Wastewater and Solid Waste Management
Brewery Solid Wastes
The most cost-effective method for significantly reducing effluent load of brewery wastewater is to separate the solid wastes from the wastewater itself. The equipment necessary includes holding vessels, tanker trucks that can haul away the material, pumps, and dedicated piping or hoses for transfer. Typical solid wastes include spent grains, trub, spent yeast, diatomaceous earth slurry from filtration, and packing materials.
Beer production results in a variety of residues, such as spent grains, which have a commercial value and can be sold as byproducts for livestock feed. The nutritional value of spent grain is much less than that of the same amount of dried barley, but the moisture makes it easily digestible by livestock.
Trub is slurry consisting of wort, hop particles, and unstable colloidal proteins coagulated during the wort boiling.
In brewing, surplus yeast is recovered by natural sedimentation at the end of the fermentation and conditioning. Only part of the yeast can be reused as new production yeast. Spent yeast is very high in protein and B vitamins, and may be given to livestock as a feeding supplement.
Diatomaceous Earth (DE) Slurry
Diatomaceous earth slurry from the filtration of beer also constitutes a very large category high in SS and BOD/COD. Different methods for regeneration are under development, but presently they are not capable of totally replacing new diatomaceous earth.
Other solid wastes include label pulp from the washing of returnable bottles, broken glass, cardboard, bottle caps, and wood that is usually disposed of at sanitary landfills.
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