Biogas Production Potential from Anaerobic Co-digestion of Grape Pomace

Grape cultivation and wine production has been in practice since 7000 BC in ancient China. Today, top wine producing countries are France, Italy, and Spain, including the United States. New York State is the third largest wine producing state in the US, with over 28 million gallons produced in 2017. Wine pomace, the residue from wine making after pressing could be used for the production of electricity and heat replacing fossil resources. One alternative route could be anaerobic fermentation of wine making residues for the production of electricity and heat from the produced biogas.

This research investigated the cumulative biogas production from anaerobic fermentation of differently prepared red wine grape pomace. Red wine grape pomace was used as received, prepared by blending using a laboratory benchtop blender, refined using a Valley beater apparatus, and cooking the refined red wine grape pomace for 2 hours at 98°C. The pH of each solution was adjusted to 8.50 with 20% Calcium Hydroxide (Ca(OH)2) solution. 300 g of each solution and 30 g of bacteria inoculate was filled into a 500 ml Erlenmeyer flask that contained a magnetic stirrer. The anaerobic fermentation experiment have been run in duplicate, lasted for up to 170 hours, at a temperature of 39°C ± 2°C.

Untreated red wine grape pomace had the lowest cumulative biogas production of 93 ml and 151 ml.

Blended grapes showed a cumulative biogas production of 283 ml and 243 ml respectively. Refined red wine grape pomace generated the highest biogas production with 566 ml and 864 ml, followed by refined and cooked red wine grape pomace with a biogas production of 365 ml and 830 ml. The maximum biogas composition without CO2 was 70% and the minimum biogas composition was 55%.

Pre-treatment such as refining, blending, and heat treatment can increase biogas production and lead to a possible lower retention time in the fermentation vessel due faster biomass conversion.