Circular economy with spent grains - recovering a valuable by-product with the Flottweg decanter

Spent grains are the solid residues of brewing malt and therefore a by-product of the brewing process. Brewer’s grains are obtained after the mash has been purified and the wort has been extracted, and consist of the undissolved portion of what is usually barley or wheat malt. Due to the high quality standards in beer brewing, brewer’s grains are a high-quality by-product.

In fact, the spent grains are much more than a mere by-product, as they are very rich in protein and trace elements, enzymes, vitamins, and fiber are all left in the spent grains. For many breweries, the reuse of spent grains is therefore an important upcycling and sustainability matter, with the aim being to reuse this valuable by-product as efficiently as possible. Currently, it is often used as animal feed, but it can also be used for foodstuffs or as an energy source for biogas systems. It makes sense to see the spent grains as a valuable by-product of the value chain within the brewing process, especially in times when sustainability is playing an increasingly important role. Instead of being disposed of as waste, this by-product can be used profitably in various sectors, thereby killing two birds – sustainability and cost-efficiency – with one stone.

Dewatering spent grains – an essential process step

Wet brewer’s grains are left behind as a valuable by-product in the brewing process, but have a high water content: 100 kg of malt yields about 110 to 130 kg of wet brewer’s grains, with water often accounting for 80-85% of the mass. For breweries, this inevitably results in a large amount of wet brewer’s grains during the brewing process, and these tie up capacities in terms of volume and weight. In a brewery with 100,000 hl output per year (standard beers with 12°P original gravity), this amounts to over 2,000 tons of brewer’s grains with about 75-80% residual moisture.

Therefore, it makes sense to dewater the wet brewer’s grains as a valuable by-product so that it can be stored, transported, and reused in the best possible way afterwards – whether as animal feed, for food production, or for biogas systems.

Quality, pure spent grains using the Flottweg decanter

Flottweg’s separation technology offers an efficient solution for this: with the Flottweg decanter, it is possible to dewater wet brewer’s grains without pretreatment or adding any more water. The decanter can reduce the moisture content of spent grains to about 60% or double the total dry solids from roughly 20% to about 40%. The main benefit of dewatering with Flottweg’s decanter is that no other process steps are necessary and the dewatering can take place immediately.

The centrifuge achieves a perfect, clear centrate and high separation of solids. This means a high yield of the undissolved cereal grain constituents in the dewatered spent grains cake, which can then be reused as a valuable by-product for upcycling. The efficient dewatering using the Flottweg decanter increases the spent grain’s value as a product. The process water obtained can either be disposed of or reused.

The dewatering of spent grains results in cost savings for the brewery in terms of handling, storage, and transport. Another advantage is the longer shelf life of the dewatered spent grains: wet brewer’s grains spoil quickly and must therefore be reused quickly. Dewatering allows the spent grain to be stored for longer. Due to the high quality yield, e.g. in terms of protein content, the spent grains can also be sold at a higher price.

Further advantages of a decanter are the closed system, easy and automated cleaning using flushing, as well as an adapted design and specification according to the brewery’s individual process requirements. What’s more, the simple installation of the decanter at breweries also offers a huge advantage, as no complicated and expensive process technology is necessary for pure dewatering.

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Contact:

Julia Deliano  
PR & content manager

Flottweg SE
Industriestraße 6-8 
84137 Vilsbiburg 
Germany

Phone: +49 (8741) 301 - 1572 
E-mail: delian@flottweg.com