Study On The Methods And Mechanism Of Purifying Black-odor Water By Microbiological Method

At present,the situation of water pollution in China is very serious.With the rapid development of urbanization,a large number of urban rivers have been polluted and turned into black-odor rivers.Urban black-odor water is becoming more and more serious,the survival rate ofaquatic organisms is declining,the structure and function of river ecosystems are seriously deteriorated,and human health is directly harmed.Therefore,how to deal with a large amount of black-odor water has become an urgent problem to be solved.In this paper,we use heavy black-odor water(inferior V water)as the research object,which adopts four treatment methods:aeration,microbial inoculum + aeration,biostimulant + aeration,and microbial inoculum + biostimulant + aeration.The purification effect of black-odor water and the composition and difference of microbial community structure were studied.In addition,in view of the fact that the purification effect of organic matter is generally unsatisfactory in the process of purifying black-odor water by microbial methods,the fluorescence properties of DOM in the inlet and outlet water of each treatment are measured and analyzed by three-dimensional fluorescence spectroscopy.In order to analyze the relationship between the changes of microbial community structure and the purification effect of black-odor water.,and to clarify the influence of different biological treatment methods on the change of DOM characteristics in black-odor water.In order to optimize the experimental conditions(such as dissolved oxygen,pH,temperature,nutrients,operation conditions and residence time)in the later research,and select efficient dominant or functional microorganisms to achieve the high efficiency of microbial treatment of wastewater under specific conditions,and provide theoretical and experimental basis for the further efficient treatment of black-odor water.The experimental results were as follows:(1)The four treatments had different purification effects on black-odor water.The purification efficiency decreased in the following order:microbial inoculum +biostimulant + aeration>biostimulant + aeration>microbial inoculum +aeration>aeration.The removal rates of NH3-N,TP and COD in the microbial inoculum+ biostimulant + aeration group were 98.21%,96.66%and 75.60%,respectively.Among them,NH3-N reached the surface water quality class V water standard,TP reached the surface water quality class III water standard,and the dissolved oxygen and transparency of the water body were greatly improved.(2)The microbial community structure during purification of black-odor water changed regularly under four different treatments.The dominant microbial population in the aeration group was mostly aerobic bacteria.In addition to aerobic bacteria,facultative anaerobic bacteria also appeared in the dominant microbial population of the microbial inoculum + aeration group.The dominant microbial population in the biostimulant + aeration group was aerobic and anaerobic bacteria.The dominant microbial population in the microbial inoculum + biostimulant + aeration group included aerobic bacteria,facultative anaerobes and anaerobic bacteria,and the relative abundance of and diversity in some functional or dominant populations were greatly improved.With the emergence of facultative anaerobic and dominantly anaerobic flora,the removal efficiency of NH3-N and COD increased.(3)Indigenous microorganism in black-odor water was the major source of dominant fungus in each treatment.The diversity and richness of fungal communities were significantly different in four treatments.There was no significant correlation between NH3-N removal performance and fungal community diversity and richness(P>0.05).And there was a significant negative correlation between TP and COD removal efficiency and fungal community diversity and richness(P<0.05).At the phylum level,the fiungi in each group were mainly distributed in Ascomycota,Zygomycota,Rozellomycota and Basidiomycota.At the genus level,dominant fungal communities were found to be highly dynamic in different treatment groups.The most dominant genus was Candida of Ascomycota,whose relative abundance was higher in the microbial inoculum group.This may be related to the fact that yeast is an important part of the microbial inoculum + aeration,and biostimulant can promote the growth of Candida.This indicated that the microbial community composition of activated sludge can be recombined through the difference of treatment operation characteristics.(4)Spectral characteristics:Five different components were resolved in different treatments,namely,dissolved microbial metabolite Cl;humic acid humus C2;tyrosine protein C3;tryptophan protein C4;fulvic acid humus C5.There were significant differences in the intensity of fluorescence peaks of different components of DOM in different treatment modes.After combined treatment with microbial agents and bio-promoting agents,the most refractory substances such as humus are the most cut,C1,C2,C3,The C4 and C5 components were reduced by 3.77%,17.15%,85.73%,2.77%,and 62.81%,respectively.The FI,HIX and BIX index analysis showed that the DOM in the water samples of each treatment group was in a strong self-generated source.Principal Component Analysis(PCA)was used to study the main factors affecting the DOM of black-odor water and its contribution.The results showed that the removal of ammonia nitrogen,TP and COD in the first principal component is related to C3 and C5S C4 and nitrous acid.Nitrogen and nitrate nitrogen are positively correlated.The first principal component is a phenomenon in which terrestrial humus and biogenic humus coexist,contributing to 54.98%of DOM in black-odor water.In the second principal component,Cl had homology with C3 and C4,C2 has homology with C4,C3 had homology with C5,and the second principal component reflected endogenous pollution represented by microbial metabolic processes.The contribution rate to DOM in black-odor water was 26.56%.