Study On Screening Of Nitrogen Removing Microorganism From Water And Its Characteristic Of Nitrogen Removement

Excessive levels of ammonia nitrogen standards in rivers and lakes is one of the main causes of water pollution in China. A series of problems caused by excessive ammonia nitrogen are calling more and more attention by the human. In this paper, water samples were collected from the trunk stream and tributaries upstream from Jalu River in Zhengzhou city, water quality characteristic was analysed. 7 denitrifying stains were screened from water samples by enrichment, separation, purification. Characteristics of nitrogen removment were tested, and 3 stains were chosen for testing removement of ammonia nitrogen in river water.The results of Jialu river water pollution characteristics analysis showed that: The most serious problem in the Jialu River was ammonia nitrogen pollution; the content of COD changed irregularly along the river, and the content of DO in downstream was higher than the upstream. Various forms of nitrogen content showed an upward trend along the river. Then select samples of each season as the key targets to research according to the changes of COD, voris forms of nitrogen and DO value and so on.Samples clected in there seasons were enriched with enrichment culture-medium, enrichment finished after about 1 months. The enrichment of samples in spring and summer perfomed good. In the enrichment, Thermomonas brevis strain and Hydrocarboniphaga effusa Dominanted. Heterotrophic nitrifying bacteria may be contained in richment, but not any autotrophic nitrogen removal was found.110 stains were screened from the enrichment, and 22 stains with higher amonia nitrogen removal efficiency were screened by 16 S r DNA test. With molecular biology methods and physiological biochemical test, the stains were classified as following: 5stains were Pseudomonas sp., and made litte difference with Pseudomonas putida、Pseudomonas mendocina、Pseudomonas mendocina、Pseudomonas chengduensis、Pseudomonas oleovorans. The other two were Diaphorobacter nitroreducens and Pseudoxanthomonas mexicana.The seven stains performed higher removment of ammonia nitrogen, and the highest nitrogen removal efficiency was 91.8% in 24 hours, but the way of removment was bacteria assimilation probably, about 20%~25% of ammonia nitrogen which was changed to gas, participated in nitrification and denitrification in the bodies of five Pseudomonas sp. stains,called heterotrophic nitrification. The seven stains were mesophilic bacteria, performed well at about 30℃; C2、C30 were neutral bacteria, and C31、C42 were alkali resistant bacteria. C42 could use different carbon sources, and nitrogen removal effect could be better when absorbed in sodium citrate. Improving the training speed of reactor was beneficial to improve the removement of ammonia nitrogen.Stains of C2 、 NC13 、 NC63 were chosen for testing their ammonia nitrogen removent in river water, it was turned out the stains had a bad ammonia nitrogen removal performance when throwed into river water directly, for the lack of nutrition; after acclimation by reducing the account of carbon source and nitrogen source added in the water, stain of C2 perfomed better, and the residual amount of ammonia nitrogen was 4.53mg/L, the other two stains could adapt the acclimation, but the removement of ammonia nitrogen is not obvious.