
TOD accuracy chart; S^ = 99 mg./l.
U.L. (M) - 50 x 10s + 9-2 x 103 (M)
L.L. (M) - -50 x 103 + 9.2 x 103 (M)
Glycol, VPC accuracy chart; S^ = 4^ mg./l.
U.L. (M) - 9.4 x 103 + l.?4 x 103 (M)
L.L. (M) - -9-4 x 103 + 1.74 x 103 (M)
The quality control program is believed to have served two
important purposes. First, it created an atmosphere of
awareness among the analysts, and secondly, it increased
our confidence in the numbers generated by the analytical
methods used.
-------
Figur. XI-1
PRECISION CONTROL CHART - TOD ANALYSIS
RANGE 50-2500 mg/l
Nov. 18, 1969
JOO
,300
+200
400
0
.100
.200
-300
Sd = 40 mg/l TOD
= 158xl03 + 29xlOs(M)
= -158xlOs+29xl08(M)
Duplicate Sample No.
10
-------
Figur, XI-2
PRECISION CONTROL CHART - GLYCOL VPC ANALYSIS
RANGE 200-2000 mg/l
Dec. 7, 1969
~ = 0.1 /3 = 0.1
S,j = 27.0 mg/l glycol
UL = 73.8 x 10s + 13.6 x 10s (M)
LL = -73.8 x 103 + 13.6 x 10s (M)
10
Duplicate Sample No.
-------
Appendix B. Activated Sludge Pilot Plant Operation
The detailed analytical results and daily measured and de-
rived values obtained during pilot plant operation are tabu-
lated in this appendix. Three operating periods, June 24 to
August 27, 1970, September 10 to November 6, 1970, and
November 20 to December 28, 1970, are given in Tables XI-2,
XI-3, and XI-4, respectively. The nearly steady state
operation of the plant under controlled conditions, from
December 29, 1970 to February 28, 1971, is given in Table
XI-5-
145
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159
-------
Appendix C. Characteristics of Bacteria From the
Activated Sludge Pilot Plant
Fresh activated sludge samples were plated out on nutrient
agar containing both ethylene glycol and propylene glycol.
The medium contained b% NaCl and the dilutions were made at
different concentrations up to 10$ NaCl. One ml. samples
were ]^"aced in sterile plastic petri-dishes, and were over-
layed with 10 ml. of molten agar. The plates were incubated
at room temperature (?7°C). Each dilution was plated in
triplicate. Forty-eight isolates were made from these
samples and identified by number. Standard biochemical tests
used in bacterial taxonomy were run on the pure cultures
isolated from the activated sludge samples. These tests
were (Bergey, 1957):
Oxidative-Fermentation Test of Hugh Liefson (O.F.)
Two tubes of medium containing glucose and acidity-alkalinity
indicator are inoculated with a single bacterium. One tube
is overlayed with sterile Squibb heavy duty mineral oil to
effect anaerobic conditions. Growth in the tube only without
mineral oil is read as "oxidative" and growth in the tube
with mineral oil is read "fermentative". No indicator change
is read as no change and is represented by a dash. This
means that growth was not accompanied by production of
either acid, or bases such as ammonia.
Lactose
Lactose fermentation is indicated by a + sign and no fer-
mentation (i.e., acid or gas) is represented by a - sign.
Each culture was inoculated into indicator broth containing
a Durham tube and lactose. Acid was indicated by a change
in color, and gas by accumulation of gas bubbles in the
Durham tube immersed in the broth.
Oxidase Test
A drop of 4$ aqueous dimethyl-p-phenylenediamine-HCl was
applied to filter paper followed by a drop of the culture.
A dark blue color is a positive oxidase test and is said to
indicate the presence of cytochrome c. The test more or
less correlates with the aerobic or facultative anaerobic
state of oxidation.
Motility
Motility was determined using hanging drop slide and soft
agar. In the latter case motile cells move beyond the site
of the inoculation stab and result in turbidity extending
beyond the stab. Motility is represented by a + sign.
-------
Nitrogen Fixation
Growth in the absence of added nitrogen source is attributed
to nitrogen fixation which occurs with certain bacteria.
Nitrogen fixation is represented by a + sign.
Litmus Milk
Various reactions can take place in milk supplemented with
the litmus indicator. Loss of color is reduction, blue
color indicates base accumulation, red color indicates acid
production and coagulation represents denaturation of protein.
Acid production is represented by the letter A. and alkaline
production is represented by the letter K.
NaCl
Growth on the indicated percent NaCl is indicated by a +
sign.
Nitrate
Reduction of nitrate is indicated by a + sign. Nitrate
reduction is exhibited by certain species of bacteria.
Catalase
Catalase is present in only certain species of bacteria.
This enzyme is detected by addition of hydrogen peroxide to
a colony on agar. Bubbles indicate the action of catalase.
Chitin
Growth on washed chitin (shrimp exoskeleton) indicates
presence of chitinase. Very few bacteria synthesize
chitinase.
Urea
Hydrolysis of urea to C02 and NH3 by urease is exhibited
by some bacteria and is an important diagnostic test. Urea
hydrolysis is represented by a + sign.
