Palm frond biochar for sludge granulation in aerobic granular sludge system

Abstract

This work investigated the role of biochar derived from palm frond addition in an aerobic granular sludge system to improve the granulation of sludge. The effect of biochar dosage was analysed based on the granules size and chemical oxygen demand (COD) removal performance. At the same time, the system performances including sludge volume index (SVI30), mixed liquor suspended solid (MLSS) and mixed liquor volatile suspended solid (MLVSS) for 50 days were studied. Three identical of 2 L reactors which operated based on sequencing batch reactors (SBR) system were used in this study named R1, R2 and R3. Difference dosage of biochar was added into R2 and R3 which is 4g and 8g, respectively while, R1 as a control system with no biochar added. The existence of biochar improved the granulation process as aerobic granule size of 0.95- 1.49 mm with clear boundary was observed at 14 days of system operation. The biochar supplemented in the reactors act as a core for microorganism to accumulate and enhanced the granulation of sludge. After the granulation, R3 shows a good settling characteristic compared to R1 and R2, with an SVI of 50 mL/g SS at the end of system operation. The reactors performed steadily with COD removal efficiencies of 85%, 90% and 96% in R1, R2 and R3, respectively at initial COD concentration of 500 mg/L and 24 h of SBR cycle. The dosage of biochar had a positive impact on granulation and reactor performances even at the short duration of system operation.