Treatment of landfill leachate in sequencing batch reactor supplemented with activated rice husk as adsorbent

The objective of this study is to evaluate the performance of ethylenediamine-modified rice husk (MRH)-supplemented sequencing batch reactor (SBR) as compared to powdered activated carbon (PAC)-supplemented SBR in the removal of COD and nitrogen from a combined landfill leachate and domestic wastewater. The SBRs were operated with the FILL, REACT, SETTLE, DRAW and IDLE periods in the ratio of 2:12:2:1:7 for a cycle time of 24 h. The performance of the reactors was evaluated by monitoring the effluent quality as well as the concentration profiles of COD, ammonia nitrogen (AN), nitrite nitrogen and nitrate nitrogen during the REACT period of an operating cycle at various mixing ratios of the wastewaters. The results showed that equivalent performance of the MRH- and PAC-supplemented SBRs in terms of the efficiency and rate of COD and AN removal was achieved at a lower loading rate of MRH compared to that of PAC. The better performance of the MRH-supplemented SBR was postulated to be due to the presence of attached-growth biomass which is less inhibited by toxic constituents in leachate than suspended-growth biomass. Overall, MRH shows a good potential of being used as an alternative adsorbent to PAC in leachate treatment.