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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That document has been superseded by the Facility Pollution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 manufactures bourbon whiskey and distiller

dried grains as a byproduct from corn, rye, and malt. The

grains are milled, mixed together, and cooked. Then the resulting mixture is allowed to ferment. After fermentation, the mixture is processed in a distillation column. The distillate is

diluted to proper proof and placed in charred barrels for aging.

After an appropriate storage period, the barrels are emptied

and the contents are shipped in tank trailers. The team’s

report, detailing findings and recommendations, indicated that

large quantities of CO2

 and ethanol are vented from the plant

and that significant cost savings could be achieved through

CO2

 and ethanol recovery.

This Research Brief was developed by the principal investigators and EPA’s Risk Reduction Engineering 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

Risk Reduction Engineering 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 waste minimization 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 waste minimization.

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.

Waste Minimization Assessment for a Bourbon Distillery

United States

Environmental Protection

Agency

Risk Reduction

Engineering Laboratory

Cincinnati, OH 45268

ENVIRONMENTAL

RESEARCH BRIEF

Research and Development EPA/600/S-95/002 April 1995

Marvin Fleischman*, Michael Parris*,

Eric W. Daley**, 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 waste minimization 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

The plant produces bourbon whiskey and distiller dried grains

from corn, rye, and malt. It operates three shifts/day to produce

approximately 5 million gal of bourbon and over 16,000 tons of

distiller dried grain/yr.

Manufacturing Process

The basic raw materials—corn, rye, and malt—are milled in

hammer mills and fed to cookers. Water and setback (thin

stillage from the drying of spent grain after the alcohol and

large solids have been removed) are added and the resulting

mixture is cooked. During cooking, the starch in the corn and

rye is converted to sugar. After the conversion has taken place,

the mixture (known as mash) is pumped to a fermenter where

yeast is added to complete the conversion of sugar to alcohol.

Upon completion of the fermentation cycle, the mash (or beer)

is pumped to an intermediate tank called the beer well.

The contents of the beer well are pumped to the distillation

column where the alcohol is steam stripped from the beer. The

steam stripper distillate is condensed and pumped to the doubler for final distillation. Distillate from the doubler is condensed

and pumped to the barrel-filling operations; spent grain is

pumped to the dry house for processing.

At the barrel-filling facility, the distillate is diluted to proper

proof with demineralized water. Barrels (of charred new white

oak) are filled with the diluted distillate and transported to the

warehouse for aging.

During the storage period (a minimum of four years), the

material in the barrel goes through a maturation or aging

process by which the distillate is transformed into a bourbon.

When the product in the barrel is determined to be of proper

quality, the barrel is transported to the dumping area. There

the contents of the barrel are poured through steel screens for

removal of solids. The product is then pumped to one of two

storage tanks from which it is loaded into tank trailers for

shipment.

Spent grain from the distillation operations is processed into

distiller dried grain (an animal feed additive) in the dry house.

The spent grain is processed in centrifuges where the solids

are concentrated and the excess water (centrate) is removed.

The concentrated solids are fed to an air dryer and the centrate

is pumped to an evaporator where the dissolved solids are

concentrated. The viscous discharge (syrup) from the evaporator is mixed with a portion of the dried grain stream as it is

recycled back to the dryer. The portion of the dried grain

stream not used as recycle is conveyed to one of two storage

silos if the moisture content is satisfactory.

An abbreviated process flow diagram for this plant is shown in

Figure 1.

Waste Management 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 waste minimization that the

WMAC team recommended for the plant. The minimization

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 minimization opportunity, in most cases, results from the need for less

raw material 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 employee health. It also should be noted that the savings

given for each 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 completely analyzed because

of insufficient data, minimal savings, implementation difficulty,

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

approaches to waste reduction may, however, increase in

attractiveness with changing conditions in the plant, they were

brought to the plant’s attention for future consideration.

• Seal the grain leaks found throughout the conveying operations.

• Install a shutoff mechanism that provides a tighter seal at the

discharge of the milled grain hoppers in order to reduce grain

losses.

• Control ethanol emissions from storage tanks.

