Processing and treatment of waste streams

Horti-BlueC has explored the potential for upcycling 5 local waste streams to contribute to sustainable soilless horticulture. :

1. CO₂ emitted by greenhouse heating
2. shellfish waste streams
3. spent growing media
4. woody fraction of green waste
5. plant fibers

Shellfish waste (e.g., shrimp shells) provides chitin, which can be used as an additive in growing media.

Spent growing media, green waste and plant fibers are feedstocks for biochar production. Biochar (charred material) is rich in carbon, and has the potential to help mitigate climate change via C sequestration. Batches of biochar, based on plant fibers, spent growing media and the woody fraction of green waste, have been produced during the project.

CO₂ from flue gases was captured at a pilot installation, and can be used for CO₂ fertilization in greenhouses.

Horti-BlueC Decision Tool

Horti-BlueC developed a tool to indicate how to process flue gases and residual biomass into CO₂ fertilizer and building blocks for growing media, i.e. biochar, chitin, fibers, or other materials. We worked on 1 gaseous waste stream (off-gasses from the chimney of a bio-energy installation) to be used as CO₂ fertilizer and 4 solid waste streams to be used as replacer for peat and mineral wool in growing media.

Some materials may only need defiberization, cutting, milling, … whilst other waste streams or applications require more advanced treatment. The pretreatment from waste to feedstock is documented in a fact sheet to select the best processing techniques. All information from the fact sheets, on the processing of these materials, is linked to the Decision Tool.

The fact sheets are also available as pdf, which will soon be available here:

• Fact sheet on the defiberization of plant fibers and the woody fraction of green waste
• Fact sheets on the treatment of shellfish waste streams:
  • Fact sheet on chemical chitin extraction from shellfish waste streams
  • Fact sheet on enzymatic chitin extraction from shellfish waste
  • Fact sheet on the torrefaction of shellfish waste streams

• Fact sheet on the gasification of plant fibers, woody fraction of green waste and spent growing media
• Fact sheet on the composting of spent growing media
• Fact sheet on the purification of flue gases