Monday, April 30, 2007

Waste to ethanol

Mai Østergaard Petersen, Frank Iversen, Niels Henriksen, and Jan Larsen. DONG Energy, Kraftværksvej 53, DK-7000 Fredericia, Denmark

Due to the world’s increasing wealth massive problems with waste disposal are emerging. The organic waste fraction is a large unexploited source for production of bioethanol or other useful fermentation products.

A simple process has been developed for production of bioethanol or other useful fermentation products by non-pressurised pre-treatment, enzymatic hydrolysis and fermentation of waste fractions containing mono- and/or polysaccharides. The whole process from non-pressurised pre-treatment over enzymatic hydrolysis and fermentation to separation of fermentable and non-fermentable solids can be processed with high dry-matter content in a single vessel without any transport of the mash and without sorting the material prior to treatment.

Experiments with municipal solid waste (MSW) have demonstrated that considerable amounts of ethanol (60-70 l per ton dry-matter) can be produced from MSW even at relatively low enzyme loadings. The strength of this process is sorting after fermentation. Results also illustrate that source sorting increases the yield per ton dry-matter considerably (110-140 l ethanol).Due to the high dry-matter content in the process, it is possible to reach an ethanol concentration of around 4 % vol. in the fermentation broth.