| At present, the emission of nitrogen-containing wastewater is one of the main causes ofthe water pollution in our country and the world. The water quality would bedeteriorated with the releasing of too much nitrogen and there is a potential threat tohuman survival and development. Therefore, the denitrification of wastewater hasturned out to be the focus in the field of water treatment research in recent years.The biological nitrogen removal is one of the most effective way in nitrogen removalcurrently. In this study, a strain with the function of heterotrophic nitrification andaerobic denitrification was screened and it overcame the shortcomings that the slowgrowth, harsh growing conditions, poor nitrogen removal of traditional denitrificationin autotrophic nitrifying bacteria, etc.In this study, a well functioned heterotrophic nitrification-aerobic denitrificationbacteria named HN-02was isolated from the laboratory simulation CASS reactor. Itgrew well in solid and liquid medium and the cell density was close to water. The shapeof HN-02bacteria was short rod with scanning microscopy and electron microscopy.The analysis based on16SrRNA showed that the strain is relative of Aeromonashydrophila with99%.Studies have shown that the optimal carbon source for the bacteria was succinic acid,followed by sucrose and citric acid; an optimum temperature of30°C; optimum pHrange of6to9. The growth curve was formed with HN-02bacteria cultured underoptimal growth conditions and showed the growth rate of0.11h-1. HN-02bacteria grewvery fast and had good nitrogen removal, with the prospect of broad practicalapplication.The bacteria can make better use of ammonia, nitrite, nitrate nitrogen for growth andreproduction. Cultured with ammonia, nitrite, nitrate as the sole nitrogen source for24h,the OD600were1.164,0.934,1.030, respectively. HN-02bacteria could use ammoniabest, followed by nitrate and nitrite. HN-02make good nitrification and denitrificationwith ammonia, nitrite and nitrate and the24h ammonia removal efficiency were82.41%,46.24%and98.55%, respectively. With the ammonia removal, there would beno accumulation of nitrate and nitrite at the same time; with the nitrite removal, therewould be no accumulation of ammonia and nitrate in the meanwhile; with the nitrate removed at the same time, there would be no accumulation of ammonia and mass nitritenitrogen accumulation. In addition, compared with the three kinds of nitrogen acted asnitrogen source, the ammonia, nitrite, nitrate alone as the nitrogen source24h TNremoval rate were31.46%,6.93%and10.49%higher, respectively. It demonstratedthat variety of forms of nitrogen to act as nitrogen source, is not conducive to thegrowth, nitrification and denitrification of HN-02. The HN-02bacteria could makeammonia, nitrite, nitrate100%biological nitrogen removed with the sufficient carbonsource and reaction time and denitrification gaseous products were nitrogen oxides andnitrogen. Therefore, propose bacteria denitrification pathway inferred: Ammoniathrough nitrification conversion for hydroxylamine, hydroxylamine converted togaseous nitrogen; nitrate converted to nitrite by denitrification, and then converted togaseous nitrogen, so that the removal of nitrogen from the water. The nitrite intogaseous nitrogen link is the bottleneck link in the entire denitrification pathway.It was indicated that HN-02bacteria was more suitable for the treatment of highammonia and high COD, high carbon and nitrogen ratio and biodegradabilitywastewater from the research of growth ofbacteria and denitrification characteristics. Itshowed that found that removal of ammonia and COD in the activated sludge+HN-02bacteria dealing with synthetic wastewater after2d lower6.15%and7.81%than thatnot adding bacteria. The probable reason was that the HN-02bacteria breaking thebalance of the ecosystem of activated sludge. It was not suitable to using HN-02bacteria to treat swine wastewater and monosodium glutamate wastewater. HN-02bacteria on maize alcohol wastewater treatment achieved good effect, and the originalwastewater was diluted10times and then deal with more appropriate. The effects ofHN-02bacteria in the treatment of diluted10times maize alcohol wastewater wereexplored in the test of using shake flask and SBR simulatio n reactor. At the same time,the blank control experiment was set to exclude the effects of the contain bacteria itselfin the wastewater. The results showed that, the ammonia, COD removal and system pHstability would be better after adding bacteria. Shake flask experiments showed thatafter2d culture, the ammonia and COD removal of wastewater with HN-02bacteriawere61.93%and46.52%higher than the blank. Simulation of SBR reactor testsshowed that the reactor revealed the best ammonia and COD removal of36.79%and61.53%respectively after6d, were35.02%and63.04%higher than that without thebacteria reactor. According to the research, the big amount of reagent and productionof excess sluge in the treatment of maize alcohol wastewater by HN-02bacteria wereanalyzed. The large amount of excess sludge can be used for recycling of solid wasteresources.This study was the expansion and enrichment of heterotrophic nitrification-aerobicdenitrification and provided guidance and reference in theoretical research andpractical engineering application in this field. |
PDF Full Text Request