Influence Of Anaerobically Mesophilic Digestion Pre-treatment Combined With Fenton Oxidation And Quicklime On Deeply Dewatering Performance Of Sewage Sludge

Municipal wastewater treatment plants(WWTPs)produce large amounts of sludge.Large amount of sludge has been a great trouble of the present domestic wastewater treatment.To reduce the sludge volume,the sludge deeply dewatering is the key fator.Recently,Fenton's reagent combined with lime could achieve sludge deeply dewatering efficiency,but it is difficult to apply into practical sludge dewatering due to huge dosages of reagents,long reaction time and expensive costs.Thus,it is necessary to develop an economic and practical sludge conditioning technology to realize sludge deeply dewatering.This study systematically researched the effect of experiments conditions on the dewaterability of typical sewage sludge via conditioning with a novle combination of anaerobically mesophilic digestion and Fenton oxidation/quicklime.And the effects of conditions of combination treatment and organic compounds on sludge dewaterability were investigated and relevant mechanisms also were analysised.On the basis of optimal condition,a novel controllable pressure filtration system assisted with ultrahigh pressure was used to investigate sludge dewatering performance and its deep efficiency.The results of effects of anaerobically mesophilic digestion pretreatment combined Fenton's reagent/lime on sludge dewatering properties showed: the combination treatment synergistically enhanced sludge dewaterability and the specific resistance to filterability(SRF)of sludge was reduced efficiently by approximately 96.53%.The experiments examined the optimal conidition,the relationship between VSS/TSS of sludge and sludge dewatering properties was estabilished.The results of mechanism that anaerobically mesophilic digestion pretreatment combined Fenton's reagent/lime enhanced sludge dewatering properties revealed: extracellular polymeric substances(EPS)was the major factor on sludge dewaterability.The positive correlationship between sludge VSS/TSS and content of EPS was proved.The distribution and morphology of sludge EPS had a significant influence on sludge dewatering performance.After combination treatment,sludge particles were disintegrated into smaller particles,surface changes were neutralize,scattered particles are re-flocculated,meanwhile,iron salt hydrolyzate and calcium sulfate in the particle surface to form a rigid skeleton,so that the sludge dewatering performance to further improve.The effects of major organic compounds(protein-like,humic-like substances)on sludge dewaterability and their correlationship were developed.The examination results of integrated technology of anaerobically mesophilic digestion combined Fenton oxidation and lime stated that: compared with using Fenton 's reagent/lime to condition sludge,combination treatment was more effective to improve the sludge dewatering properties of mechanical filter-pressing;and the moisture of dewatered sludge cake was below 50wt%;filter-pressing speed significantly increased;the consuming time of filter-pressing declined;the estimate cost of reagents was below 300 RMB/ t DS.Therefore,the combination treatment of anaerobically mesophilic digestion and Fenton oxidation/lime could economically and feasibly realize sludge deeply dewatering efficiency,which had a good application prospects.