Preparation Of Low Temperature Nitrogen Removal Agent And Its Bioaugmentation Efficiency In The Constructed Wetland

The C onstructed wetland technology has broad applicated prospects because of its low cost, high efficiency and green ecological advantages in the deep treatment of the sewage, but in cold regions of the northern C hina, temperature is very low in winter, nitrogen removal efficiency of wastewater treated by constructed wetland decrease significantly. This paper develops microbial strains which have high nitrogen removal efficiency at low temperature and constructs low temperature nitrogen removal agent. Researching the application of bioaugmentation at low temperature in constructed wetland and analysising the role of low temperature N itrogen removal agent by community structure can laid a theoretical foundation for engineering applications and construction of low temperature nitrogen removal agent.N itrogen removal bacteria were enriched and acclimated under 10oC by evaluating their nitrogen removal efficiency, we found that nitrifying bacteria and aerobic denitrifying bacteria had high nitrogen removal effic iency at 10℃,and they were low temperature resistant strains. The nitr ifying bacteria had the best nitrification effic iency in the concentration of ammonia nitrogen for 21.35 mg/L, the ammonia nitrogen removal rate could reach 85.62%; The aerobic denitrifying bacteria had best denitr ification efficiency in aerobic conditions and the nitrate nitrogen concentration for 20.14 mg/L, the ratio of carbon and nitrogen ratio was 5.05, the removal rate of nitrate nitrogen and total nitrogen reached 55.41% and 30.43% respectively, the aerobic denitrifying bacteria had best denitrification efficiency in anaerobic condit ions and the nitrate nitrogen concentration for 18.53 mg/L, the ratio of carbon and nitrogen ratio was 5. 88, the removal rate of nitrate nitrogen and total nitrogen reached 95.68% and 58.73% respectively.The bioaugmentation nitrogen removal efficiency in constructed wetland by using the nitrogen removal agent was studied. When the hydraulic retention time was 24 h, comparing to the control system, the removal rate of ammonia nitrogen and total nitrogen increased by approximately 16.32% and 16.41% in the effluent of strengthen system, the effluent ammonia nitrogen and total nitrogen concentrations of strengthen system were approximately 7.96 mg/L and 12.77 mg/ L respective ly, the effluent ammonia nitrogen and total nitrogen concentrations could almost achieve A standard. When Bioaugmentation and the hydraulic retention time were shorted to 12 h, comparing to the control system, the removal rate of ammonia nitrogen and total nitrogen increased by approximately 24.46% and 24.56% in the effluent of strengthen system, the effluent ammonia nitrogen and total nitrogen concentrations of strengthen system were approximately 7.29 mg/L and 12.93 mg/L respectively, the effluent ammonia nitrogen and total nitrogen concentrations could almost achieve A standard of the "urban sewage treatment plant pollutant discharge standard", thus it can reduce the byproduct in effluent and increase the daily processing capacity.By analysising the role of low temperature denitr ifying bacteria, we could know that the low temperature denitrifying bacteria contained Pseudomonas, Bacillus, F lavobacterium, Nit rosomonas and N itrobacter which had nitrogen removal function, comparing to the control system, the content of above microorganis m increased in the strengthen system, resulted in the decrease of effluent ammonia nitrogen and total nitrogen concentration. The content of Pseudomonas, Bacillus, N it rosomonas and Nit rospira in soil increased higher proportion, which could provide a theoretical basis for the construction of the low temperature nitrogen removal agent.