Landfill Leachate Treatment Using Aerobic Granular Sludge

This research investigated the treatment of landfill leachate using aerobic granular sludge (AGS). The AGS was cultivated from a lab-scale sequencing batch reactor (SBR). Leachate was gradually fed into the aerobic granular sludge SBR (GSBR) by mixing it with primary effluent at ratios varying from 10 to 90%. Regardless of the different mixing ratios or high free-ammonia (FA) and free-nitrous-acid (FNA) concentrations in the influent, the GSBR demonstrated high total ammoniacal nitrogen (TAN) removal efficiency, which ranged from 95 to 100%. The best results were obtained when the total nitrogen (TN) load was 0.3 +/- 0.04 kgN/m(3)day (153 mg/L of TAN in the influent), where the FA concentration was the lowest (11 +/- 1.4 mg/L). For a nitrogen load up to 0.68 +/- 0.03 kgN/m(3)day (i.e., TN 340 +/- 13 mg/L and FA 24.5 +/- 1 mg/L), chemical oxygen demand (COD), TN, and phosphorus removal of GSBR were around 64, 42, and 84%, respectively. With the further increase in the nitrogen load, the TN, COD, and phosphorus removal rate of GSBR decreased significantly; however, the TAN removal efficiency remained constant at 90-100%. This study showed that the AGS is able to treat leachate with high concentrations of TAN (912 mg/L), and simultaneous nitrification and denitrification play a significant role in nitrogen removal. From these promising results, the use of AGS for leachate treatment should be encouraged. (C) 2017 American Society of Civil Engineers.