&EPA United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati, OH 45268 Research and Development EPA/600/S-92/028 Sept. 1992 ENVIRONMENTAL RESEARCH BRIEF Waste Minimization Assessment: for a Manufacturer of Industrial Coalings Marvin Fleischman and Dermont J. Collins", 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 waste but who lack the expertise to do so. Waste Minimization Assessment Cen- ters (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). The WMAC team at the University of Louisville performed an assessment at a plant manufacturing industrial coatings — approximately 2,700,000 gal/yr. The products are diversified, being made in batches of varying size to meet customer speci- fications. Pigments are milled as needed, and batches are prepared by controlled mixing of solvents, resins, pigments or dyes, and additives. The products are packaged in small con- tainers, drums or*tanker trucks, or held in bulk storage tanks. The team's report, detailing findings and recommendations, indicated that most waste occurred as solvent loss by evapo- ration and as residual solvent in emptied containers, and that the greatest savings could be obtained by fitting batch tanks with covers and submerged-filling tubes to reduce vapor losses and storing solvent drums on an incline to reduce residual solvent remaining in drums. This Research Brief was developed by the principal investiga- tors and EPA's Risk Reduction Engineering Laboratory, Cin- cinnati, 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. 'University of Louisville, Department of Chemical Engineering " University City Science Center, Philadelphia, PA Introduction The amount of waste generated by industrial plants has be- come an increasingly costly problem for manufacturers and an additional stress on the environment. One solution to the prob- lem of 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 waste but who lack the inhouse 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 ex- perience 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 inhouse expertise in waste minimization. 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 experience1 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 pro- 066 Printed on Recycled Paper ------- cedures outlined in the EPA Waste Minimization Opportunity Asssssment 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 tech- nological and economic information is developed. Finally, a confidential report that details the WMAC's findings and rec- ommendations (including cost savings, implementation costs, and payback times) is prepared for each client. Plant Background The plant produces industrial coatings including stains, var- nishes, and pigmented products. It operates 2,000 hr/yr to produce approximately 2,700,000 gallons. Manufacturing Process This plant produces lacquer and varnishes; solvent-based and water-based pigmented metal, wood, and plastic finishes; and stains. The raw materials include resins, fillers, milling pastes, pigments, dyes, sealers, nitrocellulose, and solvents. Solvents used are methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, mineral spirits, and alcohol. The coatings are made in batches. The following steps are involved: • Tint pastes are prepared by grinding pigments with solvent in ball mills and sand mills. The mills are cleaned with a solvent-resin mixture to be used in the batch. • Other raw materials for the batch are charged to a mixing tank. • The batch is mixed, and the tints are added to adjust the color to specifications. • The batch is filtered to remove large particles and dirt and packaged in designated containers. • The mixing tank is cleaned to prepare for the next batch. An abbreviated process flow diagram is shown in Figure 1. Existing Waste Management Practices This plant already has taken the following steps to manage and minimize its wastes: • The plant uses offsite solvent reclamation, purchasing the recovered solvent for use in cleaning equipment. Off-spec and obsolete products are reworked into saleable prod- ucts. • A still Is used to recover spent wash solvent onsite. • A trial lid is under test on batch tanks to reduce evapora- tion losses and avoid dust loss when charging pigments. • A sweep-blade mixer with attached squeegees is used to minimize the amount of solvent needed for cleaning the. batch tank after mixing high-viscosity materials. • The final solvent charge used to expel the last remaining tint paste from a milling machine is incorporated into the product formulation and not disposed of as spent solvent. 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 times 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. It should be noted that, in most cases, the economic savings of the minimization opportunities result from the need for less raw material and from reduced present and future costs associated with hazardous 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 should also be noted that the savings given for each opportunity reflect the savings achievable when implementing each waste minimization opportunity indepen- dently 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 consid- ered. These measures were not analyzed completely because of insufficient data, implementation difficulty, or a projected lengthy payback as indicated below. 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. • Use a commercial alkaline cleaner instead of aqueous caustic to clean process materials buildup from the floor. Because the alkaline cleaner solutions are more effective, a 50% reduction in the volume of cleaning waste is ex- pected. • Use the same alkaline cleaner instead of solvent to clean up small spills that occur in daily operation. • Dispose of collected pigment dust through a waste ex- change. Pigment dust is now disposed of in a landfill and is regulated as a hazardous waste. • Use dedicated drip pans for particular raw materials in the drum storage area, so collected material can be used in product batches. At present the collected materials are combined and disposed of as spent solvent. • Make repeated use of wash solvent to reduce the amount of solvent that must be purchased or reclaimed. Such multiple use would require separation of solids present (by decanting, filtering or centrifuging). At present, wash sol- vent is used only twice. • Implement procedures for complete discharge of material from drums. This would result in additionaf charges for labor or equipment. • Recover solvent vapors now lost as fugitive and stack emissions. This would require installation of equipment, possibly at the point of emission of individual solvents. 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. ------- Solvents Raw Materials Lacquers, Paints, Stains to Customers Figure 1. Abbreviated process flow diagram. Table 1. Summary of Current Waste Generation Waste Generated Source of Waste Annual Quantity Generated Annual Waste Management Cost Pigment dust Residual pigment in bags Sludge and still bottoms Solvent vapors Residual solvents in containers Drum leakage Spent filter cartridges Discarded bags and spent filter media Used staging pails from prebatching Pigment dust from process dust collectors, bag breakage, and sweepings is disposed of as hazardous waste. Empty bags with residual pigment are disposed of as landfill. Sludge and bottoms from distillation of spent cleaning solvent are disposed of in a fuels or incineration program. Volatile solvents are lost by evaporation from mixing tanks and from pigment mills operated at 140 "C or higher. Solvents are lost in discarded or recycled containers. Drum leakage is collected and combined with spent wash solvent for distillation recovery by a recycler. Filter cartridges are used once and disposed of as landfill. Spent filter units are dried and disposed of with empty pigment bags as landfill. Used pails are disposed of with nonhazardous trash as landfill. 6,000 Ib 44,200 Ib 13,250 gal 27,518 gal 19,018 gal 9,1W gal 8,840 pcs Unknown 48,620 pcs $39,600 44,200 33,532 68,797 63,710 30,540 54,785 680 104,039 •fru.3. GOVERNMENT PMNTING OFFICE: IttM - 550-067/80154 ------- Table 2. Summary of Recommended Waste Minimization Options Identified Waste Generated Used staging pails from prebatching Used staging pails from prebatching Solvent vapors Minimization Opportunity Use a solvent spray washer to clean the pails for reuse instead of discarding them. The used pails can be taken by a metal scrap recycleratno charge. Install lids on coating Annual Waste Reduction Quantity Percent 39,000 pcs 48,620 pcs 26,053 gal 80 100 95 Net Annual Savings $71,330 13,584 65,000 Implementation Costs $53,320 0 300 Payback Years 0.5 0 0.0 Spent cartridge filters Residual pigment In bags Solvent vapors batch tanks to reduce solvent vapor losses. Replace disposable 8,840 pcs 100 51,887 cartridge filters with reusable stainless steel filters. Shake or scrap the bags 33,165 Ib 75 28,100 for more complete discharge of the pigment. Modify process tanks for 4,655 gal 50 11,638 submerged-filling (through a dip tube) to reduce vapor loss. 6,640 3,202 0.1 0.3 Residual solvent In drums Incline solvent drums to reduce the residual heel of solvent. 4,559 gal 25 15,270 794 0.1 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 EPA/600/S-92/028 ------- |