‘1 2’ Pollution Prevention in Mass-Finishing Operations 2\LO/L by Eugene Park, iJf Chemical Engineering Department, University of Rhode Island, Kingston, R.I.

result of any mass-finishing a variety of manufactured parts and can metal sludge that is usually dewatered operation is the generation of he found in industries such as jewelry with a filter press prior to off-site Awaste in the form of wastewa- and machine tool . Vi- disposal as waste and sometimes even ter and sludge. Traditionally, waste bratory and tumbling machines are two hazardous waste. In companies that streams from mass-finishing opera- very common types of mass-finishing rely on other waste-generating proc- tions have been chemically treated to equipment. The waste effluent, esses such as , the tuh- meet sewer discharge requirements. In whether from a batch or continuous hinglvihratory waste is sometimes most instances, and prior to chemical process, consists of soapy water, pul- mixed with these other streams prior to treatment, mass-finishing wastewater verized media, and both soluble and end-of-pipe treatment. Depending on is mixed with other metal-bearing insoluble metals of the type found in the capacity of the finishing operation waste streams originating from very the metal parts being processed. and any other wastewater-producing different manufacturing operations. Figure 1 describes the flow scheme process in the plant, the costs of these A new, preferred approach toward of a typical mass-finishing operation. chemical-treatment systems vary. minimizing the generation of waste Depending on the finishing operation, Capital and operating costs can vary from mass-finishing operations is the waste solution generated can vary. widely for different waste streams and called pollution prevention. Pollution Analytical tests were carried out on flow capacities. The major capital costs prevention or source reduction means used solutions at different companies. include tanks, controls, pumps, and that waste should be reduced or elimi- Although the results vary, some gen- mixers. The major operating costs in- nated at the source as opposed to eral consistencies are observed. Most clude chemical costs, labor, and sludge end-of-pipe treatment. For the mass- of the solids found in the waste stream disposal. If the sludge is hazardous, the finishing operation, pollution-preven- consist of plastic or media. operating costs increase significantly tion measures include process modifi- Because the hardness of the metal parts due to higher disposal and labor costs. cation and in-process recycling. Input is much higher than that of most Liabilities are also much greater. Sound materials such as the metal type, plastics and , the plastic and pollution prevention or source reduction finishing media, and soap should be ceramic media tend to erode faster than measures can result in substantial reduc- studied for possible modification to the metal; however, significant metal tions in costs and liabilities. prevent potential waste. The type of levels of the metal type used in the mass-finishing equipment employed in finishing operation are still observed. POLLUTION PREVENTION the process can also influence the For example, one company manufac- amount of waste generated. In some tures zinc alloy fasteners; the vibratory Pollution Prevention is now the cases, hazardous OT toxic cleaning operation used to clean and polish preferred method for environmental chemicals can be replaced hy the these fasteners produces a waste stream protection. In contrast to the end-of- aqueous-based tuhhing or vibratory that contains 320 mg/L of zinc and pipe waste treatment approach, pollu- operation. Once all possible process 1,770 mgL of total suspended solids tion prevention is defined by the US. modifications are made and waste (TSS). In all of these cases, the solution Environmental Protection Agency as streams segregated, the finishing solu- cannot be discharged to the sewer “the use of materials, processes or tion can be recycled to further mini- without treatment because of high practices that reduce or eliminate the mize waste leaving the operation. In levels of metals, suspended solids, and creation of pollutants at their source.” some applications, the same soap solu- sometimes oil and grease. Traditional Source reduction, the defining theme tion can be reused for up to one year. treatment has included end-of-pipe of pollution prevention, can be carried Soap purchases, waterkewer fees, chemical addition to remove metals out in many ways. Where source and environmental liabilities may all and solids prior to discharge. reduction is successfully used, the need ~ be reduced. In most cases, a reasonable for treatment and disposal is often payback is achieved on equipment TRADITIONAL TREATMENT dramatically reduced. Most of the purchases. Many companies have al- technical-based solutions are process

TECHNOLOGIES ~ ready successfully implemented pollu- engineering modifications that require tion prevention into their mass-finish- Chemical-treatment technologies varying amounts of development re- ing operations with excellent results. have been used by many companies to search and testing. As described in produce water clean enough for sewer more detail later in this article, many effective technical solutions have been BACKGROUND discharge. In most cases, different chemicals are used for pH adjustment developed by different organizations; Mass finishing is a mechanical proc- and metal flocculation. The end result this information can he readily shared ess used to deburr, polish, andor clean is metal-free water and precipitated with other companies. Examples of

