Simultaneous biodegradability enhancement and high-efficient nitrogen removal in an innovative single stage anaerobic/anoxic/aerobic hybrid airlift bioreactor (HALBR) for composting leachate treatment

Abstract

A novel hybrid airlift bioreactor (HALBR) for simultaneous carbon and nitrogen removal from composting leachate was studied. In contrast to conventional airlift bioreactors, an anaerobic chamber was mounted at the bottom part to improve biodegradability of composting leachate and optimize overall COD removal. Desired aerobic and anoxic conditions provided by airlift configuration and oxygen concentration gradients within the biofilm increased the capability of system for TN removal through SND. Three independent variables, hydraulic retention time (HRT) (18–30 h), air flow rate (AFR) (1–2 L_air/min), and aerobic volume ratio (AVR) (0.22–0.26) were evaluated as operating parameters. The optimum conditions were an HRT of 28.3–30 h and AFR of 1.7–2 Lair/min, giving 3600 mg/L (90%) of COD and 598.4 mg/L (80%) of TN removal, respectively with an effluent turbidity less than 70 NTU. The outcomes demonstrated that this innovative single HALBR is a feasible and reliable technology for treatment of composting leachate.