Results and Discussion
The numbers of bacteria per ml. of sample, assuming one
colony from one cell, were found to vary from a low of
2 x 106 to a high of 3.9 x 108. Results of the biochemical
tests reactions for the Gram negative bacterial isolates
are given in Table XI-6. Those for the few Gram positive
isolates are given in Table XI-?. All of the bacteria, both
161
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the Gram positive and the Gram negative rods are negative for
lactose fermentation, motility, and the Hugh-Liefson fermen-
tation test.
It was concluded from the biochemical test reactions and
from colony appearance that there are no more than 2 to 4
different bacteria in these isolates from the brine acti-
vated sludge. There were a few filamentous fungal spores
and a few colonies were obtained on plating of the liquids.
The Gram positive bacterium is not prevalent. The most
numerous bacterium is a Gram negative, non-motile, lactose
negative, oxidase positive, rod. It is not the same as
Bacterium T-52 isolated from the Great Salt Lake, because
Bacterium T-52 is oxidase negative.
165
-------
Appendix D. Design Calculations and Cost Estimates
of a. b MGD Activated Sludge' Plant
The details of the design calculations, equipment specifi-
cations and the installed cost of each item of equipment
installed including the piping are presented in this section,
grouped under the pretreatment , aeration and settling, sludge
handling and general services sections.
I. Pretreatment and Cooling
The pretreatment of the glycol wastewater includes neutrali-
zation, cooling and equalization, nutrient addition, and
dilution water addition.
Neutralization
Feed rate - 6 x 10s x f^- x 1.063 x 8.34
aay ga
= 53.2 x 10s Ibs./day
Anhydrous HC1 requirement = 53.2 x 10s x ° x x 0.9
- 73,750 Ibs./day
- 2.87 x 107 Ibs./year
HC1 requirement = 78,750 x x
= 21,000 gallons /day =14.5
Cost of HC1 at 0.015 $/Lb. = 2.87 x 107 x 0.015
- 431,000 $/yr.
166
-------
D-l Surge Tank for 38$ Hydrochloric Acid
'necifications:
Volume 30,000 gallons
Dimensions 18 ft. diameter x IS ft. high
Lining rubber
Tntalled Cost Breakdown:
tem
^0,000 gal. rubber
lined tank
Foundation
Site preparation R-
leveling
Painting
Piping & fittings
Cost Distribution ($j
Quantity Units Labor Material Rental Total
1 each 2,000 13,000
400 sq.ft.
1500 sq.ft.
100 ft.
120
40
600
300
160
600
300
4o
40
Total Rentals
Total Materials
Total Labor
3,o6o
I4,o6o
5 80
14,060
3,060
Contractor's Allowance
of Materials
of Rentals
1,070
2,540
90
Total Allowance
3,700
3,700
JOB COST
$20,820
Engineering,
Contingencies,
3,130
3,130
TOTAL INSTALLED COST
$27,100
167
-------
P-1A, P-1B Hydrochloric Acid Pumps
Specifications: Each of two pumps to deliver 16 gpm. of
38$ HCI at 30 psi. Goulds Model 310?
Teflon lined, 1x1x6, driven at 3600
rpm. "by 5 H.P. Class I, Group D electric
motor. Pump equipped with John Crane
mechanical seal (8 x PICK) or equivalent.
Installed Cost Breakdown:
Cost Distribution ($)
_ Item _ Quantity Units Labor Material Rental Total
Pump 4- motor 2 each 592 2,040
Foundation 2 cu.yd. 40 40
Electrical 10 KVA 250 250
Painting 50 sq.ft. 20 20
Piping Hf fittings 100 ft. 300 300
Total Materials 2,650 $ 2,650
Total Labor 1,202 1,202
Contractor's Allowance
35$ of Labor 420
18$ of Materials 480
Total Allowance 900 900
JOB COST $ 4,752
Engineering,
Contingencies, 15$
TOTAL INSTALLED COST $ 6,l80
168
-------
C o o 1 i n g _ an d E q u a 1 1 j: a t L o n
r]'he base of design of a cooling and equalization r»
chosen for operating conditions during the summe--
Wastewater flow., F - 4,200 gal./min.
Inlet temperature, TI - l8o °F
Outlet temperature, T2 - 10 3 °r'
Dry-bulb air temperature
0 day max. avg.) =
Relative humidity, R.H. -
W ind vr "i oc i t y , Vw
(daily avg. ) -
Solar heat gain, Qs
(2^ hr . avg. )
Hold-up time
The cooling pond surface area is determined iY< -y}
found on pages 15-22 and 15-2? of Perry's Chemical
Handbook, 4th Edition.
The P factor found is P4 and the Q factor is O.'7ri.
Surface area - F x PQ = 4200 x 0.r'5 x S4
- 263,600 sq. ft.
Volume =2x6- 10s - 12 x 10s gallons
- 1.6 x 106 cu. ft.
The cooling pond and the aeration basin share a common wall,
through which a 3 ft. x ? ft. Parshall flume is installed to
conduct the feed to the aeration basin. The sljpe of the levees
is 2 ft. horizontally to 1 ft. vertical rise, which provide0
long-term stability with minimum erosion due to storm wart-;/'
run-off. The two basins are designed such that the excavated
depth generates the dirt required for the above-grade earthen
.Levees. A computer program was used for ches^ calculation-'.
