Biological Treatment of Synthetic Fuel Wastewater

A wastewater biological treatability study was performed with effluent from the Grand Forks Energy Technology Center slagging fixed-bed coal gasification process. It was found that ammonia stripped wastewater could be processed reliably at 33% strength at substrate removal rates less than approximately 0.6 mg COD removed/mg MLVSS-day. The wastewater when diluted to 33% strength contained highest reported concentration of organic contaminants in coal conversion effluents processed successfully by air activated sludge. The bacterial yield coefficient for treatment of 33% strength stripped wastewater was 0.29 (COD basis) and the endogenous respiration rate coefficient was 0.038 day^-¹ (COD basis). Raw wastewater with no ammonia removed could be processed at 40% strength. Nitrification was feasible with both stripped and unstripped wastewater. COD removal rates which impaired nitrification were dependent on ammonia loading, as nitrification could be sustained at higher values of substrate rate with unstripped wastewater than was observed with stripped wastewater.