03 09 2021

Grass2Algae – progress from the first half of the project!

Grass2Algae is an Operational Group funded by the Flemish Department of Agricultural and Fisheries with the aim of creating value from waste grass from farms, i.e., clippings from the edges of fields or with too low quality for feed purposes. For that, Grass2Algae proposes a first pressing step to separate the juice from the fibers. The fibers can then be used as an input for anaerobic digestion or be sold as a feedstock for the production of biomaterials. And the juice can be used for producing microalgae!

How to produce microalgae from grass juice?

Grass juice is an excellent source of nutrients, being rich in macro and micronutrients that are necessary for the growth of microalgae. Therefore, it can fully replace mineral fertilizers and result in an organically-grown algal biomass, increasing the sustainability of algae production. However, the grass juice is full of debris and contaminating organisms right after pressing, so a treatment is required before feeding it to the algae. In Grass2Algae, we are investigating a sequence of sedimentation, coarse filtration and pH adjustment to make the juice more suitable as a nutrient source for algal growth. And the algae seem to really like it! The even grew better than in the medium with mineral nutrients, which is used commercially.

What are the next steps?

The first thing that we still need to check is the quality of the produced biomass. We already received some results from microbial analysis and the algae product seems to be up to spec for food application, so the outcomes look promising! Another important investigation is if the quality of the grass affects the quality of the juice and the growth of the microalgae – this will be the subject of our September experiments, in which the grass juice obtained from clippings of three farms will be compared. Finally, we need to check if the process is economically attractive. For that, we are comparing different mowing equipment, pressing possibilities, algae cultivation configurations, end-use applications of the fibers and assessing if we can used the sediments from the juice for some application, creating further value in the process.


Then come to our workshop (in Dutch) on October 19th at 14h30 at one of our partner farms in Temse to learn more about the Grass2Algae process!