When we take a sip of our favorite craft cocktail or whisky on the rocks, we might wonder, “Who made this batch?” “Are whiskey stones really better than ice?” or “Maybe one more dash of bitters next time.”

Rarely – well, OK, never – ever, do we think, “This process likely generated wastewater high in organics and solids that required pretreatment before discharge to the municipality.”

As with all food and beverage manufacturing, wastewater is an inherent byproduct in the creation of craft spirits. At any given distillery, two types of wastewater are generated: sanitary and industrial.

Sanitary wastewater, often called domestic wastewater, comes from human or household sources, such as toilets, kitchens, laundry, showers and other plumbing fixtures.

Industrial wastewater is generated during manufacturing and processing activities.

Most often, sanitary wastewater is segregated from industrial wastewater and discharged to the sewer collection system without treatment.

Industrial wastewater is generated from washdowns and sanitations, off-spec batches, and other stillage produced during operations, as well as from utility wastewater such as boiler blowdown and water treatment byproducts (e.g., RO brine). Depending on wastewater flow and loading, a distillery may be classified as a Significant Industrial User under the local Sewer Use Ordinance. This designation may require wastewater to be collected and treated before discharge to the municipal sewer system.

To help distilleries and other beer, wine, and spirits manufacturers identify the type of industrial pretreatment that may be required, we conducted a wastewater sampling study. Working with spirits manufacturers producing whiskey, rye, bourbon and rum, individual grab samples representing normal operations were collected and analyzed by our partner, Eurofins.

Samples were tested for common wastewater constituents typically included in Industrial Pretreatment Discharge Permits, including solids, organics and nutrients. Parameters analyzed included Total Suspended Solids (TSS), five-day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), both total and soluble, Total Kjeldahl Nitrogen (TKN) and Orthophosphate (PO4).

While a complete baseline assessment should include 24-hour composite samples collected during normal and abnormal or cleaning conditions, review of these grab samples provided valuable industry insight.

Nearly all organic contamination measured by COD and BOD was soluble. This indicates that even with solids removal, additional biological treatment may be required depending on permit limits.

High nutrient concentrations were also observed, with nitrates and phosphates estimated based on TKN and PO4 results. In some municipalities, nutrient removal is required prior to discharge.

Most samples contained elevated TSS levels, which can be readily removed through primary treatment. These solids can be collected and potentially beneficially repurposed through composting, land application, or animal feed.

Because wastewater characteristics vary between operations, sanitations, batch changes and recipe adjustments, systems should include a properly sized equalization tank, typically designed for 12 to 24 hours of hydraulic residence time. Equalization allows for hydraulic and organic stabilization prior to discharge. pH adjustment using chemical metering of acid or caustic may also be required to address pH swings caused by CIP and sanitation activities.

Not all distilleries require wastewater treatment. The type and level of treatment depend on local sewer use ordinances and industrial pretreatment programs, which are generally available online. For facilities that do require treatment, developing the right-sized pretreatment solution depends on three key inputs.

1. Total wastewater volume discharged per day, including average and peak flows.
2. Wastewater constituent data collected under different operating conditions.
3. Municipality-specific Sewer Use Ordinances and industrial pretreatment discharge limits.

With this information, a Basis of Design for a pretreatment system can be developed, if required. This document summarizes wastewater flows, concentrations and loadings generated on site and recommends design and sizing criteria for collection, conveyance, equalization and metering systems. It may also include recommendations for treatment equipment needed to meet permit limits. Pretreatment systems commonly used in this industry include pH neutralization, primary solids removal using screens or dissolved-air flotation units and biological treatment for organics and nutrients. Biological treatment may be aerobic or anaerobic, depending on loading and removal requirements.

Following treatment, the wastewater meets discharge quality standards and can be metered and monitored before being combined with sanitary wastewater and conveyed to the Publicly Owned Treatment Works.

The next time you enjoy a glass of your favorite craft spirit, consider the unseen efforts behind it: the water carefully managed throughout production and the technical expertise that allows distilleries to serve as responsible stewards of their communities and the environment.

About the Author: Colleen Grinham is an Industrial Water Senior Design Manager at Haskell, specializing in industrial water and wastewater treatment. She has more than 10 years of operations, consulting and design-build experience and has worked across multiple industrial sectors, including beer, wine and spirits, pulp and paper and aerospace. Grinham holds a Master of Science degree in civil and environmental engineering and is a licensed Professional Engineer in Texas and Georgia.