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The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective way is a promising approach. Herein, we grew two green microalgal species, Chlorella sorokinianaand Scenedesmus acuminatus,in media contaminated with Cu2+(3.2 ppm) or Zn2+(65.4 ppm) to investigate their growth and full metabolic profile. Furthermore, to integrate the potential economic impact of biodiesel production with heavy metals removal efficiencies. Although acute exposure to heavy metals, on the other hand, reduced growth and increased removal efficiencies of Cu2+(59.4, 98.1%) and Zn2+(72.4, 98.2%) in C. sorokinianaand S. acuminatus, respectively. Besides, Cu2+and Zn2+increased primary metabolites, particularly lipids (49, 47% in S. acuminatus, 27, 26% in C. sorokiniana), with a significant induction in the unsaturation levels. Indicating that C. sorokinianaand S. acuminatusare excellent phycoremediators for industrial drainage and future sustainable algal-biofuels platform. Economic assessment of daily 1000-tonne biodiesel production from S. acuminatusgrown on highly polluted wastewater via Na4SiO4transesterification catalysis has all been assessed with an accuracy of ± 10% for the price of the diesel of US$ 1000/tonne and for the cost of the evaluated algal biomass of US$ 430/tonne. The daily 1000 T algal diesel business was viable, with a return on high investment (16.4%) and a payback period of 5 years. According to break-even and sensitivity analyses, the algal diesel cost that makes this business viable should be greater than US$ 147/barrel, while the biomass cost should not exceed US$ 462/tonne. Brent Crude Oil Spot exceeds US$ 95/barrel indicating promising prospects for algal fuel industrialization. Furthermore, the protein and amino acids-based waste biomass may serve as a sustainable biorefienry platform for various biofuel industries through biomass conversion technologies.

Propiconazole (PCZ), a triazole broad spectrum fungicide has been frequently detected in agricultural water webs. This emerging contaminant imposes a serious toxic impact on soil and aquatic microbiota. Thus, we aimed to investigate the potential of the microalgae as PCZ phycoremediator. To this end, its toxicity, degradation and detoxification mechanisms by Scenedesmus obliquusand Nostoc muscorumwere studied. Over a week, both species were exposed to mild (5 mg/L) and high (10 mg/L) PCZ concentrations. Results showed a dose-dependent accumulation of PCZ typically higher in S. obliquusthan in N. muscorum.Moreover, S. obliquusdegraded PCZ into a less toxic environmental product; 1-[2-(2,4-dichlorophenyl)− 4-(hydroxypropyl)− 1,3-dioxolan-2ylmethyl]− 1,2,4-triazole and 1-(2,4-dichlorophenyl)− 2-(1,2,4-triazol-1-yl) ethanone. The metabolic pathway assumed cellular dehydroxylation and side chain breakdown in S. obliquus. The high PCZ dose significantly decreased cell growth, chlorophyll acontent and inhibited photosynthesis activity and machinery (PEPC and RuBisCo) in both species but, to lesser extend in S. obliquus. Additionally, the exposure to high concentration of PCZ caused a serious oxidative damage especially in N. muscorum. This damage is evident by increased lipid peroxidation, H2O2level, protein oxidation and NADPH oxidase activity. The two species experienced differential antioxidant and detoxification mechanisms using glutathione-S-transferases, phytochelatins and metalothionine to alleviate PCZ-oxidative stress. This study represented S. obliquusas an efficient PCZ phycoremediator and provided new data on the PCZ toxicity, environmental fate and risk of PCZ to aquatic environment.