Waste biomass of wine industry: a potential application of unbleached fibers produced by green approach

Several agricultural wastes, such as the residues of the winemaking industry, have been tested using traditional chemical methods of pulping aimed to obtain bleached pulp, but only low yields and poor fiber quality have been achieved so far. In this work, we evaluate a two-stage chemi-thermomechanical pulping (CTMP) to assess the feasibility to add value to the residues of the wine industry (grape stalks and vine shoots) by obtaining fibers with papermaking and/or cardboard quality. The first stage of the process evaluates different conditions with low chemical charges of Na2SO3 and/or NaOH (3 to 5% on wood basis) at different temperatures (130 to 160 °C) for 60 min. The second stage consists of a mechanical refining that converts fiber bundles and shives into pulps. CTMP pulping performed with 5% Na2SO3 at 160 °C from grape stalks and vine shoots showed the best combination of fiber quality regarding higher screened pulp yield, lower rejects and fines content, and adequate drainability. Results showed that pulp from waste lignocellulosic of the winery industry can be produced by a green approach (low chemical charge and severity in CTMP pulping) and became an alternative for paper, packaging, fiber additives, or new biobased materials.