Study Of Pretreatment Of Anaerobic Fermentation Based On Extracellular Polymeric Substances Of Wasted Activated Sludge

In recent years,lots of researches has been done in wasted activated sludge pretreatment technology,which mainly include physical,chemical and biological pretreatment method.These pretreatment methods are taking wasted activated sludge as a whole,that dissolved organic matter mostly in microbial cells,microbial cell wall is the main obstacles that release and use this part of organic,and then the main purpose of pretreatment is broke the microbial cells.This test combined with EPS extraction methods,explored various reagents to the effect of pretreatment of wasted activated sludge EPS,according to the changes of DNA and soluble macromolecules concentration released in solution to choose proper reagent,and through subsequent anaerobic digestion experiments explored anaerobic digestion performance by related reagents pretreatment of sludge EPS.The main conclusion as following:(1)Selecting ten kinds of chemical reagents(including sodium citrate,citric acid,sodium dodecyl sulfate,sodium oxalate,sodium tripolyphosphate,magnesium chloride,disodium hydrogen phosphate,monopotassium phosphate and zeolite)were tested in EPS pretreatment.According to the pretreatment of the total EPS and the content of DNA were screened from sodium citrate,citric acid and sodium lauryl sulfate,respectively corresponding to the optimum dosage of 0.10g/gSS,0.03g/gSS and 0.02g/gSS,the best dosage in the solution under the condition of total EPS were247.88mg/L,216.88mg/L and 213.95mg/L,DNA contents were 4.76mg/L,5.10mg/L and 11.97mg/L.This three kinds of reagents can destroy microbial cell structure as small as possible under the condition of crack EPS structure,letting protein,polysaccharides and humic substances of EPS released into the solution,adding organic matters that can quickly use in solution.Sodium citrate is the best pretreatment effect among three agents.(2)Anaerobic digestion fermentation is the traditional way to utilize the wasted activated sludge of municipal wastewater treatment plants.In this paper,anaerobic digestion was used to further investigate the utilization of organic matter in the wasted activated sludge after EPS pretreatment.The test chose ultrasonicpretreatment as contrast test,found EPS after ultrasonic extraction,ultrasonic cell breaking,adding sodium citrate,adding citric acid and adding sodium lauryl sulfate pretreatments,the specific methane production respectively than the untreated experimental group increased by 0.79%,23.39%,27.93%,7.42% and 7.42%.Sodium citrate can not only better pretreat EPS,but also can promote the specific methane production of sludge anaerobic fermentation.Similar effect of citric acid and sodium lauryl sulfate in EPS pretreatment and anaerobic digestion in the follow-up.