Microwave treatment

Technology
Technology details
Name:	Microwave pre-treatment
Category:
Feedstock:	Food and kitchen waste (lignocellulosic materials), Garden and park waste (lignocellulosic materials)
Product:	Fermentable sugar

The Microwave pre-treatment includes technologies that utilise electromagnetic radiation to induce thermal and non-thermal effects that drive physical, chemical or biological reactions. The technology is usually utilised in food drying or to break down the structure of lignocellulosic biomass leading to the release of different substances (e.g. fermentable sugar).

Feedstock

Origin and composition

Lignocellulosic biomass

Pre-treatment

• Sizing
  • Chipping
  • Grinding

Process and technologies

The breakdown of lignocellulosic biomass into its monomers and oligomers is induced via molecular collision due to dielectric polarisation. Compared to other thermal treatments, the technology brings several advantages, such as reduced plant footprint, higher throughput, higher reaction rates, as well as higher yield and purity. However, a disadvantage is the unequal distribution of the applied microwave power through non-homogeneous material (such as differences in composition, geometry, size) as well as local overheating through resonance (electromagnetic wave reflection and formation of standing waves) and low penetration for bulk materials .

The process can also be combined with chemical treatments utilising chemicals such as alkaline (to remove lignin) and acid (to remove hemicellulose) solutions, ammonia, and metal salts.

Product

• Fermentable sugar (e.g. for bio-alcohol production)

Post-treatment

• Industrial fermentation
• Solid state fermentation