TREATMENT OF COKE PLANT WASTEWATER
IN THE COUPLED PREDENITRIFICATION-NITRIFICATION
FLUIDIZED BED PROCESS
S. G. Nutt, Vice-President
Canviro Consultants Ltd.
Kitchener, Ontario N2H 5M5
H. Melcer, Head
Biological Processes Section
Wastewater Technology Centre
Environment Canada
Burlington, Ontario L7R 4A6
I. J. Marvan, Manager
Dearborn Environmental Consulting Services
Mississauga, Ontario L5A 3T5
P. M. Sutton, Senior Process Engineer
Dorr-Oliver Inc.
Stamford, Connecticut 06904
Liquid effluents generated from by-product coking operations are extremely complex,
containing high concentrations of phenolic compounds, thiocyanate, free and complex
cyanide, ammonia, and a variety of trace organic contaminants that have been shown to
produce adverse long-term environmental impacts. Treatment of such wastewaters in conventional biological systems can present considerable difficulty due to the inhibitory effect
of the contaminants generated by the coking process.
Bench-scale biological treatability studies conducted at Environment Canada's Wastewater Technology Centre (WTC) in Burlington, Ontario, have demonstrated that coke oven
wastewaters can be nitrified and denitrified in single-sludge suspended growth systems
operated in a predenitrification mode. Long hydraulic retention times (up to 60 hr) and
stringent SRT control, in conjunction with wastewater dilution or powdered activated
carbon  (PAC) addition, were required to ensure consistent process performance  11,2].
Pilot-scale investigation of the biological fluidized bed process conducted at the WTC
have shown this novel fixed-film system to offer significant advantages in terms of reduced
reactor volumes due to the high biomass concentrations that can be maintained on the
fluidized support medium [3-5]. To assess the technical and economic feasibility of treating
coke plant wastewaters by the fluidized bed process, a two-stage pilot-scale fluidized bed
reactor system was operated for a period of approximately 18 months at the WTC. The
startup procedures and pseudo-steady-state performance of the coupled predenitrification-
nitrification fluidized bed process have been presented in detail elsewhere [6]. This chapter
reviews the results of the pseudo-steady-state operation, presents performance data accumulated during a two-month period of nonsteady-state operation and develops process design
details and preliminary capital and operating cost estimates for a coupled biological fluidized
bed system treating coke plant wastewater.
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