Spent Yeast

Did you know?

The beer that leaves the fermenter is a very wet yeast slurry (85‑90% moisture content).Beer in spent yeast can represent 4‑7% of total beer production.

Where Does it Enter the Drain?

Spent yeast slurry is often sent directly to drain after it is removed from the fermenter vessel.Yeast and fermenting beer can also enter the drain through blow-off losses to the floor.

How to Keep it Out of the Drain

The solution option will depend on whether a craft brewer wants to recover the beer from the spent yeast.

Beer Recovered for Sale

Use a centrifuge to recover the beer from the spent yeast. Recovered beer can be put back into the product stream – additional revenue pays for centrifuge.

Beer Not Recovered for Sale

Different options can be considered and will depend on end-use specifications and requirements (e.g., % moisture limits).

A – Collect and divert full slurry volume to a tank.

B – Collect slurry in a separate tank and allow extended settling or “racking” to separate yeast from beer.

What to Do With It

Beer Recovered for Sale

Yeast paste can be composted, biodigested or disposed of as solid waste.

Did you Know?

Low moisture yeast solids can be mixed with spent grains and sent to farmers for use as feed (to ensure the health of the animals, the yeast component is usually limited to 3 – 4% of the total volume of spent grain).

Craft brewers should consult with farmers and their veterinary support before considering this option.

Beer Not Recovered for Sale

A – Collect and divert full slurry volume to a biodigester and/or waste disposal.

Since spent yeast slurry is very wet, consult with the biodigester operator to confirm if they can accept it.

B – If racking, settled clarified beer can go to one disposal option, and the settled yeast can be collected and either composted, biodigested or disposed of as solid waste.