Enhancing Growth, Biochemical Composition, and Pigment Production in Spirulina platensis using Sugar Mill Effluent-supplemented Zarrouk’s Medium

Abstract

Spirulina platensis, a cyanobacterium used in food and health products, faces high cultivation costs due to synthetic media requirements. This study explores the use of sugar mill effluent (SME) as a supplement to Zarrouk's medium, aiming to lower production costs and aid in pollutant removal from wastewater. Physicochemical and nutritional aspects of SME were investigated. Spirulina platensis (NCIM 5143) was cultivated in Zarrouk’s medium supplemented with 50-100 mL/L of SME for 20 days. Studies were performed on biomass, biochemical composition, pigments, oxidative stress, heavy metals, and phycoremediation efficiency. SME was nutrient-rich, containing 245 mg/L N, 28.5 mg/L P, and 310 mg/L K+. Growth increased significantly with SME concentration (p < 0.05), with SP4 producing maximum biomass, protein, pigments, and phycocyanin. Heavy metals remained within permissible limits, while COD and BOD removal reached 58.3% and 62.1%, respectively. SME enhancement increased the biomass and biochemical composition of Spirulina by providing it with organic carbon and essential nutrients, which provided a cheaper option compared to the conventional Zarrouk’s medium. Elevated malondialdehyde and antioxidant pigments indicated increased oxidative stress. Moreover, Spirulina production allowed for sustainable pollutant disposal through SME reuse. Sugar mill effluent supplementation (100 mL/L) significantly improved the growth and biomass productivity of Spirulina platensis, while also enhancing pigment synthesis and achieving effective phycoremediation, resulting in 62% BOD and 58% COD removal. This method enables sustainable, cost-effective cultivation, reduces pollution, and produces safe biomass.