169
-------
iT.C-1 Equalization and Cooling Pond
Specifications
Surface area
Bottom width & length
Top inside width .?• length
Total depth of pond
Levee height above grade
264,800 sq. ft.
Ji8rJ ft.
6.
7 ft.
Film (0.03 in. thick),
covered surface area 272,460 sq. ft,
Installed Cost Breakdown:
Item
Cost Distribution ($)
Quantity Units Labor Material Rental
5528 cu.yd. 2210 1550
3 560
Excavation
Spreading & compacting 12,735 cu.yd. 2100
Film lining of bottom
& sides 272,455 sq.ft 65,400 43,600
Concrete for Parshall
Flume
40 cu.yd 800 1,000 200
Total
Total Rentals
Total Materials
Total Labor
73510
5310 $ 5,310
4^,600 U4,600
73,510
Contractor's Allowance
35$ of Labor
18$ of Materials
105$ of Rentals
25,700
8,030
5,580
Total Allowance
39,310
39,310
JOB COST
$162,730
Engineering, 15$
Contingencies, 15$
24,410
24,410
TOTAL INSTALLED COST
170
•211,550
-------
Nutrient Addition
Ammonia and phosphoric acid are added to the aeration basin to
supply the nitrogen and phosphorus at a concentration of each
in proportion to the TOD removed.
TOD removed
= 53-2 x 10
= 67,000 Ibs./day
-) x (1400-140) x 10'
Anhydrous ammonia
requirement
67,000 v 17
30 x IT
2720 Ibs./day
Cost of ammonia
= 2720 x , = 527 gallons/day
J ' -LD
- 0.366 gpm.
x 0.032
- 2720 ^ x ,65
= 30,900 $/year
Phosphoric acid
(75$ H3P04) re-
quirement
= 67,000 v 98 100
300 31 75
= 950 Ibs./day
= 95° x
-^ gallons/day
=0.05 gpm.
Cost of phosphoric
acid
950
•^^
x
365
-^
day - yr
24,100 $/year
0.0695
"^
171
-------
D-2 Ammonia Storage Tank
Specifications:
Volume 10,000 gallons
Pressure vessel designed for 600 psi.
Dimensions 8 ft. diameter x 24 ft.
long horizontal tank
Material carbon steel
Installed Cost Breakdown:
Total Rentals
Total Materials
Total Labor
Cost Distribution ($)
Item
Pressure vessel
Foundation
Insulation
Paint
Piping & fittings
Quantity Units Labor Material Rental Total
1 each 2800 14,000
60 cu.yd. 900 1,200 300
800 sq.ft. 2000 2,000
800 sq.ft. 320 320
100 ft. 800 800
300 $ 300
18,320 18,320
6820 6,820
Contractor's Allowance
Labor
Materials
Rentals
2,400
3,300
320
Total Allowance
6,020
6,020
JOB COST
$31,160
Engineering,
Contingencies,
4,670
4,670
TOTAL INSTALLED COST
$40,500
-------
D-4 Phosphoric Acid Storage Tank
Specifications:
Volume
7,500 gallons
Dimensions 11 ft. diameter x 11 ft. hi,--
Material
316 stainless steel
Installed Cost Breakdown:
Item
Vessel
Leveling & site
preparation
Concrete
Painting
Piping 4 fittings
Cost Distribution ($)
Quantity Units Labor Material Rental
1 each 2500 11,000
200
2 cu.yd.
q.ft. 20
10
600 sq.ft. 240
100 ft. 400
10
Total Rentals
Total Materials
Total Labor
3200
11,720
Contractor's Allowance
35^ of Labor
18$ of Materials
105$ of Rentals
2,110
10
Total Allowance
3,240
JOB COST
$18,l
Engineering,
Contingencies,
TOTAL INSTALLED COST
$23,600
173
-------
P-4A and P-4B Phosphoric Acid Pumps
Specifications:
Each of two pumps circulating 75$ H3PC>4
at a rate of 5 gpm. over a constant head
device (60 ft. head). A feed rate of
0.05 gpm. from this loop is controlled by
a signal from a flow recorder controller
(FRC-4).
Goulds Model 2520, j5l6 stainless steel
self-priming centrifugal pumps with 5 H.P.,
1750 rpm. motor,, Faulk coupling and Crane
9TQP1C1 mechanical seal or equivalent.
Installed Cost Breakdown:
Item
Pump & motor
Foundation
Electrical
Painting
Cost Distribution ($)
Quantity Units Labor Material Rental
2 each 440 1,530
2 cu.yd. 90 90
10 KVA 250 250
100 sq.ft. 40 40
Piping & fittings (SS) 150 ft.
430
900
Total
Total Materials
Total Labor
1,270
2,810
2,810
1,270
Contractor's Allowance
35$ of Labor
18$ of Material
445
506
Total Allowance
951
951
JOE COST
$ 5,031
Engineering,
Contingencies, 15$
755
754
TOTAL INSTALLED COST
$ 6,540
174
-------
Dj-lution Water
Dilution water is added to replace the water lost by evaporation
in the cooling pond in order to maintain the salt content at
9fo and to supply the trace minerals required for bacterial
growth.
