Microalgae based biofertilizers: A biorefinery approach to phycoremediate wastewater and harvest biodiesel and manure

Abstract

The most important requirement of the agrarian advancement is resilient nutrient source for agriculture without jeopardizing the environmental assets and economy of the country. An algal biorefinery approach is the prime requirement for the sustainable production of biodiesel and biofertilizers after remediation of wastewater. In the present study, the microalgae Chlorella minutissima, Scendesmus spp and Nostoc muscorum and their consortium were used for the biorefinery approach. C. minutissima has shown maximum phycoremediation potential when compared to other possible microalga and their consortium. Experimental results showed that removal of NH4+-N, NO3−-N, PO4−3-P, TDS, BOD5 and COD were found to be 92, 87, 85, 96, 90 and 81% respectively. The maximum dry biomass was observed in C. minutissima followed by Scendesmus spp, and N. muscorum, i.e., 0.45 ± 0.01 g L−1, 0.44 ± 0.02 g L−1, 0.14 ± 0.03 g L−1 respectively. The nutrient fraction of nitrogen and phosphorus were maximum in C. minutissima, i.e., 5.46 ± 0.27 and 0.85 ± 0.03 respectively. The lipid productivity recorded maximum in Scendesmus (81.23 ± 4.5 mg L−1) followed by N. muscorum (14.29 ± 8.7 mg L−1) and C. minutissima (11.33 ± 5.6 mg L−1). Using this biomass as manure one can save the chemical fertilizer of worth about 5584 $ (US Dollar) ha−1 yr−1. The present study not only supports the sustainable phytoremediation, biodiesel production, and organic manure utilization directly but indirectly to combat climate change scenario through minimizing greenhouse gases production.