Development And Application Of High Efficiency Denitrification Compound Bacteria Agent

Nitrate has a high water solubility and is one of the main nitrogen pollutants in water.Nitrate nitrogen pollution is a hot topic in the current research.At present,one of the main problems faced by rivers and sewage plants is that TN is not up to standard.One of the reasons for this result is that nitrate nitrogen can not be effectively removed.Due to the flow of water,the dissolved oxygen in the water is higher.The traditional denitrification is completed under anaerobic conditions.The higher dissolved oxygen will inhibit the removal efficiency of nitrate nitrogen and make the TN in the water exceed the standard.Aerobic denitrification can make nitrification and denitrification react in the same system,simplify the sewage treatment process,and save the cost of process construction and operation.The advantages of aerobic denitrification have attracted wide attention of scholars,and have been studied in depth.However,most of these studies focus on single aerobic denitrification bacteria,but in the actual wastewater,due to the complexity of the water environment and the limitations of single strain(for example,single strain is easy to be replaced),the denitrification ability of single aerobic denitrification bacteria will be inhibited.Based on the above situation,three typical Pseudomonas heterotrophic nitrification aerobic denitrification strains(Pseudomonas monteilii W7,Pseudomonas stutzeri W12,Pseudomonas mendocina W19)were selected in this paper.The denitrification characteristics of these three strains and the influence of different environmental factors on their denitrification characteristics were studied.In addition,three strains of bacteria were used to construct the compound bacterial agent.The influence of environmental factors on the denitrification characteristics of the compound bacterial agent was analyzed by response surface method.The application of W7+W12 and W12+W19 in the actual sewage was studied.The research results are as follows:1)The best carbon source of three heterotrophic nitrification aerobic denitrifiers was sodium citrate,the best C/N of strain W7 was 14,and the best C/N of strain W12 and strain W19 was 12.Response surface analysis was carried out on three strains of bacteria respectively.The strain W7 has a nitrate nitrogen removal rate of 100% at pH 7.31,temperature of 30? and rotational speed of 150 rpm.The strain W12 has a nitrate nitrogen removal rate of 100% at pH 7.83,temperature of 27.14? and rotational speed of 110 rpm.The strain W19 has a removal rate of nitrate nitrogen of 100% at pH 8.27,temperature of 34.76? and rotational speed of 156 rpm.2)The best carbon source of W7+W12 was sodium citrate,and under the condition of pH 8.51,temperature 33?,C/N ratio 13.3,TN removal rate of W7+W12 was 80.17%;the best carbon source of W7+W19 was sodium citrate,and under the condition of pH 8.3,temperature 31.7?,C/N ratio 13.3,TN removal rate of W7+W19 was 55.4%;the best carbon source of W12+W19 was sodium citrate,and under the condition of pH 8.44,temperature 35?,C/N ratio 13.8,TN removal rate of W12+W19 was 81.54%.3)After inoculating W7+W12 to the sterilized actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 82.34%;after inoculating W7+W12 to the unsterilized actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 83.42%;after mixed culture of W7+W12 and activated sludge in the actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 90.06%.after inoculating W12+W19 to the sterilized actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 84.65%;after inoculating W12+W19 to the unsterilized actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 85.03%;after mixed culture of W7+W12 and activated sludge in the actual wastewater for 36 hours,the removal rate of total soluble nitrogen reached 91.82%.