Assuming 1000 BTU/lb. of water vaporized to cool the waste-
water from l8o°F. to 100°P., then:
Heat loss - 53.2 x 10b (^™) x (l8o-100) (°F.)
1 r, BTU
x 1'° Ib. OF.
= 4.256 x 109 BTU/day
Water lost by 4 2 6 x 1Q9
evaporation = iooo ~ ^-256 x 10s Ibs./day
= 2,960 Ibs./min.
River water re-
quirement - 2960 Ibs./min.
= 355 SP^-
Seawater (2.5$ salt) requirement is calculated from a salt balance:
36,900 x 0.09 + W x 0.025
(3^,900 -2, 9bO) + W U'0y
therefore:
W = 4100 Ibs./min = 48o gpm.
175
-------
P-6A and P-6B Dilution Water Pumps
Specifications:
Each of two pumps to deliver 800 gpm. at
26 psi. Goulds Model 3196, 4 in. x 6 in.
x 12.75 in. (CDS 1784), driven at 1150 rpm
t>y 20 H.P. electric motors.
Installed Cost Breakdown:
Item
Pump & motor
Foundation
Electrical
Painting
Piping & fittings
(8 in. pipe)
Cost Distribution ($)
Quantity Units Labor Material Rental
2 each 1,000 2,600
Total
2
40
150
50
cu.yd.
KVA
sq. ft.
ft.
50
800
60
400
50
800
60
400
Total Materials
Total Labor
3,910
2,310
$ 3,910
2,310
Contractor's Allowance
35$ of Labor
of Materials
810
705
Total Allowance
1515
1,515
JOB COST
$ 7,735
Engineering,
Contingencies,
1,163
1,162
TOTAL INSTALLED COST
$10,060
176
-------
II. Aeration and Settling
The neutralized and cooled wastewater is fed to the aeration
basin through a Parshall flume from the cooling pond. The
nutrients and dilution water are mixed in the aeration basin.
The overflow from the aeration to a clarifier is separated
into settled sludge and treated effluent.
Aeration Basin
The aeration basin is designed to remove 90$ of the TOD in the
feed and produce an effluent of average TOD concentration of
140 ppm.
Feed rate
TODf
TODe
Recycle ratio
TOD,
= 4200 gpm.
= 1400 ppm.
= 140 ppm.
25 %
1400 + 0.25 (140) , , rr,
= Ij2 = 1150 ppm.
For a mixed liquor volatile suspended solids (MLVSS) of
1500 ppm:
TODi _ ~ Tope =
TQD
VMLVSS'
(Fig
, vr_Lg
VIT-lo)
vj-i. _LO;
. 0.412
therefore:
t
f
Volume of basin
7.1 hours
8.86 hours, based on feed rate.
4200 x 60 x 8.86 = 2,300,000 gallons
300,000 cu. ft.
177
-------
Weight TOD Ioo ,0
removed = 5^.2 x 10s x 14U^b = 07, 200 Ibs. /day
Weight of Mixed
liquor in basin = 2.3 x 10s x 8.87
= 19-7 x 10s Ibs.
Weight of MLVSS in
basin - 19.7 x 10s x 1500 x 10
= 29,500 Ibs.
Loading = = 2>2g lbs> TOD removed/lb.
MLVSS -day
Oxygen Requirement
Lbs. oxygen consumed
per day = 0.256 (Ibs. TOD removed/day) +0.13
(Ib. MLVSS)
= 21,000 Ibs./day
N
where:
N = Ibs. oxygen consumed per day
= 21000 Ibs./day
No - Ibs. oxygen transferred per day to
clear water at 20°C.
= saturation value of oxygen in the
waste at temperature t. (3-5 ppm.)
CL = operating dissolved oxygen level
(1.0 ppm.)
CSH 0 = saturation value of oxygen in tap
2 water at 20°C. (9-2 ppm.)
a = oxygen transfer coefficient for the
treated wastewater = 1.2
t = temperature of the aeration basin
- 85°F. = 29.4°C.
176
-------
9-2 x 21,000
° (5-5-1.0) (1.
= 49,700 Ibs. 02/day
= 2,070 Ibs. 02/hr.
Brake H.P. required - 24°o° - 648 H.P.
.? • <-
Surface aerators, (9 x 75 H.P.), rated at 3.2 Ibs. of oxygen
transfer per hour per brake horse power are required.
179
-------
A-6 Aeration Basin
Specifications:
Volume
Bottom width & length
Top inside width & length
Total depth
Levee height above grade
Water depth
Freeboard above water level
300,000 cu.
129 ft.
189 ft.
15 ft.
6.7 ft.
12.5 ft.
2.5 ft.
ft.
