Biodegradation of Phenol with Wastewater as a Cosubstrate in Upflow Anaerobic Sludge Blanket

Abstract

Anaerobic degradation of phenol mixed with a readily degradable synthetic wastewater (DSWW) as a cosubstrate was studied in a 12 L upflow anaerobic sludge blanket reactor at 30±2°C over a period of 632 days . DSWW was prepared by diluting sugar cane based molasses. The biomass was acclimatized to high phenol concentration by gradually decreasing the DSWW chemical oxygen demand (COD) of 4,000 mg∕L . Feed made up of phenol COD and DSWW COD in the ratio of 7:3 (phenol concentration=1,176 mg∕L ) was successfully treated at a hydraulic retention time (HRT) of 12 h and organic loading rate (OLR) of 8 g COD∕L day . Phenol removal ranged from 99.9 to 84% at phenol COD varying from 10 to 70% in the feed. During the entire operation, COD removal varied from about 74 to 91.3%. The influent COD was distributed into C H4 –COD (∼72%) , effluent COD (∼17%) , and sludge and unaccounted COD (∼11%) . The process failure occurred at 4:1 phenol COD: DSWW COD. Specific methanogenic activity of granular sludge exhibited unifor...