United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati OH 45268 Research and Development EPA/600/S-92/020 May 1992 &EPA ENVIRONMENTAL RESEARCH BRIEF Waste Minimization Assessment for a Manufacturer of Motor Vehicle Exterior Mirrors 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 exterior motor vehicle mirrors approximately 3 million mirrors per yr. Galvanized steel and stainless steel stock undergo stamping, pressing, and cutting operations followed by degreasing. Stainless steel mirror housings are buffed, assembled, packaged, and shipped. Galvanized steel, zinc die-cast, and plastic mirror parts are washed then electrostatically primed and painted. Parts are assembled, packaged, and shipped. The team's report, detail- ing findings and recommendations, indicated that the majority of the waste was generated in the cleaning and washing areas but that the greatest savings could be obtained by installing an electrostatic powder coating system to reduce primer/paint overspray (100%), solvent evaporation (55%), cleaning solvent evaporation (80%), and still bottoms (80%). 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. Introduction The amount of waste generated by industrial plants has be- come an increasingly costly problem for manufacturers and an University City Science Center, Philadelphia, PA 19104 additional stress on the environment. One solution to the problem 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 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 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. 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- ^g£> Printed on Recycled Paper ------- nhy 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 th'e essential supporting technological and economic information is developed. Finally, a confidential reportjhat details the WMAC's findings and recommendations (including cost savings, imple- mentation costs, and payback times) is prepared for each client. Plant Background This plant manufactures exterior mirrors for motor'vehicles. The plant operates 6,120 hr/yr to produce approximately 3 million mirrors. Manufacturing Process This plant takes galvanized and stainless steel stock and forms ft into mirror housings for use on both automobiles and trucks. Raw materials in use include sheets and rolls of galvanized steel, stainless steel, zinc die-cast parts, plastic stock, hard- ware, and mirror glass. The following steps are involved in making the mirrors: Raw materials undergo stamping, pressing, and cutting operations to form mirror housings and arm braces. Galvanized steel mirror housings and parts and stainless steel mirror housings are rinsed in water to remove any residual dirt or grease. Buffing stones are added to the tank for parts degreasing to aid in the removal of dirt and grease. Contaminated water from the degreasing opera- tion is sent to the plant's on-site water treatment facility. The degreased stainless steel mirror housings are me- chanically buffed. Spent buffing compound, metallic waste, and soiled cleaning rags are discarded in municipal waste. Degreased galvanized steel parts, zinc die-cast parts, and high temperature plastic parts are cleaned and their sur- faces are prepared for priming and painting in a nine-stage washer. The nine-stage washer consists of an alkaline- wash tank followed by two water rinse tanks, a titanium conditioner tank, a zinc phosphate-accelerator additive tank for further surface preparation followed by a water rinse tank, and a chromic acid rinse tank followed by two water rinse tanks. Contaminated wash and rinse water is sent to the on-site water treatment facility. Spent ion-exchange columns used to produce deionized water are taken off- site by an outside contractor. After the nine-stage washer process, galvanized steel, zinc die-cast, and high temperature plastic parts are electro- statically primed, dried, electrostatically painted, and dried again before assembly. Primer and paint overspray is collected on plastic sheets which are disposed of in mu- nicipal waste. Other plastic parts are cleaned and prepared for painting in a five-stage washer. The five-stage washer consists of a heated water-rinse tank, three currently unused stages, and a conductive surface treatment tank. Contaminated water is sent to the on-site treatment facility. Following the five-stage washer process, plastic parts are electrostatically painted and dried before assembly. Paint overspray is deposited on paint booth filters which are disposed of in municipal waste. Contaminated water received from various areas of the plant is treated in the on-site facility. First, hydrochloric acid is added to the water to reduce its pH. Contaminants precipitate from the water and collect as sediment which is piped to a filter press to remove water. The water which is removed is directed back to the treatment tank, then pumped to a second tank where additional sediment is collected. That sediment is also processed in the filter press. The water is then passed through an ion-exchange column to remove residual heavy metals before being released to the municipal sewer. Existing Waste Management Practices Only non-hazardous primer and paint products are used. Contaminated water generated on-site is treated within the plant before being released to the municipal sewer. Hexavalent chrome which is used in one stage of the nine- stage washer is converted to the less hazardous form of trivalent chrome prior to water treatment. A portable distillation unit recycles spent solvent generated by the spray gun and paint-line cleaning. Electrostatic primer and paint application systems maxi- mize paint application efficiency. 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 em- ployee 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 sayings that would result when the opportunities are implemented in a package. 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 Waste Generated Source of Waste Contaminated wash water Degreasing of galvanized steel and stainless steel components. Spent buffing compound and Buffing of stainless steel components metallic waste Contaminated wash and rinse water Nine-stage washer. Spent ion exchange columns Nine-stage washer. Evaporated solvents Primer and paint application Primer and paint overspray collected Primer and paint application. on plastic sheets Contaminated water Five-stage washer. Paint overspray collected on filters Paint application. Sediment Water treatment facility. Evaporated solvent Spray gun and paint-line cleaning. Still bottoms Distillation unit for recovering spray gun and paint line cleaning solvent. Primer and paint ash Bum-off oven for cleaning parts racks. 1~The plant reports no waste management cost associated with solvent evaporation. Table 2. Summary of Recommended Waste Minimization Opportunities Annual Waste Reduction Waste Stream Reduced Minimization Opportunity Quantity Percent Evaporated solvent and Install an electrostatic 12 bbl1 100 primer and paint powder coating system 3,076 gal2 55 overspray collected on to replace painting of gal- 766 gal3 80 plastic sheets. vanized steel and zinc 616 gal4 80 Annual Quantity Annual Waste Generated Management Cost 142,800 gal $7,688 1,123 bbl 5,100 797, 150 gal 9,188 24 units 9,057 5,620 gal O1 12 bbl 8,925 10,200 gal 4,687 6,375 filters 8,925 162 bbl 26,688 957 gal 01 770 gal 15,097 3,825 Ib 7,687 Net Implementation Payback Annual Savings Cost Years $113,418 $236,880 2.1 Contaminated wash and rinse water from the nine-stage washer. Evaporated solvent. Contaminated wash and rinse water from the degreasing, five-stage, and nine-stage washing processes. Contaminated wash and rinse water from the nine-stage washer. Sediment from the water treatment facility. die-cast parts. Install a metal recovery 8 bbl5 5 system (an ion-exchange or electrodialysis system) to recover and reuse zinc phosphate from the nine- stage washer. ' Recover solvent from the 3.794 gal 68 paint curing oven stacks using a freon-refrigeration system, Construct a water recir- 855,135 gal 90 culating system in conjunction with the on- site treatment facility. Install air curtains in the 79,715 gal 10 nine-stage washer to 13 bbl5' 8 reduce solution con- tamination and loss. Use a gas-fired dryer 138 bbl 85 to dry the solid waste from the filter press before shipping the waste off-site. 17,349 74,600 4.3 11,337 11,027 7,197 8,199 104,000 42,760 6,500 40,000 9.2 3.9 0.9 4.9 1 Primer/paint overspray 2Solvent 3Cleaning solvent 4Still bottoms 5Sediment 3 GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40256 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 BULK RATE POSTAGE & FEES PAID EPA PERMIT NO. G-35 Official Business Penalty for Private Use $300 EPA/600/S-92/020 ------- |