COMPREHENSIVE WASTE REDUCTION AT VON DUPRIN, INC. Daniel Reinke, P.E. Capsule Environmental Engineering, Inc. St. Paul, Minnesota

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1 COMPREHENSIVE WASTE REDUCTION AT VON DUPRIN, INC. Daniel Reinke, P.E. Capsule Environmental Engineering, Inc. St. Paul, Minnesota James Smith Von Duprin, Inc. Indianapolis, Indiana Michael Bayman Von Duprin, Inc. Indianapolis, Indiana Introduction Von Duprin, Inc., located in Indianapolis, Indiana, is the market leader in supplying door exit hardware (panic bar devices). Von Duprin is a part of Worldwide Ingersoll-Rand Company s Door Hardware group. In 1989 and 1990, Von Duprin, together with Capsule Environmental Engineering, Inc., an environmental consulting firm specializing in process waste reduction, developed and implemented a project designed to reduce wastewater sludges from plating operations by 90 percent. Von Duprin s plating operations include automated hoist rack plating of copper cyanide, satin and bright nickel, decorative chromium, brass cyanide, and also barrel plating of alkaline non-cyanide zinc. Von Duprin s waste reduction efforts addressed methods to minimize and recover dragout from each of these process baths. Initial ActivitieS Von Duprin initiated the project by having Capsule engineers review all waste generating operations to identify reduction opportunities. Activities included recommendation of specific equipment vendors where appropriate and development of economic analyses of various options. Capsule began its work by reviewing the general characteristics of Von Duprin s processes. Von Duprin had already implemented many important measures to reduce waste and associated costs, including: * * * Modifying rack designs to minimize cupping; Adjusting automatic hoist parameters to include extended drip times; Use of two-stage and three-stage counterflow rinses; 1

2 * Use of stagnant baths for recovery of dragout from bright nickel ali: chrome baths; * Use of alkaline non-cyanide zinc bath to minimize use of cyanides; an:^ * Elimination of vapor degreasing. Capsule engineers measured dragout rates from all of the baths and compared this data with shop records on bath adds and production quantity records to develop sizing information on recovery equipment. This sizing information was sent to several vendors who were prequalified based on their equipment and experience with similar operations. After obtaining equipment quotes, Capsule contacted users of the systems (not all of which were from the vendors reference lists) to learn more about the equipment and manufacturers. Capsule presented this information to Von Duprin management, who after serious review, charted a resolute course towards waste minimization at their manufacturing facility. The goal of this program was to make Von Duprin not only a leader in parts quality, but in environmental control as well. Processes Selected 1. Cyanide Copper. Technologies investigated for cyanide copper incluclecr spray rinsing, atmospheric evaporation, vacuum evaporation, electrolytic recovery from a stagnant rinse and reverse osmosis. Technical and econonm evaluation of the options led to selection of a combination of spray rinses over the bath to further minimize dragout and atmospheric evaporation to make room in the bath for added water. Advantages of this combination included maximum recovery of solution with minimal capital and operating costs. The simple technologies used mean less operator and maintenance attention than other options. An additional factor was that the facility is contemplating the use of an alkaline non-cyanide copper plating, which may not be compatible with other options. The disadvantage with this system, because of the use of the atmospheric evaporator on a cyanide bath, is the increased rate of buildup of potassium carbonate in the bath. Carbonate concentrations are regularly reviewed and treatment made when necessary. 2. Nickel. Technologies investigated for nickel recovery included spray rinsing, atmospheric evaporation, reverse osmosis, and several methods of ionexchange. Technical and economic evaluation of the options led to thi-; selection of a reciprocating bed ion-exchange system for recovery and reme of a nickel chloride/nickel sulfate mix. 2 52

