Research On Key Technologies Of Aerobic Sludge Granulation In Urban Sewage Treatment Plant

The granulated sludge process wastewater treatment wasa new biological treatment method developed in recent years,which overcame the shortcomings of activated sludge process and was a promising and efficient biological treatment system.In order to promote the engineering application of aerobic granular sludge technology,this paper conducts in-depth research on the key technologies of aerobic sludge granulation in urban sewage treatment plants,and conducts experimental exploration on its engineering application.Activated sludge was granulated by self-aggregation of microorganisms.Study the influence of relevant factors on the formation of aerobic granular sludge and the bio-community characteristics of granular sludge,physical properties of sludge during granulation and denitrification Phosphorus performance.At the same time,the effects of phenol on the water treatment performance,microbial metabolic activity and microbial functional diversity of aerobic granular sludge were studied.The main conclusions are as follows:(1)The pilot study used artificial simulated sewage as the influent water to successfully realize the granulation of sludge under low concentration domestic sewage(300-500 mg/L).The particles are compact and structurally regular,and have good properties for COD,NH3-N and TP.The results show that the removal rate of COD by aerobic granular sludge is above 98%,the removal rate of NH3-N is above 98.5%,and the removal rate of TP is above 85%.(2)Combined with the pilot test,pilot research was further carried out to optimize the technical indicators of the key factors of granulation in the test.The optimal operating parameters of the pilot reactor and the key technologies of granulation were determined to support the large-scale application of aerobic granular sludge technology..The results show that the pilot operation parameters of the granular sludge are:pH is maintained at 6-8,sludge age is controlled at 10-13 d,hydraulic shear force is superficial gas velocity greater than 1.6 cm/s,and settlement time is finally controlledwithin 5 minutes.(3)When the concentration of phenol was 500 mg/L,the oxygen consumption rate of aerobic granular sludge and floc activated sludge was 15.79 and 7.32 mgO2/gMLVSS·h,which was 54.5%and 76.0%lower than that of the control group,the granular sludge exhibited greater tolerance to phenol toxicity.The mass transfer resistance formed by the particle structure makes the concentration of the phenol inside the particle in the mixed solution,effectively reducing the phenol toxicity faced by microorganisms inside the particle.The high concentration of phenol impact load has a serious impact on the phenol degradation ability of granular sludge and the degradation ability can not be significantly improved for a period of time.However,gradually increasing the influent phenol concentration from low concentration will not lead to a significant decrease in the removal rate and a gradual increase in system load.