UNDERSTANDING
DISTILLERY CO-PRODUCTS & EFFLUENT FOR
WASTE MANAGEMENT WRITTEN BY CHRIS DREYER
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ost likely, the best thing we can imagine coming out of a distillery would be the malt whiskeys, the grain whiskeys, the rums, the brandies, the vodkas, and gins. What we tend to pay the least attention to are the co-products and effluent streams that are as much a part of the distilling process as the spirits produced. These would include spent grains, stillage, carbon dioxide (CO2), fusel oil, and wastewater from cleaning, rinsing and facility utility systems. Factors that affect how these co-products and effluent streams are managed include the type of spirit produced, production volumes, coproduct and effluent quantities, whether the distillery is located in an urban or rural environment, local jurisdictions, and discharge limitations. To begin, it’s important to identify all the co-products and effluent types and quantities, understand constraints or limitations on the management approach, and then put a plan in place to develop the right solutions for a successful distillery operation.
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TAKING ACCOUNT OF YOUR CO-PRODUCTS AND WASTE STREAMS The items listed below will be well known by the distiller and are listed for the benefit of the folks on the business (and drinking!) side of the distillery.
SPENT GRAINS Spent grains are a byproduct of malt whiskey and grain whiskey production. These are the grains stripped of starch converted to sugars, collected off mash and lauter tuns for the malt whiskey production, better known as draff. There are also grain residues produced from the grain whiskey process, recovered from the stillage collected from the distillation process (see stillage listing below). These grains are a valuable source of fiber, protein, vegetable oils and yeast residue.
STILLAGE Pot ale is the fluid remaining after pot distillation of wash to strip out the ethanol. This byproduct contains yeast debris and non-fermentable solids and is high in Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), suspended and dissolved solids, and as much as 0.2% residual ethanol. Spent lees is the spirit pot residue remaining after low wines distillation. This liquid is considerably less strong in BOD, COD, and insoluble content relative to pot ale; its contribution to the overall facility BOD and COD needs to be considered.
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