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Abstract

The U.S. Environmental Protection Agency (EPA) has funded

a pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the expertise to do so. Waste Minimization Assessment Centers (WMACs) were established at selected universities and

procedures were adapted from the EPA Waste Minimization

Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).

That document has been superseded by the Facility Pollution

Prevention Guide (EPA/600/R-92/088, May 1992). The WMAC

team at the University of Louisville performed an assessment

at a plant that produces bourbon whiskey. Grains are ground,

cooked, and fermented using yeast. The resulting fermented

product is sent to a beer still for alcohol recovery. Overhead

vapors go to a doubler from which they flash yielding a new

whiskey. The new whiskey obtained is stored in charred wooden

barrels for several years and, after maturation, is shipped

offsite for bottling. The team’s report, detailing findings and

recommendations, indicated that carbon dioxide and ethanol

are vented to the atmosphere in large quantities and that

significant cost savings could be realized through carbon dioxide and ethanol recovery.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research Laboratory, Cincinnati, OH, to announce key findings of an ongoing

research project that is fully documented in a separate report

of the same title available from University City Science Center.

Introduction

The amount of waste generated by industrial plants has become an increasingly costly problem for manufacturers and an

additional stress on the environment. One solution to the

problem of waste generation is to reduce or eliminate the

waste at its source.

University City Science Center (Philadelphia, PA) has begun a

pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the in-house expertise to do so. Under agreement with EPA’s

National Risk Management Research Laboratory, the Science

Center has established three WMACs. This assessment was

done by engineering faculty and students at the University of

Louisville’s WMAC. The assessment teams have considerable

direct experience with process operations in manufacturing

plants and also have the knowledge and skills needed to

minimize waste generation.

The pollution prevention opportunity assessments are done for

small and medium-size manufacturers at no out-of-pocket cost

to the client. To qualify for the assessment, each client must

fall within Standard Industrial Classification Code 20-39, have

gross annual sales not exceeding $75 million, employ no more

than 500 persons, and lack in-house expertise in pollution

prevention.

The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers and reduction of waste treatment and disposal costs for participating

plants. In addition, the project provides valuable experience for

graduate and undergraduate students who participate in the

program, and a cleaner environment without more regulations

and higher costs for manufacturers.

Pollution Prevention Assessment for a Manufacturer of

Bourbon Whiskey

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

ENVIRONMENTAL

RESEARCH BRIEF

Research and Development EPA/600/S-95/010 August 1995

Marvin Fleischman*, Debra Cambron*,

and Gwen P. Looby**

 *University of Louisville, Department of Chemical Engineering.

** University City Science Center, Philadelphia, PA.

E AP
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Methodology of Assessments

The pollution prevention opportunity assessments require several site visits to each client served. In general, the WMACs

follow the procedures outlined in the EPA Waste Minimization

Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).

The WMAC staff locate the sources of waste in the plant and

identify the current disposal or treatment methods and their

associated costs. They then identify and analyze a variety of

ways to reduce or eliminate the waste. Specific measures to

achieve that goal are recommended and the essential supporting technological and economic information is developed. Finally, a confidential report that details the WMAC’s findings

and recommendations (including cost savings, implementation

costs, and payback times) is prepared for each client.

Plant Background

Manufacturing Process

Whiskey Production

The production of whiskey is described in this section. A

process flow diagram that depicts the process appears at the

end of this section.

Corn, rye, and malt grains received via railcars and trucks are

bottom-unloaded through a grate onto a screw conveyor. The

grains are carried to a vibrating screen where large foreign

material is removed, then transferred by bucket elevators to

storage silos.

As needed, the grain is transported by screw conveyor to mills

for grinding. The ground grain (also called meal) is then sent

via bucket elevator to the meal room where each type of grain

is stored in a separate bin. A small amount of malt meal is

added to bins of corn meal and rye meal to keep them from

hardening. The meal is then gravity fed to the scale room.

From the scale room, rye and malt are sent to separate slurry

tanks prior to being added to the cooker. Corn meal is conveyed to one of three mash cookers to which water and spent

stillage from fermentation are added. Steam is added to the

cooker directly in order to cook the corn at high pressure and

temperature. After the corn has been cooked, the vessel temperature is lowered by releasing the tank pressure. The rye

slurry from the slurry tank is added to the cooking vessel where

the resulting mixture is cooked at lower pressure and temperature then used for the initial corn cooking. Next, the malt slurry

is added to the mixture (called the mash) in the vessel. The

cooking process releases the starches from the grain and the

malt provides the enzyme that converts the starch to sugar.

