A Smart Integrated Biorefinery Approach for Greywater Treatment and Microalgal Biomass Production: A Review

In recent decades, microalgae have been increasingly used to generate healthy food supplements and high-value products such as polyunsaturated fatty acids, pigments, and bioactive compounds. They are also being used for bioremediation of agro-industrial wastewater and as a source of energy-rich biofuels. This article provides a critical review of the available state-of-the-art for understanding the possibility of integrated greywater treatment and microalgal lipid and other energy/non-energy resource production. Integrated greywater management through microalgae cultivation is gaining attention due to its sustainability and eco-friendliness. Greywater is mainly generated from household activities and contains fewer suspended solids than normal wastewater. Microalgal biomass produced using greywater has been found to be useful for extraction of energy-rich materials and other products like bioplastics, biofertilizers, and biofuels. For example, extracted lipid can be used to generate biodiesel. Integration of all these techniques would provide an amazing greywater management plan that would produce clean water and lipid- and other essential biomolecules-rich microalgal biomass for high-value product production. However, the major constraints to industrial application of this approach include finding the most promising microalgal strains, changes in the overall composition of greywater, large capital expenditure costs, complex downstream processing, and uncertainties associated with stable revenue generation.