| The objective of the present research was to provide biologically experimental evidences for evaluating the feasibility of biological treatment of high-temperature and high-salinity ammonium wastewater. According to the qualities of watery samples collected, Different tactics were taken for isolation and screening of ammonia-oxidizers resistant to high temperature and high salinity. For watery samples collected from high-temperature and high-salinity habitats, the methods were to enrich and isolate objects under selective conditions of high temperature and high salinity. For watery samples collected from medium-temperature and low-salinity habitats, the methods were to enrich firstly ammonia-oxidizers under medium-temperature and low-salinity, and then to isolate and screen objects under gradually increasing temperature and salinity. By the procedures of primary screening in which ammonium oxidation was measured qualitatively and of secondary screening in which the removal rate of ammonia was analyzed quantitatively, five strains of ammonia-oxidizers having practical potential were screened which were resistant to environment of 50℃ containing NaCl of 2.5%concentration. MicrobioJogically basical study was conducted to these five strains of ammonia-oxidizers. On the basis of their morphological observation and physiological and biochemical tests, the five strains of ammonia-oxidizers were classified as the genus of Nitrosomonas. During the study, a special phenomenon was observed in the strain aWGWP' s ammonium oxidation under high temperature and high salinity. To investigate and verify the phenomena, a more detailed study was conducted to the microbiology and biochemical metabolism of the strain aWGWP. The effects of four kinds of environmental factors such as pH, salinity, temperature and initial ammonium nitrogen concentration on the growth and ammonium oxidation of the strain were studied. The data indicated that pH, initial ammonium nitrogen concentration and temperature affected remarkably the growth and ammonium oxidation of the strain whereas salinity didn' t. Chemical analysis of nitrogen compounds in the culture solution of the strain indicated that the decreasing amount of ammonium nitrogen was greater remarkably than the increasing amount of nitrite nitrogen but no nitrate nitrogen was detected in the culture solution. This suggested that part of ammonium nitrogen or nitrite nitrogen might be transformed into gaseous nitrogen or nitrogen compounds and then went into the air. If not, the N imbalance in the solution couldn' t be well explained. To learn where ammonium nitrogen had gone, gas produced from the culture solution of the strain during its metabolism of ammonium oxidation was collected and analyzed with a gas chromatograph. The results indicated that the amount of nitrogen in the gas collected apparently increased as compared with the air control. This verified that the strain aWGWP could conduct a metabolic pathway other than the one generally believed in which ammonia-oxidizers could only convert NH3 to N02~. But the present study suggested that the strain aWGWP could not only convert NHi to N02~, but also continuously convert to gaseous nitrogen or other gaseousnitrogen compounds in the experimental system. Its detailed transforming pathway still needs further studies. The study of comparison of the effect of ultraviolet and diethyl sulfate mutagenesis on the ammonium oxidation of five strains of Nitrosomonas including aWGWP was also conducted to evaluate the feasibility of screening strains with high activity by mutagenesis. The study of microbiology and metabolism of ammonium oxidation of ammonia-oxidizers resistant to high temperature and high salinity is of theoretical significance with respect to biological oxidation of ammonium under high temperature and is of practical value in relation to develop technology of biological treatment of ammonium wastewater with high-temperature and high-salinity characteristics and to solve problems of bio...
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