Insights into the electro-hybrid ozonation-coagulation process-Significance of connection configurations and electrode types

The electro-hybrid ozonation-coagulation process (E-HOC) integrates electrocoagulation (EC) and ozonation simultaneously in a single unit. Nevertheless, the performance of the EC process is highly dependent on the polar connection configuration (monopolar vs. bipolar connection) and the type of generated coagulants (singlecoagulant vs. dual-coagulants). In this study, the removal efficiency of the E-HOC process with different connection configurations and types of coagulants was assessed. The E-HOC process with bipolar connection (BEHOC) exhibited higher removal efficiency for wastewater treatment plant (WWTP) effluent organic matter and ibuprofen (IBP) compared with the E-HOC process with monopolar connection (ME-HOC). Furthermore, dualcoagulant generation (released from both Al and Fe electrodes) in the BE-HOC process greatly improved the WWTP effluent organic matter and IBP removal efficiency. Lower energy consumption was observed for the BEHOC process compared with the ME-HOC process. It was found that ozonation promoted the polymerization reactions during coagulant hydrolyzis in the E-HOC process. Compared with the ME-HOC process, the BE-HOC configuration and dual-coagulant mode further facilitated polymeric hydrolyzed coagulant species formation, thereby improving ozone catalytic and coagulation performance. According to trapping experiments and EPR analysis, center dot OH formation was enhanced in the BE-HOC process and dual-coagulant mode. In addition, more active reaction sites of generated hydrolyzed coagulant species were observed with bipolar connection and in the dualcoagulant generation mode based on X-ray photoelectron spectroscopy (XPS) analysis.

Automated summary

The E-HOC process with bipolar connection (BE-HOC) demonstrated higher removal efficiency for wastewater treatment and pharmaceutical removal compared to monopolar connection (ME-HOC), with lower energy consumption. Ozone promoted polymerization reactions during coagulant hydrolysis in the E-HOC process, enhancing catalytic and coagulation performance. The BE-HOC configuration and dual-coagulant mode facilitated the formation of polymeric hydrolyzed coagulant species, along with increased center dot OH formation and active reaction sites, as observed through XPS analysis.