In-Situ and Ex-Situ Phycoremediation Competence of Innate Scenedesmus Sp. On Polluted River Water

Abstract The present study was aimed to investigate the ex-situ and in-situ phycoremediation efficacy of native Scenedesmus sp. in polluted Thirumanimuthar River water sample. Based on the macroscopic and microscopic analysis the predominant microalgae culture from polluted water was identified as Scenedesmus sp. Most of the physicochemical parameters (EC: 3110.00 micro mho cm-1, turbidity: 17.10 mg L-1, total hardness: 812.00 mg L-1, BOD: 230 mg L-1, and COD: 352 mg L-1) and some minerals such as Ca: 232.00 mg L-1 and Sulfate: 532.00 mg L-1 were crossing the permissible limits. Among three sets of treatments (I, II, & III), 3% in ex-situ (treatment III), and 30% in in-situ (treatment III) were shown a better reduction in physicochemical properties of polluted river water in 14 days of treatment. The in-situ study has shown better pollutants reduction than ex-situ as it reduced BOD & COD 27.83% and 23.30%, respectively. Further, the chloride, sulphate, phosphate, sodium, calcium, and magnesium were reasonably reduced up to 40.00, 43.61, 31.03, 18.75, 70.26, and 33.93%, respectively. The FTIR analysis confirmed that the presence of pollutants absorbing functional groups in dried biomass of Scenedesmus sp. and the SEM analysis image confirmed the absorption of pollutants by resulting in morphology changes of Scenedesmus sp. The results concluded that a significant reduction was found in most tested physicochemical and minerals contents in the treated water through the in-situ study than the ex-situ approach. Through this sustainable phycoremediation strategy, the pollutant reducing Scenedesmus sp. could be used as feedstock for biofuel production.