Performance assessment of biofuel production in an algae-based remediation system

•Cultivation of Chlorella sp. and Nannochloropsis sp. in fish water is demonstrated.•Chlorella sp. removes 98% ammonia and 66% nitrate in fish water with lipid productivity of 1.1 mg L−1 h−1.•Nannochloropsis sp. removes 75% ammonia in fish water with lipid productivity of 1.3 mg L−1 h−1.•Obtained fatty acids are suitable for biodiesel production.

The production of biofuel from microalgae has been an area of great interest as microalgae have higher productivities than land plants, and certain species have high lipid constituents which are the major feedstock for biodiesel production. One way to enhance the economic feasibility of algal-based biofuel is to couple it with waste remediation. This study investigated the technical feasibility of cultivating Chlorella sp. and Nannochloropsis sp. with fish water for biofuel production. The remediation potential of Chlorella sp. was found to be higher but the lipid yield is lower, when compared to Nannochloropsis sp. Lipid productivities were found to be similar for both types of algae at 1.1–1.3 mg L−1 h−1. The fatty acid profiles of the obtained lipids were found suitable for biofuel production, and the calorific values were high at 30–32 MJ/kg. The results provide insights into lipid production in Chlorella sp. and Nannochloropsis sp., when coupled with waste remediation.