Study On Bio-technology Of Ammona Removal With Coupling Oxidation Catalyzed Enzymes In Single Cell

Nitrogen content of wastewater effluent exceeding the public criteria is one of theimportant factors causing the natural water nutritional. Among various treatmenttechnologies, the bio-treatment method with nitrification and denitrification is themost economic, effective and friendly to the environment. But with limitations of thetraditional bio-treatment methods, the nitrogen content of wastewater effluent has notyet met the public criteria, which has become the bottle-neck problem of the watercleaning engineering.Based on the review of the external and internal research achievements related tobio-de-ammononium of the wastewater, scheme of study on the mechanism of theammonium oxidation of the wastewater by the single cell bacteria was forwarded.At first, isolation of facultative microorganisms from the active sludge of SequentBatch Reactor (SBR) with the characteristics of ammonia oxidation under oxic andanoxic condition was conducted based on the metabolism requirement of energy.Identification with BIOLOG system and characterization of ammonia-oxidation bysequencing the genes encoding 16SrDNA and functional protein were carried out. Theresults of characterization showed that the four strains belonging to Nitrosomonas sp.,Hyphomicrobium sp., Rhoropseudomonas sp. and Rhizobium rhizogenes. The fourstrains all can convert ammonium into NO2 under atmosphere condition (DO ->1mg/L), but lacking of organic carbon source, pH>7.0; they can suffer from theammonium load <200 mg/L, adapting best to 20-35℃.Variation of δ15N of N2 and N2O emitted from wastewater by artificial synthesisin a close system was traced by Thermo Finnigan MAT253. The determination resultsshowed the energy metabolism approach of the strains under the condition with lowoxygen content without organic source. The result is similar to that obtained by VandeGraaf A A etal. with Lithoautotrophic bacterium, Nitrosomonas eutropha. With all the IIIfour strains, ammonia could be oxidized into N2 under the low dissolved oxygencontent condition (DO<0.5mg/L). From the results obtained in the lab, it might bederived that anaerobic ammonium oxidation phenomena exist rather extensively.Ammonium oxidation by single strain and by the four strains mixed together arecompared, the result showed the amount of N2 emitted in the ammonium oxidation bymixed strains is much more than that by single strain in the same experiment period,which means the rate of ammonium oxidation catalyzed by complex enzymes ofmixed strains is higher than that catalyzed by enzymes of the single under the samecondition, this fact means great deal significance for the development of the novelwastewater treatment technology. It has been yet seen the same research resultreported.Based on the result obtained from microbiological study as above, theapplication experiment with the strains in the complex treatment process of thedomestic wastewater is conducted. The results showed that the nitrogen removalefficiency is up to 88.5%, the CODCr removal efficiency is over 90% by the newtreatment method. The microorganisms isolated are of high efficiency to oxidizingammonium in wastewater. The achievement obtained in the present thesis is greatvaluable and means a promising application prospect.