Typical Micro-polluted Water And Poor Nutrition Microbial Community Structure Of Aerobic Denitrifying Bacteria Denitrification Performance

As the increasing pollution of the reservoirs, lakes and urban landscape waterbody, and the higher standard of the urban supply water quality, microbial populationstructure of landscape water and biological treatment of slightly polluted water arebeing paid more and more attention. Based on the preliminary study in our researchgroup, we selected nine landscape water bodies and explored the water quality anddetermined the water bacterial and fungal communities by using nested PCR-DGGEand clone sequence techniques. For the further we screened and isolated out theaerobic denitrifying bacteria from the sediment of a reservoir, and applied it to the newexperimental technology research of micro-polluted water body purification and waterquality improvement. And then this study analyzed the process of nitrogen purificationin micro-pollution water by directly adding the efficient aerobic denitrifying bacteria,selecting the preferably bacteria and experimental control conditions. Making thebacteria can adapt to the raw water quality and biological conditions, which play thebest denitrification efficiency. Main results of this study are as follows:(1) The water qualities of nine landscape water bodies were belonged to inferiorⅤ water. The pH values were between8.5-9.5, the water temperature in the range of20-30℃, the dissolved oxygen concentration between8.0-10.5mg/L.The totalnitrogen content of water are higher than2mg/L.The results of nested PCR-DGGE andPCA analyses suggested that water communities in LH, YY and DMG was similar, thediversity of water bacterial community of FQ, XJY, QJ and GM was similar, however, water bacterial community in XQ is different from other water bodie The waterbacterial communities in LH, YY and DMG were regulated by the highest nitrate, totalnitrogen and dissolved oxygen concentrations. Whilst, highest ammonia nitrogenconcentration had a significant influence on water bacterial community, there wasnegative correlation between highest nitrate and CODMn. CODMnconcentration had asignificant influence on XQ water bacterial community diversity. DMG, LH, FQ, XJYand XQ had similar water fungal community structure, however, GM had a significantdifferent fungal community from other water bodies, which was regulated by totalnitrogen, the highest nitrate and ammonia nitrogen. YY water fungal community wasinfluenced by highest ammonia nitrogen concentration. Phoma sp. was the dominatedwater fungal species.(2) From November2012to March2013, we selected337aerobic denitrifyingbacteria from the sediments of a Shandong reservoir. Choose eight strains which havethe better denitrification and different forms from all the bacteria as experimentalbacteria. Culture the eight bacteria in the same conditions, within48h nitrate removalefficiency greater than70%, of which two strains48h nitrate removal efficiency canreach above90%; highest total nitrogen removal rate within48h to62%. According tothe different nitrogen removal efficiency of for eight bacterias, combined thebacterias which have different characteristics, and picked the high denitrificationefficiency F3and F6combination, used in raw water as test bacteria in cultureconditions.(3) According to the experimental feasibility, nitrogen removal efficiency and thetime spent, we compared five methods for adapted the bacteria to the target waterquality. The results suggest that the method No.4: five steps to replace the sterilizedraw water adaptation method and the method No.5: five steps to replace theno-sterile raw water adaptation method have better effect. Two methods of adaptationin raw water can reach40%of nitrate nitrogen removal.(4) Through four raw water test, we can get the following results: using theselected bacterias and bacterias combinations in raw water test, the F6and D7combinations have the better nitrogen removal efficiency, followed by is F3combinations, D3&D7complex combinations and D3strains. Calculation of the amount of inoculum bacteria should used the methods of bacteria plate count method.It will determine the number of bacteria which inoculated in water. The betterinoculated bacteria amount which determined by the water experiments is about105CFU/ml. Relative to the control group, the nitrogen removal effect can reach40%oftotal nitrogen, nitrate nitrogen removal rate reached58%, and no nitrite accumulatedremoval stable.(5) By analyzing the raw water control conditions can be obtained: the raw watertemperature is not controlled, under nitrogen we can obtain better nitrogen removalefficiency at room temperature state; the dissolved oxygen is between3-5mg/L is theoptimal conditions. But it had little difference from dissolved oxygen and nitrogen, so,we consider the mixing effect is one of the factors affecting the nitrogen remove effect.