vvEPA United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati, OH 45268 Research and Development EPA/600/S-94/011 September 1994 ENVIRONMENTAL RESEARCH BRIEF Waste Minimization Assessment for a Manufacturer of Aerial Lifts Harry W. Edwards*, Michael F. Kostrzewa*, 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. In an effort to assist these manufactur- ers Waste Minimization Assessment Centers (WMACs) were established at selected universities and procedures were adapted from the EPA Waste Minimization Opportunity As- sessment Manual (EPA/625/7-88/003, July 1988). That docu- ment has been superseded by the Facility Pollution Prevention Guide (EPA/600/R-92/088, May 1992). The WMAC team at Colorado State University performed an assessment at a plant that manufactures aerial manlifts, ventilating driers, and air driers. The production of aerial manlifts requires sawing, cutting, and machining of metal, zinc plating or painting, and assembly. For the most part, only assembly operations are required for production of the ventilating and air driers. The team's report, detailing findings and recommendations, indi- cated that the waste streams generated in the greatest quantity are spent rinse waters from plating and paint preparation, and the greatest cost savings could be achieved by replacing the currently used parts washer with a system that uses a less hazardous solvent. 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 University City Science Center. ' Colorado State University, Department of Mechanical 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 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 Colorado State University's (Fort Collins) WMAC. The assessment teams have consider- able direct experience with process operations in manufactur- ing 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 minimiza- tion. 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 participat- ing plants. In addition, the project provides valuable experi- ence for graduate and undergraduate students who participate in the program, and a cleaner environment without more regu- lations and higher costs for manufacturers. iŁ3) Printed on Recycled Paper ------- 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 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 support- ing technological and economic information is developed. Fi- nally, 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 This plant manufactures aerial manlifts (for use by electric and telephone utilities), ventilating driers, and air driers. Approxi- mately 1,500 aerial lifts and several thousand miscellaneous items are manufactured annually during approximately 4,000 hr/yr of operation. Manufacturing Process The production of ventilating driers and air driers requires mostly assembly operations, but aerial manlift production re- quires a significant number of manufacturing processes. Steel, in pipe, flat, and round stock form, is the raw material used in the greatest quantity in producing the lifts. Smaller quantities of aluminum, brass, copper, and bronze are also used. The steel stock is cut to length to form blanks using a power saw or a plasma cutting machine. Then the blanks are punched to the proper length and shape using presses. Addi- tional machining, including bending, welding, grinding, milling, drilling, and lathe working, follows. After machining, parts are either painted or zinc-plated. Parts that are to be zinc-plated are processed through a series of tanks containing solutions and rinses to clean, prepare, and plate the parts. Plated parts are sent to the assembly area. Many of the parts to be painted are processed in a five-stage preparation and painting system. In the prep and paint line, parts are mounted onto a conveyor system which carries them through various operations including washing, phosphating, rinsing, drying, spray painting, and baking. Other parts are painted in a standard paint-booth type system or a stand-alone paint/bake oven. In those systems, parts are placed inside the booth or oven and are painted in batches. All parts that are painted are baked in the bake oven. A significant amount of welding is required in the production of many of the products. Stock sheet metal is bent, punched, and form welded to produce the main structural members of the lifts. Sheet metal is welded to the structural components of the lifts. The lift parts are painted in the stand-alone paint booth. In the assembly area, painted, plated, and miscellaneous parts are assembled into finished products. Hydraulic fluid is pumped into reservoirs. The completed lifts are inspected, hydraulically tested, stored, and then shipped to customers. An abbreviated process flow diagram for the manufacture of aerial lifts is shown in figure 1. Existing Waste Management Practices This plant already has implemented the following techniques to manage and minimize its wastes. Spray-mist lubricant is used on the saw in order to avoid generating a hazardous waste stream. Scrap metal from the machining processes is recycled. Spent solvent generated in the painting area is recovered through distillation and reused. High-volume, low-pressure