Source separated biowaste with a share of 34% of municipal waste in the EU stands as a serious environmental, economic, and social problem. This is a key waste stream with a high potential in contributing to the transition to a circular economy. Production of biosolvents such as bioethanol is a sustainable pathway promoting circularity and resource efficiency.
National Technical University of Athens reports…
Feedstock: In total, around 3 tonnes of source separated food waste were collected in 23 different batches from the municipality of Vari-Voula-Vouliagmeni. According to analysed physicochemical characteristics the mean initial moisture of the feedstock was around 75.86±2.18% while starch 7.68 ±3.42%, cellulose 14.55 ± 3.56% and free glucose 1.57 ±1.07%, revealing the high potential of this waste for bioethanol production.
Pilot demonstration: Initially the source separated biowaste were dried in a commercial food waste dryer and the dried feedstock was used to produce bioethanol in pilot scale. The optimum conditions applied in pilot scale were 25% solids loading, amylolytic enzymes 40μL/g starch, cellulolytic enzymes 175 μL/g cellulose and 2% w/w S. cerevisiae for more that than 10 continuous cycles. The results from pilot trials were very successful and repeatable, the mean ethanol yield was 86.60± 4.91%, while structural component such as starch and cellulose were efficiently hydrolyzed. The produced ethanol was recovered and purified meeting the standards of absolute ethanol, rendering it suitable for industrial uses.