The team led by Professor Chen Guangxu and Professor Qiu Guanglei of South China University of Technology (SCUT) published a paper titled 'Realizing the practical application of CO₂ electroreduction (CO₂RR) for urban wastewater denitrification' in the top-tier journal Nature Water. Based on a detailed comparison of the CO₂RR system and municipal wastewater denitrification, the teamproposed a novel electrochemical–biological hybrid system that merges CO2 electrolysis with municipal wastewater denitrification.

In this hybrid system, CO₂ was efficiently and electrocatalytically converted into formate (formatee), which directly serves as the carbon source and energy carrier for biological denitrification. Results show that the system achieves an excellent nitrate nitrogen (NO₃−-N) removal rate (~3.06 mg L-1h-1). Moreover, after long-term continuous operation of the tailored denitrification bioreactor, formate-e exhibits a higher denitrification rate than acetate, a widely used commercial carbon source. Further environmental and techno-economic analyses indicate that integrating this electrochemical–biological hybrid system with an electrochemical recovery and separation system can significantly reduce electrolyte costs, thereby enabling large-scale application of the hybrid system. This research offers a novel approach for the coordinated development of CO₂ mitigation and urban wastewater treatment and demonstrates the significant potential of directly applying electrochemical products in environmental governance. With ongoing engineering design optimization, the system holds promise of achieving both technical and economic viability. More importantly, by recycling and utilizing CO₂ released from sources such as thermal power generation, sludge or waste incineration, and biologicaldenitrification processes as a reaction feedstock, the system is expected to achieve net-zero or even carbon-negative emissions.