일시: 2024.02.11 11:00

장소: 302-619

Irene M.C. LO

Chair Professor, Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China

Abstract: Conventional wastewater treatment facilities face significant challenges such as high carbon emissions and energy consumption. In this study, we developed a low-carbon-emission photoelectrochemical (PEC) system utilizing a reduced BiVO₄ (r-BiVO₄) photoanode for the treatment of saline sewage, coupled with green hydrogen (H₂) generation. The PEC system demonstrates exceptional performance in treating saline sewage, effectively meeting Hong Kong discharge standards for chemical oxygen demand (COD), ammonia-N, and E. coli within 40 minutes at 2 V (vs. Ag/AgCl) when treating simulated saline sewage. When applied to real saline sewage (sampled from Stonecutters Island Sewage Treatment Works in Hong Kong), which has a more complex composition and higher turbidity, the PEC system still meets the discharge standards within 2 hours of PEC treatment.  The mechanism studies reveal that Cl^•, ClO^•, and Cl₂^•− primarily contribute to the efficient degradation of organic pollutants to CO₂, while ClO^• is dominant in converting ammonia to N₂, thereby reducing the formation of greenhouse gases such as CH₄ and N₂O. Additionally, we demonstrate the scalability of the PEC system from batch to a large-scale continuous flow reactor, achieving excellent performance in real saline sewage treatment by meeting discharge standards within a 2-hour retention time. Most importantly, this system generates 18.13 mol/m³ of green H₂ (equivalent to 0.92 kWh/m³ of electricity) and results in significant reductions of 96% in scope 1 emissions (direct GHG emissions) and 95% in total carbon emissions compared to conventional wastewater treatment plants, demonstrating its excellent environmental benefits and enormous practical potential.