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.
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Corn,

rye,

malt

Grain

storage

Grain

milling Mashing Mashcoolers

Distillation Fermentation

Spent

grains

Spent grains

separation

Thick slop

drying

Thin slop

evaporation

Distiller dried

grains shipped

Distillate

Doubler

Barrel

filling

Product

aging

Barrel

dumping

Bourbon

shipped

Figure 1. Abbreviated process flow diagram for bourbon whiskey production.
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Table 1. Summary of Current Waste Generation

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

Generated Management Cost1

(lb/yr)

Grain losses Raw material handling Shipped offsite to landfill 24,000 $6,000

Carbon dioxide Fermentation Vented from plant 25,680,000 0

Ethanol Fermentation Vented from plant 205,920 43,680

Wastewater Fermentation tank cleaning Treated in onsite WWTP; discharged to creek 846,600 —-2

Ethanol Distillation Vented from plant 228,100 48,000

Spent caustic Cleaning of distillation equipment Treated in onsite WWTP; discharged to creek 830,000 —-2

Spilled ethanol Barrel filling Evaporates 1,040 660

Char Charring of new barrels Shipped offsite to landfill 480 ft3/yr 40

Ethanol Warehoused barrels Vented from plant 3,181,080 1,020,540

Char/bungs Emptying of barrels and filtering of contents Mixed with coal; incinerated in onsite boiler 60,000 0

Filter pads Filtering of barrel contents Shipped offsite to landfill 3,200 pads/yr 40

Scrubber solids Dry house air scrubber Shipped offsite to landfill 3,000 1,090

Scrubber water Dry house air scrubber Treated in onsite WWTP; discharged to creek 149,400 —-2

Spent caustic Dry house cleaning Treated in onsite WWTP; discharged to creek 415,000 —-2Slop Dry house Sold to farmers 640,000 gal/yr -7,000

` (revenue received)

Distiller dried grain losses Truck loading, equipment leakage Shipped offsite to landfill 200,000 17,000

Wastewater Boiler feedwater treatment Treated in onsite WWTP; discharged to creek 4,191,500 —-2

Wastewater Boiler blowdown Treated in onsite WWTP; discharged to creek 24,000,000 —-2Spent liquids Demineralizer regeneration Treated in onsite WWTP; discharged to creek 664,000 —-2Ashes Coal-fired boiler Shipped offsite to landfill 129,600 ft3/yr 17,600

Ethanol Storage tanks Vented from plant 11,780 5,230

Spent oils Equipment lubrication Shipped offsite 275 gal/yr 125

Spent mineral spirits Parts cleaning Shipped offsite for recycle 235 gal/yr 1,460

Cloth filters Dust collectors Shipped offsite to be cleaned; returned for reuse 110 filters/yr 380

1 Includes waste treatment, disposal, and handling costs and applicable lost raw materials value.2 Cost is included in the annual WWTP operating cost of $118,300/yr.
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Table 2. Summary of Recommended Waste Minimization Opportunities

Annual Waste Reduction

Net Annual Simple Payback

Minimization Opportunity Waste Reduced Quanity (lb/yr) Per cent Savings Implementation Cost (yr)

Install air ducting from the storage Grain losses 4,800 20 $1,200 $3,000 2.5

hopper vents to the inlet of an

existing pulsating dust collector

in order to minimize grain losses

from the vent lines.

Modify the metal funnel apparatus Grain losses 1,200 5 300 500 1.7

used during grain unloading from

the railcars in order to reduce grain

losses.

Install a recovery plant to recover Carbon dioxide 20,160,000 79 223,6001 930,000 4.22

CO2 and ethanol from the fermenters. (from fermentation)

The recovered liquefied CO2 can be Ethanol (from fermentation) 161,700 79sold to a distributor or an end-user

as a food and beverage grade

product. Recovered ethanol can

be sold to a fuel alcohol facility or

used as supplemental fuel onsite.

Install a refrigerated water-cooled Ethanol (from distillation) 228,100 100 19,800 39,000 2.02

condenser on the vent discharges

from the distillation process in order

to recover ethanol. Use the recovered

ethanol onsite as a supplemental fuel.

Recover ethanol emissions from the Ethanol (from warehousing) 2,900,000 90 495,380 2,050,000 4.12

barrel warehouse using activated carbon

adsorption. Redistill the recovered

ethanol and sell the product obtained.

Replace the loading apparatus currently Distiller dried grain losses 2,000,000 100 17,000 45,000 2.7

used for loading the distiller dried grains

with a telescoping loading nozzle in order

to reduce grain losses.

1 Exact savings may vary from this estimate depending on the exact price obtained for the CO2.2 A much shorter payback will be realized should a carbon emissions tax and/or a VOC emissions tax or permit for ethanol be required in the future.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/002