3 Advanta es of this option included the ability to recover the nickel from both the satin and bright nickel baths without fear of bath contamination associated with recovery of bath brighteners. The reciprocating bed design offered direct ability to reuse recovered solution without further processing to remove excess water. 'The disadvantage of this system was a relatively high capital cost, although payback on the capital investment was very favorable - under two years. 3. Chrome. Technologies evaluated for chrome recovery included spray rinsing, atmospheric evaporation, and ion-exchange. Technical and economic evaluation led to the selection of a combination of spray rinsing, atmospheric evaporation, and a stagnant rinse to minimize dragout and recover solution captured in the.first rinse. Advantages of this system were the ability to greatly improve recovery with a minimal capital investment. This was especially important since the facility is contemplating switching to a trivalent chrome process for environmental reasons. The system selected was also seen to be applicable for a trivalent chrome system. The primary disadvantage of this system was the buildup of impurities from reuse of the dragout. Ability of the existing tank steam coils to handle the heat loss from the evaporator was also found to be a problem after the system was installed. 4. Brass. Technologies evaluated for brass recovery included spray rinsing, atmospheric evaporation, vacuum evaporation, electrolytic recovery from a stagnant bath, and reverse osmosis. Technical and economic evaluation led to the selection of reverse osmosis to capture dragout and return clean water for rinsing. Advantages of this system were the ability to close-loop the rinsing system, eliminating cyanide discharges. This positions Von Duprin to eliminate all cyanide in the wastewater when a non-cyanide copper process is implemented. The disadvantages with this system include the high capital cost and operating costs of the equipment. Buildup of carbonates is also a concern, but this has not been observed at the plant. 5. Non-cyanide alkaline zinc. Technologies evaluated for this bath included ion-exchange, and reverse osmosis. Technical and economic evaluation led to the selection of reverse osmosis to capture dragout from this barrel line and atmospheric evaporators to make room in the bath for reuse of all of the recovered solution. 3 53

4 The primary advantage of this system was the ability to close-loop the zinc system. Zinc provides the most difficulties in wastewater treatment, so eliminating this discharge was seen to ease end-of-pipe treatment. Another advantage of the reverse osmosis system was the ability to recover and reuse the zinc, unlike ion exchange systems which were designed to recover a zinc metal which would be shipped off-site. The primary disadvantage of the reverse osmosis system was the lack of a good base of in-plant experience on the part of the vendor with this particular bath, although testing and a thorough review of the system indicated a high likelihood for success. i 6. Peripheral equipment. As part of this project, process water for bath makeup and rinsing in the plating area was upgraded through the installation of a reverse osmosis water treatment system. Water produced by the reverse osmosis treatment system is then passed through rented mixed-bed deionizers to give the high quality (2 micromho) water necessary for bath adds anc! makeup for the zinc and brass recovery systems. The reverse osmosis system includes dual water softeners, cartridge filters, the reverse osmosis unit which uses polysulfone membranes, a holding tank, and repressure pumps. Both deionized water of 2 micromho or better quality and reverse osmosis water of 30 to 70 micromho quality are used in the plating area. The reverse osmosis water is used for most rinses. Water use on rinses after cleaning and activation processes was reduced through the use of reactive rinsing. Water that was used to rinse parts after acid activation steps was pumped to rinse parts after compatible alkaline processes, such as electrocleaning. This reduces rinse water flows, improves rinsing after the electroclean bath, and reduces acid use since parts then entering the acid bath are neutralized or slightly acidic, rather than slightly alkaline. This was accomplished through the installation of in-tank pumps controlled by level sensors. Equipment Installation - Lessons Learned The first system installed was the reverse osmosis water treatment line. The system was purchased with installation, startup and training, which helped make the installation proceed smoothly. One problem that developed, however, was a lack of constant adequate water pressure to feed the reverse osmosis unit, resulting in system shutdowns. This low pressure was first found to associated with a partially closed valve in the line feeding the system, but this did not fully solve the problem. The plating area is on the end of the plant water supply line, and heavy water use during shift changes and breaks seemed to cause low pressure shutdowns on the reverse osmosis system. Von Duprin 4 54