In a separate operation, yeast is prepared for the fermentation

process. An inoculum and a mixture of rye and malt meals are

combined in one of several yeast tubs. Once the yeast is

ready, it is mixed with the mash and cooled. The mixture is fed

to a fermentor where the yeast metabolizes the sugars to

produce alcohol.

The fermented product, beer that is approximately 9% alcohol

by volume, is sent to the beer well for storage. From the beer

well the product is pumped to the beer still for alcohol recovery.

The overhead vapors from the still go to a thumper (also called

a doubler) where they flash into the high wine condenser,

yielding a 145-proof new whiskey. The still bottoms or “slop”

are sent to the dryhouse for further processing into distillers’

dried grains for use as animal feed.

The new whiskey is sent to one of several storage tanks where

it is reduced in proof using demineralized water. Charred white

oak barrels are then filled with product. The filled barrels are

sent to a temperature- and humidity-controlled warehouse where

the product matures for several years.

Following the maturation process, the barrels are conveyed to

vacuum pumps which transfer the whiskey into storage tanks.

The whiskey is loaded into trucks and taken to an offsite

bottling facility.

A process flow diagram for whiskey production is shown in

Figure 1.

Dried Grains Production

The processing of the still bottoms begins with the initial separation of “thin slop” from “thick slop” by passing the mixture

over a screen. A portion of the thin slop is sent to the mash

cookers. The remaining thin slop is sent to a small holding

tank. The thick slop is passed through a paddle screen and a

press for further recovery of thin slop. Remaining thick slop is

conveyed to a drier and then a storage tank. From the holding

tank the thin slop is sent through a four-stage multi-effect

evaporator and two finishing evaporators. The syrup is sent to

a dehydrator and then to storage. Dried grain from the thin and

thick slop is mixed and sold as animal feed.

A process flow diagram for production of distillers’ dried grains

is shown in Figure 2.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes:

• A product, distillers’ dried grains for animal feed, is made

from the distillation residue.

• Spillage of grain during unloading has been reduced by

funneling the grain into the delivery grate.

• Leakage of grain from the grain handling system has been

reduced through the use of relatively new and tight equipment and through frequent routine maintenance.

Pollution Prevention Opportunities

The type of waste currently generated by the plant, the source

of the waste, the waste management method, the quantity of

the waste, and the annual waste management cost for each

waste stream identified are given in Table 1.

Table 2 shows the opportunities for pollution prevention that

the WMAC team recommended for the plant. The opportunity,

the type of waste, the possible waste reduction and associated

savings, and the implementation cost along with the payback

time are given in the table. The quantities of waste currently

generated by the plant and possible waste reduction depend

on the production level of the plant. All values should be

considered in that context.

It should be noted that the economic savings of the opportunity, in most cases, result from the reduction in raw materials

and from reduced present and future costs associated with

waste treatment and disposal. Other savings not quantifiable

by this study include a wide variety of possible future costs

related to changing emissions standards, liability, and em-
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Grains

Unloading Cleaning Storage Milling

Corn Meal Rye Meal Malt Meal

Bin Bin Bin

Scale Scale Scale

Beer Fermentor Mash Slurry

Well Cooker Tank

Still Thumper Condenser High Wine Barrel

Storage Filling

Barrel Barrel

Dumping Warehousing

Grain Slop to

Byproducts Processing Whiskey Shipped to

Offsite Bottling

Facility

Yeast Rye, Malt

Figure 1. Abbreviated process flow diagram for whiskey manufacturer.

ployee health. It also should be noted that the savings given for

each pollution prevention opportunity reflect the savings achievable when implementing each waste minimization opportunity

independently and do not reflect duplication of savings that

would result when the opportunities are implemented in a

package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, several additional measures were considered. These measures were not analyzed completely because

of insufficient data, minimal savings, implementation difficulty,

or a projected lengthy payback. Since one or more of these

approaches to pollution prevention may, however, increase in

attractiveness with changing conditions in the plant, they were

brought to the plant’s attention for future consideration.

• Install a system to reduce the concentrations of BOD5

 and

suspended solids in the wastewater currently sent to the

POTW.

• Use an enclosed filter on the off-gas of the granary cyclone;

direct the collected dust to the corn meal storage bin.

• Use high-pressure water spraying to clean cookers in order

to reduce the quantity of water required for cleaning.

