Isolation, Identification Of Ammonia-oxidizers In Active Sludgeunder Different PH Condition And Their Characteristics Of Oxidize Ammonia

Nitrification,performed oxidation of ammonia to nitrate by ammonia-oxidizers is a key process in the cycling of nitrogen and an impotent component of modern wastewater treatment.Ammonia-oxidizers have many unfavorable physiological characteristics, namely,slow growth,small biomass and susceptible to environmental factors.Among the total,pH value is correlated with FA and FNA level of wastewater,this make it to be the important factor of denitrogenation.We directly enriched ammonia-oxidizers of activated sludge via controlling pH factors of sludge acclimatization,to increase the biomass of destination bacteria gradually to be the ascendancy strain.By the procedures of primary screening in which ammonium oxidation was measured qualitatively,six strains of ammonia-oxidizers under there corresponding pH conditions.We identified these six bacteria and studied their character of oxidize ammonia.The results are summarized in the following:(1)The acclimated active sludge had capacity of oxidize ammonia under their corresponding pH factors,and they had ammonia-oxidizers.(2)Through analyzing physiological properties,the results showed that the six strains all identified as Nitrosococcus.(3)During the study,the AOBpH5 and AOBpH6 screened from the pH conditions of 5 and 6,showed the had wide pH adaptability.And AOBpH9 and AOBpH10 screened from the pH conditions of 9 and 10 had better toleration of alkalinity.AOBpH7 and AOBpH8 screened from the pH conditions of 7 and 8 only had better ammonium oxidation in neutrality and weak base condition.(4)AOBpH5 had the best capacity of oxidize ammonia when the concentration of NaC1 was 5g/L,and it increased with the rising of concentration of ammonia nitrogen.The best concentration of NaC1 to AOBpH6 was 20g/L,and the concentration of ammonia nitrogen was 50mg/L.The higher concentration of NaC1 and ammonia nitrogen was better to AOBpH7.To AOBpH8,the capacity of oxidize ammonia increased with the rising of concentration of ammonia nitrogen.AOBpH9 had the best capacity of oxidize ammonia when the concentration of NaC1 was 5rag/L,and it increased with the rising of concentration of ammonia nitrogen.The best concentration of NaC1 and ammonia nitrogen to AOBpH10 was 10g/L and 20mg/L.