Installed Cost Breakdown:
Item
Cost Distribution
Excavation
Spreading & com-
pacting
Film lining of bottom
% sides
Concrete base under
aerators
Floating surface
aerators
Mooring cables %
anchores
Electrical
Painting
Piping (18 in. under-
ground)
Total Rentals
Total Materials
Total Labor
Contractor's Allowance
35$ of Labor
of Material
of Rentals
Quantity Units Labor Materia_l Rental Total
6,567 cu.yd. 2,630 1,840
5,263 cu.yd, 2,100 1,470
38,069 sq.ft. 9,150 6,100
67 cu.yd. 1,000 1,350 350
9 each 4,500 6^,500
9
600
2 ,000
100
each
KVA 1 5
sq.ft.
ft. 1
37
450
,000
800
,500
,130
540
15,000
800
1,500
3,660
92,790
$ 3,66o
92,790
37 , 130
13,000
16,700
5,100
ifio
_ "3 4 ^800
$^ £\ Jl ^f^ f\
104,780
-------
A-6 Aeration Basin (Continued)
Engineering, 15% 24,6';0
Contingencies, 15$ 24,600
TOTAL INSTALLED COST $214,000
181
-------
Clarifier
The data presented in Figure VII-24 is used to design the
clarifier.
Overflow rate, (O.K.) - d x 7-48 x 1440 gal>/day/ft.2
where
d = depth of the experimental column
= 6 ft.
t = settling time in minutes.
Using the method described by Ekenfelder (1962), the following
table can be calculated from the data of Figure VII-24.
Time (min.) Velocity ft./hr. Removal % O.K. gal./ft.2/day
10 36 49 6,500
15 24 75 4,300
21 17 90 3,000
For 90% removal,
O.K. = 3,000 gpd/ft.2
t = 21 minutes
Using a scale-up factor of 2.0,
O.K. = 1,500 gpd/ft.2
t = 42 minutes
For a Dorr-Oliver Glarifier, 75 ft. diameter and 6 ft. deep,
surface area = 4,400 sq. ft.
O.R. = 04*0o°6 = 1370 gpd/ft.2
volume = 26,400 cu. ft. = 197,500 gallons
retention time, t - ' 6° = 47 minutes
182
-------
CL-7 Clarifier
Specifications:
Concrete base, steel tank with raking
arms and sludge vacuum pick-up. (Dorr-
Oliver or equivalent) .
Diameter
Depth
75 ft.
6 ft.
Installed Cost Breakdown:
Item
Excavation
Reinforced concrete
Clarifier, tank, rakes,
etc.
Electrical
Piping & fittings
Painting
Total Rentals
Total Materials
Total Labor
Cost Distribution ($)
Quantity Units Labor Material Rental Total
800
100
1
5
140
2,000
cu.yd. 320
cu.yd. 1,500 2,000
each 29,000 112,500
KVA 350 350
ft. 1,660 1,660
sq. ft. 800 800
117,310
33,630
224
SOO
724 724
$117,310
33,630
Contractor's Allowance
35$ of Labor
18$ of Materials
105 of Rentals
11,760
21,100
760
Total Allowance
JOB COST
33,640
33,64o
$184,580
Engineering,
Contingencies,
27,700
27,700
TOTAL INSTALLED COST
$239,980
-------
P-7A and P-7B Sludge Recycle Pumps
Specifications:
Each of two pumps to deliver up to 2400 gpm.
of sludge at 15 psi.
Goulds Model 3175 (CDS 1998) or equivalent,
8_in. x 10 in.-l8 in. powered by 40 H.P.,
rpm. electric motors.
Installed Cost Breakdown:
Item
Pumps & motors
Foundation
Electrical
Painting
Piping & fittings
Cost Distribution ($)
Quantity Units Labor Material Rental Total
2 each 2,000 6,450
2 cu.yd. 50
100 sq.ft. 40
50 ft. 800
50
KVA 1,600 1,600
40
Total Materials
Total Labor
4,490
8,Q4o
8,9^0
4,490
Contractor's Allowance
of Labor
of Materials
1,570
1,610
Total Allowance
3,180
3,180
JOB COST
$16,610
Engineering,
Contingencies,
TOTAL INSTALLED COST
2,490
2,500
$21,600
134
-------
Sludge Recycle
The sludge blanket in the clarlfier is calculated to be about
1.25 feet deep. The concentration of MLVSS in the sludge
return averages about 7000 ppm. The flow of 2^$ recycle is
3050 gpm., and is pumped from the clarifier to the aeration
basin.
III. Sludge Handling
The excess sludge formed is calculated using data shown in
Figure VII-22.
Lbs. VSS formed/day = 0.137 (Ibs. TOD removed/day)
- 6.04 (MLVSS)
therefore:
Excess sludge = 0.133 (67,000) - 0.04 (29,500)
= 7730 Ibs./day
= 5-37 Ibs./minute
This excess sludge is removed in a stream from the sludge
recycle, having the same concentration of about 7000 ppm. of
volatile suspended solids. This flow of 92 gpm. is thickened
to a 3.2$ solids and centrifuged to 18% solids, then hauled to
landfill.
Sludge Thickener
The sludge was found to compact to a 3-2$ solids. A sludge
thickener for this sludge is designed for an overflow rate of
400 gals./day/ft.2 and a residence time of 2 hours.
Underflow from
thickener = 20.2 gpm., (3.2$ solids)
Overflow from
thickener =92 - 20.2 - 71.8 gpm.
Surface area = 71"\o014^0 = 259 sq. ft.
Volume = 2 x 60 x 92 = 11,040 gallons
= 1474 cu. ft.
Depth = iffi- - 6 ft.
Diameter
-------
Centrifuging
Limited laboratory experiments showed the sludge to centrifuge
to 18$ to 20fo solids, easier than filtration.
