Reverse osmosis concentrate conditioning for microalgae cultivation and a generalized workflow

Previous studies have demonstrated the feasibility of using wastewater as the nutrient source for microalgae cultivation. However, there is still a lack of guidance in wastewater conditioning to achieve optimum microalgae growth rate and complete N and P consumption in wastewater. In this study, a reverse osmosis concentrate (ROC) from the wastewater treatment unit of a dyeing company had been evaluated and conditioned for the phototrophic cultivation of Chlorella sp., with its toxicity, nutrient profile, salinity, pH and N/P ratio adjusted where necessary. After the wastewater was conditioned, Chlorella sp., which could not grow in the original ROC, achieved a growth rate comparable to that in an artificial medium. The percentages of N and P consumption were also balanced so that the nutrient utilization efficiency could be maximized. A generalized workflow and guidelines to develop wastewater conditioning plans for microalgae cultivation have also been proposed to guide the conditioning of wastewater streams for microalgae cultivation.