Study On The Acid Production Efficiency Of Alkaline Fermentation Of Dewatered Sludge Enhanced By Persulfat

As a by-product of wastewater treatment process,the resource utilization of dewatered sludge is a serious bottleneck problem.As a sludge reuse technology,anaerobic fermentation can transform the organic matrix in activated sludge into valuable biological products,such as volatile fatty acids（VFAs）,and can be used as an additional carbon source for biological nitrogen and phosphorus removal in sewage treatment plants.In addition,the content of polyacrylamide（PAM）in dewatered sludge is high,and the presence of PAM may have a certain impact on the acid production of anaerobic fermentation of dewatered sludge.This study takes dehydrated sludge from sewage treatment plants as the research object to explore the inhibitory effect of PAM on the fermentation of dehydrated sludge for acid production.Through persulfate（PDS）pretreatment of dehydrated sludge for alkaline fermentation,the VFAs production of sludge is increased,further revealing the acid production mechanism of PDS enhanced alkaline fermentation of dehydrated sludge.The main research is as follows:（1）By comparing and analyzing the acid production efficiency of dehydrated sludge and surplus sludge,this study explores the inhibitory law of PAM on the fermentation acid product ion of dehydrated sludge and reveals its inhibitory mechanism.The results showed that PAM i nhibits the acid production of anaerobic fermentation of dehydrated sludge,and the inhibitory effect increases with the increase of PAM content.PAM impedes the dissolution and release of soluble organics in sludge,and promotes the release of refractory organics such as fulvic acid like and humus.In addition,PAM reduces the richness and diversity of microbial communities in sludge,and reduces the relative abundance of acid producing bacteria such as Proteobacteri a,Bacteroidetes,Firmicutes,and Actinobacteria.The relative abundance of acid-producing mi croorganisms also decreased with the increase of PAM content,such as norank＿f＿＿norank＿o＿＿OPB41、norank＿f＿＿Bacteroidetes＿vadin HA17、Bacillus、Arthrobacter.（2）By using PDS to enhance alkaline fermentation of dehydrated sludge,the production of VFAs was increased,and the process parameters of the sludge fermentation system were op timized.The results showed that the maximum VFAs production of PDS pretreated dewatered sludge in alkaline fermentation process was 4005 mg COD/L,13.40 times that of dewatered s ludge fermentation.When the dosage of PDS is 0.08 g PDS/g VS,the VFAs of dewatered slud ge reach the maximum output of 5278 mg COD/L.When the optimal dosage of PDS and p H=9,the VFAs output of dewatered sludge is the highest,1.91 times of the acid output of the cont rol group.The total VFAs output at different temperatures is:45℃（13985 mg COD/L）>3 5℃（10030 mg COD/L）>55℃（9846 mg COD/L）>25℃（8219 mg COD/L）.Therefore,when P DS=0.08 g PDS/g VS,p H=9,and fermentation temperature is 45℃,PDS enhanced alkaline fer mentation of dehydrated sludge has the best acid production efficiency.（3）By exploring the hydrolysis and acid production process of PDS pretreatment dehydra ted sludge alkaline fermentation,and further analyzing the acid production mechanism of PDS enhanced dehydrated sludge alkaline fermentation from a microbial perspective.The results i ndicate that dewatered sludge had the smallest particle size,the sludge surface was loose and p orous,the highest porosity,the highest content of hydrolase,and the sludge had good dewateri ng performance.Some humic acid like substances undergo degradation under this treatment m ethod,and the fermentation process conforms to Logistic equation.In addition,the contributio n of PDS pretreatment to alkaline fermentation of dewatered sludge was SO₄^2->PDS.The enri chment of microbial populations in the alkaline fermentation process of PDS enhanced dewate red sludge is relatively high,enriching many hydrolysis and acid producing bacteria,breaking through the inhibition of PAM on acid producing bacteria.The relative abundance of Proteinip hilum,Proteiniboru,Acetoanaerobium,and Desulfobulbu genera is relatively high.The micro bial functions of PDS enhanced alkaline fermentation of dewatered sludge are mainly chemica l heterotrophic,fermentation,sulfur,and nitrogen cycling.In addition,there are many microor ganisms related to the degradation of aromatic compounds in this treatment method,which is conducive to the degradation of difficult to degrade organic compounds during the fermentatio n process,thereby increasing its acid production.