TWO-STAGE CULTIVATION OF MICROALGAE C. Vulgaris FOR TANNERY INDUSTRIAL EFFLUENT TREATMENT: STRAIN VERIFICATION, GROWTH PERFORMANCE, POLLUTANT REMOVAL, AND FAME CHARACTERIZATION

Tannery industrial effluent (TIE) contains high levels of organic matter, nitrogen, and dissolved solids, which can challenge the ability of conventional biological treatment to consistently achieve regulatory compliance. This study evaluated a two-stage cultivation system using Chlorella vulgaris (C. vulgaris) with centrifuged TIE at three C. vulgaris concentrations (CVG 10%, CVG 20%, and CVG 30%). The study evaluated pollutant removal, microalgal growth, molecular and morphological strain identification, and fatty acid methyl ester (FAME) characterization. The operational performance of the existing full-scale activated sludge (AS) system was also used as a practical benchmark to provide context for the laboratory-scale treatment. Among the tested conditions, CVG 30% exhibited the highest treatment performance, achieving removal efficiencies of 92.94±1.40% for BOD5, 91.60±0.16% for COD, 99.80±0.07% for ammonia, and 58.40±5.05% for TDS. Final BOD5, COD, and ammonia concentrations complied with regulatory discharge standards, whereas TDS remained above the permissible limit, indicating the need for additional polishing treatment. FAME analysis of the harvested biomass from the best-performing condition (CVG 30%) showed a fatty acid profile dominated by methyl linoleate (C18:2), methyl cis-11-eicosenoate (C20:1), and methyl palmitate (C16:0). Overall, two-stage C. vulgaris cultivation demonstrated potential for use as a complementary biological treatment approach for tannery wastewater, while FAME characterization provided insights into the fatty acid composition of biomass from the best-performing condition.