| With the rapid development of China's industrial and agricultural,a lot of nitrogen compounds discharged into the water,that threaten to human's heath and the growth of plants and animals.Therefore,looking for efficient and feasible biological denitrification technology has been one of the hot issues of sewage treatment.Due to a traditional biological denitrification exist in the process of reaction device large and sensitive to high load concentration of organic matter,lead to many insurmountable problems.The study found that heterotrophic microorganisms at the same time had aerobic nitrification and denitrification ability,can be caused by a single strain,ammonia nitrogen finally transformed into nitrogen at the same time.This makes heterotrophic aerobic nitrification and denitrification can be carried out simultaneously,for wastewater biological denitrification provide a better value and heterotrophic microbial denitrification have been attracted more and more attentions.A heterotrophic nitrification bacteria with high efficiency of removing ammonia nitrogen and significant accumulation of nitrite nitrogen,named Alcaligenes faecalis C16,which was isolated from the activated sludge of a coking wastewater treatment plant.Firstly,in this experiment,C16 under pyruvic acid,succinic acid and fumaric acid three different carbon sources,analysis of growth,nitrogen removal ability and nitrite nitrogen accumulation were detected by culture medium of ammonia nitrogen,hydroxylamine,nitrite nitrogen of strain C16 and finding out the most suitable carbon sources for the growth and nitrogen removal of C16.After 32 h laboratory training,under three kinds of carbon sources have showed good growth and the ability of removing ammonia nitrogen of C16.In addition,in the culture medium of pyruvate as carbon source,nitrite nitrogen and hydroxylamine were only present in trace amounts.Secondly,Mg2+,Mn2+,Fe2+,Cu2+and Zn2+ ions were selected to study their influence on the growth,nitrogen removal ability and nitrite nitrogen accumulation were detected by culture medium of ammonia nitrogen,hydroxylamine,nitrite nitrogen of C16 and finding out the most suitable metal ions and their concentrations for the growth and nitrogen removal of C16.After 24 h laboratory training,these five kinds of metal ions,respectively for the growth,denitrification performance,nitrite nitrogen accumulation had caused different effect.Mg2+significantly promoted the growth and ammonia nitrogen oxidation rate of strain C16;C16 could not grow in higher concentrations of Mn2+;lacking of Fe2+in original medium inhibited the growth and ammonia nitrogen oxidation rate of C16;adding 0.1 mmol/L Cu2+in the original culture medium could stimulate the growth and nitrogen removal rate of strain C16,meanwhilenitrite nitrogen and hydroxylamine were only present in trace amounts;the existing of Zn2+of different concentrations inhibited the growth and ammonia nitrogen oxidation rate of C16.This experiment also studied hydroxylamine oxidoreductase(HAO),nitrate reductase(Nar)and nitrite reductase(Nir)activities for denitrification process.And pyruvic acid,succinic acid and fumaric acid carbon sources and Mg2+,Mn2+,Fe2+,Cu2+ and Zn2+ions on the effect of these enzymes.In addition,ammonia monooxygenase(AMO)gene by PCR amplification of denitrification process,verify nitrogen metabolic pathways from genetically of C16.A further enzyme testing results showed that,pyruvic acid significantly promoted the activities of HAO,Nar and Nir;Succinic acid and fumaric acid significantly promoted the activities of Nar and Nir,but for the promotion of HAO effect is not obvious.A further enzyme testing can be very good to explain different carbon sources on the nitrification performance of C16.0.1 mmol/L Mg2+promoted the activity of HAO;0.1 mmol/L Cu2+promoted Nar and Nir activities.The addition of Cu2+could explain the phenomenon of no nitrite nitrogen accumulation and hydroxylamine were only present in trace amounts. |
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