Valorisation of brewery wastes in a circular bioeconomy – from low-cost animal feed to high-value products

The global brewery industry generates around 46 million metric tonnes of by-products annually. The brewing process produces solid wastes such as spent grains, spent hops and spent yeasts. Wastewater is generated from the production and cleaning of fermentation and storage tanks as well as vats and bottles rinsing. The majority of the solid wastes are either disposed of in the environment or used as low-cost animal feed. Brewery wastes are in fact viable and sustainable commodities. They contain residual compounds and materials that can be used to produce valuable chemicals, pharmaceuticals and biopolymers, or act as platform chemicals to be further processed into higher-value products. Brewery
wastes and wastewater can also function as feedstock for energy production. This chapter provides an overview of the brewing process to highlight the major waste streams of the industry. The chemical properties of the wastes are detailed to illustrate their intrinsic values. The state-of-the-art biotechnological advances to valorise brewery waste are discussed and a circular bioeconomy conceptual model is proposed. It is hoped that the knowledge presented in this chapter will help to maximise the socio-economic potential of brewery wastes and the sustainability of the brewery industry to reduce their impact on the environment and burden on the ecosystem.