Flashing light alleviates photoinhibition and promotes biomass concentration in purple non– sulfur bacteria wastewater treatment

Abstract

High light is beneficial for purple non-sulfur bacteria (PNSB) growth. However, excessive light causes photoinhibition. In this novel study, flashing light was used to alleviate photoinhibition and promote biomass growth in PNSB wastewater treatment. Results showed that flashing light effectively increased biomass production. The highest biomass concentration (2688.8 mg/L) and chemical oxygen demand removal (in 177 μmol/m2/s-0.75 duty cycle-1000 Hz group) were 41.5% and 28.4% higher than that in the constant stress light group (same incident light). This group also increased biomass concentration by 21.3% and reduced energy consumption by 26.2% compared with the constant normal light group (same energy input). The shortened single light provision time of flashing light increased the relative electron transportation rate by 116.6%, avoiding photoinhibition, promoting energy utilisation, and enhancing substance synthesis. Flashing light can be used as a light regulation strategy to enhance biomass accumulation and reduce energy consumption in PNSB-based industries.