Treatment and recycle of harvested microalgal effluent using powdered activated carbon for reducing water footprint and enhancing biofuel production under a biorefinery model

Abstract

In this study, the suitability of cultivating Monoraphidium sp. KMC4 was exhibited in different effluent based culture (EBC) media concentrations, the latter being treated with powdered activated carbon (PAC) with a loading of 5–50 mg L-1. The optimum EBC media treated with 30 mg L-1 PAC enhanced the biomass yield by 21.9% as compared to the untreated one (1.21 g L-1). A recyclability study performed in five batches resulted in an optimal growth up to three batches with an overall biomass yield of 4.21 g and a total water savings of 30%. Additionally, physico-chemical characterization and FAME profile of the biomass from the recyclability study validated feedstock's energy potential. Moreover, this study proposes a biorefinery model which could recover nutrient rich liquid effluent (3.1 million litres) and solid residue for various applications along with the generation of 5760 kg of biomass followed by 113 L d-1 biodiesel yield.