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Handy&Harman 300 RYESTREET, SOUTH WINDSOR,CONNECTICUT 06074 TELEPHONE1-800-421-041 1 Clrcle 032 on reader lnformatlon card process modifications include replac- Table I. Pollution Prevention Hierarchy ing waste-generating input materials i Source reductiin Process modification to eliminate or reduce pollutants at the source, e.g.. with other materials that do not pro- wlvent elimination, better housekeeping, in-process recycling of spent duce as much waste. In-process recy- materials cling of spent materials is also consid- Recycling OKsite processing 01 waste materials for reuse, e.&, sludge reclamation ered a viable source reduction measure lor metal recovery since the amount of waste leaving the Treatment and disposal End-of-pipe treatment 01 waste prior to disposal, e.g.. chemical treatment system that treats several waste streams prior to sewer discharge with process is reduced. Off-site recycling, hazardous sludae aeneration such as the reclamation of waste materials at a commercial treatment facility, is considered to be a secondary type of mass-finishing machine must and may require a special permit for option to source reduction. End-of- also be considered. While process on-site management. Reducing the use pipe treatment and disposal are consid- modifications are considered to be true of hazardous materials may lead to ered the last resort, to be used only source reduction, much of the follow- considerable cost savings. when source reduction and recycling ing discussion concerns varying para- If potential hazardous metal constit- are impractical (see Table I). meters that may not at first seem uents can be eliminated, source reduc- Management commitment is critical changeable. The most important aspect tion is successfully applied. A manu- to the success of any pollution-preven- of mass finishing, final product qual- facturer may have to modify its opera- tion program. Unless managers are ity, cannot be compromised. It is tion. Investigation into the use of the willing to ensure that process modifi- suggested that companies investigate finished product may provide some cations are implemented, changes will any possible process modification that helpful insight. Is it possible for alter- not take place and waste will not be may reduce waste. Once all possible native metal alloys to be used? Careful reduced. Better housekeeping on the process modifications have been made, consideration into all the possibilities manufacturing floor will inevitably in-process recycling and off-site recy- should be taken. Meetings with manu- lead to less waste. Careful monitoring cling should then be considered. fadturing personnel as well as custom- of process input materials (e.g., elimi- ers may be necessary. In most cases, a nating excess chemical usage) will also Metal Parts test program is required to determine prevent some waste generation. The feasibility. At least one metal manufac- success of any pollution-prevention Metal composition and part finish are usually dictated by the customer, so tufer has recently developed a “lead- program, then, is the result of a free” casting metal substitute, which cooperative working approach that in- the entire operation is designed around customer specifications. Nevertheless, offers a potential material substitute to volves management and worker com- many costume jewelry companies. The mitment and a well thought out plan. opportunities may exist to modify incentive for successful metal replace- Even where effective processes have alloy compositions to reduce or elimi- been developed to reduce pollution, nate the generation of pollutants and/or ment is reduced liabilities and waste success can be limited when proper hazardous waste. Sludge from mass- managementldisposal costs. implementation and supervision are finishing operations would be charac- (.. lacking. terized as hazardous if it fails the Fihishing Media Process inputs and waste solutions Toxicity Characteristic Leaching Pro- Selection of the proper media plays vary from operation to operation. cedure (TCLP) test for any of the eight an important role in the minimization Changing one variable may result in listed heavy metals. The metals that are of potential sludge generation. Two significant pollution reductions; chang- listed as potentially hazardous include critical parameters are the shape and ing more than one variable may prove cadmium, chromium, lead, silver, mer- hardness of the finishing media. Media to be even more effective. The recom- cury, beryllium, barium, and arsenic. are selected on the basis of metal part mendations presented here are in- The costs of generating hazardous type, shape, and desired finish. As part tended to provide the manufacturer waste are significant. Hazardous waste of the mass-finishing operation, me- with practical options for reducing creates more paperwork, exposes com- chanical erosion of both media and mass-finishing waste. panies to liabilities, costs more to treat metal occurs continuously, causing the or dispose of than nonhazardous waste, formation of metal and media particles MASS-FINISHING PROCESS MODIFICATIONS As shown in Figure 1, there are four Media basic input materials in the mass- finishing operation: metal parts, media, 1 soap, and water. The type and amount (or flow rate) of each input material are considered in the overall analysis of the process. Replacement or modifica- tion of process material types and wa tewator quantities may reduce or increase the --LIZ amounts of pollutants generated. The Figure 1. Process flow diagram.

