[A novel municipal wastewater treating process for energy production and autotrophic nitrogen removal based on ANAMMOX].

Using a innovative system consisted of methanogenesis,partial nitritation and anaerobic ammonium oxidation (ANAMMOX) reactors, simultaneous methane production and autotrophic nitrogen removal from domestic sewage was successfully achieved. The results showed that the effluent NH4(+) -N of the combined treatment process was below the detection limit. The effluent NO3(-)-N and NO2(-) -N were less than 0.5 mg x L(-1) and 3.6 mg x L(-1), respectively. The effluent COD of the combined treatment process was 10 mg x L(-1) and a COD removal rate of 98% was achieved. More than 80% COD was removed by the up-flow anaerobic sludge fixed bed (UAFB) and the anaerobic gas production was 3.3 L x d(-1) with a methane yield of 0.3 L x g(-1). About 39.2% of influent COD was removed in form of methane and about 6.52% was transferred to VFAs. Partial nitritation with high nitrite accumulation efficiency of 97% was realized in a Sequencing Batch Reactor (SBR). Ammonium was partly oxidized to nitrite with an ammonium: nitrite ratio of 1: 1.13, which was suitable for the sub-sequent ANAMMOX reaction. In terms of N balance, the N conversion rate of SBR was 36.59% while the anaerobic ammonium oxidation (ANAMMOX) reactor, which was the major system in nitrogen removal, removed 56.91% of N. The TN removal rate of the ANAMMOX reactor was 0.62 kg x (m3 x.d)(-1) and the ratio of NH4(+)-N removal: NO2(-) -N removal: NO3(-) -N generation was 1: 1.18: 1.25. The new process achieves energy recovery by reclaiming methane and autotrophic nitrogen removal by the partial nitritation-ANAMMOX process, and provides a new approach and technology for reforming of domestic wastewater treatment plants.