Abstract:Heparin sodium production wastewater (HSW) is rich in nutrients, making it a potential culture medium for microalgae. To explore its feasibility for microalgal cultivation, three strains of Chlorella sorokiniana (GT1, XY3-3, and CMBB276) were cultured in HSW at varying volume fractions (10%~40%), and Chlorella sorokiniana CMBB276 with high tolerance to HSW was screened. To determine the optimal volume fraction of wastewater, the author investigated the removal processes of nutrients, along with the variations in biochemical composition and calorific value, during the growth of the strain CMBB276 in HSW at different volume fractions. Results demonstrated that as the wastewater volume fraction increased, the maximum cell density, total nitrogen (TN) removal efficiency, mass fractions of carbohydrates and fatty acids, and protein productivity of CMBB276 gradually decreased, while the total organic carbon (TOC) and TN removal rates and protein mass fraction gradually increased. The TOC removal efficiency and calorific value remained relatively unchanged. The optimal wastewater volume fraction was determined to be 20%. At the end of cultivation, the cell density of CMBB276 was 6.4×107 cells/mL, with TOC and TN removal efficiencies of 83.3% and 63.0%, respectively. The mass fraction and productivity of protein was 52.5% and 22.22 mg/(L·d), respectively, with a calorific value of 20.37 MJ/kg. Therefore, cultivating C. sorokiniana in HSW at an appropriate volume fraction can efficiently remove TOC and TN from the wastewater, while the cultured CMBB276 strain, characterized by its high protein content and calorific value, holds significant potential for resource utilization.
