Tannic Acid Coupled with Fe3O4/MoS2 Modified Biochar to Activate Permonosulfate for Improving Sludge Dewaterability
In order to improve the dewatering performance of municipal residual sludge,Fe3O4/MoS2 modified biochar(FeMo-BC)was prepared by using potassium ferrate activation method and followed hydrothermal treatment,and the FeMo-BC was used to active permonosulfate(PMS)combined with tannic acid(TA)to condition sludge.The sludge specific resis-tance(SRF)and water content(Wc)of sludge cake were used as evaluation index,the effects of structural characteristics and dosage of FeMo-BC,pH,conditioning time,PMS dosage and TA dosage on sludge dewatering performance were studied.The results showed that the highest efficiency of FeMo-BC in activating PMS was achieved when the pyrolysis temperature was 550 ℃,and the mass ratio of iron-loaded biochar(Fe-BC)to sodium molybdate in the hydrothermal process was 1∶1.When the dosage of FeMo-BC was 100 mg/g(calculated based on total solid,TS),the pH was 4,the dosages of PMS and TA were both 40 mg/g,and the sludge was stirred and conditioned for 30 minutes,the capillary suction time was decreased from 29.3 s to 17 s,SRF was decreased from 9.77×10 11 m/kg to 2.59×10 11 m/kg,and the Wc was decreased from 85.68％to 70.64％.Through active radical capture experiments,also analyzing the concentration changes of the protein and polysaccharide in extracellular polymeric substances(EPS)before and after sludge conditioning,it was found that the highly oxidative SO4-·and 1O2 derived from PMS which activated by FeMo-BC could effectively destroy EPS in the sludge,so as to reduce the con-tent of tightly bound EPS(TB-EPS).The addition of TA further complexed and precipitated proteins in EPS,and it could reduce protein content.SEM observation showed that the floccules of the conditioned sludge were fragmented,which was favorable for sludge dewatering.
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