United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati, OH 45268 Research and Development EPA/600/SR-93/150 October 1993 EPA Project Summary Watts Nickel and Rinse Water Recovery via an Advanced Reverse Osmosis System C. Schmidt, I. Erbas-White, and R. Ludwig The full report summarizes the re- sults of an 8-mo test program conducted at the Hewlett-Packard Printed Circuit Production Plant, Sunnyvale, CA (HP) to assess the effectiveness of an ad- vanced reverse osmosis system* (AROS). The AROS unit, manufactured by Water Technologies, Inc. (WTI) of Minneapolis, MM, incorporates mem- brane materials and system compo- nents designed to treat metal plating rinse water and produce two product streams: (1) a concentrated rnetal solu- tion suitable for the plating bath, and (2) rinse water suitable for reuse as final rinse. Wastewater discharge can be virtually eliminated and significant reductions realized in the need for new plating bath solution and rinse water. The AROS unit performed very reli- ably during the test program. During a 5,000-hr trial, approximately 190,000 gal of rinse water were treated to produce 1,100 gal of concentrated plating bath for recycle. The second output stream from the AROS unit was recycled as clean rinse water, reducing the demand for deionized water production. In addi- tion, wastewater treatment and disposal costs were reduced by approximately $13,000. If operated at full capacity, the unit capital cost was estimated to have a payback period of approximately 2 yrs. The AROS was evaluated under the California/EPA Waste Reduction Inno- 'Mention of trade names or commercial products does not constitute endorsement of recommendation for vative Technology Evaluation (WRITE) Program, in which the cooperative ef- forts of the U.S. Environmental Protec- tion Agency (EPA) and the California Environmental Protection Agency were used to evaluate innovative pollution prevention techniques. This Project Summary was developed by EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction The metal plating industry produces large quantities of metal contaminated waste- water requiring treatment before discharge. An AROS manufactured by WTI was in- stalled in the HP plant in Sunnyvale, CA, to treat and recover Watts nickel plating bath solution and rinse water. The tech- nology approaches zero discharge capa- bility. An 8-mo test program was conducted to assess the effectiveness of the AROS and estimate the incremental cost savings resulting from less use of deionized water, reduced wastewater volume being pre- treated, lower effluent and sludge disposal quantities, and recovery of plating solu- tion. The HP facility manufactures printed cir- cuit (PC) boards for use in personal com- puters. In one step of the manufacturing process, Watts nickel plating is used to plate a thin layer of conductive material on a non-conductive surface, like epoxy/plas- tic or ceramic. Watts nickel is also widely used in other industries for decorative plat- Printed on Recycled Paper ------- ing operations. The plating operation con- sists of the following steps: • Rrst, the PC boards are attached to moving racks. The moving racks carrying the parts move through the Watts nickel solution plating bath where the nickel plating is eloctrolytically applied to the PC boards. When the PC boards are removed from the bath, plating solution adheres to them. This adhering solution is called "dragout." • Second, the PC boards move sequentially first through a "dirty" rinse tank and, second, through a "clean" rinse tank. The clean rinse water enters the second "clean" rinse tank and flows in the opposite direction from the movement of the PC boards. In this way, the PC boards encounter the cleanest rinse water last just before exiting the second "clean" rinse tank. This method of having the parts and the rinse water move in opposite directions is called countercurrent rinsing. Normally, the discharge from the "dirty" rinse tank is wastewater to be treated and discharged. The ARCS unit, however, treats this wastewater to separate out the metal compounds. This separation creates two product streams: a stream of deion- ized water called the permeate and a liq- uid stream of concentrated metal com- pounds called the concentrate. Both of these product streams are reused in the production process. The permeate stream is returned to the "clean" water rinse tank. The concentrate stream of metal com- pounds is returned to the plating bath. This recycling eliminates the need for nor- mal wastewater discharge. In addition, the AROS unit greatly reduces the volume of new deionized makeup water needed for the rinse tank and generates concentrated Watts nickel solution that can be recycled to the plating bath. The heart of the AROS unit is a special- ized reverse osmosis unit. Reverse osmo- sis is a physical process in which water containing dissolved materials can be sepa- rated from those dissolved materials. Pres- sure is applied to the solution on one side of a membrane barrier. Water passes through the membrane, but dissolved metal tans remain behind, thus becoming more concentrated. The membranes are made of polyamide, thin-film plastics that can perform well under a wide range of pH conditions (1 to 13.5) and high pressures (400 to 1100 psi) as needed to reconcen- trate a wide range of dilute rinse waters to produce recycled plating bath solutions. In addition to the reverse osmosis mem- brane, the AROS unit contains pumps, valves, interim solution holding tanks, sen- sors, and piping needed to manage the flows into and out of the membrane unit. The operation is automatically controlled by a computer program that monitors flow quality (using conductivity), flow volumes, and other operating parameters. The unit is enclosed in a lidded box about 3 ft high by 4 ft wide by 8 ft long. The plumbing and electrical and communications connections are relatively simple. The objectives of the study were to (1) evaluate the AROS unit performance and reliability, (2) assess the quality of the re- cycled plating bath solution and the re- cycled rinse water, and (3) analyze costs and benefits. Procedure The test program was conducted by HP with assistance from the AROS manufac- turer. The program included continuous monitoring of flow volume, conductivity, and pH at various monitoring points in the sys- tem. Streams monitored include the deion- ized rinse water makeup line, the concen- trate return line, and the permeate return line. The plating bath was sampled and analyzed weekly. Analyses were conducted for