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

摘要：

采用 Fe(Ⅱ)活化过硫酸盐,产生强氧化性硫酸根自由基(SO₄^-·),以污泥释放的溶解性COD(SCOD)、相对疏水性(RH)和污泥比阻(SRF)为表征,考察了SO₄^-·氧化破解剩余污泥强化脱水的影响因素,并解析了机理。结果表明:当初始pH为4.5,n(S₂O₈^2-)=2.2 mmol·(g VSS)^-1,n(Fe²⁺)=1.32 mmol·(g VSS)^-1,常温下反应3 h后,SCOD由66.5 mg·L^-1增加到472.3 mg·L^-1,RH由26.9%升高到41.1%,SRF由24.9×10⁸ S²·g^-1降低至4.5×10⁸ S²·g^-1;在此基础上利用响应面法,根据Box-Benhnken中心组合试验设计,以SRF为响应指标,优化条件为pH 4.27,n(S₂O₈^2-)=2.6 mmol·(g VSS)^-1,n(Fe²⁺)=1.59 mmol·(g VSS)^-1时,SRF为3.8×10⁸ S²·g^-1,泥饼含水率为72.7%。镜检发现,破解后污泥变为颗粒碎片状;傅里叶红外光谱显示污泥表面官能团对应的特征吸收峰强度有一定程度的减弱;热重分析表明无明显物理吸附水失重区。证实了在SO₄^-·作用下,污泥菌胶团结构破坏,溶胞释放了有机物,使表观疏水性更强,与水结合力明显减弱,脱水性得到了较大提高,有利于污泥减量化应用。

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