Harvesting of microalgae (Chlorella sp.) from aquaculture bioflocs using an environmental-friendly chitosan-based bio-coagulant

Aquaculture bioflocs is an agglomeration of organic matter and microorganisms in the aquaculture system. The bioflocs is capable of controlling water quality through absorption of undesirable nutrients in wastewater. It also contains microalgae such as Chlorella sp. that can be harvested for use in aquaculture applications. Nevertheless, the current harvesting technologies are based on chemicals or expensive membrane filtration. This study investigated the utilization of chitosan as a natural bio-coagulant to harvest Chlorella sp. with an emphasis on the coagulation-flocculation efficiency. The optimum dosage of chitosan at 30 mgL−1 achieved 98% of microalgae removal efficiency and 80% of biomass recovery. The treated water was safe within a neutral pH level with less than 5 NTU of turbidity. The results show that chitosan can be an alternative and environmental-friendly bio-coagulant for microalgae harvesting.