Experimental Study On The Biological Mode And Decreasing Measure Of High No₂-N In The Guangzhou Tap Water

For a long term, water source in our country is seriously polluted due to nitrogenous fertilizers and living sewage. The water in lake and reservoir is abundant in alga and much ammonia nitrogen. Nitrobacteria exist in the layer of sand because of not thorough antiirrigation. Although few of ammonia nitrogen is removed, the content of nitrite salt increases, which still consumes chlorine during continuing sterilization and rest chlorine hi the network of pipes.Recently, the monitoring content of nitrogen is very high in the Zhujiang River flowing through Guangzhou. Especially, the existence of nitrite salt causes much problem of water purification. With the aim of solving this problem, the procedure about the conversion of nitrogen must be investigated and analysed particularly. Thereby methods of controlling and reducing the content of nitrogen must be explored.ObjectivesThe methods of controlling and reducing the content of nitrogen are exp lored, through the research of the conversion of nitrogen, as well as the pattern of nitrification of nitrobacteria by laboratory simulation.The kinds of bacteria are evaluated by the method of molecular biology. Then a fast, effective measuring method applied to analysis on environmental samples is asked hard for.-5-Materials and methodsThe diversity of autotroic and heterotroic ammonia-oxidizing bacteria in waterworks in Guangzhou xichun county was investigated; the nitrification ability of pure strain and water sample was Assayed; 16S rDNA sequences were determined.Autotroic ammonia-oxidizing bacteria was cultivated in accordance of enrichment, then assayed by Morological, ysiological and biochemical methods. Meanwhile, genes of amoA, which can be used in sequencing, were amplified from one strains chosen at random.pure strains and strains in water sample was measured by different interventions.ResultsAmong of the 121 the strains, 25 strains belong to Pseudomonas genus and the others belong to Bacillus and Arthrobatcer, respectively. Results about autotroic ammonia-oxidizing bacteria identification show that strains of Ammonia-Oxidation belong to Nitrosomonas and Nitrosococcus, but nitro-oxidizing bacteria belong to Nitrobacter genus.The result of amoA is same with result by cultivation and to be similar to Nitrosomonas europaea.Results of strains and sample treated with different intervation show that activity of nitrification strains and sub-nitrification's change regularly following the changes of pH, DO, temperature and sterilization of chlorine dioxide. But changes of water sample is not rapid, which indicts that the influence of heterotrophic ammonia-oxidizing bacteria exists at the same time.ConclusionsHeterotrophic ammonia-oxidizing bacteria and nitrification strain can be used in the field of water treatment agent. Specificity of amoA gene can benefit the study of a fast, effective measuring method applied to analysis on environmental samples. The high rate of variation of the amoA gene fragment is advantageous for the study of variation about autotrophic ammonia-oxidizing bacteria. The changes about activities of nitrification strains and sub-nitrification , following the changes of pH, DO, sterilization of chlorine dioxide can be used to predict the content of nitrogen in waterworks. Moreover, it can ameliorate treatment link and reduce the manufacturing cost.