Ultrahigh recovery rate of nitrate from synthetic wastewater by Chlorella-based photo-fermentation with optimal light-emitting diode illumination: From laboratory to pilot plant

Abstract

To achieve ultrahigh recovery rate of nitrate from synthetic wastewater by Chlorella pyrenoidosa-based photo-fermentation, light-emitting diode (LED) spectrum was firstly evaluated in 5-L glass photo-fermenter with surrounding LED panels. Results showed that warm white LED was favorable to improve biomass yield and recovery rate of nutrients than mixed white LED. When scaling up from laboratory (50-L, 500-L) to pilot scale photo-fermenter with inner LED panels, the maximum recovery rates of NO3- (5.77 g L-1 d-1) and PO43- (0.44 g L-1 d-1) were achieved in 10,000-L photo-fermenter, along with high productivity of biomass (11.06 g L-1 d-1), protein (3.95 g L-1 d-1) and lipids (3.79 g L-1 d-1), respectively. This study demonstrated that photo-fermenter with inner warm white LED illumination is a superhigh-efficient system for nitrate and phosphate recovery with algal biomass coproduction, providing a promising application in pilot demonstration of wastewater bioremediation and facilitating novel facility development for green manufacturing.