Released soluble COD (SCOD)

relative hydrophobicity (RH)

and specific resistance of sludge (SRF) were used to characterize sludge disintegration degree

surface hydrophobicity and dewatering performance. The enhanced dewatering influence factors and mechanism of oxidation disintegration of excess sludge were investigated by oxidative sulfate radical (SO4-·) generated from persulfate activated by Fe(Ⅱ). SCOD increased from 66.5 mg·L-1 to 472.3 mg·L-1

RH increased from 26.9% to 41.1%

SRF decreased from 24.9×108 S2·g-1 to 4.5×108 S2·g-1 after disintegration reaction when pH was 4.5

n(S2O82-) was 2.2 mmol·(g VSS)-1

n(Fe2+)=1.32 mmol·(g VSS)-1 and reaction time was 3 h at room temperature. According to the center combination experimental design of Box-Benhnken based on the response surface method

the optimal results were pH=4.27

n(S2O82-) =2.6 mmol·(g VSS)-1

n(Fe2+)=1.59 mmol·(g VSS)-1

SRF=3.8×108 S2·g-1 and sludge cake moisture content rate = 72.7% when SRF was taken as response. Microscopic observation revealed that floc sludge was disintegrated into smaller particles and debris. FT-IR showed the surface functional group corresponding to the absorption peak intensity of sludge decreased to some extent

and thermogravimetric analysis indicated that physical adsorption combined water loss region disappeared. The above results suggested that under the influence of SO4-·

stable sludge zoogloea structure was destroyed

cell lysis and organic matter was released into the liquid phase

sludge surface was more hydrophobic

water binding capacity decreased and sludge dewatering performance was improved considerably

thus facilitating sludge reduction application.