Breweries throughout the world are 
increasingly concerned about the by-products generated by their brewing activities, and about the environmental, profitability and legal issues surrounding these by-products, reports multinational engineering group Alfa Laval.

A typical brewery with a yearly output of one-million hectolitres produces between 100 t 
and 120 t of wet spent grains, between 10 t and 12 t of wet spent yeast, between 6 t and 10 t of wet wort trub and between 2 t and 3 t of wet kieselguhr slurry.

Further, about 1 000 m3 of waste effluents containing solids is sent to wastewater treatment plants, located either in the brewery or externally, every day.

That is why more and more breweries all over the world are interested in spent yeast dewatering, explains Alfa Laval.

The reasons for this may vary for each brewer, but the most common reasons are to find new customers or higher paying customers for the drier spent yeast, reduce the biological oxygen demand impact at the wastewater plants, recover/separate a large part of the extract alcohol contained in the yeast slurry (about 95% alcohol is recovered/separated), decrease transportation costs for these by-products and combine the dewater-
ing process with the kieselguhr slurry dewater-
ing process, enabling most breweries to solve both problems with only one system.

The Foodec Decanter Approach

The Foodec decanter with centrifuge technology helps breweries recover as much primary products as possible, ensuring drier by-products, while simultaneously reducing both chemical and biological oxygen demand in the effluent that has to be treated.

Alfa Laval is able to meet brewery yeast dewatering requirements using a distinct screw conveyor design that paves the way for the best possible separation efficiency. Dry yeast can be obtained at 27% dried matter, 
thus removing a minimum of 95% of the 
alcohol in the slurry.

Brewers Heineken, SABMiller, Carlsberg and InBev are currently using this yeast 
dewatering solution with the new Foodec decanter.

Meanwhile, almost

all breweries worldwide use kieselguhr filtration, and are there-
fore also potential customers for the Alfa Laval Foodec solution. The company has documented kieselguhr dewatering results as high as 35% dry matter, with hardly any solids present in the liquid phase.

Most breweries also have spent yeast tanks situated very close to the kieselguhr slurry 
tanks. 
This means that breweries can easily 
change over to another task, when the decan-
ter is not in operation for the dewatering of yeast slurry.