Bioremediation of dairy industry wastewater and assessment of nutrient removal potential of Chlorella vulgaris.

The expanding urbanization and industrialization lead to a large amount of wastewater discharge that is toxic and harmful to the environment. In particular, the discharge from dairy industries has chemical oxygen demand (COD) up to 95,000 mg/L and other pollutants that exceed the standard limit and are hazardous. Wastewater can be treated efficiently using microalgae which reduces the pollutants and also yields higher biomass that is further processed to produce various value-added products. This study investigated the effect of Chlorella vulgaris in treating wastewater collected from the dairy industry. Three different growth mediums, such as modified CHU-10, Bold Basal, and BG-11 (Blue Green-11), were tested for algal growth. Since the turbidity of wastewater was high, the dairy wastewater was diluted with distilled water at various concentrations of 100% (pure), 75%, 50%, and 25%. Chlorella vulgaris showed a promising result when grown in dairy wastewater, with a maximum biomass concentration of 2.43 g/L and maximum biomass productivity of 225 g/L/day. Overall, the bioremediation results revealed that the maximum removal efficiency was 81.48% (COD), 87.70% (total nitrogen-TN), and 93.5% (total phosphorus-TP). The lipid composition consists largely of c16:0 (hexadecanoic acid), c18:2 (linoleic acid), and c18:3 (linolenic acid), which shows the obtained FAME (fatty acid methyl esters) has suitable properties for biodiesel production. The Michaelis–Menten model was used for the batch kinetic studies, the kinetic coefficients of total nitrogen, and total phosphorus removal were determined for total nitrogen kinetic coefficients (k_m) = 198.77 mg/L, saturation constant (k) = 0.025 mg TN/mg biomass day, and R² = 0.9547 and for total phosphorus removal as k_m = 668.09 mg/L, k = 0.17 mg TP/mg biomass day, and R² = 0.9947. These results showed that the C. vulgaris is a suitable microalga that can grow in high turbidity DWW resulting in pollutant removal, higher biomass, and reducing the environmental impact caused by wastewater. [ABSTRACT FROM AUTHOR]