Degradation of organic pollutant by natural biofilm based biophotovoltaic cells: The combined role of illumination, reactive oxygen species, and enhanced electron transfer

Abstract

Autotrophic biofilms in natural water can produce reactive oxygen species (ROS) and degrade organic pollutants. To test the feasibility of applying natural biofilms in biophotovoltaic (BPV) cells, a simple single-chamber BPV using biofilms developed in lake water as the microbial anode was constructed, and electricity production and pollutant removal capacity of the BPV were evaluated. The natural biofilm BPV (NB-BPV) established was a robust and self-sustaining BPV with positive light response in electricity generation and sustainable power generation in the dark. Under visible light illumination, the voltage of the NB-BPV reached a maximum output of 150.6 ± 0.7 mV, with a power density of 326.4 μW/m² (per electrode surface area). Meanwhile, it could effectively degrade sodium dodecylbenzene sulfonate (DBS), while generating electricity, and the removal rate of DBS and TOC in 36 h was 77.1 % and 53.2 %, respectively. Under sunlight, NB-BPV could also produce electricity steadily in lake and the removal rate of DBS in simulated lake water was 93.7 % (120 h). Visible light significantly affected the performance of NB-BPV mainly through photosynthesis. Photosynthesis of biofilm promoted electricity generation and significantly enhanced the degradation of DBS by promoting electron transfer activity and generating ROS. Compared with biofilm system, the closed-circuit in NB-BPV promoted electron transfer, allowing more efficient degradation of DBS at relatively low level of ROS. Such a novel self-sustainable BPV has the potential to degrade refractory pollutants, and to be used in natural water.