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ATOSlCRl Atotech USA Inc., Two Riverview Drive, P.O. Box 6768,Somerset, NJ 08875-6768 Cirde os4 on reader intomion card in the soap solution. In addition, some cling program is ultimately desired Machine Modification metal is dissolved into solution. The after all finishing process modifica- Two basic mass-finishing machine resultant “dirty” solution contains tions have been implemented, it is designs are vibratory and tumbling. potential pollutants that have been critical to minimize the number of Many variations exist depending on traditionally treated with chemicals to different soaps that arc used. If many the application. More elaborate designs remove metals and suspended solids different soaps arc used, in-process may prove to be more cost-effective prior to discharge. While product qual- recycling becomes more difficult and and prevent more pollution by increas- ity may be satisfactory, some compa- expensive because a separate recycling ing efficiency. Process cycle times and, nies may be using media that is too soft system would be required for each hence, waste generation are reduced. and wears down quickly, thus creating soap. Many companies use a different There arc now available new types of excess waste and high media purchase soap for each type of part that is mass-finishing equipment that have costs. Consultation with the media manufactured. While certain com- been designed to be more efficient in supplier may open up opportunities to pounds are more effective than others material use and pollution prevention. change the media to another type that for certain metal parts, many soaps For example, in applications where still provides for the same product have a much broader range of applica- large quantities of identical parts are quality hut docs not wear down as fast. bility than often is realized. Because manufactured, a machine is available Testing at various Rhode Island the traditional approach has been end- that cleans each part individually and facilities indicates that solids from the of-pipe treatment and discharge, there quickly with relatively little waste. A waste solutions are predominantly was little concern about the number of company can work with the machine made up of finishing media when different soaps used; everything would supplier to determine which design is plastic and/or ceramic media are used. eventually end up in the sewer. J & L best for its operation. One company Solids analyses carried out at different Finishing (Providence, R.I.), a mass- switched the majority of its mass companies revealed that over 80% (by finishing job shop that accepts parts of finishing from barrel tumblers to small weight) of the waste solids collected all types and shapes, was able to reduce vibratory units, which resulted in less were nonmetallic. If traditional chemi- their number of soaps from four to two. soap/water use and less waste genera- cal treatment is used to clean the waste After having eliminated their chemical tion. solution prior to discharge, the total treatment process, the company in- stalled a large (500 galiday) membrane volume of sludge generated can actu- Water and Soap Conservation ally increase by 100% due to the filtration system for one soap and a small membrane system for another In continuous-feed operations where addition of precipitating chemicals. a continuous flow of solution is fed The more waste sludge generated, the compound. The company has thus been able to recycle soap and water into the basin, the amount of finishing higher the costs and potential liabilities solution and water used may be re- of disposal, especially if the sludge is much more economically. (For further discussion on this topic, see In-Process duced. Pilot tests at various companies considered to be hazardous waste. have indicated that satisfactory part A carefully designed test program Recycling below.) In some cases, the mass-finishing finishes can be obtained even when can provide insight into the best possi- flow rates are reduced. Lower flow i ble media that not only provides the operation presents opportunities to eliminate hazardous chemicals. For rates lead to decreased volumes of best part finish but also allows for waste solution, which in turn results in effective pollution-prevention options. example, Miniature Casting Carp. (Cranston, R.I.) uses an alkaline com- lower equipmentloperating costs. In For any waste sludge that is produced, addition, shorter cycle times can re- off-site reclamation possibilities pound in its vibratory operation and had originally discharged to sewer. duce water consumption. Some parts should be investigated. Many impuri- may not have to be run as long as ties, including the eroded metal itself, Due to local sewer requirements, the pH of the solution could not be above previously believed for proper surface are present in the waste solids. Al- 10. Because the alkaline compound finish. Reductions in cycle time not though in some cases metal can be was not strong enough, some heavily only reduce water and soap use, hut recovered, media recovery options are contaminated parts required preclean- also reduce the amount of sludge limited. Most finishing equipment sup- ing with mineral spirits, a hazardous generated. Because each application is pliers will work with the manufacturer solvent, prior to the vibratory step. different, on-site testing needs to be to find the best media and soap to Although a stronger concentration of carried out to determine optimal flows minimize waste. the alkaline soap could successfully and cycle times. clean all the parts, the pH of the Mass-Finishing Compounds solution would be raised to 11 and In-Process Recycling The type of soap in the finishing would not meet discharge require- operation is an important variable that ments. Recycling the solution, on the In-process recycling, or recycling at ~ is dependent on the metal part and other hand, relieves the company from the source, is another pollution-preven- __ media used. As previously mentioned, all discharge requirements as the solu- tion approach that can be implemented many different compounds exist. Some tion is no longer being discharged. By once all of the other possible process soaps are best for polishing, whereas employing an in-process recycling modifications described above have others are better suited for deburring, scheme, higher pH solution can be been made. The following discussion and the pH varies from chemical to used, and the mineral spirits cleaning is describes several techniques that have chemical. Because an in-process recy- eliminated. proven to be successful in many appli-

