PHYSICAL/CHEMICAL AND BIOLOGICAL TREATMENT
OF COKE-PLANT WASTEWATER
Richard Osantowski, Research Engineer
Environmental Research Center
Rexnord, Inc.
Milwaukee, Wisconsin 53214
Robert V. Hendriks, Project Officer
U.S. Environmental Protection Agency
Industrial Environmental Research Laboratory
Research Triangle Park, North Carolina 27711
The production of metallurgical coke is an essential part of the iron and steel industry.
In the coke-making by-product recovery business, volatile compounds are recovered from
the gas stream and processed into a variety of valuable materials. However, process wastewater streams originate from the various recovery techniques, and these concentrated flows
must be treated prior to discharge. Typical pollutants include ammonia, cyanide, phenol,
sulfide, thiocyanate, oil and grease, suspended solids, and many toxic pollutants.
The objective of this project was to determine the feasibility of treating by-product
coke-making wastewater to best available technology (BAT) levels by physical/chemical
and biological techniques. Two coke plants were studied as a part of this investigation:
the physical/chemical research work was performed at Shenango, Inc., Pittsburgh, PA,
while the biological testing was conducted at Wheeling-Pittsburgh Steel Corporation's
Follansbee, WV, plant. The studies were performed on a pilot scale using the U.S. Environmental Protection Agency (EPA) mobile physical/chemical and biological treatment systems.
These pilot plants are housed in three semi-trailer vans as shown in Figures 1 to 3.
PHYSICAL/CHEMICAL EXPERIMENTAL RESULTS
During the physical/chemical investigation of Shenango's by-product coke-making wastewater, coke production averaged 1,673 metric tons (1,519 tons) per day, while the average
wastewater flow was 1,025 m /day (0.271 x 106 gal/day). The corresponding water application rate (liters of water/1,000 kg of coke produced) during the study was 743 liters/
1,000 kg (178 gal/ton). Based on BAT (excluding priority pollutants) limits [ 1 ], the allowable pollutant concentrations in the effluent would be as given in Table I. The pilot studies
were structured toward meeting these guidelines.
The advanced waste treatment trains that were investigated on a pilot scale included:
1. alkaline chlorination + dual-media filtration + activated carbon;and
2. alkaline chlorination + sodium bisulfide dechlorination + dual-media filtration.
WASTEWATER TREATMENT SYSTEM OF PLANT INVESTIGATED
Four process water streams are associated with the by-product coke-making operations
at the plant investigated: (1) final cooler wastewater; (2) phenolate wastes (excess flushing
liquor), which have been passed through a free-ammonia still, a dephenolizor and a fixed-
ammonia still;(3) light oil separator effluent; and (4) hot oil decanter underflow.
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