A complex system of activated sludge and bio-membrane system was used for enrichment of denitrifying phosphorus bacteria (DPB).DPB strains were isolated and identified.In order to study their metabolic mechanism

activity test of denitrifying and accumulating phosphorus was carried out on both fermented and non-fermented bacteria.The result shows: (1)YU-1 and YU-2 were obtained by separation of DPB with combined activated sludge and biofilm method.The former is similar to Acinetobacter junii

a kind of non-fermented DPB and the latter similar to Escherichia coli

a kind of fermented DPB.(2)During the anaerobic stage for every 1 mg of PHA generated the phosphorus release is 0.2 mg larger for non-fermented bacteria YU-1 than the fermented bacteria YU-2.The energy required for the synthesis of PHA is mainly from the degradation of poly-phosphate

the majority of carbon from the acetic acid

reduced coenzyme NADH not from the glycolysis process of glycogen.The mechanism for generation of ATP

PHA and NADH are different from the traditional metabolic mechanism.(3)Under anoxic environment for every 1 mg of PHA decomposed the phosphorus accumulation is 0.3 mg higher for non-fermented bacteria YU-1 than the fermented bacteria YU-2

which means the accumulating efficiency is 12.8% higher.The reason can be that in this stage the most of ATP generated from the decomposition of PHB is used for the transport of phosphate and the synthesis of poly-phosphorus

reduced coenzyme NADH come from the breakdown of PHA for the reduction power required for anaerobic process.The mechanism of PHA decomposition is different from the metabolic mechanism of traditional phosphorus accumulating bacteria.