Microalga Chlorella sp. in the cultivation with chicken farm biogas fermenter effluent and simultaneously nutrient removal

Abstract

The aim of the present study is to grow microalgae to remove CO2 from a stripping column as well as macronutrients from a biogas digester effluent. In mixotrophic conditions, non-sterilized and sterilized chicken farm biogas effluents were used to cultivate Chlorella sp. Endogenous bacteria in the wastewater had no effect on the rate of algal growth. Continuous experiments by feeding wastewater at COD loadings of 1.89–6.30 kg COD/m3/day were also conducted. The CO2 removal efficiency was in the range of 13–39%. Chlorella sp. showed the nutrient removal efficiency of COD, TN, and TP was 44%, 30%, and 54%, respectively. CO2-rich off-gas from a biogas upgrading system’s stripping column can be used to boost algal growth in biogas digester effluent. The CO2 can be extracted in part, but the wastewater can be treated simultaneously. Consequently, this study established that an integrated system is economically viable.