Integrating Microalgae Cultivation with Wastewater Treatment: a Peek into Economics

Microalgae cultivation on wastewater is one of the most promising processes in perspective of green and circular economy. This study investigated the economics of integrating the microalgae cultivation with the wastewater treatment in perspective of biomass production and wastewater treatment. The cost of integrated process was evaluated for six cases: three cases for domestic wastewater at different stages of treatment including sewage, anaerobically digested domestic effluent, and centrate and three cases for industrial wastewater including agro-industrial wastewater, anaerobically digested piggery effluent, and anaerobically digested abattoir effluent. The cost of biomass production was found ranging from $ 0.39 to $ 0.92/kg with minimum for the anaerobically digested domestic effluent and centrate. The cost of wastewater treatment was found ranging from 0.18 to 1.69/m³ with minimum for the sewage. These costs did not include any credits generated from the biomass or the treated wastewater. The concentration of limiting nutrient, flowrate of wastewater, and the extent of nutrient removal are the major cost-influencing parameters for the integrated process.