Study On The Efficiency And Mechanism Of In-situ Anaerobic Sidestream Sludge Reduction Process Based On Bio-enhanced

The anaerobic side stream reactor(ASSR)process is considered as a promising in-situ sludge reduction technology.However,in order to achieve satisfied sludge reduction effect in the ASSR process,the side stream reactor must maintain a relatively long sludge(hydraulic)retention time,which causes problems such as a large side stream reactor capacity,excessive energy consumption,and excessive infrastructure costs,weakening its application advantages in practical engineering.Therefore,a new in-situ anaerobic sludge reduction process(FA-MBR)based on biological enhancement technology is proposed in this paper.Based on the analysis of its operation efficiency and sludge reduction effect,the characteristics of sludge microbial community structure and metabolic regulation mechanism in FA-MBR system are analyzed by high-throughput sequencing technology.The internal driving mechanism of sludge reduction is analyzed from the perspective of microecology,which provides theoretical guidance and technical support for the practical application of new-type in-situ sludge reduction process.The main results are as follows:During the stable operation,the denitrification and phosphorus removal capacity and sludge reduction effect of FA-MBR system were improved by adding volcanic rock porous carriers(VRPC)to the anaerobic side stream reactor.The average removal rate of TN and TP was 79% and 77.66%,higher than that of Anoxic-Oxide-Membrane(C-MBR)and Anoxic-Oxide-Membrane-ASSR(A-MBR)systems in the control group.After 120 days of continuous stable operation,the observed sludge yield Yobs of C-MBR,A-MBR and FA-MBR systems were 0.146,0.124 and 0.109gSS/gCOD,respectively.Compared with C-MBR system,A-MBR and FA-MBR achieved 16.2% and 26.4% sludge reduction rates,and FA-MBR system had the highest sludge reduction rate.High throughput sequencing technology was used to characterize the microbial community structure of sludge samples in the three systems.It was found that VRPC increased the microbial richness and diversity in FA-MBR system.At the same time,abundant denitrifying bacteria Azospira and phosphorus accumulating organisms Dechloromonas were significantly enriched on the FA-MBR system and VRPC,which was the important reason for the improvement of nitrogen and phosphorus removal efficiency.Some functional microorganisms related to sludge reduction were obviously enriched on VRPC,including hydrolysis bacteria,fermentation bacteria and slow-growing microorganisms,which all contributed to reductions in sludge yield.The macrogenomic sequencing of C-MBR,A-MBR,FA-MBR sludge and VRPC sludge was carried out,and the microbial community structure,gene function,metabolic pathway and carbohydrate enzyme were compared and analyzed.Compared with C-MBR and A-MBR systems,the relative abundance of metabolic mechanism genes in FA-MBR system decreased,but the relative abundance of cellular process and genetic information genes increased,which was conducive to maintaining the activity of microorganisms in the system.The number of functional genes involved in nitrogen metabolism and glycolysis metabolism was the highest in FA-MBR system,which helpd to improve the system's ability of pollutant removal and sludge reduction.GTS and GHS active enzyme genes were enriched in FA-MBR system and VRPC,which was helpful to maintain microbial activity and accelerated the process of sludge hydrolysis.This all had positive significance to improve the pollutant removal and sludge reduction capacity of FA-MBR system.