• Reuse the evaporator scrubber effluent for cleaning of the

vent from the steam tube dryers.

• Recover ethanol emissions from the storage tanks in various

stages of the manufacturing process.

Thick Stillage

Tank Screens

Grain Slop From

Bottom of Still

Screen

Thin Stillage

Tank

Evaporators

Dehydrators

Presses

Dryer

Mixing

Dried Grain

Figure 2. Abbreviated process flow diagram for dried grain production.
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• Reduce dust losses that occur during the loading of distillers’

dried grains into trucks.

This research brief summarizes a part of the work done under

Cooperative Agreement No. CR-814903 by the University City

Science Center under the sponsorship of the U.S. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.

Table 1. Summary of Current Waste Generation

Waste Generated Source of Waste Waste Management Method Annual Quantity Annual Waste

Generated (lb/yr) Management Cost1

Grain waste Vibratory screens and cleaning Given to employees for use 6,350 0

of conveyors as animal feed

Grain and water Water scrubber for cyclone Sewered 33,259,000 4,6802

Grain Granary operations Dust reduced using water scrubber Included in above 369,000

(lost material value)

Water and caustic Cleaning of mashers, fermentors, Sewered 25,146,500 3,3902

beer well, and mash lines

Wastewater Rinsing of cooker and cleaning Sewered 8,300 negligible

of sight glasses on cookers

Carbon dioxide Fermentors Vented to atmosphere 106,240,000 0

Ethanol Fermentors Vented to atmosphere 637,400 136,000

Water and caustic Cleaning of stills Sewered 5,196,000 6802

Ethanol Condensers Vented to atmosphere 630,530 134,400

Water, acid, and caustic Regeneration of cation and Used for neutralization; sewered 3,572,940 1,2402

anion exchangers

Ethanol Filling of storage tanks Vented to atmosphere 4,960 1,060

Ethanol Barrel breathing during maturing Vented to atmosphere 2,545,000 1,027,000

process

Ethanol Transfer of product for bottling Vented to atmosphere 8,320 3,360

Dried grains and water Cleaning of equipment used Sewered 37,413,000 5,0802

for byproduct processing

Water and soluble grain Evaporator condensate from Sewered 666,782,800 90,6302

byproduct processing

Other wastewater Various processes Sewered 143,161,500 12,9152

Coal ashes Burning of coal for steam generation Shipped to landfill 32,000,000 98,700

Spent oils Changing of lubricating oils Recycled offsite 2,300 1,500

1 Includes waste treatment, disposal, and handling costs and lost materials values.

2 Estimated cost of individual waste stream. Additional surcharges of $113,410/yr are incurred for BOD and suspended solids.
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Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Reduced Quantity (lb/yr) Percent Savings Cost Payback (yr)

Install a packaged CO2 recovery Carbon dioxide 106,240,000 100 $1,248,2001,2 $2,600,00 2.1

plant to recover CO2 and ethanol from fermentors

vented from the fermentors. Sell Ethanol from 573,700 90

the recovered liquified CO2 to a fermentors

CO2 distributor. Recovered

water/ethanol can be sent to the

beer well to be further processed.

Recover ethanol vent losses from Ethanol from condensers 567,500 90 7,3601,3 16,600 2.3

the still condensers using a

refrigerated water-cooled condenser.

Use the recovered ethanol as a

supplemental fuel in the boilers.

Replace the currently used ion Water, acid, and caustic 3,572,940 100 2,7401,4 160 0.1

exchange system with a reverse

osmosis unit that is available onsite for demineralizing water.

Recover ethanol from the ware- Ethanol from barrel 2,375,191 93 864,2101,3 831,000 1.0

house exhaust air using carbon breathing

adsorption and steam stripping

and distillation. Return the recovered ethanol to the beer well.

Ship coal ash to a nearby cement Coal ash 32,000,000 100 68,300 0 0

kiln that can use the ash as a raw

material instead of shipping it to a

landfill.

1 Total annual savings have been reduced by the operating cost required for implementation.

2 If a tax is imposed on CO2 emissions in the future, the savings from this WMO would be even higher. 3 If a tax is imposed on VOC emissions in the future, the savings from this WMO would be even higher.

4 It is possible that this plant will be reclassified as a hazardous waste generator in the future because of new regulations concerning the pH of regenerant material.

 In that case, savings from this WMO would be even higher.
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United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

EPA/600/S-95/010

Official Business

Penalty for Private Use

$300

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35