Nutrient removal from pickle industry wastewater by cultivation of Chlorella pyrenoidosa for lipid production

Abstract

The present research examined the feasibility of cultivating Chlorella pyrenoidosa in pickle industry wastewater for simultaneous nutrient removal and lipid production. The characteristics of microalgae growth, nutrient removal, lipid accumulation and composition of C. pyrenoidosa cultivated in pickle wastewater with different dilution ratios were investigated. The results showed the maximum algae biomass concentration of 1.57 ± 0.12 g L-1 was achieved in non-diluted pickle wastewater with the highest biomass productivity of 170.65 mg L-1 day-1. Maximum nutrient removal efficiency was observed in 20.0% pickle wastewater with removal rates of chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN) and NH4-N at 84.67%, 92.46%, 85.82% and 93.42%, respectively. The lipid content of C. pyrenoidosa growing in pickle wastewater ranged from 29.73% to 31.78%, with a highest lipid productivity of 57.23 mg L-1 day-1. The relative content of triolefinic acids (C16:3 and C18:3) decreased while the monoenoic acids (C16:1 and C18:1) increased synchronously with the pickle wastewater concentration. Unsaturated fatty acid methyl esters were the main components, ranging from 73.04% to 77.6%. The biodiesel properties satisfied the major specifications in US and European biodiesel standards. The results indicated that C. pyrenoidosa is a promising species for nutrient removal together with lipid production in pickle industry wastewater.