How chemical products can be derived from waste products

Washington, Nov 11 : Researchers have demonstrated how chemical substances can be derived from waste products generated by the food industry, leftover biomass from agriculture and forestry, and residual materials.

The team of researchers is from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart, Germany.

They demonstrated how the biotechnical recycling works, using colza, whey and crab shells as examples.

When producing biodiesel from colza oil, raw glycerol is accrued as a byproduct.

Scientists at the IGB have now developed a method of converting this raw glycerol into 1,3-propandiol - a chemical base for producing polyesters or wood paint.

Until now, 1,3-propandiol has always been chemically synthesized, but it can also be derived from glycerol by certain micro-organisms.

Clostridium diolis bacteria, for example, can produce a comparatively high yield of chemical feedstock. However, these bacteria cannot convert raw glycerol.

This is because raw glycerol contains fatty acids left over from the colza oil, and these have to be separated out.

"Furthermore, high concentrations of both the glycerol substrate and the 1,3-propandiol product inhibit the growth of the bacteria," said Dr. Wolfgang Krischke of the IGB, pointing out another challenge in developing this biotechnological process.

"We have managed to solve this problem to a large extent by keeping the bioreactor in continuous operation, because once the glycerol has been almost fully converted, it loses its inhibiting effect. In this way, we have achieved a stable process with high product concentrations," he added.

The fatty acids can be converted by yeasts to long chain dicarboxylic acids providing novel building blocks for polymer industries.

ANI