Nutrient Removal and Lipid Production Using Chlorella pyrenoidosa in Unsterilized Domestic Wastewater

Microalgae-based wastewater treatment is a prospective technology. This study used domestic wastewater as culture medium for Chlorella pyrenoidosa (C. pyrenoidosa) strain 15–2070 to evaluate its effectiveness in removing nutrients from domestic wastewater and its ability to produce lipid and other organic compounds. The results indicated that C. pyrenoidosa achieved removal efficiencies of 92.70% for TN, 95.51% for NH₄⁺-N, 100% for NO₂⁻-N, 100% for TP and 85.44% for COD in domestic wastewater. The contents of organic compounds were based on microalgal dry cell weight (DCW). C. pyrenoidosa cells produced pigment (chlorophyll a of 22.36 mg/g DCW, chlorophyll b of 8.18 mg/g DCW, carotenoid of 6.61 mg/g DCW), protein (255.56 mg/g DCW), carbohydrate (198.87 mg/g DCW), starch (33.61 mg/g DCW) and lipid (62.46%) in domestic wastewater. Lipid content (62.46%) of C. pyrenoidosa cultured in domestic wastewater was equivalent to that cultured in BG11 medium (63.10%). These results indicated that C. pyrenoidosa had certain potential in removing pollutants from domestic wastewater and producing microalgae lipid. This study provided a prospective strategy for resource utilization of domestic wastewater and the protection of freshwater resource.