Biohybrid-based pyroelectric bio-denitrification driven by temperature fluctuations.

Bio-denitrification is vital in wastewater treatment plants (WWTPs), yet its integration with naturally abundant thermal energy remains unexplored. Here, we introduce a biohybrid-based pyroelectric bio-denitrification (BHPD) process that harnesses thermoelectric energy from ambient temperature fluctuations. By integrating Thiobacillus denitrificans with tungsten disulfide (WS), we develop a biohybrid system that achieves complete denitrification over three 5-day cycles under 5 °C temperature fluctuations. WS either precipitates on the cellular surface or is internalized by cells, generating pyroelectric charges that serve as reducing equivalents to drive bio-denitrification. In real wastewater, the BHPD process enhances nitrate removal by up to 8.09-fold under natural temperature fluctuations compared to stable-temperature conditions. Life-cycle assessment demonstrates that the BHPD process has significantly lower environmental impacts than the conventional anaerobic-anoxic-oxic process, and cost analysis confirms its economic feasibility. Our findings highlight the potential of the pyroelectric effect in enhancing bio-denitrification, offering valuable insights for a paradigm shift in WWTPs.