ALGACEL

Knowledge

Harvesting and processing of microalgae biomass

Harvesting separates microalgae from the culture water: a key and costly step due to their small size and low concentration. Once concentrated, they are dried and, depending on the product, the cells are disrupted to extract the compounds of interest.

Harvesting methods

Because microalgae are microscopic and the culture is very dilute, separating them from the water is one of the most costly steps of the process. Common methods are centrifugation, flocculation (aggregating cells so they settle), gravity sedimentation and membrane filtration.

The choice depends on species, scale and cost: centrifugation is effective but energy-intensive, while flocculation can lower the cost of pre-concentration.

Dewatering and drying

After concentrating the biomass, the remaining water is removed by drying, which stabilises the product and extends its shelf life. Techniques such as spray drying, freeze-drying (lyophilisation) or solar drying are used.

The drying method affects the final quality: gentle processes better preserve pigments and sensitive compounds, while harsher ones can degrade them.

Cell disruption and extraction

To obtain specific compounds —pigments, lipids or proteins— it is often necessary to break the cell wall or membrane and release the content. Mechanical, enzymatic or physical methods are used depending on the compound.

This downstream processing is key to the final product value, and research seeks to make it more efficient and gentler on the activity of the target molecules.

FAQ

By separating them from the culture water through centrifugation, flocculation, sedimentation or membrane filtration, depending on species, scale and cost.

Because they are microscopic and the culture is very dilute, so concentrating the biomass requires a lot of energy or extra processes; it is one of the sector's biggest cost challenges.

Sources

  1. Richmond, A. & Hu, Q. (eds.) (2013). Handbook of Microalgal Culture: Applied Phycology and Biotechnology. Wiley-Blackwell.
  2. Chisti, Y. (2007). Biodiesel from microalgae. Biotechnology Advances, 25(3), 294–306.
  3. Spolaore, P. et al. (2006). Commercial applications of microalgae. Journal of Bioscience and Bioengineering, 101(2), 87–96.
  4. Mata, T.M. et al. (2010). Microalgae for biodiesel production and other applications: A review. Renewable and Sustainable Energy Reviews, 14(1), 217–232.

Scientific outreach based on specialised literature. Scientific review: pending.

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