Effects of organic matters in domestic wastewater on lipid/carbohydrate production and nutrient removal of Chlorella vulgaris cultivated under mixotrophic growth conditions

BACKGROUND The combination of wastewater treatment and algal biofuel production has received increasing attention in recent years owing to its many advantages. In order to clarify the influence of different organic pollutants such as carbohydrates, volatile fatty acids (VFAs) and proteins in domestic wastewater on the cultivation of Chlorella vulgaris, three simulated domestic sewages containing glucose, sodium acetate (NaAc) and protein respectively were prepared in this study to culture C. vulgaris in mixotrophic way. RESULTS The biomass productivities of C. vulgaris cultured in wastewaters containing glucose and NaAc were 63.5 and 55.2 mg L-1 day(-1) respectively, which were 2.61- and 2.27-fold larger than that achieved in photoautotrophic condition. Owing to the higher biomass productivity, better performance of nutrient removal was also achieved in wastewater containing glucose or NaAc. Different from glucose and NaAc, protein in the wastewater had no significant effect on C. vulgaris growth and nutrient removal. Chlorella vulgaris cultured in NaAc and glucose wastewaters achieved the highest lipid (17.35 mg L-1 day(-1)) and carbohydrate (18.75 mg L-1 day(-1)) productivities respectively, indicating that wastewater containing these two organic substances has certain advantages in microalgal liquid biofuel production. CONCLUSIONS Organic matters in wastewater have important effects on microalgae growth and the chemical composition of algal cells. Carbohydrates and VFAs in wastewater can significantly promote the growth of C. vulgaris and promote the accumulation of lipid by microalgae. (c) 2019 Society of Chemical Industry