Effects of in situ nitrogen removal on degradation/stabilization of MSW in bioreactor landfill

The effects of in situ nitrogen removal on degradation of municipal solid waste (MSW) in bioreactor landfill system were investigated. The in situ nitrogen removal bioreactor landfill (NBL) consisted of fresh–refuse filled, methanogenic and nitrifying reactors was operated. The two-phase bioreactor landfill (BL) comprised of fresh–refuse filled and methanogenic reactors was used as control. The methanogenic and nitrifying reactors were all loaded with aged refuse whose placement time was 6–7 yr. Furthermore, the nitrifying reactor was in situ aerated. The results showed that the degradation of fresh–refuse was delayed and CH4 production also was reduced in the in situ nitrogen removal bioreactor landfill. It was feasible to perform in situ ammonia nitrification in aged refuse. Moreover, the efficiency of oxygen utility was high during the in situ nitrification because of the porous characteristic of aged refuse. Supplementing only 8.5 mg O2 mg 1 N d 1 to aged refuse could make ammonia removed completely. However, aeration did not accelerate the further stabilization of aged refuse.