电凝聚臭氧化耦合工艺的二级出水处理特性与机理研究

构建电凝聚臭氧化耦合工艺对城市污水处理厂二级出水进行深度处理，研究了不同初始pH值、臭氧投加量和电流密度对二级出水处理效果的影响.结果表明，当初始pH值为5、臭氧投加量为1.5 mg·mg^-1、电流密度为15 mA·cm^-2时，该工艺处理效果达到最佳，二级出水中溶解性有机物的去除率可达到58.6%.与单独电絮凝和臭氧氧化工艺相比，耦合工艺对有机物有更好的去除效果.由于金属盐水解产物可以作为臭氧化的催化剂，为了甄别其活性点位，将磷酸盐引入体系中，结果表明磷酸盐占据了混凝剂水解产物表面的羟基，从而阻碍了臭氧与水解铝盐混凝剂之间的反应，使得有机物的去除率降低，傅立叶红外（FT-IR）分析的结果进一步证明表面羟基是产生的铝盐混凝剂催化臭氧化的活性点位.为了进一步明确该耦合工艺去除溶解性有机物的机理，选择对氯苯甲酸（pCBA）探针法间接证明和电子顺磁共振（EPR）实验直接证明体系中羟基自由基（·OH）的存在，结果表明，电凝聚臭氧化耦合工艺较单独臭氧氧化工艺产生了更多的·OH，说明电絮凝产生的铝盐混凝剂水解产物可以作为催化剂催化臭氧产生·OH，提升体系对有机物的去除效率.

Characteristics and mechanism of electro-coagulation ozonation hybrid process in the treatment of WWTP effluent

Herein, the Hybrid Ozonation-Electro-Coagulation (E-HOC) process was created for the advanced treatment of WWTP effluent. The results showed that the removal efficiency of the dissolved organic matter reached 58.6% at optimal condition of pH=5, 1.5 mg·mg^-1 of ozone dosages and 15 mA·cm^-2 current densities. Compared with the electrocoagulation and ozonation processes, the E-HOC process exhibited higher treatment efficiency. The hydrolysed Al species could play the role of the catalyst during ozonation. To identify the active catalytic sites of the hydrolysed Al species, phosphate was introduced to the E-HOC system. The results indicated that low organic removal efficiency was obtained, which can be attributed to the occupation of hydroxyl groups by phosphate on the surface of the hydrolytic product of the coagulant, further hindered the reaction between ozone and the hydrolyzed Al species. The fourier transform infrared spectroscopy (FT-IR) analysis revealed that the surface hydroxyl groups were the active sites for catalytic ozonation. In order to reveal the mechanism of the E-HOC process, hydroxyl radical (·OH) generation in the E-HOC system was determined by para-chlorobenzoic acid (pCBA) probe indirectly and electron paramagnetic resonance (EPR) directly. The results showed that E-HOC process produced more ·OH than that of single ozonation process, indicating that the hydrolysed Al species in the E-HOC process could act as a catalyst to produce more ·OH via ozone catalysis.