United States
Environmental Protection
Agency
Industrial Env ronmental Research
Laboratory
Research Triable Park NC 27711
SEPA
Research and Development
EPA-600/S2-81-052 Sept. 1981
Project Summary
Two-Stage Biological
Treatment of Coke Plant
Wastewater
R. Osantowski, A. Geinopolos, James Meverden, and Joseph Milanowski
The report documents a pilot-plant
study of the use of advanced waste
treatment methods in upgrading metal-
lurgical cokemaking wastewaters to
Best Available Technology (BAT) levels.
Mobile treatment units, operable at a
flow rate of 19 l/min, were used.
Methods used included two-stage acti-
vated sludge treatment for removal of
organic carbon compounds and ammo-
nia; filtration and activated carbon were
also studied as polishing steps. For each
treatment studied, samples (including
toxic pollutants) and operational data
were obtained for later use in assessing
and comparing treatment adequacy.
The study showed that high levels of
organic pollutant removal were
achieved in the first stage of biological
oxidation. Abnormal operating condi-
tions in the coke plant wastewater pre-
treatment system during the testing
resulted in ammonia levels as high as
2000 mg/l, making it necessary to
dilute the second stage feed before nitri-
fication could be achieved. Ammonia
reductions of > 97% were achieved in
the second stage. Activated carbon and
filtration effectively removed suspend-
ed solids, total organic carbon, color,
and thiocyanate.
This Project Summary was
developed by EPA's Industrial
Environmental Research Laboratory,
Research Triangle Park, NC, to
announce hey findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
In 1972, the Federal Water Pollution
Control Act (PL92-500) was enacted by
the U.S. Congress. The Act directed the
U S. Environmental Protection Agency
(U S EPA) to develop effluent limitation
guidelines for all major industrial
groups, among them the steel industry.
EPA was also mandated to recommend
appropriate levels of treatment and esti-
mate costs to meet the proposed limita-
tions. As part of its overall mission, the
EPA's Industrial Environmental Re-
search Laboratory (Research Triangle
Park, NC) funded this study to determine
the feasibility of treating steel plant
wastewater to Best Available Technol-
ogy (BAT) Economically Achievable
levels. This particular project was con-
cerned with the'biological treatment of
coke plant wastewater.
The primary purpose of this project
was to investigate the technical and
economical feasibility of biological
treatment of by-product cokemaking
wastewater to Best Available Technol-
ogy (BAT) levels.* Principal wastewater
sources produced from the by-product
recovery process at the plant investi-
gated included excess ammonia liquor
and benzol plant wastes. Wastewater
treatment at this plant consisted of
stripping the waste ammonia liquor via
steam and caustic solutions, followed
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by blending with' the benzol plant
wastes and biological treatment with a
single-stage activated sludge system.
The wastewater for the pilot study was
obtained after an equalization basin and
prior to the existing biological system.
The combined wastewater contained
pollutants such as suspended solids, oil
and grease, ammonia, phenolic com-
pounds, cyanide, sulfide, thiocyanates,
and toxic materials.
The study was performed using the
mobile bio-oxidation system of the EPA.
This pilot plant is contained in a semi-
trailer van (van No. 3) as shown in
'Figure 1. Near the end of the investiga-
tion, a second EPA semi-trailer van (van
No. 2) containing the activated carbon
pilot plant system (Figure 2) was
brought to the test site. The purpose of
this system wastoevaluatetheefficien-
cy of activated carbon for removing toxic
pollutants present in the coke plant
wastewater. A small pilot-size dual-
media filter was also set up in the
second trailer. Dual-media filtration
was investigated as a method of polish-
ing the biological oxidation effluent.
'Because the development of final Effluent
Limitation Guidelines was under way during the
time of this study, the reference BPT (Best
Practicable Technology) and BAT pollutant
parameters used throughout this report are those
listed m the "Development Document for Proposed
Effluent Limitations Guidelines and Standards for
the Iron and Steel Manufacturing Point Source
Category - Vol II, By-Product Cokemaking
Subcategory," October 1979
The wastewater treatment trains that
were investigated on a pilot scale
included:
1. AS(C) +AS(N)
2. AS(C) + AS(Nj + AC
3. AS(C) + AS(N) + DMF
Key
AS(C): activated sludge
(carbonaceous removal)
AS(N): activated sludge
(nitrification)
AC: activated carbon
DMF: dual-media filtration
In the first treatment train, plant
wastewater from downstream of the
coke pla.nt cooling tower was passed
through a mixing tank, through the first-
stage activated sludge system (carbon-
aceous removal), and then through the
second-stage activated sludge system
(nitrogen removal). The second treat-
ment train consisted of the first treat-
ment train (bio-oxidation) followed by
45' L
Trailer
8'W x 13'-6"H
Aeration
Tank
Sample
Refrigerator
Clarifier
Blower
Temperature
Control System
Biological Treatment
System No. 2
Biological Treatment
System No. 1
Figure 1. Steel plant mobile bio-oxidation treatment system—trailer No. 3.
Trailer
45'L x 8'W x 13'-6"H
Sample
Refrigerator
Carbon
Columns
Ozone
Generator
Reverse Osmosis
System
Ozone Contact
Tanks
Figure 2. Steel plant mobile treatment system—trailer No. 2.
activated carbon adsorption. The third
treatment tram included the compon-
ents of the first treatmenttramfollowed
by dual-media filtration. The detailed
treatment train arrangements are
shown graphically in Figure 3.
The small sump tank shown in Figure
3 was used for pH adjustment, dilution,
and chemical dispersal. As the waste
water flowed through the first-stag*
activated sludge system, carbonaceoui
material (BOD, phenol, etc.) was re
moved. Effluent from the first-stage
clarifier was pumped through th<
second-stage activated sludge systen
where ammonia nitrogen was oxidize<
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(1) Activated Sludge, Nitrification
Waste water—.
