Grape pomace is the major component in grape fruits and is mostly wasted after wine and juice making processes. To recycle the residual biomass in grape pomace, extraction conditions of polysaccharides from grape pomace (GPP) were investigated. Three parameters affecting the crude GPP extraction, material to solvent ratio, extraction time, and extraction temperature were determined through single parameter optimization and then further optimized by orthogonal test. Results showed that the optimum extraction conditions were material to solvent ratio of 1:25, extraction temperature of 75 °C, and extraction time of 40 min, with extraction time as the most significant factor among them. Crude GPP was purified by gel column chromatography and chemically characterized. UV-Vis spectra analysis indicated that the GPP fraction did not contain any proteins or nucleic acids. FT-IR analysis implied that GPP consisted of α- and β-pyranose with carboxyl groups. Monosaccharide composition analysis indicated that GPP was composed of arabinose, glucose, galactose, and mannose with a molar ratio of 18.4:14.1:10.8:3.0. These results provide a theoretic basis for the production and utilization of GPP.
The effect of different pretreatment methods on anaerobic H2 production from a sucrose-rich synthetic wastewater was investigated in this work. The substrate utilization, formation of aqueous products, H2 production and microbial diversity in anaerobic sludge all markedly depended on these pretreatment methods. The highest H2 production according to the values for the maximum H2 production rate of 27.57 ml h−1, specific H2 production rate of 2.962 ml g-VSS h−1, and H2 yield of 1.617 mol H2 mol glucose−1 was observed in the H2 production by the sludge pretreated with butyrate (pH = 2). Correspondingly, the main microbial communities were Clostridium sp. HPB-16, Clostridium sp. HPB-46, Clostridium sp. HPB-2, Clostridium sp. HPB-4, Oxalobacteraceae bacterium QD1, uncultured bacterium clone HPR93, uncultured Olsenella sp. clone J27, and uncultured bacterium clone SR_FBR_E5. This result demonstrates that acid pretreatment such as butyrate could be also as an effective method to enrich H2-producing bacteria from anaerobic sludge for large-scale biological H2 production.
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