The overflow from the centrifuges will be l6.6 gpm. while the
sludge discharged at 18$ solids will be about 3-6 gpm.
IV. General Services
Included under general services are the piping not included
in equipment installation costs, buildings for office,
laboratory and instrument room, control instruments and roads
and parking lots.
-------
THK-8 Sludge Thickener
Specifications:
Diameter - 18 ft.
Surface area = 254 ft.2
Depth = 6 ft.
Overflow rate = 400 gpd/ft.2
A Dorr-Oliver settling tank with mechanical
raking arms.
Installed Cost Breakdown:
Item
Tank & rakes
Concrete
Electrical
Painting
Piping & fittings
Total Materials
Total Labor
Contractor's Allowance
35% of Labor
of Materials
Total Allowance
JOB COST
Engineering,
Contingencies,
TOTAL INSTALLED COST
Cost Distribution ($)
Quantity
1
6
10
1500
240
)
Units Labor Material
each 5,300 27,000
cu.yd. 150 150
KVA 2 50 2 50
sq.ft. 600 600
ft. 660 700
28,700
7,060
2,470
5,170
7,64o
Rental Total
$28,700
7,060
7,640
$43,400
6,500
6,500
$56,400
187
-------
CF-9AXB Centrifuges
Specifications:
Each of two centrifuges of 20-40 gpm.
capacity driven by a 25 H.P. motor at an
operating speed of 3000 to 6000 rpm.
Dorr-Oliver Model 12-L or equivalent.
Installed Cost Breakdown:
Item
Centrifuge
Electrical
Foundations
Painting
Piping PC fittings
Cost Distribution ($)
Quantity Units Labor Material Rental Total
2 each 7,000 70,000
KVA 1,500 1,500
cu.yd. 600 600
sq.ft. 400 400
each 4,000 4,000
60
30
1000
2
Total Materials
Total Labor
13,500
76,500
$ 76,500
13,500
Contractor's Allowance
35% of Labor
I&fo of Materials
Total Allowance
JOB COST
Engineering,
Contingencies,
TOTAL INSTALLED COST
4,800
13,700
18,500
18,500
$108,500
16,250
16,250
$141,000
188
-------
P-8A and P-8B Sludge Pumps Forwarding Prom Thickener
To Centrifuges
Specifications:
Each of two pumps delivering 20-40 gpm. c
sludge (3-2$ solids) at 40 psi.
Goulds or equivalent, Model 3196, 1 x 1-1,
8 powered by 5 H.P. motor at 1750 rpm.
Installed Cost Breakdown:
Item
Pump & motor
Foundation
Electrical
Painting
Cost Distribution ($}
Quantity Units Labor Material Rental TotcuL
2 each 400 1,070
2 cu.yd. 50 50
10 KVA 250 250
100 sq.ft. ho 40
Total Materials
Total Labor
740
1,410
Contractor's Allowance
35^ of Labor
of Materials
260
250
Total Allowance
510
510
JOB COST
Engineering,
Centingencies,
400
TOTAL INSTALLED COST
-------
P-9A and P-9B Pumps for Overflow From Thickener
and Centrifuges
Specifications:
Each of two pumps to deliver l6o gpm. at
73 psi.
Goulds Model 3196, 316 S.S., 2x^-8
(6-1/2 in.) driven by 20 H.P. 3500 rpm.
electric motor.
Installed Cost Breakdown:
Item
Pump & motor
Foundation
Painting
Electrical
Piping & fittings
Cost Distribution ($)
Quantity Units Labor Material Rental Total
2 each 1,030 2,450
50 50
30 30
2 cu.yd.
75 sq.ft.
40 KVA 1,000 1,000
50
ft.
250
250
Total Materials
Total Labor
2,360
3,780
3,780
2,360
Contractor's Allowance
of Labor
of Materials
826
681
Total Allowance
JOB COST
1,507
1,507
$ 7,647
Engineering,
Contingencies,
1,142
1,141
TOTAL INSTALLED COST
9,930
-------
Piping Not Included With Equipment
Installed Cost Breakdown:
Item C
14 in. pipe to cooling
pond includes one
overhead road crossing
and one valve.
14 in. pipe recycling
sludge from clarifier
to aerator.
