Study On Enhanced Nitrogen And Phosphorus Removal By Composite Ferric Enzymatic Activated Sludge And Its Biological Mechanism

At present,the urban sewage treatment plants in China generally have the problems of low nitrogen and phosphorus removal capacity,low efficiency,high operation cost and poor stability.Especially,there is no good solution to the general problem of low nitrification ability in winter in northern area.It is urgent to find an efficient,economic and stable new technology for nitrogen and phosphorus removal.The main body of biological treatment of sewage is microorganism.The level of microbial metabolic capacity and biological activity is the most fundamental factor determining the ability of biological nitrogen and phosphorus removal.The composite ferric enzymatic activated sludge technology is the breakthrough point to improve the biological activity of activated sludge microorganisms.It involves the process of energy and material metabolism of microbial biochemical reactions through iron elements to increase the efficiency of nitrogen and phosphorus removal in activated sludge systems.It effectively solves many bottlenecks and fundamental problems of biological nitrogen and phosphorus removal technologies.This research started with three aspects of microbial activity,population structure and functional genes.The biochemical reaction law of composite ferric enzymatic activated sludge from nitrogen and phosphorus removal was studied from a macro perspective.The biological mechanism of composite ferric enzymatic activated sludge for nitrogen and phosphorus removal was studied from microcosmic perspective.The main results are as follows:Firstly,composite ferric enzymatic activated sludge has high pollutant removal ability and microbial activity.Under the reaction temperature of 22?,the removal efficiency of organic matter and ammonia of the composite ferric enzymatic activated sludge and ordinary activated sludge was good and stable,and the removal rates were over 90%.The removal effect of nitrogen and phosphorus was unstable and the removal rates were 89.93%and 57.03%.When the reaction temperature is reduced to5?,the COD removal rate,NH₄⁺-N removal rate,and PO₄^3--P removal rate of the composite ferric enzymatic activated sludge and ordinary activated sludge effluent are62.78%,60.16%,62.55%,and 34.25%,28.36%,26.16%.With the decrease of temperature,the removal efficiency of nitrogen and phosphorus pollutants in both systems gradually deteriorated.The TTC-DHA activity and INT-ETS activity of composite ferric enzymatic activated sludge were 25.76mg/gVSS·h⁹.45mg/gVSS·h and 283.56mg/gVSS h¹17.98mg/gVSS·h.The TTC-DHA activity and INT-ETS activity of ordinary activated sludge are 15.99mg/gVSS·h⁵.06mg/gVSS·h and234.34mg/gVSS·h⁹1.35mg/gVSS·h.In the process of reducing the reaction temperature from 22?to 5?,the content of cytochrome C oxidase in composite ferric enzymatic activated sludge was 5.86mg/gVSS⁴.21mg/gVSS,and the content of the cytochrome C oxidase in the the ordinary activated sludge was5.50mg/gVSS³.82mg/gVSS.The average cytochrome C oxidase activity of composite iron enzyme activated sludge and ordinary activated sludge is3.44mg/gCcO and 3.35mg/gCc O.The content of cytochrome C oxidase in activated sludge decreased with the decrease of temperature,and the content of cytochrome C oxidase in the compound ferric activated sludge was higher than that of ordinary activated sludge.The iron content of cytochrome C oxidase in the two activated sludge was stable and no significant difference.Second.Microbial community structure of composite ferric enzymatic activated sludge changed compared with ordinary activated sludge.High throughput sequencing showed that the proportion of the main components of the composite ferric enzymatic activated sludge and the ordinary activated sludge was approximately the same at 22?,and the proportion structure of the dominant bacteria and the bacteria group of the two activated sludge was greatly changed at 12?.The total OTUs of functional bacteria of denitrification and dephosphorization of composite ferric enzymatic activated sludge is higher than that of ordinary activated sludge.Activated sludge samples of composite ferric enzymatic activated sludge and the ordinary activated sludge were mainly composed of Proteobacteria,Bacteroides and Firmicutes.The dominant bacteria of ammonia oxidizing bacteria is Nitrosomonas.The dominant bacteria of nitrifying bacteria is Nitrospira.The main dominant bacteria of denitrifying bacteria include Bacteroides,Hydrophila and Bacillus.The main dominant bacteria of phosphorus removal bacteria include Aeromonas and Pseudomonas.Third.The microbial functional gene structure of composite ferric enzymatic activated sludge was changed compared with ordinary activated sludge.The results of functional gene structure analysis show that under the same reaction temperature,the overlap gene detected by composite ferric enzymatic activated sludge and ordinary activated sludge accounted for a large proportion?95.4%⁹6.85?.Under the conditions of 22?,the functional group diversity of the composite ferric enzymatic activated sludge was slightly lower than that of the ordinary activated sludge system,and the functional diversity of the composite ferric enzymatic activated sludge was slightly higher than that of the ordinary activated sludge system at 12?.When the reaction temperature was 12?,the microbial functional diversity of the two activated sludge system increased significantly compared to the 22?.At 22?,the metabolic potential of composite ferric enzymatic activated sludge of various functional groups has significant advantages.At 12?,the metabolic potential of composite ferric enzymatic activated sludge in secondary metabolism,metal homeostasis,organic remediation and carbon cycling has significant advantages.Under the condition of22?,the number of key genes in carbon cycling,nitrogen cycling and phosphorus cycling of composite ferric enzymatic activated sludge and ordinary activated sludge is basically the same.Under the condition of 12?,the number of key genes in carbon cycling,nitrogen cycling and phosphorus cycling of composite ferric enzymatic activated sludge increased significantly compared with ordinary activated sludge.