Aerobic granulation with industrial wastewater in sequencing batch reactors

Abstract

The high operational cost of drinking water supply is mostly encountered following the upsurge of pollutant concentration in wastewater, surface water and ground water. Palm Oil Mill Effluent (POME) generated from palm oil industries and the micropollutant from pharmaceutical industries are amongst the main contributor to this problem. Two identical SBR bioreactors without granules (R1) and with granules (R2) were fed with 5 mg acetaminophen per 1 L of POME, organic loading rate (OLR) in a range 2.5 to 3.5 g COD L-1 were used. The reactors were operated at 27oC (room temperature) with 12 hrs successive cycles involved 5 min of feeding period and 2 min for effluent withdrawal, resulting 50% of volumetric exchange ratio (VER). The reaction time was initially set as an anaerobic and aerobic period, 45 min and 10 hrs 35 min, respectively. On day 50 the biomass concentration and the sludge volume index (SVI) for both reactors were between 11,160 mg L-1 to 11,430 mg L-1 and 15 mL g-1 SS to 17 mL g-1 SS, respectively, indicating fair biomass accumulation in the reactor and good settling properties of granular sludge. Moreover, COD removal was 81% and 67% for R2 and R1, respectively. Phosphate was removed at 28% in R1 while R2 removed a higher phosphorous removal at 55%. The average color removal for both reactors ranged from 45% to 54%. In addition, the paracetamol concentration was depleted and the aerobic granules was developed 0.5 to 3.0 mm in size for both reactos. This study provided an insight of the feasibility of aerobic granular sludge formation in SBR to be an effective biodegradable process for high strength wastewater with emerging pollutants, such as pharmaceutical wastewater.