Biotreatment of oil-bearing coke-oven wastewater in fixed-film reactor: A viable alternative to activated sludge process

Coke-oven wastewater is produced in the integrated steel plants at coke-ove n gas-cleaning operations. It is laden with phenol, cyanide, thiocyanate, a nd oil. Although the activated sludge process is widely practiced in the bi ological treatment of coke-oven wastewater, it was observed during field vi sits that oil contamination and poor sludge settleability had resulted in p oor maintenance of the activated sludge process. These problems can be mini mized by the use of fixed-film systems such as trickling filters; however, availability of a microbial consortium, which would sustain oil contaminati on, was a major constraint. Research endeavor at this Institute has resulte d in the development of such a microbial consortium, and the same was appli ed on a bench-scale fixed-film system such as a trickling filter, for the t reatment of coke-oven wastewater. The unit was set up in the steel industry , and fresh coke-oven wastewater was treated over a period of 45 days. The results indicated that phenol and oil were simultaneously degraded and the system was stable. The studies established that the fixed-film system could be a viable alternative to the activated sludge process if appropriate mic robial consortium is adopted.