Regulation And Operation Of Microbial Degradation Process For Wastewater Containing Typical Phenolic Compounds

In recent years,with the development of industrial technology,the wastewater containing organic poisons discharged from factories has shown a trend of diversification and high toxicity.The existing nitrification and denitrification processes of sewage treatment plants have been affected by wastewater containing organic pollutants.Phenolic compounds of waste water is acommon industrial waste water,it is mainly used in the production of dyes,pesticides,explosives,wood preservatives,herbicides,plasticizers,etc.It has very strong electron affinity,stable structure and has the characteristics of difficult to oxidation,high toxicity,so their emissions to the environment can cause serious pollution to the environment,great harm to human body.Many studies use physical,chemical and other methods to remove toxic organic matter from wastewater,but these methods are often expensive and produce intermediates that are more toxic in the middle.Therefore,microbial method is an economic method in terms of natural nutrient circulation and economic benefits Effective method of removing phenolic compounds.In this paper,nitrified sludge and nitrified granular sludge are selected as research objects to effectively degrade phenolic compounds in industrial wastewater.Using fluorescence spectroscopy to explore the release rule of microbial products in the system,and using high-throughput sequencing to study the evolution of microbial communities in sludge and explore the dominant strains that degrade different phenolic compounds,which is in line with the future development direction of biological treatment technology.1.The system performance,sludge property and microbial community shift were evaluated in a nitrifying sludge?NS?bioreactor for simultaneous treating p-Nitrophenol?PNP?and high ammonia wastewater.After acclimation of PNP toxic environment,the removal efficiencies of PNP and NH₄⁺-N reached to 99.9%and 99.8%,respectively.The particle size of NS increased from 115.2?m to 226.3?m,indicating that nitrified sludge protects it from toxic effects through agglomeration when it is affected by toxic substances In the presence of PNP,the humic acid in soluble microbial product?SMP?increased significantly,which was 2.5 times higher than that in the blank stage.The increase in the relative abundance of Thauera,Nitrospiraceae and Nitrosomonas indicated the nitrification and denitrification capacities of NS increased,which maybe the PNP cometabolic biodegradation effect.Moreover,Ignavibacteria and Aeromonas were responsible as the dominant bacteria for degrading PNP in the nitrifying system.2.The effects of two membrane bioreactors?presence and absence of 2,4-dichlorobenzol?on the treatment of high ammonia nitrogen wastewater and the degradation performance of 2,4-dichlorobenzol were analyzed.MBRs showed good results after 130 days of operation,NH₄⁺-N removal rate was greater than 98%,2,4-DCP removal rate was greater than 96%.After the addition of 2,4-dichlorophenol,nitrifying bacteria were more severely inhibited than heterotrophic bacteria.At the same time,the transmembrane pressure difference?TMP?of MBR with 2,4-DCP increased rapidly from 0.025 MPa to 0.051 MPa in the first ten days,indicating that 2,4-DCP has an adverse effect on the membrane structure.The ratio of loosely bound EPS?LB-EPS?and tightly bound EPS?TB-EPS?protein and polysaccharide increased to 1.1 times and 6.3 times under 2,4-DCP exposure,indicating that PN substance was more sensitive to chlorophenol than PS substance.Mesorhizobium and Paracoccus were proved to be the main degrading strains of 2,4-dichlorobenzol in membrane bioreactor.3.A nitrified granular sludge sequential batch reactor?NGS-SBR?was established to strengthen the degradation of 2,6-DCP.After the 90-day acclimation,the removal efficiencies of NH4+-N and 2,6-DCP and NH4+-N reached to 99.8%and 99.9%,respectively.After 2,6-DCP exposure,the content of polysaccharide and protein in LB-EPS and TB-EPS showed an upward trend.The activity of AOB and NOB in NGS were enhanced in the presence of 2,6-DCP,the enhancement of AOB activity improves the ability of NGS cometabolism.Molecular weight?MW?data indicated that SMP consists of compounds with molecular weights less than1 kDa or greater than 10 kDa.The relative abundance of Nitrospirae and Nitrosomonas were enriched in NGS after acclimatization.At the same time,Amaricoccus and Acidovarax were proved to be the main degrading strains of 2,6-DCP in aerobic granular sludge.