[Characteristics of nitrogen removal in SBR for the mature landfill leachate treatment].

Characteristics of biological nitrogen removal for the treatment of a mature landfill leachate with a 1200 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 < or =190 mg x L(-1), COD < or =400 mg x 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 NH4+ -N and SO4(2-) removal was observed in the agitation and recirculation stage, and up to 27.06% of NH4+ -N and 76.17% of SO4(2-) 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.

Advanced treatment of landfill leachate by a new combination process in a full-scale plant.

Advanced treatment of mature landfill leachate from a municipal landfill located in southern China (Jiangmen) was carried out in a full-scale plant using a new process. The combined process has a sequencing batch reactor (SBR) serving as the primary treatment, with polyferric sulfate (PFS) coagulation coupled with a Fenton system as secondary treatment, and a pair of upflow biological aerated filters (UBAFs) in parallel as tertiary treatment. The overall removal efficiency of chemical oxygen demand (COD) in this process was 97.3%, with an effluent COD less than 100 mg/L. Up to 99% ammonia (N-NH3) removal efficiency was achieved in the SBR, with an effluent of less than 3 mg/L, which meets the discharge standard (< or =25 mg/L) with only primary treatment. The total phosphorus (TP) and suspended solids (SS) in the final effluent were reduced to less than 1 mg/L and 10 mg/L, respectively. The experience gained in the operation and maintenance will lead to a more stable performance of this combined process. An economic analysis shows that the overall operating cost of the advanced treatment was $2.70/m(3). This new combination process was proved to be highly compatible and efficient in a small-scale landfill leachate treatment plant and is recommended for small-scale landfill leachate treatment plants.