4>EPA
                        United States
                        Environmental Protection
                        Agency   	
                                       Risk Reduction
                                       Engineering Laboratory
                                       Cincinnati OH 45268
                        Research and Development
                                       EPA/600/S-92/022  May 1992
ENVIRONMENTAL
RESEARCH   BRIEF
         Waste Minimization Assessment for a Manufacturer Producing
                                Treated Wood Products


                           F. William Kirsch and J. Clifford Maginn, Jr.*
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 hazardous waste but
who lack the expertise to do so. Waste Minimization Assess-
ment Centers (WMACs) were established at selected universi-
ties and procedures were adapted from the EPA Waste Minimi-
zation Opportunity Assessment Manual (EPA/625/7-88/003, July
1988).  The WMAC team at Colorado State University per-
formed an assessment  at a  plant producing treated wood
products—approximately 1,700,000 ft 3/yr. Railroad crossties
and poles are treated with creosote in pressure cylinders to
increase their serviceability under conditions that promote de-
cay, weathering, insect destruction, or exposure to fire.  Lum-
ber is treated by Wolmanizing, a closed loop process in which
a 2% chromated copper arsenate solution is used for treatment
in a pressure cylinder.  The team's report, detailing findings
and recommendations, indicated that most waste was gener-
ated in the creosote treatment process, and also that cost
savings could be obtained by arranging an exchange of accu-
mulated bark and wood chips with others who use wood scrap
as a raw material.

This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, OH, to announce key findings of an ongoing research
project that is fully documented in a  separate report of the
same title available from the authors.
• University City Science Center, Philadelphia, PA 19104
                        Introduction
                        The amount of hazardous 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 hazardous waste 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 formation of hazardous waste but
                        who lack the  in-house expertise  to do so.  Under agreement
                        with EPA's Risk Reduction Engineering  Laboratory, the Sci-
                        ence Center has established three WMACs. This assessment
                        was done by engineering faculty and students  at Colorado
                        State University's (Fort Collins) WMAC. The assessment teams
                        have considerable direct experience with process operations in
                        manufacturing plants and also have the knowledge and skills
                        needed to minimize hazardous 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 $50 million, employ no more than
                        500 persons, and lack in-house  expertise in waste minimiza-
                        tion.
                                                                            Printed on Recycled Paper

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The potential benefits of the pilot project include minimization
of the amount of waste generated by manufacturers, reduced
waste treatment and disposal costs  for participating  plants,
valuable experience for graduate and undergraduate students
who participate in the  program, and a cleaner environment
without more regulations and higher costs for manufacturers.


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 Opportu-
nity Assessment Manual (EPA/625/7-88/003, July 1988).  The
WMAC  staff  locates the sources of hazardous waste in the
plant and Identifies 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, imple-
mentation costs,  and payback times) is  prepared for each
client.


Plant Background
The plant produces treated wood products. It operates 8,760
hr/yr to process approximately 1,700,000 ft 'Vyr of wood.


Manufacturing Process
The plant treats crossties and poles with creosote and No. 6 oil
in heated pressure cylinders.   Lumber is treated with  2%
chromated  copper arsenate solution  in a pressure cylinder.
The raw materials used are the wood products, creosote, No. 6
oil, and chromated copper arsenate.  Steam is used for clean-
ing the surface of the wood in the creosote treatment cylinders,
and ozone is used to destroy phenols in the steam conden-
sate.

The following steps are involved in treating the wood products:

  • Crossties and poles  are trimmed on the ends and
    stacked on rail trams which are pushed into a pres-
    sure treatment cylinder.

  • A heated mixture of 50% (v/v) creosote and No. 6  oil
    is pumped into the cylinder and pressured to force the
    liquids into the wood cells.

  • The liquid is drained from the cylinder and held for re-
    use.

  • The cylinder is flooded with steam to clean excess
    creosote and oil from the surface of the wood.  A
    vacuum is drawn on the cylinder to enhance removal
    of the liquid from the wood and the cylinder.

  • Steam condensate drains to a blowdown tank.  Re-
    sidual creosote and oil that drains when the cylinder is
    opened is pumped to the blowdown tank.  The creo-
    sote is separated from the condensate and held for
    re-use.

