United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-60Q/S2-82-075   Nov. 1982
Project Summary
Treatment Compatibility of
 Municipal  Waste  and
 Biologically  Hazardous
 Industrial  Compounds

A. F. Gaudy, Jr., Don F. Kincannon, and T. S. Manickam
  The overall objective of this research
was to gain information on the effect of
organic priority pollutants on the
performance of activated sludge units at
publicly owned treatment works. The
study was designed to gain information
on the  effects of a wide array of
compounds and to determine the most
useful study procedures to be used in
assessing effects related to the need for
pretreatment of industrial wastes.
  Batch and continuous flow bench-
scale activated sludge pilot plants were
fed settled municipal sewage. The
general approach was to compare the
performance of control systems with
that of comparable systems dosed with
various concentrations of priority
pollutants. Twenty-four compounds
were studied in batch pilot plants; eight
of these were also studied in continuous
flow pilot plants operated at a sludge
age of 5 days. Four of the eight were also
studied in extended aeration  pilot
plants. Each compound was studied for
a period of six months under each mode
of operation.
  In batch operations, only pentachlo-
rophenol and 2-chlorophenol caused
increases in soluble residual chemical
oxygen demand (COD) at feed concen-
trations of 5 mg/l. None of the eight
compounds tested in continuous flow at
a sludge age of 5 days showed increased
effluent soluble COD at the 5 mg/l
dosage.  However, the effluent of the
units dosed with phenol and methylene
chloride did show increased suspended
solids concentrations. Higher dosage
levels of several compounds led to
higher soluble COD and suspended
solids concentrations in the effluent.
Effluents from the extended aeration
process were better than from compar-
able systems at lower sludge age. From
the analyses made for specific com-
pounds, there was  no evidence for
excessive pass-through  of priority
pollutants on publicly owned treatment
works.

  This Project Summary  was devel-
oped by EPA's Robert S. Kerr Environ-
mental Research Laboratory, Ada,
OK, to announce key findings of the
research  project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).

Introduction
  The magnitude of the information
base required for formation of regulatory
policy to protect the public health and
the public  investment in  biological
treatment facilities is best realized by
considering the  engineered natural
process employed for treatment. The
microbial population involved in the
biological waste treatment is  very
diverse and the species making up the
sludge may change due to interspecies
interactions alone without change in
the environmental conditions. So the
task of determining whether a particular

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chemical at low  concentrations is
responsible for an observed malfunction
of an activated sludge process requires
considerable data collection.
  This 2-year study was undertaken to
evaluate as many compounds as possible
but  for  a  sufficient time  and  with
sufficient depth of  investigation to
provide reliable and useful information.
The  most critical need is to  assess the
effect  and  magnitude of effect rather
than the mechanism  involved. The
major  effect would be  the  leakage of
soluble  organics  and  solids in the
effluent. The fate of the priority pollutant
is also of concern.
  Some compounds were studied con-
currently in extended aeration, activated
sludge, and batch systems. This enables
one to assess  the usefulness of batch
systems as well as the effect of sludge
age  in accommodating the priority
pollutant. Also,  auxiliary short-term
batch studies were made to assess the
rate of  purification under  various
dosages  of toxic compounds and to
determine  the degree to which the
priority pollutants can be stripped under
conditions of aeration in the  pilot plant.
In addition to determining the biological
effects of specific  compounds on
activated sludge, this study was designed
to evaluate methods which can be
employed to obtain data for the formula-
tion of pretreatment policy.

