Assessment of municipal wastewaters at various stages of treatment process as potential growth media for Chlorella sorokiniana under different modes of cultivation

Abstract

Wastewater utilization for microalgal biomass production is potentially the most economical route for its fuel and feed applications. In this study, suitability of various wastewater streams within a domestic wastewater treatment plant was evaluated for microalgal cultivation. Pre-treatment methods were evaluated to minimize bacterial load. Biomass, cell physiology, nutrient removal efficiencies and biochemical constituents of Chlorella sorokiniana were investigated in influent (INF) and anaerobic tank centrate (AC) under mixotrophic (Mixo) and heterotrophic (Hetero) cultivation. Promising biomass (77.14mgL^-1d^-1), lipid (24.91mgL^-1d^-1), protein (22.36mgL^-1d^-1) and carbohydrate (20.10mgL^-1d^-1) productivities were observed in Mixo AC with efficient ammonium (94.29%) and phosphate (83.30%) removal. Supplementation of urea at a concentration of 1500mgL^-1 further enhanced biomass (162.50mgL^-1d^-1), lipid (24.91mgL^-1d^-1), protein (22.36mgL^-1d^-1) and carbohydrate (20.10mgL^-1d^-1) productivities in Mixo AC. Urea supplemented mixotrophic cultivation of microalgae in AC is developed as a biomass production strategy.

Keywords: Biomass; Heterotrophic; Microalgae; Mixotrophic; Wastewater.