Effect Of Aged Refuse On Hydrolysis-acidification Of Waste Activated Sludge Anaerobic Fermentation

The application of waste activated sludge(WAS)anaerobic fermentation has attracted wide attention and been widely researched.On the one hand,it can realize the reduction and resource of sludge through sludge anaerobic fermentation.On the other hand,valuable by-products Such as short chain fatty acids(SCFAs),hydrogen,etc.can be obtained through the above process.The anaerobic fermentation process of WAS is mainly composed of three successive reactions of hydrolysis,acidification and methanation.Hydrolysis,the control and rate limiting step of sludge anaerobic fermentation,could directly affect the subsequent reaction of anaerobic fermentation and the acquisition of the corresponding target product.The ways of how to improve the anaerobic hydrolysis rate of sludge,accelerate the process of anaerobic fermentation of WAS and obtain more target products(such as SCFAs,hydrogen,methane and so on)have always been the research hotspots of scholars.Mechanical,chemical,and biological pretreatment methods are applied to the sludge fermentation system,but most of these pretreatment methods require a large amount of energy input or chemical reagent consumption.And it is urgent to study and explore the promotion mode of high efficiency and low energy consumption.Studies have shown that aged refuse contains a large number and a wide variety of anaerobic microbial flora and enzymes,aged refuse can significantly improve the microbial activity of anaerobic fermentation system,and to promote hydrogen production of anaerobic fermentation system.And the application of aged refuse with above unique properties to improve the anaerobic hydrolysis and acidification rate of WAS has not been reported so far.In this paper,it mainly investigated the influence of aged refuse addition on the hydrolysis and acidification processes of waste activated sludge(WAS)anaerobic fermentationas well as the related action mechanism during the above process.The aim of this paper is to provide a method with low energy input and high efficiency,and the theoretical basis for the improvement of WAS anaerobic fermentation rate as well as the yield of the subsequent stage products.At the same time,it provides a new idea for the WAS treatment of aged refuse.Experimental results showed that significant improvements of hydrolysis and acidification of WAS anaerobic fermentation were achieved within 1/3g/g TSS(total suspended solid)addition dosage and the optimum addition dosage of aged refuse was 1/3g/g TSS.The ratio of SCOD/TCOD and the short chain fatty acids(SCFAs)production(183.45mg COD/g VSS,6d)in the reaction system under the presence of aged refuse were largely higher than those in the system without aged refuse addition(79.45mg COD/g VSS,10d).Mechanism study showed that the appropriate inoculation quantity of aged refuse could enhance sludge solubilization,hydrolysis of protein and polysaccharide,acidification of glucose and amino acid.In addition,the activity of key enzymes,and OTU Percent content of Proteobacteria,Bacteriodetes,Fimicutes,Acidobateria relevant to hydrolysis and acidification process under the presence of aged refuse were much higher than those in the system without aged refuse addition,which further confirmed that aged refuse could improve hydrolysis and acidification process of WAS anaerobic fermentation by increasing the variety and number of anaerobic microbial flora and enzymes,and improving the activity of enzymes relevant to the hydrolysis and acidification process.