MICROALGAE BASED PHYCOREMEDIATION OF DAIRY WASTEWATER FOR CIRCULAR BIOECONOMY: OPPORTUNITIES, CHALLENGES AND IMPLEMENTATION STRATEGIES: Microalgal Phycoremediation of Dairy Wastewater

Abstract

India is the world's largest milk producer (≈239.3 million tonnes per year (2023-24 and its fast-growing
milk industry produces an estimated 275 million litres of high-strength wastewater each day with high
nutrients and residual fats. Oleaginous microalgae such as Chlorella, Scenedesmus, Spirulina and
Desmodesmus have been found to be a biologically sound, low carbon and resource-recovering
alternative as they are able to incorporate N, P and CO2 from dairy effluent and accumulate
triacylglycerols which can be trans-esterified to biodiesel (FAME). It is seen that under tropical
conditions, the Indian-isolated strains can remove >90% of the nutrients and can contain 30–50% lipids
resulting in biodiesel yield of 250–360 L/ton biomass. This review i) specifically targets the unique
requirements of India's dairy industry; ii) proposes a decentralized biorefinery configuration specifically
aligned with GOBARdhan, SATAT and existing ETPs; iii) incorporates the techno-economic and life-
cycle considerations under Indian context; and iv) provides a policy and implementation roadmap with
steps that can be taken. The review concludes that if anchored in the Indian cooperative infrastructure
and policy framework, microalgal biorefineries can be able to transform the dairies effluent from an
environmental liability to clean water, renewable fuel, soil amendment and rural livelihood.