Study On The Treatment Of Aniline Compounds By Flora Enhanced MBBR Technique

With the rapid development of the pharmaceutical industry,a large number of pharmaceutical wastewater has been produced.If not treated,it will seriously pollute the environment and cause damage to human health.Biological method has the advantages of economy,high efficiency,low cost and no two pollution,so it has been widely used in water treatment.N-methylaniline and N-ethylaniline are two kinds of aniline compounds which are difficult to degrade and are toxic in pharmaceutical wastewater,which can be absorbed by inhalation,ingestion or skin into the organism,causing damage to the central nervous system,cardiovascular system and other organs.Therefore,the treatment of N-methylaniline and N-ethy-l aniline wastewater is essential.Direct treatment with general biological method usually can not degrade this substance,in this study,the removal effect of N-methylaniline and N-ethylaniline was studied by means of aerobic co-metabolism,and the microbes that could degrade characteristic pollutants were acclimated.The effective microbial flora is loaded on the filler by the moving bed biofilm reactor(MBBR)process to increase the number of effective flora and further enhance the removal effect and the degradation mechanism of N-methylaniline and N-ethylaniline was analyzed from microbiology.The degradation of N-methylaniline and N-ethylaniline was studied by acclimating the activated sludge with aerobic co-metabolism,and the concentration of characteristic pollutants was gradually increased during acclimation.The results showed that when N-methylaniline was used as a pollutant,activated sludge was acclimated for 32 days,the acclimated activated sludge could degrade 170mg/L N-methylaniline in 9 hours,COD removal rate was 87%,TOC removal rate was 90%,and ammonia nitrogen removal rate was lower,only 42.8%.W hen N-ethylaniline was used as a pollutant,activated sludge was acclimated for 40 days,the acclimated activated sludge could degrade 90mg/L N-ethylaniline in 7 hours,COD removal rate was 83%,TOC removal rate was 85%,and ammonia nitrogen removal rate was lower,only 52.1%.The MBBR method was used to further treat N-methylaniline and N-ethylaniline wastewater.The sludge was inoculated with acclim ated activated sludge,and the treatment effect of wastewater was studied after membrane-hanging successfully.The results showed that,compared with the acclimated activated sludge,the time of degrading N-methylaniline in the MBBR reactor was reduced from 9 hours to 6 hours,the removal rate of COD was 89%,the removal rate of TOC was 93%,and the removal rate of ammonia nitrogen was 82.5%.The time for microbial degradation of N-ethylaniline was reduced from 7 hours to 4.5 hours,the removal rate of COD was 84%,the removal rate of TOC was 90%,and the removal rate of ammonia nitrogen was 70.4%.Microbial community structure analysis with high throughput sequencing.The results showed that when the pollutant was N-methylaniline,the dominant population changed significantly after acclimation.After acclimatization,Proteobacteria and Bacteroidetes accounted for the major advantages on the phylum level,Betaproteobacteria were the dominant species on the class,Rhodoferax and Zoogloea were the dominant species on the genus,and the Rhodoferax increased to 25.81% compared with the microbial biomass of the activated sludge.The change of microbial community structure is related to the change of matrix and the toxicity of N-methylaniline.When the pollutant was N-ethylaniline,the dominant population changed significantly after acclimation.After acclimatization,Proteobacteria and Bacteroidetes accounted for the major advantages on the phylum level,Betaproteobacteria were the dominant species on the class,Zoogloea and Taibaiella are dominant genera at the genus level,with relative abundance of 19.59% and 5.39%.Compared with the activated sludge microbes,the dominant population Zoogloea increased to 27.54% and Acidovorax increased to 10.4%.