Study On Co-Treatment Technology Of Synergic Treatment System With Baijiu Wastewater And Low C/N Domestic Sewage

Liquor brewing wastewater is a high-concentration organic wastewater with low pH value,high chroma,high nitrogen and phosphorus,and easy degradation.At present,large and medium-sized liquor enterprises have relatively complete wastewater treatment facilities,but most small and medium-sized enterprises are faced with the problems of complex wastewater treatment process,high treatment cost and difficulty in reaching the effluent standards.In addition,some urban sewage treatment plants have insufficient carbon sources due to the imperfect sewage collection pipe network and incomplete separation of rain and sewage.In order to achieve high denitrification efficiency,an external carbon source is usually required,which has the problems of waste of resources and high operating cost.In view of the high proportion of easily degradable organic matter and good biodegradability in liquor brewing wastewater,this study selected liquor cellar bottom wastewater and low C/N(COD_Cr/TN)domestic sewage as the research objects,and adopted a moving bed biofilm reactor（MBBR）.A co-treatment system for the bottom wastewater of liquor cellar and low C/N domestic sewage was constructed,and the effects of volume load,hydraulic retention time,aeration intensity and aeration method on the removal efficiency of pollutants were investigated.Fourier transform infrared spectroscopy and three-dimensional fluorescence spectroscopy were used to analyze the changes of pollutant components,through metagenomics technology analysis of microbial community structure and functional genes and metabolic pathways,and the microbial action mechanism of the cooperative treatment system of liquor pits bottom wastewater and low C/N domestic sewage was discussed.The main conclusions are as follows:（1）The cooperative treatment system of liquor wastewater and low C/N domestic sewage was successfully constructed,and the removal effects of COD,NH₄⁺-N and TN were all good.When the volume load is 0.111 kg COD/（m³·d）,hydraulic retention time is 3 d,aeration intensity（based on the concentration range of dissolved oxygen in water）is 1-2 mg·L^-1 and intermittent aeration（take the ratio of stop aeration time to aeration time as index）is 3:1,the removal efficiency of pollutants in the system is the highest.The removal rates of COD,NH₄⁺-N and TN reached 94.91%,98.81%and 83.56%,respectively.（2）Fourier transform infrared spectroscopy analysis further proved that nitrogen pollutants were efficiently removed,and phosphorus compounds were effectively removed during the intermittent aeration stage.Three-dimensional fluorescence spectrum analysis showed that the influent contained a large amount of soluble microbial metabolites and a small amount of refractory organic matter,while the content of soluble microbial metabolites in the effluent was significantly reduced,and the refractory organic matter also decreased to a certain extent.In the cooperative treatment system,the components variation under different control conditions were less different.（3）Through scanning electron microscope analysis,it was found that in the optimal volume loading stage,the biofilm contained rod-shaped bacteria and spherical bacteria.In the best hydraulic retention time stage,the distribution of bacteria is relatively unconcentrated,the pores of the biofilm are larger,and the shape of the bacteria is relatively simple.At the stage of optimum aeration intensity,the biofilm contained coccus,bacillus,filamentous bacteria and spiral bacteria,and the microbial species were abundant.In the optimal intermittent aeration stage,the biofilm is composed of spheroidal bacteria,rod-shaped bacteria,silk fiber material and gelatinous viscous material.（4）The analysis of microbial community structure showed that the dominant genera of the cooperative treatment system were Micropruina,Propionibacterium,unclassified＿p＿＿Chloroflexi and Nakamurella.Species functional annotation analysis showed that metabolic function was dominant in level 1,and the main pathways in level 2 were Global and overview maps,carbohydrate metabolism,amino acid metabolism,and metabolism of energy metabolism cofactors and vitamins.Species and functional contribution analysis showed that Nitrospira（5.64%）had the highest contribution to environmental information processing,Micropruina（7.39%）had the highest contribution to gene information processing,and Nocardioides（14.86%）had the highest contribution to cell processing.KO analysis of systematic microbial nitrogen metabolism showed that metabolic function accounted for the largest proportion,and among the metabolic functions,the main pathways were energy metabolism,Global and overview maps and amino acid metabolism.Module analysis showed that the nitrogen metabolism pathways of microorganisms in the system included nitrogen fixation,nitrification,denitrification,dissimilatory nitrate reduction and assimilated nitrate reduction.Enzyme analysis showed that oxidoreductase was the key enzyme of nitrogen metabolism in the system,among which,glutamate synthase reductase,nitrate reductase,hydroxylamine reductase and glutamine synthase were the main functional enzymes of the system microbial nitrogen metabolism pathway.The above analysis is based on metagenomics technology.