Conclusions
  Based  on  the  results of  pilot  plant
studies, the following  conclusions were
made. Of the 24  compounds studied in
batch systems, only pentachlorophenol
and  2-chlorophenol gave evidence of
causing metabolic stress to the system
at a feed concentration of 5  mg/l. At a
feed concentration  of 25  mg/l and
higher,  4-chloro, 3-methyl phenol
showed metabolic  disturbance. In the
continuous flow  activated sludge unit,
none of the compounds tested showed
leakage of soluble organics at a dosage
level  of  5  mg/l. Leakage  of soluble
organics  and effluent suspended solids
at higher dosage levels was observed
for phenol and  methylene chloride.
Trichloroethylene  showed  metabolic
disturbances and  increased effluent
solids  concentrations when subjected
to cyclic loading with alternating
concentration.
  In the  case of  the extended aeration
systems, there was  evidence for in-
creased soluble COD in the effluent only
from the  unit dosed with phenol at the 5
mg/l dosage level. There was no in-
crease in effluent suspend ed solids for
any of  the  four  compounds at this
dosage  level. At the higher levels of
dosage  (25 mg/l and 50 mg/l}, there
was evidence of increased soluble COD
and suspended solids only in the units
dosed with phenol. Also, only in  the
units  dosed  with  phenol  was  there
evidence of  disturbance of effluent
quality when the dosage was changed
on alternate days.  From the results of
this study, there was evidence that the
effluents of the extended aeration pilot
plants were  lower  in soluble COD and
particularly in suspended solids con-
centrations. Any assessment of the ef-
fects of  priority pollutants on activated
sludge should include ecological con-
siderations such as effluent clarity and
sludge species diversity.
  In  regard  to  study  techniques for
assessment of effects of priority pollut-
ants on publicly  owned  treatment
works, it is concluded that batch pilot
plant operations, although more easily
facilitated, cannot be used in place of
continuous flow pilot plant studies as a
means of gaining information on which
to base pretreatment policy regulations.
  The analysis made for specific test
compounds gave indication of the fateof
the compound. With  exception  of
nitrobenzene and 2-chlorophenol, most
of the other compounds studied were
present  in the effluent only at very low
concentrations. Most of the test com-
pounds were removed by either stripping
biodegradation,  or attachment  to  the
surface  of the microorganisms.

Recommendations
  In future assessments of the effect of
priority  pollutants on the activated
sludge process, a study period of about 6
months  should be sufficient for each
compound. Batch  pilot  .studies should
be abandoned as a basis for formulation
of regulatory policy because, as observed
in the current investigation, operation
environment, e.g., different sludge
ages, effected changes in the ecology of
the sludge which translated to changes
in effluent quality in the presence of
various toxicants.
  Bench-scale continuous  flow- pilot
plants should be  run on  municipal
wastes  relatively  devoid of  industrial
wastes  at three or more sludge ages.
Variations in dosage and mode  of its
administration should  include steady
dosages, variations in mode of dosage
including steady concentration levels,
and pulsating levels with various time
periods  of  resting between dosages.
Combinations of priority pollutants
should be  run.  The analyses should
include  specific toxicant levels in
effluent and sludge, forms of nitrogen,
detailed  observation of changes in
predominant species of microorganisms
in the biomass and  auxiliary batch
growth studies to establish whether the
presence of toxicant causes changes in
the biokinetic constants used in design
and operational  models.

Results
  Twenty-four compounds on the priority
list were studied in batch pilot plants.
Eight compounds  were  studied in
continuous flow activated  sludge pilot
plants, and four were studied in extended
aeration systems. The continuous flow
units operated were of internal recycle
type. A listing of the compounds studied
and operational conditions under which
they were studied is given in chronolog-
ical order  in Table 1. The feedstock
consisted of effluent from the primary
clarifier  of the  Stillwater Treatment
Plant  supplemented with glucose  and
ammonium sulfate. To this feedstock
various  concentrations of the test
compound were  added during conduct
of the experiment. The major analytical
techniques employed were COD, sus-
pended solids concentration, and specific
compound  concentration measured by
gas chromatography.
  The batch units were  operated on a
24-hour  fill and draw schedule.  The
internal recycle continuous flow units
were operated at a mean cell residence
time of 5 days and hydraulic retention
time of 8 hours. The extended aeration
activated sludge systems were operated
at a hydraulic  retention  time of  16
hours.
  The  performance of the batch  and
continuous flow  pilot plants was evalu-
ated based on the statistical analysis of
the data  along with plotted data for a
control and the  unit receiving the test
compound. Changes  in predominant
species,  presence or absence of proto-
zoa and/or  filamentous organisms
were also taken  into account.
  In the  batch  studies, pentachloro-
phenol and 2-chlorophenol showed the
most adverse effects upon soluble COD
removals.  These effects were at all
concentrations.  The other compounds
showed very little effect.
  For the  compounds tested in the
continuous flow activated sludge pilot
plants, there was no  evidence  for
increased soluble COD in the effluent at
the 5 mg/l dosage. At this lower dosage,

