电凝聚臭氧化耦合工艺的二级出水处理特性与机理研究

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.