Grape pomace, generated during wine making, is one of the most abundant and underutilized fruit-derived wastes on the planet. The large amount of pomace waste may present a serious environmental problem if not being properly disposed of. In the meantime, grape pomace contains valuable components that can be recovered or used as intermediates for the production of other chemicals or materials. Although many studies have been working on grape pomace utilization, they were limited to the production of a single product leading to the generation of secondary waste. Therefore, to make comprehensive utilization of grape pomace, a biorefinery approach converting grape pomace to multiple value-added products including seed oil, polyphenols, biofuels, and biochars was developed. Grape pomace was dried and ground to fine powders followed by pressurized hexane extraction to get seed oil. The oil-free solid residue was then extracted by ethanol and water mixture under the pressurized condition to obtain polyphenols. After extractives removal, NaOH was used to pretreat oil- and polyphenol-free solid residue to dissolve lignin which was further purified by acid precipitation. The lignin-partial-removed solid was then hydrolyzed by enzyme to obtain structural carbohydrate hydrolyzed sugars, which were used as fermentation medium for acetone-butanol-ethanol (ABE) production by<i> Clostridium beijerinckii</i> P260. The residual solid left after hydrolysis was pyrolyzed to biochar for potential heavy metal (lead) removal in contaminated water. Under optimized conditions, from 1 kg dry grape pomace, 71.9 g crude seed oil, 322.8 g crude polyphenols (equivalent to 72.6 g gallic acid), 20.7 g ABE, 219.3 g lignin, and 132.0 g biochars could be obtained. The biochars showed the lead adsorption capacities upward of 134 mg/g and followed pseudo-second-order kinetics, with 66.5% adsorption capacity reached in 30 min. The designed process shows a novel way of grape pomace utilization and has the potential to reduce winery waste disposal and promote a sustainable bioeconomy.

Toward a winery waste biorefinery: converting grape pomace to seed oil, polyphenols, biofuels, and biochar

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.