Abstract
The beer brewing process is one of the most polluting industrial processes, generating a huge amount of wastewater effluent and solid wastes (i.e. spent grain and yeast), which must be disposed of or treated in the least costly way to meet strict discharge regulations set by government entities. Particularly, spent grain, the leftover malt and adjuncts after the mash has extracted most of the sugars, proteins, and nutrients, can constitute as much as 85 % of a brewery’s total by-product. However, sustainability is a hallmark of the craft beer industry and therefore there is a great interest to find innovative ways to prevent spent grain from going to waste.
At this regard, the “Birraverde” project, coordinated by CREA and funded by the National Rural Network, aimed to develop some technical solutions for the recovery and reuse of brewer’s wastes (spent grain, spent yeast and wastewaters), according to the principles of circular economy. In particular, for the recovery and valorisation of spent grain two alternative solutions were proposed: 1) conversion of dried spent grain into pellets that can be used for heat generation to be reused in the beer production cycle; 2) production of biochar (charcoal) from dried spent grain through a thermochemical process of pyro-gasification. In the latter case, a preliminary trial was carried out using a lab-scale pyrolytic reactor. The first proposed model, if integrated within the brewing process pipeline, can reduce the costs of buying pellets on the market, producing gain margins even under low rate of plant utilisation (160 h y-1). On the other hand, the second model, the conversion of spent grain into biochar, a new organic amendmen, can offer the possibility to realize a diversification of the farm activities opening to new markets.