5 investigated several measures to solve this problem, and settled on adding a new feed from the c'hy supply directly to the plating area. The second system installed was the nickel recovery ion-exchange system. This system was supplied with detailed drawings which were used to obtain installation quotes from local electrical and mechanical contractors. This system was installed smoothly, although piping contractors inappropriately mounted several transfer pumps outside of the diked area provided for the equipment. The major problems associated with the system included the control logic which had to be modified to allow smooth operation, and the rinse conductivities. On two of the nickel lines, operators added acid to the last rinse to activate the surface before chrome plating. Since the ph of these rinses varied based on the manual acid adds, the conductivity of the rinses varied. This caused difficulty in the control system, which determined nickel concentration in the rinses based on conductivity. Ultimately, this was solved by reducing the amount of acid used and adjusting the conductivity control loop for this acid level. The next series of installations involved the reverse osmosis systems for brass and zinc. Substantial time was spent cleaning rinse tanks to remove hardness salts which could foul the reverse osmosis membranes. Both systems were provided with adequate installation diagrams, although some field modifications had to be made for piping lines. Extra costs were incurred to provide additional electrical noise isolation to protect system components. Equipment deliveries were delayed to allow negotiation of a purchase agreement with system performance guarantees. The reverse osmosis installations proceeded smoothly, but several problems were found in the first few months of operation. A diatomaceous earth (DE) prefilter included on the zinc system repeatedly plugged with a hard deposit that also clogged piping to the DE filter. This clogging subsequently caused several failed prefilter pumps. Vendor analyses associated these problems with 8:alcium carbonate in the system, coming from the use of insufficient quality water before installation of softeners and reverse osmosis membranes on the water supply. The calcium carbonate also apparently passed through the DE filter, plugging one set of reverse osmosis membranes. Von Duprin is still working with the vendor to identify and remove any sources of calcium to the plating system. One major advantage was that the zinc and brass recovery systems are linked by phone modem to the vendor, who can then observe the system performance and modify program parameters to improve the quality of the recovered solution. On more than one occasion, however, vendor control of the system through the phone modem has resulted in spills from overfilled rinse or process tanks. Von Duprin has subsequently directed the vendor not to 5

6 make program changes without preapproval from Von Duprin process engineering. The last items to be installed were the spray rinses, evaporators, and transfer pumps for reactive rinsing. These items were all installed and wired with rough sketches prepared by equipment vendors and Von Duprin s consultant. Attempts were made to save the cost of preparing detailed drawings, however, in the long run it may have cost more due to rework required to make the systems operational. On startup of one of the chrome evaporators it was found that the existing bath heating system was fouled and could not provide the extra heat load from the evaporator. Within an hour, the temperature of me bath dropped enough to affect plating quality. Also, with both chrome recovery systems, the piping contractor used piping which failed when subjected to me warm chromic acid solution. Svstem Performance While all systems are still not fully operational on a continual basis, some reduction in sludge volumes has been seen. Additional dumping of cleaning baths and lack of consistent performance of the zinc reverse-osmosis recovery system have prevented the drastic sludge volume reductions that were expected, but further gains will be obtained as remaining recovery equipment problems are resolved. increased plating sludge disposal costs associated with land ban regulations provided very positive, direct economic payback for economic justification of the recovery systems. In addition, Von Duprin anticipates positive publicity from implementing waste reduction technologies. By significantly reducing metals from the wastewater stream, Von Duprin also expects to provide continual compliance with present and future wastewater effluent limitations without excessive effort. Since problem components such as zinc and cyanides are being kept out of the wastewater stream, constantly increasing efforts will not be required to destroy or remove these materiaii The other significant effect of reducing metals in the wastestream is reducec purchases of metal anodes and salts. Even with all systems not completety operational, metal usage in the third quarter of 1990 was less than half of that in the first quarter of While there were and continue to be several problems to work out with the metal recovery systems installed at Von Duprin, the systems provide a costeffective means to reduce waste generation and disposal costs, enhance community and customer relations, and reduce the potential for wastewater treatment upsets. Von Duprin effectively utilized the support of an independent environmental consultant knowledgeable in electroplating and metal finishing to provide them with the technical support necessary to identify and implement the 6 56

7 various options. Von Duprin sees these activities as becoming more important in the future with tightening wastewater discharge levels, and spiraling wastewater treatment sludge disposal costs. 7 57