A study from Sri Lanka shows a locally isolated Desmodesmus microalga can grow on cafeteria wastewater and clean it at the same time. The culture reduced chemical oxygen demand by about 76%, removed roughly 48% of total nitrogen and 38% of total phosphorus, and produced a biomass concentration of 0.65 grams per liter without synthetic nutrient inputs. Under higher light stress at 450 micromoles per square meter per second, lipid concentration rose from 0.31 to 0.53 grams per liter, a gain of about 70%. The estimated biodiesel properties from the extracted fatty acids met ASTM D6751-12 and European EN standards. The catch is scale: the work is lab-level, needs 75% effluent dilution, and does not cover harvesting or extraction costs. Still, coupling wastewater treatment with biofuel feedstock production is the practical angle worth following.
