United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S1-81-029 Apr. 1981
Project Summary
Mutagenic Activity and
Chemical Characterization for
the Palo Alto Wastewater
Reclamation and Groundwater
Injection Facility
P. L. McCarty, J. Kissel, T. Everhart, R. C. Cooper, and C. Leong
At the Palo Alto Reclamation Plant
0.044 m3/s (1 mgd) of secondary
effluent is reclaimed through a series
of wastewater treatment processes
including high lime treatment,
aerator-fountain spraying, single-
stage recarbonation, ozonation,
mixed-media filtration, activated-
carbon adsorption, final chlorination,
and storage. A portion of the
reclaimed water is injected into a
series of wells to serve as a barrier
against the intrusion of sea water from
San Francisco Bay.
Mutagenic activity (by the Ames
test) was consistently found to be
present in the secondary treated
municipal wastewater influent to the
Reclamation Facility. This activity was
not reduced significantly by high lime
treatment, air stripping, recarbona-
tion, or ozonation, even though these
processes did remove a portion of the
overall organic content of the waste-
waters and many of the volatile
organic compounds. Activated-
carbon adsorption was effective in
removing mutagenic activity to such a
degree that mutagenic activity could
not be found in water used for injec-
tion or that taken from monitoring
wells. Chlorination resulted in an
increase in mutagenic activity. A
laboratory study demonstrated that
this increase in activity would not
result if chlorine dioxide rather than
chlorine was used for disinfection.
The extracts used for mutagenic
analyses contained a broad range of
fatty acids, phthalates, aromatic com-
pounds, and several unidentified
bromine-containing compounds.
This Project Summary was develop-
ed by EPA's Health Effects Research
Laboratory, Cincinnati, OH, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Discussion
Water reclamation and reuse are be-
coming more important as increasing
pollution and water usage reduces the
supply of clean water available for bene-
ficial uses. Advanced wastewater treat-
ment processes have been developed to
protect receiving waters and to reclaim
wastewater for a variety of purposes.
The nature of wastewater is depend-
ent upon the types of industrial and
municipal wastes introduced into the
sewerage system Wastewaters may
contain a variety of toxic compounds,
some of which may not be altered or
removed during treatment, and some
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may be formed during the treatment
process itself.
The direct use of reclaimed waste-
waters as part of a municipal drinking
water supply is not currently permitted.
Before this is allowed, the concern over
the potentially harmful effects of con-
taminants remaining in the water must
be alleviated. Although research aimed
at the identification and quantification
of trace materials in water constitutes
an active area of environmental chemi-
stry, little is known aboutthe long-term,
or chronic, effects of exposing a popula-
tion to trace levels of these dissolved
impurities over a time period of many
years. There is a reasonable probability
•that many of these compounds are car-
cinogenfc Epidemiological studies do
exist which tend to show a degree of
correlation between the increased
incidence of several forms of cancer and
polluted surface waters serving as
potable water sources, as well as to
chlorinated drinking water.
Several reports document the
presence of mutagenic substances in
drinking water as well as reclaimed
wastewater These investigations relied
chiefly upon a bacterial mutagenicity
assay, the Ames test, to detect the
presence of mutagens. There is some
evidence that many compounds which
are bacterial mutagens, as determined
by the Ames test, are also carcinogenic
to animals. Thus, this relatively simple
test may provide some indication of the
presence of potentially harmful sub-
stances in water.
This study on the presence of
bacterial mutagens in reclaimed waste-
water at Palo Alto, California, was insti-
gated as a result of a previous study
evaluating the presence of such
mutagens in samples taken from sixdif-
ferent California municipal wastewater
treatment facilities. For two of the
plants, including the one at Palo Alto, it
was reported that the mutagenic activity
was intensified during the course of the
treatment process In the study reported
here, the mutagenic activity at the Palo
Alto Reclamation Plant was evaluated
in more detail on samples taken after
various stages of treatment so that their
effect in either producing or reducing
mutagenic activity could be better
evaluated. In addition, chemical
analyses were conducted on collective
parameters, such as chemical oxygen
demand, total organic carbon, and total
organic halogens, as well as on a wide
range of specific organic compounds, in
order to determine if any correlation
with mutagenic activity existed
Special studies were conducted on
the formation of mutagemcally active
compounds during the chlormation
process, and a comparison was made
with an alternative disinfectant,
chlorine dioxide. In addition, an evalua-
tion was made of the reduction in
mutagenic activity during passage of
the reclaimed water through an aquifer
following groundwater injection.
