Anaerobic Fermentation of Certain Products of Food Industry – Food Waste, Spent Grain and Grape Pomace

Abstract

Biodegradable products of food industry represent input substrates of biogas plants. Of these, food waste, grape pomace and spent grain were the products of choice for analyzing which tested biogas production and quality. The latter being in particular determined by methane and hydrogen sulfide content. Anaerobic fermentation was underway 26 days at mesophylic temperature 42 °C in a batch labscale reactors with volume 120 dm 3 . The following values were measured in relation to specific yield of methane: food waste: 0.347 m 3 per kg, grape pomace: 0.238-0.246 m 3 per kg, spent grain: 0.283 m 3 per kg. The specific production of hydrogen sulfide: food waste 752 mg per kg, spent grain: 585 mg per kg, red pomace: 74 mg per kg and white pomace 98 mg per kg. 

Obtaining Multiple Coproducts from Red Grape Pomace via Anthocyanin Extraction and Biogas Production

“…The biogas qualities for the raw, extracted, and E+S pomace were 57.4 ± 0.924, 58.0 ± 1.22, and 58.9 ± 1.47%, a difference determined to be nonsignificant ( P = 0.26). These values are comparable to the value obtained by Gersl et al (62%), though other studies report lower quality values of 31–41%. , …”

“…The average methane yields of the raw pomace, extracted pomace, and extracted pomace with aqueous supplement (E+S), adjusted per gram of volatile solids (VS), were 213.6 ± 10.15, 190.5 ± 18.27, and 205.9 ± 18.39 mL, respectively. These values are comparable to those from other studies of anaerobic digestion of RGP, in the range of 110–360 mL per gram of VS. − , Methane production over time for each treatment is depicted in Figure . One-way ANOVA analysis of the terminal methane could not discern any significant differences ( P = 0.17).…”

“…In addition to anthocyanins, RGP also contains a small portion of nonfermented soluble sugars , and significant lignocellulose content (roughly half on a dry basis). − Thus, it represents a potential feedstock for second-generation biofuel technologies such as anaerobic digestion. Several studies have found substantial biomethane yield from the anaerobic digestion of RGP, − at values comparable to many other lignocellulosic agricultural residues …”