Study Of Nitrification And Denitrification Performances And The Community Stuctrue In A New Submerged IEM-MF Composite Memb Rane-O/A Bioreactor

In our country, organic matter concentration of wastewater is difficult to meet the requirements of traditional biological nitrogen removal process. How to improve removal efficiency of nitrogen and organic matter of the low C/N wastewater, has become one of the biggest concern in the field of wastewater treatment. To address this issue, the study applied the New Submerged IEM-MF Composite Membrane which had the functions of both enriching NH₄⁺-N and isolation organics to Low C/N wastewater treatment. The feasibility of sewage treatment was investigated by controlling the operation the membrane module and the long run test under 1 and 2 sets of membrane module. The community structure of nitrifying and denitrifying bacteria were studied by building amo A and nir S gene clone library.?1?The results showed that the suitable operation current under condition 1 and 2 were 0.15 A and 0.2A, respectively. The optimum on/off ratio is 10:5?10:6?min?, respectively. NH₄⁺-N enriching performance firstly increased and then decreased with the effluent of the membrane rising under condition 1. The optimum rate of flow turned out to be 2.9ml/min. On the other hand, NH₄⁺-N enriching performance was negatively related to the effluent of the membrane rising under condition 2. The suitable rate of flow turned out to be 4.1ml/min. The influence of the distance between memrane module and anode on NH₄⁺-N enriching performance was not obvious under condition 1. The influence of the distance between memrane 1 and memrane 2 on NH₄⁺-N enriching performance was not obvious under condition 2.?2?The COD removal and biological denitrification performances of the New Submerged IEM-MF Composite Membrane-O/A system were observed to identify whether the membrane module had impacts on the nitrifying and denitrifying process. The NH₄⁺-N enrichment and COD intercepting performances were contrasted when 1 set of membrane module?condition 1?and 2 sets of membrane modules?condition 2? were in operation, to investigate how the amounts of membrane module in operation affected its performances. Results showed the removal efficiency of COD maintained stable despite the great fluctuation in influent, indicating that the system had a good capacity to resist the loading shock. The average COD concentration in effluent achieved 31.15 mg/L and 23.58mg/L under condition 1 and 2, respectively. The NH₄⁺-N removal efficiency were 54.41% and 76.92%, respectively, indicating that the breeding of heterotrophic microorganisms were restrained by applying the membrane module under condition 2. The TN removal efficiencies achieved 53.49% and 67.24%, respectively. Total nitrogen in the effluent existed mainly in the form of NH₄⁺-N,indicating that denitrification proceeded almost completely. Membrane module performed the function of replenishing carbon source to denitrification process,successfully. The average NH₄⁺-N enriching efficiency reached 70.37% and 118.57% under condition1 and 2, respectively. The average COD concentration in the effluent of the membrane module reached 39.03mg/L and 56.11 mg/L, respectively. The results showed that the separation of NH₄⁺-N and organics was almost achieved and the amounts of membrane module in operation had a great influence on the NH₄⁺-N enriching performance. The influence on COD intercepting performance remained not that obvious.?3?The community structures of AOB and denitrifying bacterium were studied by building amo A and nir S gene clone libraries. The correlation between system efficiencies and microbial structures were discussed. The NH₄⁺-N enriching efficiency achieved 119% on average.The removal efficiency of COD kept higher than 92.34%.The efficiencies of nitrifying and denitrifying reached 90.03% and 92.88% on average,respectively.According to the phylogenetic trees analysis,the AOB community included 2 major bacterium: Nitrosospira and Nitrosomonas,both of which blonging to the ?-proteobacteria group. Nitrosospira was supposed to be the major functional bacteria of AOB, for the proportion of which was as high as 89.65%.?4?The denitrifying bacterium which were found more abundant than the AOB,could be mainly consisted of 3 groups:?-proteobacteria, uncultured bacteria and ?-proteobacteria,the proportions of which were 48.49 %,34.84% and 16.67%,respectively.?-proteobacteria was the dominant group. Azoarcus and Rhodanobacter could possibly be the most important bacterium in denitrifying bioreactor.