Study Of Fe~Ⅲ(Edta) And Fe~Ⅱ(Edta)-No Biological Reduction And The Change Of Microbial Community Structure In Biodenox

The air pollution caused by nitrogen oxides (NOx) is becoming more and more seriously in recent years. Chemical absorption-biological reduction integrated process (BioDeNOx) was used to treat NOx. It has many advantages such as high removal efficiency, low secondary pollution, acceptable running cost and so on. Reduction and regeneration of the absorbent (FeⅡ(EDTA)) are the key points of BioDeNOx. The biological reduction of FeⅢ(EDTA) and FeⅡ(EDTA)-NO by pre-denitrification sludge which had be domesticated was investigated under55℃. The generation and accumulation of N2O which was the intermediate product of FeⅡ(EDTA)-NO reduction was also detected. The changes of microbial community structure and dominant species in the reduction process were discussed by PCR-DGGE.1) Glucose was considered as the most suitable carbon source for FeⅢ(EDTA) reduction under55℃, the optimal pH was7.5. FeⅢ(EDTA) reduction rate decreased with the presence of NO3-, NO2-and SO32-. Moreover, the inhibitory effect was proportional to the concentrations of NO3-, NO2-and SO32-in the media. The inhibitory effect of NO2-is stronger than that of NO3-at the same amount of addition.2) Glucose was the best carbon source for FeⅡ(EDTA)-NO reduction under55℃, the optimal pH was7.0. FeⅡ(EDTA) could be used by creatures in the activated sludge as electron donor for FeⅡ(EDTA)-NO reduction, but at the same addition of glucose and Fen(EDTA), the system which used glucose as electron donor had a higher FeⅡ(EDTA)-NO reduction rate. It was found out that N2O was a intermediate product of Fen(EDTA)-NO reduction no matter used glucose or FeⅡ(EDTA) as electron donor. In the conditions of lacking carbon source (<2000mg/L), acidic condition (pH=6.0), excessive temperature (60℃) and using Fen(EDTA) as electron donor, would result in more generation and accumulation of N2O.3) The results of PCR-DGGE showed that the main microbial communities of FeⅢ(EDTA) reduction system were Anoxybacillu、 Saccharococcus、Pseudomonas、Clostridium、Calorbacillus、 Geobacillus、Thermoanaerobacterium、Bacillus at55℃. Pseudomonas、 Halalkalibacillus、Anoxybacillu、Aeribacillus、Bacillus were the main microbial communities of FeⅡ(EDTA)-NO reduction system. The microbial community structures of these two systems had significant changes on the effects of different parameters, and they had different dominant microbial communities.