These steps are involved in treating lumber:

  • Lumber is stacked on rail trams which are pushed into
    a pressure treatment cylinder.
  • A closed-loop Wolmanizing process with 2% chromated
    copper arsenate is used for treatment.  The cylinder is
    pressurized to 125 psig.

  • Solution drained from the cylinder is held for re-use.

Steam condensate from creosote treatment is treated with a
flocculant to settle contained creosote, and the pH is adjusted
to 3.6  - 4.0.  An  ozone treatment is used  to  break down
phenols in  the steam condensate before it is discharged as
industrial wastewater.  Creosote wastes are  also generated
from periodic steam cleaning of the treatment cylinders.  No
steam is used in cleaning the Wolmanizing cylinders. Accumu-
lated waste containing chromated copper arsenate is disposed
of as hazardous waste.


Existing  Waste Management Practices
  • Cylindrical tanks holding creosote and chromated cop-
    per arsenate have been fitted with conical  bottoms for
    accumulation of sludge, minimizing the need  for peri-
    odic cleaning.
  • The Wolmanizing pressure cylinder does  not require
    steam  cleaning,  lessening the quantity of contami-
    nated waste.
  • Storage tanks are heated to maintain proper viscosity
    and reduce sludge formation.

Waste Minimization  Opportunities
The type of waste currently generated by the plant, the source
of the waste, the quantity of the waste, and the annual man-
agement costs are given in Table 1.

Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the plant. The type of waste,
the minimization opportunity, the possible waste reduction and
associated savings, and the implementation cost along with the
payback time are given  in the table. The quantities of hazard-
ous 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.'


Additional Recommendations
In addition to the opportunities recommended and  analyzed by
the WMAC  team, three  additional measures were considered.
These  measures were  not  analyzed completely  because of
insufficient data or low projected savings. Since one or more
of these  approaches to waste  reduction may, however, in-
crease in attractiveness with changing conditions  in the plant,
they were brought to the  plant's attention for future consider-
ation.

  • Use steam condensate from creosote treatment as
    boiler feedwater.
  • Collect creosote  drainage generated when the cylin-
    ders are opened for removal of crossties and  poles.
  • Preclean the crossties and poles before treatment to
    reduce the quantity of creosote sludge generated when
    the cylinders are cleaned.

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. Environmen-
tal Protection Agency.  The EPA  Project Officer was Emma
Lou George.

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Table 1. Summary of Current Waste Generation

Waste Generated                          Source of Waste
                                                                                        Annual Quantity
                                                                                           Generated
                                                                   Annual Waste
                                                               Management Cost
Spent chromated copper
arsenate solution
Water and creosote mixture
Creosote sludge
Bark and wood chips
                                Residual solution collected when cleaning                       280 gal
                                the Wolmanizing pressure cylinder used for
                                treatment of lumber is disposed of as
                                hazardous waste.

                                Steam condensate from cleaning of creosote-treated          720,000 gal
                                crossties and poles to remove excess creosote is
                                treated with a flocculant, settled and decanted,
                                treated with ozone and caustic soda, and  •
                                discharged as industrial wastewater.

                                Cleaning of the creosote treatment cylinders                   16,550 gal
                                results in a creosote sludge.  Part of the
                                sludge is shipped for use as boiler fuel,
                                and the remainder is disposed of as
                                hazardous waste.

                                Chips, bark, and wood trimmings are stored                    9,750 yd3
                                in an open area on leased property awaiting
                                disposal.
                                                                                                                       $700
                                                                                                                       4,175
                                                                                                                      16,625
                                                                                                                        1,200
 Table 2. Summary of Recommended Waste Minimization Opportunities


                  Minimization Opportunity
  Waste
Generated
    Annual Waste Reduction
 Quantity            Percent
Net Annual Implementation     Payback
  Savings        Cost           Years
Bark and wood
                 Arrange a waste
                 exchange with
                 others who use
                 wood scraps as
                 raw material.
9,750 yd3
                                                                        100
  $1,200
                                                                            •itV.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40273

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United States                                   Center for Environmental                          BULK RATE
Environmental Protection                         Research  Information                       POSTAGE & FEES PAID
Agency                                        Cincinnati, OH 45268                         EPA PERMIT NO. G-35

Official Business
Penalty for Private Use $300

EPA/600/S-92/022

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