Study On Preparation Of Compound Bio-stimulant And Its Improvement Effect On Black-odor Water

The black-odorous water body is an extreme expression of water body pollution,which has became an environmental problem that cannot be ignored and is thorny,treating black-odorous water bodies is the focus of our country.The habitat of black odorous sediment has led to the dominant microbial groups of anaerobic microorganisms such as sulfate-reducing bacteria.The growth and metabolism of these special microbial communities is an important cause of black odorous water.Taking effective measures to suppress the growth of microorganisms which can cause black odorous water and promote the adjustment of the community community for the eliminating black and odor in the direction of succession,it will have important significance for the control of black and odorous rivers.To study the characteristics of microbial community structure in black-odorous sediment,two black odorous inland rivers in the lower reaches of the Shaying River Basin were selected as research objects in this study.Furthermore,this study developed a compound bio-stimulant(comprised of calcium peroxide,calcium nitrate,bio-stimulant,and bentonite).And then,this study optimized the formulation of the compound bio-stimulant and explored the effect and mechanism of the compound microbial promoter on the black-odorous water.The main results are as follows:(1)In order to study the seasonal variation characteristics of microbial communities in the sediments of the black-odorous river located in lower reaches of Shaying River,the 16S r DNA gene of surficial sediments from the Zhongqing river and the Qiyu river,was sequenced using high-throughput sequencing approach.The results showed that microbial species diversity in urban black-odorous river were not high and changed with different seasons:spring>winter?summer>autumn.The redundancy analysis revealed that microbial diversity was significantly affected by seasons and p H of sediment.By analyzing microbial community structure in sediment at phylum level,it is found that seasons,temperature,TN and SOM have a greater impact on microbial populations.The relative abundances of dominant bacteria such as Proteobacteria,Firmicutes,Chloroflexi,Verrucomicrobia,Bacteroidetes and Actinobacteria differed at the seasonal level.The relative abundances of Firmicutes,Chloroflexi,Actinobacteria and Acidobacteria were higher in spring,but Proteobacteria was relatively lower.The relative abundances of Verrucomicrobia and Bacteroidetes decreased dramatically in autumn,but Proteobacteria increased significantly compared with other seasons.A total of 16sulfate-reducing bacteria genus were detected in all samples,of which Desulfoprunum was the most abundant.SRB was the most abundant in spring with the highest relative abundance;and SRB was positively correlated with SO₄^2-,TN,SOM,Cl^-etc.To some extent,the above results also provide a reference for the selection of control time to effectively avoid the generation of black and odorous substances in rivers.(2)Aiming at the pollution characteristics of black odorous water body with low dissolved oxygen and low redox potential,and anaerobic microorganisms as dominant flora,a compound bio-stimulant consisting of calcium peroxide,calcium nitrate,bio-stimulant and bentonite were preparated to repair black-odorous water body.Using calcium peroxide and calcium nitrate to increase the dissolved oxygen and redox potential of black odorous water bodies,and promote the growth of aerobic microorganisms;Using bio-stimulant to reduce total organic matter in the sediment and improve the activity of microbial;the use of bentonite to control the release rate of the above agents.In order to obtain better repair results,the formula need to be optimized on the basis of the above materials.Optimizing compound microbial biostimulant formulations through orthogonal experiments,and the results showed that:Calcium peroxide can significantly increase the DO and p H of the experimental water,The presence of bentonite can inhibit the increase in p H caused by calcium peroxide.Calcium nitrate can cause the nitrate nitrogen content of the experimental water increase significantly,bentonite can control the release rate of nitrate from calcium nitrate,and the compound bio-stimulant can significantly reduce the ammonia nitrogen content in the experimental water and sediment.The formula of the compound bio-stimulant was determined through experiments:The mass ratio of calcium peroxide,calcium nitrate and microbial growth promoter is 5:5:1,and the ratio of bentonite is 1:1.(3)The effect of compound bio-stimulant on black and odorous water was studied.When the dosage of the compound bio-stimulant was 0.275 g/L.Comparing with the control group after 31 days,the ammonia nitrogen removal rate in the sediment of the experimental group was significantly increased by 66.97%,and the ammonia nitrogen removal rate in the water of the experimental group was significantly increased by 61.14%.The microbial community in the sediment changed to aerobic microorganisms.The number of amonifying bacteria and nitrite-oxidizing bacteria in the sediment of the experimental group was significantly higher than control group,which were 3.36 times and 236 times,respectively.The number of sulfate-reducing bacteria in the sediment of the experimental group was 1-2 order of magnitude lower than that of the control group.The nitrite bacteria in the experimental group was 4.42 times that of the control group,but there was no significant difference.The ammonia oxidized archaea in the experimental group and the control group were detected.The relative abundance of the ammonia oxidized archaea in the experimental group was significantly higher than that of the control group.The result showed that the compound bio-stimulant can promote the growth of nitrogen cycling bacteria and accelerate the conversion of ammonia nitrogen in the sediment to other nitrogen.