Biotreatment of Oil-Bearing Coke-Oven Wastewater in Fixed-Film Reactor: A Viable Alternative to Activated Sludge Process

Abstract

Coke-oven wastewater is produced in the integrated steel plants at coke-oven gas-cleaning operations. It is laden with phenol, cyanide, thiocyanate, and oil. Although the activated sludge process is widely practiced in the biological treatment of coke-oven wastewater, it was observed during field visits that oil contamination and poor sludge settleability had resulted in poor maintenance of the activated sludge process. These problems can be minimized by the use of fixed-film systems such as trickling filters; however, availability of a microbial consortium, which would sustain oil contamination, was a major constraint. Research endeavor at this Institute has resulted in the development of such a microbial consortium, and the same was applied on a bench-scale fixed-film system such as a trickling filter, for the treatment 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 microbial consortium is adopted.