| Characteristics of biological nitrogen removal for the treatment of a mature landfill leachate with a 1 200 m3 sequencing batch reactor (SBR) was investigated. The results indicate that obvious enhancement of nitrogen removal in the SBR treating landfill leachate was obtained by adding fecal supernatant to modulate the C/N ratio. The total nitrogen (TN) removal efficiency was found high up to 82.62% during day 112 to day 136, with an effluent of TN≤190 mg·L-1，COD≤400 mg·L-1. An equilibrium state of various nitrogen compounds removal reactions was achieved, and subsequently the ratio of BOD5 to TN maintained approximately at 1.43. In the equilibrium phase, by monitoring the cyclic variations of the nitrogenous compounds and sulphate in the reactor, a simultaneous proportional NH+4-N and SO2-4 removal was observed in the agitation and recirculation stage, and up to 27.06% of NH+4-N and 76.17% of SO2-4 removal was found. Simultaneous nitrification and denitrification and simultaneous removal of nitrogen and sulphate were exsited. The quantification of nitrogenous compounds removal reactions in the reactor was also conducted, and the calculation shows that the heterotrophic denitrification, simultaneous nitrification and denitrification, assimilation, simultaneous removal of nitrogen and sulphate, and endogenous respiration denitrification which are responsible for the TN removal are 62.6%, 33.8%, 7.0%, ＞26.1%, and 2.7% respectively. |