nickel, pH, Nickel PC-3 (Saccharin), boric acid, chloride, and ductility. Independent sampling and analysis were performed by the EPA contractor over a 1 - day period to verify results reported by HP. Cost information was provided by HP and the AROS manufacturer. Where pos- sible, the costs were checked against other sources. Results and Discussion The AROS unit achieved excellent sepa- ration of contaminants from the influent dirty rinse water. Removals of. contami- nants usually ranged from 95% to 97%. Overall the HP staff regard the AROS unit as having shown good performance dur- ing the test period. Rinse water quality was maintained at a low level of nickel contamination. It was reported that no printed circuit boards were rejected be- cause of Watts nickel plating deficiencies. The recycling of the rinse water resulted in a dramatic 98% reduction in the use of new deionized water makeup for this plat- ing process, equivalent to about 425,000 gal annually per shift per plating line. The AROS unit also successfully pro- duced concentrated Watts nickel solution of adequate quality to return to the plating bath solution. Fresh Watts nickel solution costs about $5.00/gal, so recovery and recycling represented a significant direct savings. It was also calculated that ap- proximately 3 tons of category F006 sludge was not generated by the industrial waste water treatment system that otherwise would have been without use of the AROS unit. The AROS unit demonstrated excellent reliability during most of the test period. For example, during the period February 28 through June 29,1990, the system was on-line 3,594 hrs and experienced a down- time of only 20 hrs. Mechanical failures experienced in July and August1990, how- ever, caused over 200 hrs of downtime during these months. The manufacturer is reported to have made design changes that will prevent similar future mechanical failures. Economic Analysis Cost information provided by HP (see Table 1) indicated that the AROS unit would produce an estimated annual cost savings of $26,250 at the HP facility using the unit at less than half its rated hydraulic capac- ity. This savings is reduced by an esti- mated annual operating and maintenance cost of $9,419 for a net annual savings of approximately $17,100/yr. Capital invest- ment is approximately $75,000, which rep- resents approximately $63,000 for the AROS unit plus another $12,000 for mak- ing the installation permanent and for train- ing of operating personnel. Dividing $75,000 by $17,100 results in a payback period of 4.4 yrs and a 23% return on investment. The AROS unit at HP was operated at less than 50% of its capacity. The eco- nomic benefits would havs been more fa- vorable if the Watts nickel plating process had been operating for more hours and producing more printed circuit boards. The AROS unit volumetric design capacity for influent rinse water is over twice the vol- ume of rinse water processed at HP Another economic factor is that at HP the AROS unit treated only a small frac- tion, e.g., about 3%, of the total wastewa- ter flow. Therefore, in its cost analysis HP made no allowance for reduced labor cost at its main wastewater pretreatment plant. At another facility, however, the AROS unit treated a larger percentage of the total wastewater flow, a labor reduction credit might have been included in the cost analysis. Finally, the HP facility has a fully amor- tized wastewater treatment facility in place. Elsewhere at a new facility under design, it could be feasible to reduce the capacity ------- and capital cost of the wastewater treat- ment facility because the inclusion of an AROS unit would reduce design flow vol- ume. In addition, it would be possible to reduce the capacity of the deionized wa- ter production units. Economic cost-ben- efit analysis will be different for each po- tential application of an AROS-type unit depending upon the site specific situation. Conclusions and Recommendations • Overall the AROS unit performed very well during the test program. Recovery and recycling of plating bath solution and deionized rinse water was routinely successful and no loss of plating quality occurred. Significant cost savings resulted from reduced use of deionized water, reduced wastewater volume being pretreated, less effluent and sludge disposal, and recovery of plating solution. Payback period and return on investment will vary depending on site- specific conditions. If the AROS unit was operating near capacity at HP, the payback period is estimated at about 2 yrs. This demonstration indicates that there are many situations where the unit should be considered for its economic benefits as well as its environmental waste minimization advantages. The full report was submitted in fulfill- ment of Contract 68-C8-0062, WA 3-18, by Science Applications International Cor- poration under the sponsorship of the U.S. Environmental Protection Agency. Table 1. Estimated AnnualIncrementalSavings from Use of the AROS Unit as Reported by Hewlett- Packard Company, 1990 Costs Description of Costs Estimated Savings ($/gal) Quantity (gal) Total Annual Savings ($) Sewer discharge fees and water costs Deionized (Dl) water production cost* Plating wastewater treatment coste* Purchase of new plating chemicals at 85% reduction 0.004 0.0064 0.0062 5.00 1,275,000 1,275,000 1,275,000 1260x 0.85 5,100 8,160 7,905 5,355 Total estimated annual savings $26,520 *DI water production cost is for chemicals, electricity, and resin replacement only. No labor, deprecia- tion, or other costs are included because it is assumed that they would remain the same whether the AROS unit was used or not. + Plating wastewater treatment cost includes sludge disposal, chemicals, and electricity. As in the note above, no labor, depreciation, orothercosts are included because itisassumedthattheywouldremain the same whether the AROS unit was used or not. 6 U.S. GOVERNMENT PRINTING OFFICE: 1993 - 750-071/80073 ------- C. Schmidt and I. Erbas-White are with Science Applications International Corp., Santa Ana, CA 92705, and R. Ludwig is with the California Environ- mental Protection Agency, Sacramento, CA 95812-0806. Lisa M. Brown Is the EPA Project Officer (see below). The complete report, entitled "Watts Nickel and Rinse Water Recovery via an Advanced Reverse Osmosis System," (Order No. PB93-229 011'/AS; Cost: $19.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Risk Reduction Engineering Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 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/SR-93/150 ------- |