Treatment of starch-processing wastewater in sequencing batch reactor

Abstract

Starch processing industries have increased their production recently due to high demand in various food products. As a result, water consumption was increased and discharged without proper treatment which may cause pollution. Major problems caused by tapioca starch wastewater is water pollution due to high biological oxygen demand (BOD), chemical oxygen demand (COD) and suspended solids (SS) concentrations causing low water quality. Untreated starch wastewater contained high BOD3, COD and SS concentrations at 2,532 mg/L, 14,966 mg/L and 4,869 mg/L with pH 6.33 and high colour range at 1770 ADMI, respectively. High water consumed had increased the production cost for treatment of starch processing wastewater. Sequencing batch reactor (SBR) is a simple, compact and save spacing technology to treat wastewater due to simultaneous operation in one tank. SBR also had great potential to remove organic matter as desired with variables cycle time and operation. In this study, starch wastewater was treated at organic loading rate of 1.5 kg COD/m3d. SBR was operated at 24h cycle for 60 days. The treatment was conducted in two columns namely R1; operated without granules and R2; operated with granules in activated sludge, respectively. The efficiencies of BOD3, COD and colour removals were observed to monitor the SBR performance while mixed liquor suspended solid (MLSS) and mixed liquor volatile suspended solid (MLVSS) were the parameters that used to monitor the activated sludge performance in SBR. After 60 days of operation, R1 showed BOD3, COD and colour removal achieved at an average of 97%, 70% to 96% and 50% to 89% while R2 showed higher removal at an average of 98%, 85% to 94% and 76% to 95% removals respectively.