Study On Formation And Rheological Properties Of Granular Sludge In Internal Circulation Anaerobic Reactor

According to the current state of municipal sludge in small and medium-sized cities and towns,it is urgent to develop an efficient and low-cost urban sludge treatment process.This study in terms of traditional anaerobic digestion and gravity concentration pool operation mechanism on the basis of research achievements,independent designing and producing a new anaerobic reactor(Stirring internal circulation anaerobic reactor,SICAB),the system is combined with the internal circulation anaerobic reactor(IC)and upflow anaerobic reactor(USAB),the advantages of such as rich microbial diversity,stir fully effective,less covers area,easy to operation and management,etc.The purpose of this system is to introduce concentration and digestion into a reactor,which provides a new way to solve this problem.High-efficiency anaerobic reactor is the main body of anaerobic sludge digestion technology,and it is more critical that stable anaerobic granular sludge can be formed in the anaerobic reactor.In order to further understand the mechanism of the granulation process,this study has also conducted in-depth research on the rheological behavior of sludge,the extracellular polymer of sludge particles,and the change of biological community structure during the formation of anaerobic sludge particles.In this study,in order to improve the efficiency of sludge anaerobic digestion,cultivated anaerobic granular sludge(AGS)in SICAR,and online analysis of reactor torque and biogas production rate.The aim of this study is to analyze the formation of anaerobic granule sludge process and its influence mechanism on the change of torque,extracellular polymer material(EPS),rheological behavior and microbial diversity.This article mainly includes three aspects,first of all,successful cultured AGS internal circulation anaerobic reactor in the process of anaerobic sludge digestion,through the analysis the removal rate of COD of sludge in the system,volatile fatty acid(VFA),biological gas,biomass(VSS/TSS)as well as the change of extracellular polymers(EPS),and combining with the rheological behavior of sludge and real-time online monitoring of reactor torque value by torque sensor in the operation process of the reactor,multi-angleanalyse anaerobic digestion efficiency of excess sludge and operation condition of reactor;Secondly,through a variety of representation,such as the laser particle size analyzer and microscope,scanning electron microscope(SEM),laser electron microscope(CLSM),in-depth discussed mechanism of anaerobic sludge granulation in the sludge digestion process and its interaction of various parameters.Finally,the changes of microbial communities in anaerobic sludge in different stages were analyzed based on high-throughput sequencing technology,and the succession of microbial communities in the process of anaerobic sludge digestion and sludge granulation was discussed.The main results are as follows:(1)anaerobic reactor at the beginning of the domestication of microbes rapid proliferation and secreting of fast hydrolysis enzyme for decomposed the hard dissolved organic matter of adding sludge.The significant drop in TCOD,SCOD and VFA concentrations indicates that the anaerobic microorganisms in the reactor sludge can quickly adapt to the reactor environment and improve organic removal efficiency,but also improve the efficiency of anaerobic gas.The formation of granular sludge can reduce increasing trend of the viscosity and shear force of the sludge in the later stage,which also means that AGS can delay the increase of sludge viscosity.(2)the formation of AGS is a complex process in which the filamentous and EPS secretion increases the adhesiveness of small particles.Granular sludge can remove more microorganisms make its become larger,as anaerobic granular sludge particle size analysis result(large size particles peak appeared between 500 microns to 1200 microns,the largest diameter of AGS can reach 2.45 mm.).(3)through high-throughput PCoA analysis diagram IS compared with the distance between the other AGS,microbial structure has greatly changed after anaerobic digestion and graining process,Betaproteobacteria(23.74%)is dominant species of AGS2 in the class levels.AGS are layered phenomenon,appearance attached with filamentous bacteria and various forms of bacteria,and methane-producing filamentous bacteria are only mixed in the middle.Surface bacteria are mainly Methanobacterium,and Candidiasis also present on the surface of granular.