Study Of The Effects Of Nonivamide On SBRs And The Mechanism Of Bioaugmenation By Combining Multi-omics

As the fasting development of pepper industry and food processing industry,a large amount of nonivamide is produced in the waste water of spicy food industry.Nonivamide has strong antibacterial property,which will impact the biochemical sewage treatment units and then affect the growth of activated sludge.Based on this background,the effects of different concentrations of nonivamide on sequential batch reactor(SBR)were studied by using genomics and metabolomics methods.In addition,this paper provides a solution for the adverse impact of 120 mg·L^-1 nonivamide on SBR system:bioaugmentation.The SBR system was biologically-repaired by the periodic inoculation of Serratia marcescens JK(CICC 24870),which be able to degrade nonivamide efficiently.The main conclusions of this thesis are as follows:(1)Under the long-term press of nonivamide(30,60,120 mg·L^-1,respectively),the growth of activated sludge was inhibited.What's more,the nonivamide of 60 mg·L^-1and120 mg·L^-1 had a significant negative effect on the performances of SBR to remove nitrogen and COD_Cr,and resulted a gradual increase in EPS,SVI,and sludge load F/M.(2)Long-term nonivamide press reduced the community richness and diversity of activated sludge microbes.The higher the concentration of nonivamide,the more significant effects were observed.Then the composition and function of microbial community were shifted:adaptive genera such as norank?f?Pleomorphomonadaceae,norank?f?37-13 and Acidovorus were gradually increased,while nonivamide sensitive bacteria gradually decreased or even disappeared;all nonivamide groups were significantly inhibited the metabolism of most carbohydrates on KEGG level 3,but significantly enhanced nitrogen metabolism,which may be related to the degradation of nonivamide(a kind of nitrogen-containing pollutant).(3)Metabolomics results of LC-MS showed 11 kinds of potential metabolites of nonivamide after being biodegradating in SBRs.Specific biodegradation pathways include methylation,nitro reduction,acetylation,dealkylated,oxidative deamination to ketone,oxidation,dehydration and desaturation.(4)Bioaugmentation can significantly improve the removal rates of COD_Cr,TN,NO₃^--N and NH₄⁺-N of SBRs under long-term press of 120 mg·L^-1 nonivamide,as well as the ability of biodegradation of nonivamide.(5)The success of bioaugmentation did not attribute to the proliferation of bioaugmentation strain in activated sludge,but by triggerring microbial domino effects,especially the enrichment of microbes being able to degradate nonivamide.Thus,after the rapidly degradation of nonivamide,the microenvironment of SBR was significantly improved,which ensured the amounts and normal activities of important functional genera.(6)The metagenomic results of bioaugmentation group K indicated that several unique metabolic pathways involved in the degradation of foreign pollutants were found,and three possible metabolites of nonivamide different from N120 group were detected in the effluent.Thus,the group K changed the response pattern of activated sludge microbial communities under the press of nonivamide.