Wastewater denitrification driven by mechanical energy through cellular piezo-sensitization

Abstract

Mechanical energy as a main energy form in wastewater treatment plants is generally used to enhance the physical mixing of reactor compartments. However, utilizing mechanical energy for directly driving microbial metabolism has not been explored. Here we developed an innovative mechano-driven bio-denitrification approach, whereby the electronic energy produced from mechanical energy by piezoelectric materials supported the metabolism of denitrifying microorganisms. When autotrophic denitrifying bacterium Thiobacillus denitrificans was stimulated with in situ formed struvite under mechanical agitation, a powerful cellular piezo-sensitization enabled nearly 100% nitrate reduction in synthetic wastewater with H2O as the electron donor. Such a self-sustained bio-denitrification process powered by mechanical energy was successfully implemented in real wastewater treatment, resulting in a maximum 117% increase of nitrate removal. These findings introduce a new paradigm for wastewater denitrification, unveiling previously unappreciated mechanisms for the energy–microbe–element nexus during wastewater treatment, and offer crucial insights for optimizing wastewater treatment plant operation. The use of mechanical energy in wastewater treatment has been associated with accelerating physical mixing in compartments, and its effect on microbial activities has not been explored. The implementation of the developed mechano-driven bio-denitrification approach in real wastewater treatment provides a new method for wastewater denitrification.