8 in. pipe for
dilution water
Total Materials
Total Labor
Contractor's Allowance
35$ of Labor
of Materials
Cost Distribution
Total Allowance
JOB COST
Engineering,
Contingencies,
.ntity Units Labor Material Rental Total
20
400
160
ft. 3,360 3,360
ft. 7,200 7,200
ft. 3,330 3,330
13,890 $13,890
13,890 13,890
3,500
2,500
6,000 6,000
$33,780
5,100
5,100
TOTAL INSTALLED COST
$43,980
191
-------
Control Instruments
Specifications:
As in instrument list
Installed Cost Breakdown:
Item
Total Base Cost
Piping
Instrument Panel
Structural
Electrical
Painting
Total Materials
Total Labor
Cost Distribution ($)
Quantity Units Labor Material Rental Total
1 all 8,500 16,820
2,000 5,180
1 each 250 500
2 50 500
800 1,700
200 100
12,000
24,800
$24,800
12,000
Contractor's Allowance
35$ of Labor
18$ of Materials
Total Allowance
JOB COST
Engineering,
Contingencies,
4,400
4,600
9,000
9,000
$45,800
6,900
6,900
TOTAL INSTALLED COST
$59,600
-------
Instrument List and Cost Estimate
Tag
LT -
L1C
LV -
LI -
pHT
pHRC
pHV
FO -
FE -
FT -
FR -
FI -
PI -
PI -
LT -
LIC
LV -
FT -
FO -
FRC
PT -
PR -
PSV
FV -
LT -
LI -
FT -
FO -
Item
1
- 1
1
1
- 1
- 1
- 1
1
1
1
1
1
1
2
2
- 2
2
2
2
- 2
2
2
- 2
2
4
4
4
4
Description
Foxboro M13FA-HS teflon-faced, WM-13R-
HS-315 repeater
Foxboro M43A-A2-PC3-15
Annin 1560 with Kynar body and trim
Moore receiver gauge
Foxboro M699A-FN pH converter electrodes
and holder
Foxboro M5422-Ts, with M58P4 controller
Annin 1560 with Kynar body and trim,
1 in. CV = 10
14 in. slip-on meter run flanges
14 in. hastelloy "c" orifice plate
Foxboro M13A - MS -2
Second pen of pHRC-1
Moore receiver gauge
Ashcroft M-1279-S
Ashcroft M-1279-S
Foxboro 13A-HS-2R
Foxboro M43A-A2-PG315
Annin 1560 SS 316 1 in.
Foxboro M13A-MS2
I/O manifold, 3l6 SS orifice
Foxboro M5422-Ts with M58P4 controller
Foxboro M-11GM-AS-2
Second pen of FRC-2
Crosby 2-1/2 J4 style J035 or equal
Annin 1560 1 in - 150 Ib. flanged, SS
Foxboro M13A-MS2
Moore receiver gauge
Foxboro M13A-MS-2
I/O manifold, 316 SS orifice
Cost, $
970
270
445
19
965
865
445
740
350
287
19
32
32
297
270
283
287
97
865
296
700
342
287
19
287
97
193
-------
Instrument List and Cost Estimate (Continued)
Tag Item Description Cost,
FRC - 4 Foxboro M5422TS with M58P4 controller 865
FV - 4 Annin 1560, 1 in. - 150 Ib. flanged
316 SS 342
AT - 5 Dynatrol S.G. (1.0 to 1.1) $3200 0_R
Foxboro M15A D/P cell with stand pipe
assembly 600
ARC - 5 Foxboro M5422-TS and M58P-4 865
AV - 5 Annin - Butterfly, 3 in. flanged 680
FT - 5 Foxboro M13A-MS2 287
FE - 5&6 Parshall flumes, 3 ft. x 3 ft. 1,000
pHT - 6 Foxboro M699A-FN complete 965
pHR - 6 Second pen of ARC - 5
TR - 1 Bristol 12PG570 includes $400 for thermo-
couples 1,692
TR - 2 one point on above
TOTAL COST $16,862
194
-------
Instrument Air Supply
Capacity 29 CPM
Pressure 125 Psig-
Unitized with dryer and 120 gallon receiver
tank and cooler.
Ingersol-Rand Model 57-T or equivalent.
Installed Cost Breakdown:
Item
Compressors
Piping, 1 in.
Reinforced concrete
Electrical
Painting
Total Materials
Total Labor
Contractor's Allowance
35$ of Labor
18$ of Material
Total Allowance
JOB COST
Engineering, 15$
Contingencies, 15$
TOTAL INSTALLED COST
Cost Distribution ($)
Quantity
2
100
2
20
100
Units Labor Material Rental
each 200 6,000
ft. 150 150
cu.yd. ' 50 50
KVA 400 400
sq.ft. 40 40
6,640
840
310
1,210
1,520
Total
$ 6,640
840
1,520
$ 9,000
1,350
1,350
$11,700
195
-------
Office and Laboratory Building
Specifications:
40 ft. x 60 ft. air-conditioned buildim
Installed Cost Breakdown:
Cost Distribution ($)
Item
Shell
Heating %• cooling
Lighting
Plumbing
Laboratory Equipment
Office Equipment
Shop Equipment
Fire Protection
Total Materials-
Total Labor
Quantity Units Labor
2,400
2,400
2,400
2,400
400
400
400
2,400
sq.ft. 7,200
sq.ft. 7,200
sq.ft. 5,600
sq.ft 2,400
sq.ft. 3,200
sq.ft. 400
sq.ft. 400
sq.ft. 2,400
26,800
Material Rental Total
12,000
9,600
2,400
2,400
8,000
2,000
2,000
2,400
40 , 800
$ 4o,8oo
26,800
Contractor's Allowance
of Labor
of Materials
Total Allowance
JOB COST
Engineering,
Contingencies,
TOTAL INSTALLED COST
9,300
7,400
16,700
16,700
$ 84,300
12,300
12,400
$109,000
196
-------
Roads and Parking Lots
Specifications:
22 ft. wide; 2 in. asphalt over 1 ft. of
sand stabilized shell or equivalent.
