Effect of inoculated indigenous denitrifying bacteria on nitrogen removal in paddy soil in Chaohu Lake basin
The attenuation of nitrate in soil by bioremediation is an environmentally friendly and eco-efficient method.In this study,four reaction columns including A(soil),B(soil+sawdust),C(soil+sawdust+Bacillus cereus)and D(soil+Sawdust+indigenous denitrifying bacteria)were constructed,and the indigenous denitrifying bacteria(Pseudomonas sp.P10)isolated from the soil fillers and the denitrifying bacteria Bacillus cereus from lake sediment were inoculated into the columns,aiming at investigating the effect of indigenous denitrifying bacteria on nitrogen removal in the columns filled mainly with the same paddy soil.The results showed that inoculating Pseudomonas sp.P10 into the reaction column could shorten the start-up time of NO3--N removal.The removal rate of NO3--N in the column B was up to 96.05％.NH4+-N accumulation appeared in the column D inoculated with indigenous denitrifying bacteria.NO2--N accumulated in columns B,C,D was lower than 2.4 mg·L-1.Under the condition of 30 mg/L and 50 mg/L NO3--N in influent,the TN removal rate of each reaction column was between 50％～70％.The TOC concentration in all effluents meets the water quality standard.The dominant bacteria in column D inoculated with indigenous denitrifying bacteria were Pseudomonas,while the dominant bacteria in column C inoculated with Bacillus cereus failed to compete with the original microbial community.Inoculation of indigenous denitrifying bacteria could enhance the denitrification ability of soil to a certain extent.Under the condition of sufficient available carbon source,the reaction column without inoculating microorganism has the advantage of denitrification.The results can provide more powerful clues for enhancing the attenuation of exogenous nitrogen in soil and lake,in addtion to more information for the resource utilization of lake sediment and the steady-state maintenance and sustainable system dynamics of ecosystem during pollution control.
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