paint spray guns are used in the painting area thereby reducing overspray, paint usage, and solvent air emissions. Waste Minimization 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 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 simple payback time are given in the table. The quantities of waste currently generated by the plant and pos- sible waste reduction depend on the production level of the plant. All values should be considered in that context. ft should be noted that the economic savings of the minimiza- tion opportunity, in most cases, results from the need for less raw material and from reduced present and future costs asso- ciated 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 indepen- dently and do not reflect duplication of savings that may result when the opportunities are implemented in a package. Additional Recommendations In addition to the opportunities recommended and analyzed by the WMAC team, one additional measure was considered. This measure was not analyzed completely because of a projected lengthy payback. Since this. approach to waste reduction may, however, increase in attractiveness with chang- ing conditions in the plant, it was brought to the plant's atten- tion for future consideration. Reduce rinse water consumption and drag-out from the zinc- plating bath by installing counterflow rinsing and an atmo- spheric evaporator to evaporate excess water from the rinses. This research brief summarizes a part of the work done under Cooperative Agreement No. CR-819557 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. ------- Steel Waste cooling water shipped oflsite Spent cutting KuM shipped offslte Waste liquids pro-treated onslte and sewered Paint preparation Wastes shipped off site for Incineration Waste oil shipped off site for blending as fuel Completed lifts shipped to customers Figure 1. Abbreviated Process Flow Diagram for Lift Manufacturing. ------- Table 1. Summary of Currant Waste Generation Waste Stream Generated Cooling fluid Cutting fluid Wastewater treatment sludge Rinse water Waste alkaline solutions Waste acidic solutions Alkaline cleaner Overflow rinse water Phosphating solution Rinse water Body wash Paint solvent still bottoms Evaporated paint solvent Expired paint Paint cleaning solvent Waste oil Absorbent clay Cardboard Nonrsusabls pallets Pefroleum naphtha Source of Waste Plasma cutting of metal Machining operations Treatment of waste liquids from plating and paint preparation Metal plating Metal plating Metal plating Preparation of metal for painting Preparation of metal tor painting Preparation of metal for painting Preparation of metal tor painting Cleaning of product bodies Onsite recovery of spent paint solvent used for paint gun cleaning Cleaning of paint guns Panting operations Cleaning of paint guns Assembly of product Cleanup of spills during assembly Various sources Various sources Parts washers Waste Management Method Shipped offsito; solidified and buried Shipped offsite; solidified and buried Shipped offsite; buried Treated onsite; sewered Treated onsite; sewered Treated onsite; sewered Treated onstta; sewered Treated onsrte, sewered Treated onsite; sewered Treated onsite; sewered Treated onsite; sewered Shipped offsite; incinerated Evaporates to plant air Shipped offsite; incinerated Shipped offsite: recycled or incinerated Shipped oft site, blended into boiler fuel Shipped to municipal landfill Shipped to municipal landfill Shipped to municipal landfill Shipped offsite; recycled or incinerated Annual Quantity Generated (Ib) 21,870 36,440 41,690 6,122,550 29,990 59,980 8,330 26,660 8,330 992,840 612,260 2,020 2,270 10,120 410 3,670 5,640 91,160 72,000 6,730 Annual Waste Management Cost' $5,680 6,530 6,890 1,980 10 20 0 0 0 320 200 8,910 1,570 19,650 1,310 20 570 6,990 3,880 8,450 Includes waste treatment, disposal, and handling coses, and applicable raw material costs. ------- Table 2. Summary of Recommended Waste Minimization Opportunities Annual Waste Reduction Minimization Opportunity Replace the currently used rental parts washer with a cleaning system that uses a less hazardous solvent. Institute a formal cutting fluid manage- ment program. Engage a recycling firm to collect the pallets that currently are shipped to a landfill. Install an enclosed spray gun washer system to reduce evaporation of cleaning solvent. Replace clay absorbent used for cleanup with absorbent pads and a wringer. Filter and reuse the plasma cutter cooling fluid. Waste Stream Reduced Petroleum naphtha Cutting fluid Wooden pallets Evaporated paint solvent Absorbent clay Cooling fluid Quantity (Ib) 6,730' 31,700 0 1,700 5,640 3 11,000 Per cent 100 87 0 75 100 50 Net Annual Savings $6,250 2 4,800* 3,580 1,180 540 460 2 Implementation Cost $8,840 8,000 0 2,000 700 1,050 Simple Payback (yr) 1.4 1.7 0 1.7 1.3 2.3 ' A total of 1,000 Ib/yr of combined solvent and filter waste will be generated. 2 Total possible savings have been reduced by a required annual operating cost. 3 740 Ib/yr of waste oil and used pads will be generated. ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 EPA/600/S-94/011 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 ------- |