活性污泥脱水性能与电化学阻抗谱参数的关联特性

Study on the correlation between dewatering performance of activated sludge and electrochemical impedance spectroscopy parameters

为探究FeCl_(3)混凝调理过程中活性污泥脱水性能与电化学阻抗谱参数的关联关系,选取北京3座污水处理厂的剩余活性污泥,研究不同调理投药量下活性污泥的毛细吸水时间(CST)、比阻(SRF)、抽滤含水率、Zeta电位、电导率以及电化学阻抗等指标的变化,通过Pearson相关性分析讨论污泥脱水性能与阻抗谱参数(d_(s)/f_(c))的相关性,并探讨d_(s)/f_(c)预测污泥脱水性能的可行性。实验结果表明,FeCl_(3)调理活性污泥的较适投加量为100 mg·g^(-1);超过100 mg·g^(-1)时,活性污泥CST、SRF、抽滤含水率基本不再下降,Zeta电位却缓慢升高;电化学阻抗Z则随着投加量的增加而持续下降,且Nyquist图中高频区半圆面积减小,这表明电子更易转移、污泥更易导电。相关性分析表明,活性污泥的脱水性能均与d_(s)/f_(c)呈显著正相关(r>0.639,p<0.01);3种活性污泥CST、SRF、抽滤含水率分别与d_(s)/f_(c)的线性回归结果显示它们之间呈线性关系,且线性方程斜率为正值(R^(2)>0.921,p<0.01)。上述研究结果表明,活性污泥的d_(s)/f_(c)参数可以作为指示脱水性能的潜在指标。本研究结果可为污泥减量化技术提供参考。

In order to explore the correlation between the dewatering performance and electrochemical impedance spectroscopy parameters of activated sludge(AS)conducted by FeCl_(3) coagulation,the AS samples were taken from three sewage treatment plants in Beijing.The variations of capillary suction time(CST),specific resistance to filtration(SRF),moisture content after vacuum filtration,zeta potential,conductivity and electrochemical impedance spectroscopy with FeCl_(3) doses were investigated.Pearson coefficient was used to explore the correlation between sludge dewatering performance and impedance spectrum parameter(d_(s)/f_(c)),and the feasibility of impedance spectrum parameter d_(s)/f_(c) predicting the sludge dewatering performance was also discussed.The results showed that the appropriate dosage of FeCl_(3) was determined as 100 mg·g^(-1).Beyond this dosage,CST,SRF,moisture content after vacuum filtration of activated sludge basically did not decrease,and the rising rate of zeta potential slowed down.However,with the increase of dosage,the electrochemical impedance Z decreased,the semicircle area in the high frequency region in Nyquist plot decreased,which indicated that more easy charge transferred and higher conductivity could occur.Significant positive correlations occurred between AS dewatering performance and d_(s)/f_(c) with the corresponding indicators of r>0.639 and p<0.01.Moreover,the linear regression equations with positive slopes(R2>0.921,p<0.01)could be determined between the dewatering performance parameters,such as CST,SRF and moisture content after vacuum filtration,and the d_(s)/f_(c) values of three types of AS,respectively.This implied that the parameter d_(s)/f_(c) can be taken as the potential index to indicate the dewatering performance of AS.Therefore,this study provides a support for sludge reduction technology.