Coupled Anaerobic Baffled Reactor (ABR)/Activated Sludge Treatment of Synthetic Wastewater with High Concentration of Sulfate and COD

A synthetic wastewater with high concentration of sulfate and COD was treated in anaerobic baffled reactor (ABR) coupled with an activated sludge. The work was accomplished in two phases. In the first phase, the concentration of sulfate was kept constant at ۵۰۰mg/l, but COD concentration was increased from (۳۰۰۰mg/l to ۶۰۰۰mg/l), consequently, COD and sulfate removal in ABR reached to ۸۰% and ۹۵%, respectively. Some of produced sulfide in ABR converted to sulfur by photosynthetic bacteria which appeared on the top of the ABR. Effluent from the ABR entered to activated sludge where COD removal reached ۶۰%, but some of sulfide converted to sulfate. In the second phase, at constant concentration of COD, when sulfate concentration was increased from ۵۰۰mg/l to ۱۷۵۰mg/l by steps about ۲۵۰mg/l, inhibition was not observed. When effluent of thissecond phase was entered in activated sludge, COD removal was decreased, and sulfide cause bulking in activated sludge. The ABR and activated sludge were worked with hydraulic retention time (HRT) about ۲۴ hours and ۱۵ hours, respectively. The temperature of ABR system was maintained at ۳۵ºC.

Keywords:

Anaerobic Baffled , Activated sludge , COD removal , Sulfide , Sulfide Removal