An environmentally sustainable process for remediation of phenol polluted wastewater and simultaneous clean energy generation as by-product

Abstract

The study reports a novel algal system for biofuel production coupled to phenol remediation. High-performance liquid chromatography analysis shows phenol-acclimatized Chlorella pyrenoidosa completely degrades high phenol concentrations of 50–1200 mg/l. The ability of C. pyrenoidosa to efficiently grow on high phenol concentrations was endorsed by its high growth kinetic parameters of Ks (400.54 mg/l) and KI (800.41 mg/l). An enhanced growth rate of 0.072 h−1 was obtained by utilizing optimized physical parameters of biomass concentration (200 mg/l), photoperiodicity (14 h light: 10 h dark) and pH 7. Preadaptation of C. pyrenoidosa to target phenol concentration before actual application for phenol treatment is proposed as a strategy for eliminating lag phase and thus faster growth (0.078 h−1) and degradation (0.561 h−1) rates. Preadaptation further increases µmax (0.22 h−1), Ks (500.54 mg/l) and KI (900.41 mg/l) enhancing efficiency for growth on high phenol concentrations. The practical applicability of C. pyrenoidosa for phenol contaminated wastewater remediation was proved by its ability to completely degrade 10 and 250 mg/l phenol in petroleum refinery wastewater. Phenol stress induced total and neutral lipid production in algal biomass qualifying the spent biomass as a promising source for biodiesel production. Additionally, the residual biomass after lipid extraction served as substrate for bioethanol fermentation adding to efficiency of the process for biofuel applications. These findings suggest an environmentally sustainable process for treatment of phenol pollution and clean energy production which is the need of the hour. The developed process has been covered by an applied patent.