COMBINED BIOLOGICAL TREATMENT OF
COKE-PLANT WASTEWATER AND
BLAST-FURNACE RECYCLE-WATER SYSTEM BLOWDOWN
Joseph J. Gauthier, Associate Professor
Daniel D. Jones, Associate Professor
Biology Department
University of Alabama in Birmingham
Birmingham, Alabama 35294
Leon W. Wilson, Jr., Sr. Research Engineer
Environmental Research Division
Research Laboratory
United States Steel Corporation
Monroeville, Pennsylvania 15146
Carl R. Majors, Project Engineer
Fairfield Works
United States Steel Corporation
Fairfield, Alabama 35064
Coke production results in the generation of wastewater containing phenols, thiocyanate,
cyanide and ammonia. State and federal regulations require that the wastewater be treated
prior to discharge. The treatment options available include physical-chemical methods and
biological processes. Studies dealing with the biological treatment of coke-plant wastewater
indicate that the activated sludge process may provide the best available technology economically achievable (BATEA) for meeting 1984 proposed effluent limits [ 1-6].
Although the biological removal of phenol and thiocyanate from coke-plant wastewater
has been successful, ammonia removal has met with more limited success [ 1-4]. Ammonia is
utilized by the bacterium Nitrosomonas as an energy source and is oxidized to nitrite. The
nitrite is then further oxidized to nitrate by Nitrobacter. This process of nitrification, i.e.,
the conversion of ammonia to nitrate is the most difficult step in biological treatment of
ammonia-containing wastewater.
The earliest microbiological studies of the nitrifying bacteria suggested that they are
incapable of growth in the presence of organic compounds. This unfortunate misconception
has persisted until only recently. It is now known that, although the nitrifying bacteria are
indeed sensitive to a variety of environmental conditions, including pH, temperature, dissolved oxygen (DO) concentration, certain metals and specific organic compounds [5-11],
they are generally not inhibited by the presence of organic compounds.
Both double-stage [1,12] and single-stage [13-16] systems have been studied for treatment of wastewaters containing organic compounds and ammonia. Investigations of the
single stage system with coke-plant wastewater indicate that the proposed 1984 BATEA
limits can be met, provided that adequate pretreatment, equalization, temperature control
and solids retention time are maintained [ 17-21 ].
The biological wastewater treatment facilities at the United States Steel Corporation
(USSC) plant in Fairfield, AL presently treat excess ammonia liquor and additional miscel-
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