Conclusions
Positive mutagenic activity to strains
TA98 and TA1535 with S9 activation
was consistently measured in the
secondary treated wastewater influent
to the Reclamation Facility. Chlorination
of the secondary treated influent
resulted in an increase in mutagenic
activity, especially to strain TA1 535.
Laboratory disinfection studies con-
firmed that mutagenic activity of the
secondary treated wastewater
increased following Chlorination, but
would not result had chlorine dioxide
disinfection been used. Subsequent
processes of high lime treatment, strip-
ping, recarbonation, and ozonation had
little effect in reducing mutagenic activ-
ity, although in combination these
processes were effective in removing
many volatile organic constituents of
health concern.
Activated-carbon adsorption proved
very effective in reducing mutagenic
activity as well, as in reducing the
organic content of wastewater as
measured by the collective parameters
of chemical oxygen demand (COD), total
organic carbon (TOG), and total organic
halogens (TOX). Because of the effec-
tiveness of activated-carbon adsorption
in reducing mutagenic activity, few
samples of the reclaimed wastewater
used for groundwater injection con-
tamed positive mutagenic activity.
Positive mutagenic activity was not
found in any samples taken from the
groundwater monitoring wells.
An average of only about 12 percent
of the organic material present in the
samples analyzed for mutagenic activity
was contained in the XAD-acetone
extract concentrates. Fatty acids,
phthalates, several aromatic
compounds, and several unidentified
bromine-containing compounds were
present in the XAD-acetone extracts
used for mutagenic analysis.
The Palo Alto Reclamation Facility
was proven effective in reducing the
concentration of a wide range of specific
organic compounds and mutagenic
activity contained in the secondary
treated influent wastewater. Several
materials remain in the reclamation
plant effluent at low concentration, and
mutagenic activity was detected in
some samples.
Results and
Recommendations
The efficiency of the individual treat-
ment processes for removal (or forma-
tion) of a wide range of specific organic
compounds and group parameters was
measured and are summarized in this
report Chlorination results in the pro-
duction of a significant concentration of
non-purgeable, but otherwise uniden-
tified, chlorinated organic compounds,
as well as trihalomethanes. Formation
or removal of such compounds did not
seem to correlate with changes in
mutagenic activity Air stripping by the
fountain-spray system was most
effective in removing volatile organic
compounds, while activated carbon was
responsible for removals obtained for
most other organic materials. t
Future work should be directed
towards evaluating further the organic
material remaining m reclamation plant
effluent, as most of this material
remains uncharactenzed. In addition,
the nature of compounds or mixtures of
compounds responsible for mutagenic
activity should be determined. The use
of the Ames mutagenic analysis for
judging the health risk of reclaimed
wastewater should be further
evaluated
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P L. McCarty, J. Kissel, andT. Everhartare with the Department of Civil Engineering,
Stanford University, Stanford, CA 94305, andR. C. Cooper and C. Leong are with
the School of Public Health, University of California. Berkeley, CA 94720.
Herbert R. Pahren is the EPA Project Officer (see below).
The complete report, entitled "Mutagenic Activity and Chemical Characterization
for the Palo Alto Wastewater Reclamation and Groundwater Injection Facility,"
/Order No PB 81 -179 590, Cost: $9.50. subject to change] 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:
Health Effects Research Laboratory
U S. Environmental Protection Agency
Cincinnati, OH 45268
> US 30VERNMENT PRINTING OFFICE 1961 757-012/7066
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Environmental Protection
Agency
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Information
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