Coupling nutrient removal and biodiesel production by cultivation of Chlorella sp. in cafeteria wastewater: assessment of the effect of wastewater disinfection

Abstract

Cultivation of microalgae using wastewater as nutrient resource is a promising strategy to reduce the microalgae biodiesel production cost and increase nutrient recovery in one step. However, the inhibitive effect of indigenous bacteria on microalgae could negatively affect microalgal growth. Thus, in this study, the effect of wastewater disinfection methods on the growth and biochemical composition of Chlorella sp. and the nutrient removal efficiency in cafeteria wastewater was eval- uated. Results showed a significant increase in the microalgal density and a reduction in bacterial abundance in the disinfected wastewater. Moreover, chemical oxygen demand removal ranging from 83.53%–87.16% was achieved in 15-d incubation and complete removal of total nitrogen and total phosphorus was achieved after 6 d of incubation. The total carbohydrate, protein and fatty acid contents in the harvested biomass were 128.49–139.33, 43.24–56.14 and 17.34–23.58 mg·g –1 on dry weight basis, respectively. Palmitic acid, palmitoleic acid, stearic acid and oleic acid accounted for more than 90% of the total fatty acids in the biomass, indicating great potential as an alternative feedstock for biodiesel production. This study provides a simple and efficient disinfection strategy to enhance Chlorella sp. growth and biomass production for biodiesel production.