Sustainable Particleboards Based on Brewer’s Spent Grains

Abstract

Brewer’s spent grain (BSG) is the main solid waste generated in beer production and primarily consists of barley malt husks. Based on the active promotion of circular economy practices aimed at recycling food industry by-products, this study assessed for the first time the production of particleboards based on BSG as the sole source of lignocellulosic material and natural adhesive without the use of additives or other substrates. In order to achieve particleboards from entirely sustainable sources, BSG particles have to self-bind by thermo-compression with water. In this context, the aim of this study is to assess the effects of pressing temperatures and particle size on properties such as modulus of elasticity, modulus of rupture, internal bond, thickness swelling, and water absorption. The performance of binderless boards was compared with that of a control panel (control) using BSG combined with phenolic resin. Processing conditions were selected to produce boards with a target density of 1000 kg/m³ and a thickness of 5 mm. To confirm the efficiency of the self-adhesion process, scanning electron microscopy was used to examine the boards. The processes of self-adhesion and particle-to-particle contact were facilitated at a pressing temperature of 170 °C and a particle size range of 200–2380 µm (ground BSG), resulting in improved flexural properties and enhanced water resistance. The properties of BSG-based binderless boards were comparable to those reported for other biomass residues, suggesting that they might be used in non-structural applications, such as interior decoration.

Effect of Pulping Waste Liquid on the Physicochemical Properties and the Prediction Model of Wheat Straw Residue Granular Fuels

“…Compared with the granules with water, the granules with pulping waster liquid have a smaller difference between initial and relaxed density. Lignin and sugars in the pulping waste liquid has good adhesive function [ 21 , 22 ] and elastic performance; they can produce plastic deformation after compression molding process, and have a fast stress transmission speed [ 23 , 24 ].…”

“…Compared with the granules with water, the granules with pulping waster liquid have a smaller difference between initial and relaxed density. Lignin and sugars in the pulping waste liquid has good adhesive function [21,22] and elastic performance; they can produce plastic deformation after compression molding process, and have a fast stress transmission speed [23,24]. Figure 3b,c show that the transverse compressive strength is obviously higher than the longitudinal compressive strength of granular fuels, and they all show a descending tendency with increasing moisture.…”

“…•e − x 6.90 (22) y ′ = 3.48×10 −2 •e − x 6.90 (23) in which, x ∈ [0, 50], and y ′ > 0. So, the value of relaxed density is positively associated with the solid content of pulping waste liquid.…”