Tap water—, | Air Polymer
Chemicals
Air-
Powdered
Activated
Carbon Polymer
Effluent
WAS
(2) Activated Sludge. Nitrification, Activated Carbon
WAS
Effluent
WAS WAS
(3) Activated Sludge, Nitrification, Dual-Media Filtration
Effluent
WAS
WAS
Figure 3.
Process trains investigated for treatment of by-product coke plant
wastewater.
by the nitrification process. The use of
powdered activated carbon was investi-
gated for removal of toxics and to im-
prove settling. Final effluent from the
second-stage activated sludge system
was passed through the activated
carbon/dual-media filtration system
late in the test program to complete the
second and third treatment tram
arrangements, respectively
During the pilot study, samples were
collected for both conventional and toxic
pollutants. Operational data were also
recorded on a daily basis to evaluate the
effectiveness of the respective treat-
ment trains. The pilot study results were
evaluated using three primary criteria-
1. Process and/or treatment train
performance.
2 Capital and operating costs.
3. Space requirements.
Conclusions
The two-stage activated sludge
treatment train was successful in
reducing influent concentrations of
coke plant pollutants. Because of upsets
in the coke plant pretreatment system
during the pilot study period, high dilu-
tion of the waste stream was necessary.
Significant reductions in pollutant con-
centrations were still achieved, how-
ever.
The treatment tram consisted of. (1)
diluting the raw coke plant wastewater
in a ratio of 1 part service water to 3
parts coke plant wastewater; (2) blend-
ing the mixture for pH control and phos-
phorus addition; (3) removing carbon-
aceous material in the first-stage
activated sludge system, followed by
clarification of the wastewater with
polymer addition; (4) further waste-
water dilution in a ratio of 3 5 parts
service water to 1 part first-stage acti-
vated sludge effluent; (5) addition of
sodium carbonate, powdered activated
carbon, and pH control chemicals to the
second-stage mixed liquor; and (6) oxi-
dation of ammonia in the second-stage
activated sludge unitto nitrate, followed
by clarification with polymer addition.
Late in the study, filtration of the
second-stage activated sludge effluent
was investigated.
1 The first-stage activated sludge
unit was capable of removing 95
percent of the influent BOD and
90-100 percent of the incoming
phenol. Thiocyanate and TOC
reductions were also achieved.
An estimated capital cost of
$2,654,000 and annualizedcostof
$4 51/3,785 I ($4.51 /1,000 gal )
would be realized for a 1,892
m3/day (0.5 mgd) treatment
facility, assuming current waste-
water pollutant concentrations If
ammonia still (fixed and free) effi-
ciency could be improved, capital
costs could be reduced to $2,427,
000 and annualized costs to
$4 21/3,785 I ($4.21 /1,000 gal.),
assuming a similar design flow
2. Influent ammonia to the second
•(nitrification)-stage activated
sludge system was quite variable,
ranging from 230 mg/l to 2,090
mg/l It was necessary to dilute
the first-stage activated sludge
effluent to maintain a consistent
feed ammonia strength before
nitrification could be achieved
After a sufficient population of
nitrifiers were in the system, am-
monia reductions of > 97 percent
were consistently achieved. Due to
the large quantity of dilution water
required, it was not possible to
determine the effect of other con-
taminants on the nitrification
process Suspended solids, oil and
grease, thiocyanate, and phenol
were also reduced to low levels. To
treat a 1,892 mVday (05 mgd)
wastewater stream as received
during the pilot study would re-
quire an estimated capital invest-
ment of $3,209,000 The expected
annualized cost would be $14.17/
3,785 I ($14 17/1,000 gal) For
comparison, if thefeedwater were
from an efficiently operating
ammonia still, a similar size design
would have a capital cost of about
$1,238,000 and an annualized
cost of only $4.12/3,785 I ($4.12/
1,000 gal.).).
3. Activated carbon, when used as a
polishing step for the nitrified
effluent, was capable of removing
53 percent of the influent TOC, 60
percent of the color, 40 percent of
the BOD, and 79 percent of the
remaining thiocyanate.
4. Dual-media filtration was found to
remove about 50 percent of the
suspended solids present in the
second-stage activated sludge
nitrified effluent. The expected
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capital cost for a 1,892 mVday
(0.5 mgd) design is $237,000 The
corresponding annualized cost is
$0.27/3,785 I ($0.27/1,000 gal.).
5. Priority pollutant analyses were
performed on 13 samples taken
from various points in the treat-
ment system All priority pollutant
metals were reduced to less than
100 yug/l except selenium and
zinc. The biological treatment train
was efficient in removing all vola-
tile organics, base/neutral ex-
tractable organics, and acid-
extractable organics to non-
detectable levels.
References
1. Development Document for
Proposed Effluent Limitations
Guidelines and Standards for the
Iron and Steel Manufacturing
Point Source Category-Vol. II,
By-Product Cokemaking Subcate-
gory, October 1979, EPA-440/1-
79/02400.
R. Osantowski, A. Geinopolos, and J. Meverden are with Rexnord, Inc., 5103
West Beloit Road, Milwaukee, Wl 53201
Robert V. Hendriks is the EPA Project Officer (see below).
The complete report, entitled "Two-Stage Biological Treatment of Coke Plant
Wastewater," (Order No PB81 -240 798. Cost: $18.5O, subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Spring field, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S Environmental Protection Agency
Research Triangle Park, NC 27711
U S GOVERNMENT PRINTING OFFICE, 1981 — 757-012/7332
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
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