Zeolite-intermittent cycle moving bed air-lift bioreactor (Zeo-ICMBABR) for composting leachate treatment; simultaneous COD, nitrogen and phosphorous compounds removal.

Abstract

Anaerobically pretreated composting leachate contains high ammonia load and soluble organic matter, which requires further treatment. In this study, simultaneous removal of COD, nitrogen, and phosphorus compounds from anaerobically pretreated composting leachate investigated by using an intermittent cycle moving bed airlift bioreactor (ICMBABR) supported by zeolite as a biofilm. The efficiency of COD, Total Kjeldahl Nitrogen (TKN), and phosphorous removal and contaminants profile during the process, and the mass balances were analyzed. A multilayer design used for the experimental design, and the effect of four variables including hydraulic retention times (4, 6, 8h), the zeolite ratios (20, 35, 50%), the influent COD concentration (1, 2, and 3g/L) and aeration duration (64, 73, and 82%) investigated by Response Surface Methodology (RSM). According to the results and process profile the sequence of anoxic and aerobic conditions, presence of the anaerobic zone in the bottom of the reactor, as well as the use of zeolite as adsorbent media, significantly allowed the simultaneous removal of COD (99%), TKN (95%), and total phosphorus compounds (90%) from anaerobically pretreated composting leachate and favorable potential to remove nitrogen compounds by high efficiency (79%) through simultaneous nitrification and denitrification (SND).