Studies On Isolation And Application Of Aerobic Denitrifying Bacteria To Nitrogen Removal Of Wastewater

With the rapid development of China's economy and the improvement of people's living standard.Rural domestic wastewater has become the important pollution which leads to envirormental degradation in rural water.Therefore,the treatment of rural domestic wastewater has been more and more attention by government at all levels.An aerobic denitrifying bacteria was screened from the soil of paddy field which was identified by morphological characteristics,physiological and biochemical characteristics and 16S rDNA sequence analysis,and the liquid fermentation medium and fermentation conditions and the treatment technology of the rural domestic wastewater were studied.The results were obstained as follows:1.One strain with strong denitrification was isolated from the soil of paddy field which named LKX-1,was identified as Pseudomonas monteilii according to the results of morphological,physiological and biochemical characteristics,and the 16s rDNA sequence analysis and phylogenetic tree construction.2.The composition of fermentation medium and fermentation conditions were studied by using single-factor test,and the fermentation conditions were optimized by using orthogonal experiment.The results showed that the optimal fermentation medium were:maltose 2%,yeast powder 2%,KH2PO4 0.15%,MgS04.7H20 0.10%and the optimal fermentation conditions were:fermentation temperature 30?,inoculation 1%,the initial pH value 7.0,the liquid volume 100mL/250mL triangle bottle,fermentation time 24h.Under these conditions,the viable count reached 4.5×1014cfu/mL.3.Effects of nitrogen removal of domestic wastewater such as carbon sources,inoculation quantity,initial pH value,dissolved oxygen,temperature,processing time and other environmental factors were studied.The results showed that the nitrogen removal process were as follows:glucose 0.03%,inoculation 0.00015%,initial pH value 7.0,temperature 30?-32?,rotation speed 120r/min,processing time 48h,the removal rate of total nitrogen and nitrite nitrogen reached 91.55%and 96.33%.4.The condition of bamboo charcoal fixing process and the effect of nitrogen removal were primarily studied.The results showed that the appropriate fixed technology were:Charcoal burning temperature 550?,adsorption time 25min,adsorption temperature 35?,bamboo charcoal input 10%,the adsorption rate reached 97.5%.The removal rates of total nitrogen and nitrite nitrogen were 96.52%and 99.89%,respectively,under the condition of the fixed amount of LKX-1 was 12%and the treatment time was 36h.