关键词: 硫酸根自由基, 剩余污泥, 强化脱水, 氧化破解, 响应面优化

Abstract:

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(S₂O₈^2-) 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(S₂O₈^2-) =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.

Key words: sulfate radical, excess sludge, dewatering enhancement, oxidation disintegration, response surface method