Study On The Enhancement Of Sludge Dewatering Efficiency By Persulfate Activation

In recent years,more and more wastewater treatment plants have produced a large number of waste activated sludge with the development of urbanization.How to treat these sludges with high moisture content has attracted wide attention.Effective treatment before sludge dewatering is able to greatly reduce the moisture content of sludge.Persulfate oxidation technology based on sulfate radicals is a new advanced oxidation technology,which is widely used in the process of treating refractory organic pollutants,and the field of sludge dewatering has also begun to emerge.The effects of heat activation,alkali activation and ethylenediaminetetraacetic acid(EDTA)complexed with Fe3+ activation to activate peroxymonosulfate(PMS)and peroxydisulfate(PDS)to treat waste activated sludge for the dewatering performance and mechanism of activation were investigated in this study.In this study,the capillary water absorption time(CST)of the sludge,the content of protein,polysaccharide,total nitrogen and total phosphorus in sludge filtrate were used as the main indicators to evaluate the dewatering performance of the sludge,the effects of activated PDS and PMS on the sludge dewatering performance were investigated respectively under the conditions of different heating time in 80 ℃ water bath,different Na OH dosage and EDTA-Fe(Ⅲ)dosage.The experimental results show that thermal activation and EDTA complexed with Fe3+ activated persulfate can effectively enhance the sludge dewatering performance,while alkali activated sludge dewatering performance has deteriorated.When the dosage of 0.05 mmol/g DS persulfate were added,the best reaction condition of heat activation treatment is 80 ℃ water bath heating for 10 minutes,the CST reduction rate of PDS group is 33.7%,and the CST reduction rate of PMS group is 23.6%;the best reaction condition of EDTA complexed Fe3+ activation is the dosage of EDTA-Fe(Ⅲ)0.2 mmol/g DS,the CST reduction rate of PDS group is 47.1%,and the CST reduction rate in the PMS group is 32.4%.PDS shows an better activation effect than PMS,EDTA complexed with Fe3+ to activatePDS is the most economical and efficient way to enhance sludge dewater treatment.Through the analysis of protein and polysaccharide content in sludge EPS and the three-dimensional fluorescence spectrogram(EEM)analysis,the mechanism of activated persulfate to enhance sludge dewatering performance is: under the action of thermal energy or EDTA-Fe(Ⅲ)system,persulfate produces sulfate radical(SO4·‐),and the efficiently oxidized SO4· ‐acts on the sludge EPS and sludge floc microbial cell structure,the structure of EPS was destroyed,a large number of proteins were degraded into small molecular amino acids,the hydrophobicity of sludge flocs increased,the bound water in EPS was released,the sludge moisture content decreases,thus the dewatering performance of sludge was improved.The protein content of sludge EPS(especially TB-EPS)is the main factor affecting sludge dewatering performance.The key to improve sludge dewatering performance is to reduce the protein content in sludge EPS.