Sustainable Microalgal Harvesting Process Applying Opuntia cochenillifera: Process Parameters Optimization

Microalgae harvesting by coagulation can use coagulant agents such as alum, synthetic polymers or biocoagulants. Biocoagulants have attracted the attention of researchers because they are natural, biodegradable, and promote high microalgal harvesting efficiencies. This study aims to optimize the harvesting of Chlorella vulgaris based on the dosage of the Opuntia cochenillifera extract and the choice of eluent for biopolymer extraction. The outdoor cultivation of C. vulgaris achieved a specific growth rate of 0.455 d(-1) and a maximum biomass concentration of 1.28 g(DW) L-1. In order to harvest the microalgal biomass, the polymer present in the mucilage of O. cochenillifera was extracted using NaOH and HCl. Coagulation and sedimentation assays were performed with different coagulant dosages: 3.5, 5.9, and 8.2 g L-1. The maximum harvesting efficiencies using the acid and alkaline extract coagulant solutions were 80.8% and 99.5%, respectively, with a dosage of 3.5 g L-1. According to the results, the C. vulgaris biomass can be harvested with the mucilage from O. cochenillifera in acid and alkaline eluents. The application of this biocoagulant constitutes a sustainable solution for microalgal harvesting.

Automated summary

Microalgae can be harvested using coagulant agents, with biocoagulants being a natural and biodegradable option that promotes efficient harvesting. This study focused on optimizing the harvesting of Chlorella vulgaris using Opuntia cochenillifera extract and different eluents for biopolymer extraction. The results showed that the microalgal biomass can be effectively harvested using mucilage from O. cochenillifera in acid and alkaline solutions, with high harvesting efficiencies achieved.