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 Tattle 1,
   Batch
Compounds Studied and Operational Conditions

                             Continuous Flow
                  Un-0.2 days'
    extended Aeration
Period
Naphthalene
Toluene
Hexachlorobenzene
Benzene
Phenol
Pentachlorophenol

Nitrobenzene
2-Chlorophenol
Anthracene
2-Nitrophenol
Hexachloroethane
Fluorene

Methylene Chloride
Carbon Tetrachloride
Chloroform
Trichloroethylene
Chlorobenzene
Tetrachloroethylene

4-Chloro,3-methyl
  phenol
Ethylbemene
1,2-Dichloroethane
1,1,2-Trichloroethane
Bromoform
Tetrachloroethane
            Benzene
            Phenol
            Nitrobenzene
            2-Chlorophenol
            Methylene Chloride
            Trichloroethylene
Phenol
2-Chlorophenol
Methylene Chloride
            4-Chloro,3-methyl phenol   4-Chloro.3-methyl phenol
            1,2-Dichloroethane
7/15.
1977
  to
1/15.
1978
1/15.
1978
  to
7/15.
1978
7/15.
1978
  to
1/15.
1979
                          1/15,
                          1979
                           to
                         6/15.
                         1979
there was evidence  for  increased
suspended solids in the effluent of pilot
plants dosed with phenol and methylene
chloride. At the  higher dosage levels,
there was  evidence  for an  increase  in
both soluble COD and suspended solids
in the effluent for the pilot plant dosed
with phenol. For the units dosed with  2-
chlorophenol, methylene chloride, and
1,2-dichloroethane, soluble COD in the
effluent was not affected, but there was
some disturbance in effluent suspended
solids concentration. In addition, cyclic
loading of  nitrobenzene and trichloro-
ethylene led to increased suspendeds in
the effluent.
  Based upon the analyses made, there
was no evidence of massive passthrough
of any  of  the  compounds  for which
specific  analytical determination was
made, even at  the dosage level of 50
mg/l.  However,  small quantities  of
some of the compounds were detected
in the effluents.
  The results of this study showed that
the effluents of the extended aeration
pilot plants were lower in  soluble COD
and  suspended solids  than effluents
from comparable faster growing systems.
Among reasons for such results may be
lower mass loading rate,  i.e.,  higher
biomass concentration  and  longer
mean hydraulic  retention  time. The
                               reason for the lower suspended solids
                               concentration is probably due to gener-
                               ally greater abundance of protozoa.
                               Generally in the faster growing systems,
                               an  increase in dosage  of. the test
                               compound  appeared to cause more
                               serious reduction in protozoan activity
                               than in the extended aeration system.
                               Thus,  while the biomass with  fewer
                               grazing species could provide nearly
                               equal efficiency with respect to residual
                               soluble COD, it would not provide a low
                               suspended  solids concentration in the
                               effluent.  Therefore, in designing study
                               procedures to assess effects of priority
                               pollutants on activated sludges, the eco-
                               logical  considerations as reflected in ef-
                               fluent clarity as well as other aspects of
                               ecology, such  as  limiting effects on
                               species diversity, should be included as
                               parameters for assessment.

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      A. F. Gaudy, Jr., Don F. Kincannon. and T. S. Manickam are with Oklahoma State
        University, Stillwater. OK 74074.
      Thomas E. Short, Jr. is the EPA Project Officer (see below).
      The complete report consists of two volumes, entitled "Treatment Compatibility
        of Municipal Waste and Biologically Hazardous Industrial Compounds,"
          "Volume l,"(0rder No. PB 83-105 536; Cost: $19.00, subject to change)
          "Volume/I. (Appendix}," {Order No. PB 83-105 544; Cost: $23.50, subjectto
         change)
      The above reports will be available only from:
              National Technical Information Service
              5285 Port Royal Road
              Springfield,  VA 22161
              Telephone: 703-487-4650
      The EPA Project Officer can be contacted at:
              Robert S. Kerr Environmental Research Laboratory
              U.S. Environmental Protection Agency
              P.O.Box 1198
              Ada, OK 74820
      U.S. GOVERNMENT PRINTING OFFICE:  1982—6S9-O17/O859
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
           CHICAGO  1L  60604

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