United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
**' '•-! \v
' i I *
Research and Development
EPA/600/S2-86/103 Mar. 1987
&EPA Project Summary
Pilot Plant Demonstration
of the Hyperbaric
Oxyozosynthesis Process
A 3-month field demonstration study
was conducted on the hyperbaric oxy-
ozosynthesis process for sludge condi-
tioning and stabilization at the Monroe,
Michigan, Metropolitan Area Waste-
water Treatment Facility. The process
involves contacting sludges, under
pressure and at reduced pH of 3 to 4,
with oxygen and ozone for periods of
up to 3 hours. The primary objective of
this study was to evaluate the process
with respect to its effect on sludge de-
waterability, as measured by the Buch-
ner funnel specific resistivity test. The
process had been demonstrated previ-
ously for sludge stabilization measured
by bacteria destruction. The present
study confirmed that advantage, also
the ability to reduce odors. The findings
of the present study, however, indicate
that the oxyozosynthesis process did
not improve sludge dewaterability, but
actually decreased dewatering charac-
teristics somewhat. Also, the oxy-
ozosynthesis process did not achieve
any significant reduction of sludge
volatile solids or total chemical oxygen
demand.
This Project Summary was prepared
for EPA's Water Engineering Research
Laboratory, Cincinnati, OH, to an-
nounce the major results of a project
that is documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
The hyperbaric oxyozosynthesis
process involves contacting sludge at
ambient temperatures with an oxygen-
ozone gas mixture under pressure. The
sludge is pretreated by screening and/
or comminution and pH adjustment.
The sludge is continously recirculated
and mixed into the gas phase of the re-
action vessel into which the oxygen-
ozone gas is injected. Retention in the
vessel is in the order of 1 to 3 hours.
The process was marketed by Interna-
tional Wastewater Reclamation Tech-
nologies, Inc. (IWWRT), at the time of
the project. IWWRT supplied the pilot
plant used for the study. Synox Corpo-
ration and Ozonics Corporation
presently hold license rights to the proc-
ess. One full scale batch system was in
operation at the time of the study at the
West New York, New Jersey, waste-
water treatment facility. It was sized to
process 20,000 gallons/day of primary
sludge. This system pretreated sludge
prior to flotation and belt filter press de-
watering. The sludge was reported to be
dewatered to a cake solids over 40 per-
cent. A pilot plant was also operated on
waste activated sludge from the Wash-
ington Suburban Sanitary Commission
(WSSC) Western Branch Sewage Treat-
ment Plant, prior to dewatering and
composting. Those studies indicated
that the process produced effective
pathogen destruction and significant re-
duction in odor; however, improve-
ments in dewaterability were difficult to
detect.
Test Procedure
The experimental program consisted
of processing and evaluating primary,
secondary, and combined sludge sam-
ples in the IWWRT pilot reactor. The re-
actor's volume was 0.76 m3. A total of
62 batch processing runs were con-
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ducted on the sludge samples utilizing
the pilot plant. Starting with operating
parameters recommended by IWWRT
from experience at the West New York
plant, the parameters of pH, ozone uti-
lization rate, contact time, pressure, and
mode of operation were varied in an at-
tempt to determine optimum operating
conditions for dewaterability of the
Monroe sludge. The effects on sludge
dewaterability of polymer addition and
pH adjustment with oxygen synthesis
were assessed and compared with de-
waterability results for untreated
sludges.
The Buchner funnel resistivity test
was used as a measure of sludge de-
waterability. The analytical schedule for
sludge samples also included testing
for a variety of other parameters, includ-
ing solids, pH, COD, BOD5, nitrogen,
phosphorus, and coliforms.
Results
Variation in the major process vari-
ables for the hyperbaric oxyozosynthe-
sis process did not indicate any signifi-
cant effect on improving sludge
dewaterability. In general, oxyozonated
sludges even exhibited somewhat
poorer dewatering characteristics than
the raw sludges tested.
Polymer conditioning, used normally
at the Monroe plant in conjunction with
vacuum filtration dewatering, was also
required to obtain dewaterability char-
acteristics on oxyozone contacted
sludges equivalent to polymer treated
raw sludges. Optimum polymer re-
quirements for oxygen-ozone contacted
sludges were higher by about 40 to 60
percent than for noncontacted sludges
to achieve comparable dewaterability
characteristics. Acidification effected a
substantial reduction in fecal coliform
concentration. Subsequent oxyozona-
tion for 60 minutes reduced coliform
levels to <10 MPN/100 ml. Adjustment
of pH of the oxyozonated sludge from a
pH of 3 to 4 to a pH of 6 to 7 increased
dewaterability characteristics both with
and without the use of polymer condi-
tioning chemicals.
Measurements of total COD and total
and volatile solids on raw and oxy-
ozonated sludges indicated that the
process did not significantly reduce any
of these constituents. Some solubiliza-
tion of COD, determined by a measured
increase in filtered COD after oxyozona-
tion, was observed. Soluble BOD was
reduced and soluble phosphorus was
increased by oxyozonation of the
sludges. The measurement of the effect
of oxyozonation on soluble total
Kjeldahl nitrogen (TKN) and ammonia
nitrogen concentrations was variable.
Acidification of the combined sludge
solubilized iron; however, after ozona-
tion the process apparently reduced the
solubilized iron concentration. Soluble
zinc concentration was increased by
ozonation. Chrome, lead, and copper
were in very low concentrations in the
raw filtrates and were not measurably
affected by the oxyozosynthesis proc-
ess in these studies.
Consumables for the process, oper-
ated as suggested by the pilot plant
study results, were determined; how-
ever, they could not be optimized based
on a dewaterability criterion. A unit op-
erating cost for the process was devel-
oped for the Monroe plant based on this
consumables determination. The
present worth unit cost for the process
was estimated at $230/ton dry solids
processed.
Conclusions
The hyperbaric oxyozosynthesis
process for sludge conditioning, tested
on the sludges produced at the Monroe
Metropolitan Area Wastewater Treat-
ment Facility, had no significant benefi-
cial effect on improving the dewater-
ability of the primary, secondary (waste
activated sludge), or combined sludges.
Thus the process is not recommended
for sludge conditioning for dewatering
purposes.
The process does, however, stabilize
sludges as measured by reduction in
fecal coliforms and by obvious odor re-
duction. It is recommended, therefore,
that the process be considered primar-
ily for sludge stabilization. Optimization
of operating conditions and chemical
and power usage would be required for
this application. The use of the hyper-
baric oxyozosynthesis process for
heavy metals removal from highly con-
taminated sludges, in addition to sludge
stabilization, may be practical. Further
studies would be required to optimize
the pH for heavy metal solubilization
and to optimize conditions for subse-
quent dewatering and filtrate treatment
or disposal.
Comments received after completion
of the project from Ozonics Corpora-
tion, which presently has license rights
to the process, are included in the Ap-
pendix to the report.
The full report was submitted in fulfill-
ment of Cooperative Agreement No. CR
810765 by Monroe County, Michigar
under sponsorship of the U.S. Enviror
mental Protection Agency.
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This Project Summary was prepared by staff of Greenhorne and O'Mara, Inc.,
Greenbelt. MD 20770; and HydroQual, Inc.. Mahway, NJ 07430.
Harry £. Bostian is the EPA Project Officer (see below).
The complete report, entitled "Pilot Plant Demonstration of the Hyperbaric
Oxypzosynthesis Process," (Order No. PB 87-129 813/AS; Cost: $13.95,
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:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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POSTAGE & FEES PL
EPA
PERMIT No G 35
Official Business
Penalty for Private Use $300
EPA/600/S2-86/103
ST
60604
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