Semiconductor-assisted photofermentation system for terephthalic acid degradation and methane production

Abstract

The fermentation degradation approach of purified terephthalic acid wastewater remains a grand challenge, due to the low degradation efficiency of the refractory terephthalic acid (TA) compound. Here, photocatalytic semiconductors (g-C3N4 and its-derived composites) are introduced to the anaerobic reactor to construct a semiconductor-assisted photofermentation system that enables to intensify the electron transfer process, in turn enhancing the overall TA degradation performances. Specifically, the g–C3N4–added group exhibits significantly improved methane production efficiency and TA degradation rate, increasing by 67.7 % and 36.1 %, respectively. Mechanisms reveal that such enhanced TA degradation is contributed from the key direct-interspecies-electron-transfer (DIET) process (that is intensified by the produced photogenic electrons) and the photocatalytic degradation process (that is amplified by the generated photogenic holes and hydroxyl radicals capable of efficiently oxidizing TA to simple organic matters). This study underscores the importance and high-efficiency of simply constructing semiconductor-assisted photofermentation systems for TA wastewater treatments, which can be implemented to harness other types of recalcitrant compounds-contained wastewaters.