Installed Cost Breakdown:
Item
Cost Distribution ($)
Quantity Units La_bor Material Rental Total
Roadway & parking lot 25,000 sq.ft. 10,000 12,500 2,500
Total Rentals
Total Materials
Total Labor
2,500 $ 2,500
12,500 12,500
10,000 10,000
Contractor's Allowance
35$ of Labor
l8fo of Materials
105$ of Rentals
3,500
2,250
2,750
Total Allowance
8,500
8,500
JOB COST
$31,000
Engineering,
Contingencies,
4,650
TOTAL INSTALLED COST
$40,300
197
-------
Appendix E. Microbial Metabolism of Ethylene and Propylene
Glycols in Presence of Sodium Chloride"
Dr. Willard A. Taber, Department of Biology
Texas A. & M. University, College Station, Texas
fc-BS TRACT
Many bacteria, fungi and algae were tested for capacity to
metabolize ethylene glycol and propylene glycol in the
presence of high concentrations of sodium chloride. The
algae did not grow well in the presence of salt and only a
small percent of the bacteria and fungi utilized either
ethylene glycol or propylene glycol. £ still smaller percent
could utilize both glycols. A fungus (Fusarium1) referred to
as Fungus T-33 was isolated which was capable of growing on
ethylene glycol in diluted waste water and respiring on
neutralized but undiluted waste water enriched with ethylene
glycol. A bacterium (Acinetobacter) referred to as
Bacterium T-52 was isolated from a solar evaporation pond,
Great Salt Lake, Utah, which could grow on both ethylene
glycol and propylene glycol in synthetic media containing
1.2.% NaCl and glycol, and in undiluted but neutralized waste
water containing glycol. Diagnostic ana nutritional
characteristics of the bacterium are given. It is a Gram
negative, non-motile, oxidase negative, non-fermentative rod
which cannot grow on lactose or cetrimide, produce indole
or hydrolyze urea. It can reduce nitrate. It does not re-
quire an external source of vitamins for growth but does re-
quire sodium ion, which cannot be replaced by potassium ion.
Approximately 1 gram/liter medium UaCl is required. Maximal
growth occurs between 3-^ and 7$ NaCl but growth is fairly
abundant in the presence of 12^ NaCl. It will not grow well
below pH 5.^-- It is killed by high concentrations of di-
chloroethylether and ethylene chlorohydrin but not by
ethylene dichloride. Studies with radioactive ethylene
glycol and propylene glycol revealed that this bacterium can
readily assimilate and respire both of these glycols. Tvhen
the culture is grown on radioactive glycol in the presence
of suboptimal amount of nitrogen source, the culture converts
most of the glycol carbon to carbon dioxide carbon. The
presence of glucose suppresses glycol metabolism but does
not completely prevent it.
The detailed report is available on request from Dr. Uillard
A. Taber of the Department of Biology, Texas A. p,~ M. Univer-
sity, College Station, Texas 778^0.
193
-------
1
Access/on Number
2
Subjet t Fit-Id & Group
^5G
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
^ [ Organization
. I The Dow Chemical Company
Texas Division
Freeport, Texas 775^1
Title
Treatment of Wastewater From The Production of Polyhydric Organics
1 Q Authors)
M. A.
W. F.
Zeitoun
Mcllhenny
16
21
Project Designation
EPA, Project No.
12020-EEQ
Note
22
Citation
23
Descriptors (Starred First)
Brine Wastewaters*, Wastewaters From Glycol Production*, Biological
Treatment*, Renovation Methods*, Solvent Extraction, Carbon
Adsorption, Membrane Separations, Activated Sludge
25
Identifiers (Starred First)
Wastewater Characterization*, Treatability*, Pilot Plant Operation*.
Plug Flow and Completely mixed activated sludge.
Sludge From Pilot Plant Data,. Cost Estimate.
Design of Activated
27
Abstract
The brine wastewater resulting from the production of glycols, by
chlorohydrin process, is characterized by high salt content (8-10$ Nad
excess alkalinity, and the presence of several organic compounds.
Solvent extraction of the glycol wastewater with amines produces
raffinate that is .salt-saturated and a product enriched in glycol. The re-
quired large solvent-to-f eed ratio and operation at near freezing tempera-
tures make the process uneconomical. Adsorption of glycols on activated
carbon was found unfeasible because of the low capacity of carbon for the
glycols. Cellulose acetate membranes with low salt rejection were unable
to significantly separate the salt and glycol.
Activated sludge pilot plant was successfully operated for the
treatment of an equalized glycol wastewater. Removal of over 90^ of the TC
at a retention time of 8.0 hours and loadings of 2.0 to J.O Ibs. TOD/lb.
MLVSS-day were obtained. Design parameters determined from pilot plant
operation were used to design a 6 MG-D treatment plant, at an estimated cost
of 3-3 cents per pound of TOD removed or less than 0.2 cents per pound of
propylene glycol produced.
lbs/rac£or
M. A. Zeitoun
Ins titution
The DQVJ ChPHI-IP.a. 1
Company
'RC ES S"CI ENTI F
WR I 02 (REV JULY 1969)
WR SI C
SEND TO: WATER RESOUf
U S DEPARTMENT OF THE
WASHINGTON D C 2Q24O
N FORMATION C EN "1
N TER1OR
*U S. GOVERNMENT PRINTING OFFICE 1972 48A-d83/ 116 1-
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