&EPA United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati OH 45268 Research and Development EPA/600/S-92/017 June 1992 ENVIRONMENTAL RESEARCH BRIEF Waste Minimization Assessment for a Manufacturer of Military Furniture F. William Kirsch and Gwen P. Looby* 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 Tennessee performed an assessment at a plant manufacturing military furnitureap- proximately 12,000 units/yr. Wood and formica are laminated together via glue curing and then undergo woodworking opera- tions including cutting, drilling, and routing. Finished boards are either packaged and shipped or transported to assembly. Metal stock is cleaned with solvent and then undergoes various metalworking operations. Metal pieces are partially assembled, painted, then either packaged and shipped or transferred to assembly before being packaged and shipped. The team's report, detailing findings and recommendations, indicated that the majority of waste was generated during the painting opera- tions and that the greatest savings could be obtained by installing an electrostatic powder coating system to completely eliminate paint solvent evaporation, paint solids waste, and paint-laden air filters. 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 document of the same title available from the authors. 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 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 Tennessee's (Knoxville) WMAC. The assessment teams have considerable direct experience with process operations in manu- facturing 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 $50 million, employ no more than 500 persons, and lack in-house expertise in waste minimiza- tion. 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. GyD Printed on Recycled Paper University City Science Center, Philadelphia, PA 19104 ------- Methodology of Assessments The waste minimization assessments require several site visits to each client served. In general, the WMACs follow the proce- dures outlined in the EPA Waste Minimization Opportunity Assessment Afanoa/(EPA/625/7-88/003, July 1988). The WMAC staff locates the sources of 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 tech- nological and economic information is developed. Finally, a confidential report that details the WMAC's findings and recom- mendations (including cost savings, implementation costs, and payback times) is prepared for each client. Figure 1 shows a simplified process flow diagram of the operation of the plant. Plant Background The plant manufactures military-specification furniture for use in military barracks. Ninety employees operate the plant 2,080 hr/yrto produce approximately 12,000 units of furniture annu- ally. Manufacturing Process The plant produces wooden, wood with steel frame, and steel furniture. Raw materials include heavy-density particle board, steel frame, rolls and strips of sheet steel, formica, and as- sorted hardware. ! j Unit operations performed in processing wood include the following: Raw wood and formica are glued together to form a laminate. Several laminations are then positioned in a press for glue curing. Next, the boards undergo vari- ous woodworking operations including cutting, drilling, and routing. Boards are either transferred to assembly or directly packaged and shipped. ; Metal processing involves the following unit operations: Metal stock is cleaned by immersion in a toluene dip tank. Waste from this process includes evaporated , toluene and sludge containing toluene, grease, and dirt, which is pumped from the bottom of the tank. After cleaning, the metal undergoes various metal- working operations including cutting, punching, fold- Wood/Formica Laminating Woodworking Metal Stock Dipped in Toluene 2*. ^ Solvent Evaporation and Sludge Generation V Partial Assembly Wastewater 5-Stage Cleaning Dip Painting Paint Waste and Wastewater £ Spray Painting Assembly Package and Ship Flgun 1. Simplified process flow diagram. ------- ing, and welding. Pieces are partially assembled, then transferred to one of two spray-paint lines or a dip- paint line. In the spray-paint line, parts undergo a five-stage cleaning in preparation for spray-painting. The first stage is an alkaline-wash tank held at 110°F. That wash stage is followed by a rinse tank. Next, parts are sprayed with an iron phosphate solution. The fourth stage is a rinse tank, fn the final stage, parts are sprayed with a rust preventive. After cleaning, the parts are conveyed first through a dry-off oven and then through the spray-painting process. In spray-painting, paint is applied to the parts with hand-held spray guns. The paint booths are equipped with continuously recirculating water curtains to en- trap paint overspray. Entrapped paint solids and waste- water are dumped to a holding tank periodically. Air filters which are used in two of the four booths to collect overspray are also disposed of periodically. After painting, the parts are conveyed through a dry- off oven and undergo further assembly. Small metal parts are dip-painted, allowed to air dry, and then transferred to the assembly area. Assembly and packaging. Existing Waste Management Practices A steam-cleaning operation to eliminate the five-stage cleaning of some metal parts is being investigated. The use of dip-painting has been minimized. 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 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 waste treatment and disposal. Other savings not quantifi- able 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 imple- menting 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, two additional measures were considered. These measures were not analyzed completely because of insufficient data or minimal savings as indicated below. They were brought to the plant's attention for future reference, how- ever, since these approaches to waste reduction may increase in attractiveness with changing plant conditions. If the spray paint process is not replaced as recom- mended in the WMOs, there are two other possible improvements to be considered. A state-of-the-art dip paint line with safeguards to minimize paint dripping on floors could be installed to replace the paint lines. Another alternative is to switch from solvent-based to water-based paints. Use air-tight spray gun cleaning tanks to reduce evapo- rative losses of toluene. 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. Table 1. Summary of Current Waste Generation Annual Annual Quantity Waste Manage- Waste Generated Toluene sludge Evaporated toluene Evaporated paint solvent Paint-laden air filters Source of Waste Toluene-dip tank for cleaning of metal stock. The sludge, which contains toluene, grease, and dirt, is hauled offsite as a hazardous waste. Toluene-dip tank for cleaning of metal stock. Spray-paint booths. Spray-paint booths. Generated 715 gal 172 gal 915 gal 832 filters 3,390 gal paint ment Cost $8,230 0' 0> 1,020 Toluene sludge Evaporated toluene Paint solids Cleaning of paint guns. The sludge, which contains toluene and paint, 55 gal 630 is hauled offsite as a hazardous waste. Cleaning of paint guns. 44 gal 0' Holding tanks which receive wastewater from the five-stage cleaner 7,515 gal 3,750 and the painting operation. ' According to plant personnel, there are no waste management costs associated with evaporation of solvents. U.S. Government Printing Office: 1992 648-080/60013 ------- Tsb!a2. Summary of Recommended Waste Minimization Opportunities Waste Stream Reduced Evaporated paint solvent Paint laden air filters Evaporated toluono Paint solids Toluene sludge Evaporated toluene Minimization Opportunity Install an electrostatic powder coating system to replace the paint-spray and dip- paint lines. The proposed system will provide more even coating of parts and easy collection and reuse of overspray powder. Protect the clean metal stock from environmental dirt to eliminate the need for subsequent cleaning In the toluene-dip tank. Annual Waste Quantity 915 gal 832 filters 3,390 gal paint2 44 gal 7,515 gal 715 gal 172 gal Reduction Percent 100 100 100 100 100 100 100 Net Imple- Annual ! mentation Savings Cost $49,770' 8,40V $145,880 3,800 Pay- back Years 2.9 0.5 Evaporated Repair the lid of the toluene-dip tank to toluene reduce evaporative losses. Institute a program to keep lid closed whenever possible. 86 gal 50 180' 100 0.5 Paint solids Re-install the existing electrostatic 2,210 gal 29 39.SSO'-3 spray paint system in building 4 and Install an electrostatic spray paint system in building 3. The electrostatic spray paint systems will be considerably more efficient than the current spray- paint systems. 66,900 1.7 * Paint associated with the spent air filters. 3 Total savings have been reduced by the operating cost of the proposed system. United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 i BULK RATE PQSTAGE & FEES PAID EPA PERMIT NO. G-35 r Official Business Penalty for Private Use $300 EPA/600/S-92/017 ! ------- |