The Fate Of Mycelium Pellets In The Activated Sludge System And Bioenhancement Applications

With the acceleration of China's urbanization and industrialization process,the sources and types of refractory organic matter in sewage are increasingly complex,the water quality discharge standards formulated by the state are constantly improving,and efficient and stable biological reinforcement technology has become one of the hot research directions.In the process of bioaugmentation,the selection of carriers is very important,directly affecting the fixation effect of functional bacteria and the removal efficiency of pollutants.The choice of carrier directly affects the application effect of bioreinforcement technology.As a new biomass pellet carrier,mycelium pellets have the advantages of good sedimentation performance,large specific surface area and low cost.However,as a specific existence form of filamentous bacteria,its feasibility as a carrier has not been systematically discussed.Based on this,this article to strengthen urban sewage denitrification effect as the goal,the optimization of hypha ball culture conditions,clear,on the basis of its ball features,focuses on the feasibility of hypha ball as biomass carrier,and strengthen its load function bacteria denitrification efficiency,so as to hypha ball as a carrier for water treatment technology to provide strong theoretical guidance and technical support.To obtain stable mycelial pellets,the culture medium conditions(C/N ratio,initial p H value)and characteristics of mycelial pellet formation were discussed.The results showed that There was a positive correlation between the biomass of mycelium pellets and carbon source content when the C/N ratio was in the range of10-60.The mycelium pellets presented the best formation performance with compact structure and regular shape.under the condition of initial p H value of 5.Considering the economic factors,the optimal parameters of mycelial bulb culture conditions were as follows: the C/N ratio of medium was 30-60,and it was not necessary to adjust the initial p H of medium artificially(p H=5).By drawing the growth curve of mycelial ball,the best culture time was 60-84 h.The results showed that the formation process of mycelium pellets was mainly composed of conidia aggregation,spore germination,branching hyphae growing in large quantity,and outer hyphae twining with crystal nucleus.The porous structure of mycelium pellet provided a place for the growth and reproduction of microorganisms,and thus could be used as a biomass carrier inwastewater bioaugmentation treatment.Using artificial simulated wastewater,the fate of mycelial pellets in the activated sludge system and the effect of added mycelial pellets on the sludge performances were investigated when different dosages of mycelial pellets were added in the sequencing batch reactors(SBR)under conditions of different organic loadings.The results showed that,under different operating conditions,the occurrence law of mycelial balls in activated sludge system is basically the same.As the skeleton of loading activated sludge,mycelial balls can adsorb activated sludge and become mycelial aggregates.The results showed that different dosage of mycelial ball had no effect on pollutant removal efficiency,but could promote the secretion of extracellular protein and improve the hydrophobicity of sludge,showing good sludge settling performance.The svi30 values of R1,R2,R3 and R4 reactors were stable at58.07ml/g,56.67ml/g,59.26ml/g and 53.63ml/g.In comparison,when the dosage of mycelium pellets was the same as SV30 volume of sludge,the sludge retention performance and sludge sedimentation performance of the system were better.Therefore,it is feasible to use the mycelial ball as a carrier for bioaugmentation,and its addition will not cause sludge bulking.The results of microbial community structure analysis showed that Proteobacteria and bacteroidota were dominant in the system,and there were acidobacteria,acidobacteriota,Nitrospira and Firmicutes,which promoted EPS secretion and organic pollutant removal.Proteobacteria accounts for 91.56% of Proteobacteria,which can enhance its adhesion by secreting a large number of extracellular polymers.The enhanced nitrogen removal efficiency of T13 loaded with aerobic denitrifying bacteria T13 was investigated by comparing the different methods of aerobic denitrifying bacteria T13 loaded on mycelial balls.The results showed that when inoculated with 7.5% functional bacterial suspension,the co culture method loaded with T13 had better denitrification efficiency.Compared with the traditional activated sludge system,the denitrification efficiency of T13 enhanced by nearly 10%,and the TN removal rate was 44%(influent TN was about 22 mg / L).When adding3 ‰ T13 inoculant directly into the reactor,the TN removal effect is better if themycelium pellets is added simultaneously.It can be seen that the mycelial ball as a biomass carrier can effectively prevent the loss of functional microbial agents and optimize the effect of bioaugmentation.Comparison was made between the co-culture method and the immersion method for the aerobic denitrifying bacteria T13 loaded with mycelium pellets to investigate the enhanced denitrifying efficiency of the actual urban sewage treatment with mycelium pellets loaded with T13.The results showed that the optimal inoculation amount of functional bacterial agent in the co-culture method was 7.5% of T13 bacterial suspension,and the best soaking time for the mycelium pellet loaded T13 by the immersion method was 6h,among which the co-culture method had better loading effect.Compared with the traditional activated sludge system,the denitrification efficiency of the biological reinforcement system with mycelium pellet loaded T13 was improved by nearly 10%,and the TN removal rate of the actual urban sewage treatment was up to 44%(about 22mg/L in the inflow TN).When 3‰ of T13 bactericidal agent was directly added to the reactor,if mycelium pellets were added synchronously,TN removal effect would be better.It can be seen that mycelium pellets as biomass carrier can effectively prevent the loss of functional bactericidal agent and optimize the effect of biological enhancement.