Implication of municipal wastewater on growth kinetics, biochemical profile, and defense system of Chlorella vulgaris and Scenedesmus vacuolatus

Abstract

In the present investigation, the growth pattern, cellular modification, oxidative stress markers, and defense responses in Chlorella vulgaris and Scenedesmus vacuolatus were analyzed after treatment with municipal wastewater (25%–100%). The main aim was to compare the Chlorella vulgaris and Scenedesmus vacuolatus on account of remediation efficiency, lipid production and defense responses under different concentrations of wastewater. The results revealed that the nutrients (93.28%) and heavy metal (92.08%) removal was highest at 25% of wastewater concentration while maximum specific growth rate (0.0708 day−1), total chlorophyll (0.118 mg g−1 fw), and carbohydrate content (24.06 mg L−1 fw) was observed with Scenedesmus vacuolatus at 50% concentration of wastewater. Additionally, fourier transform infrared spectroscopy showed 100% concentration of wastewater enhanced lipid accumulation in Scenedesmus vacuolatus than Chlorella vulgaris. The lesser accumulation of thiobarbituric acid reactive species and hydrogen peroxide while increment in antioxidants activity (1.87–15.63 folds) may be responsible for imparting tolerance to Scenedesmus vacuolatus against different concentrations of municipal wastewater. Overall, the study revealed that 50% and 100% wastewater concentration was suitable for excellent growth and lipid accumulation in Scenedesmus vacuolatus, respectively. Thus, due to high nutrients reutilization potential, metal removal rate, growth profile, lipid production, and anti-oxidative responses, Scenedesmus vacuolatus seems more effective and tolerant than Chlorella vulgaris. Therefore, exploiting Scenedesmus vacuolatus may be the successful step towards sustainable management of wastewater and lipid production.