18 METAL FINISHING NOVEMBER 1994 water, once can cause a 50% reduction in the Media volume of waste solution that has to be II treated or disposed of. Since 1992, Unfinished Finished Metal Parts Metal Parts Miniature Casting has utilized a simple recycling program. The company Finishine reuses the same solution for many , I F, weeks with simple settling. After two

Sal“ti.3“ Operations to three months, the parts cannot be Recycling cleaned adequately and more advanced System filtration technologies are used to “re- charge’’ the recycled solution. A dis- cussion of these other filtration tech- niques is presented below. The equip- Waste Treatmentc & Disposal ment costs for the simple recycle system include tank, pump, and piping Figure 2. Stream segregation. costs. A small operation (less than several hundred gallons per day) can use drums, whereas larger operations cations. Some recycling programs are recycling. The more times a solution is (thousands of gallons per day) would more costly than others and each recycled, the less wastewater is gener- require the installation of holding company should test all available op- ated. For example, if a company gener- tanks. Anticipated costs range from tions to determine the most cost- ates 1,OOO gallday of waste finishing several hundred dollars to several thou- effective program. solution, reusing the 1,000 gallons just sand dollars. The solids that are period- once will reduce actual waste solution ically removed from the settling tank Waste Stream Segregation generation down to 50% of the original consist mostly of media and some Before any recycling program is waste volume. Because mass-finishing metal. Depending on the nature of implemented, it is important to ensure operations vary from company to com- these solids, some off-site reclamation that specific operations are separated in pany, several types of solution recy- opportunities may exist. But because such a way that prevents solution cling systems have been developed to chemical treatment is not used, the suit almost any application. The fol- volume of removed solids is much mixing. If the waste stream from the original finishing operation is mixed lowing techniques are based on actual smaller than what would be obtained tests and case studies at several differ- with other waste streams prior to with chemical flocculation. ent companies. end-of-pipe treatment, the finishing Coarse Fikration solution must be captured prior to Simple Recycle Many companies have utilized car- mixing with the other waste streams As the solution is used and leaves tridge or bag filtration to clean the used (see Fig. 2). Similarly, if more than one the tubbing or vibratory machine, it is finishing solution. Since most compa- fmishing solution is used, each of these usually considered “waste” and no nies who recycle their solution ulti- streams must be separated and will longer suitable for reuse. The solution mately use membrane filtration (dis- require individual recycling systems. It may be reused more than once with cussed later), some type of coarse is important that soaps not be mixed as little or no filtration. Although the prefiltration is usually required. the original soap solution is desired for solution may appear spent or visibly “Coarse” filtration can be defined as reuse. dirty, in some cases companies have removing particles that are larger than captured the machine effluent and 3W200 pm in size. Although settling Solution Recycling Options simply reused the solution after simple is often considered to be one type of As shown in Figure 2, a properly settling (see Fig. 3). Final part quality coarse particle removal, separation is designed material recovery system pre- is not affected, and the volume of not always well defined. Different vents waste solution from entering the waste solution is minimized. Table 11 mass-finishing media have different treatment and disposal stream. Table I1 shows how reusing the solution even settling characteristics, which are not describes how significant savings in process waste can be achieved with

Table II. Effect of Reuse on Wste Reduction Number d nm % Wme Reduction of SaWx Reused OriOiDal WsfeSoluiim i 50 2 67 3 75 SolidsPeriodic Dump Settling 4 80 ---p 5 e3 io 91 Figure 3. Simple solution recycle.

METAL FINISHING NOVEMBER 1994 19 Table 111. Approximate Costs for Complete Membrane Recycling Svstem

Flow Rafe, lnifial Annual gaVday Cajifal, $ meratiig, $

50 4.onn,... mn... Filter 150 7,000 1,000 Settling 500 18,000 2,500 Periodic 1.000 34.000 4.000,~~~ Solids Removal 1o;ooo ~O;OOO 10,000

relevant if a bag or cartridge filter is Figure 4. Solution recycle with coarse filtration. used. A filter separates particles of a specified size regardless of settling Most companies prefer to filter all of mented to improve a particular mass- characteristic. Usually, settling is used the used solution with membranes (Fig. finishing operation, some “waste” prior to any filtration to remove the 5) so that the soap solution is as clean as materials will inevitably need to be large particles and extend the lifetime possible before reuse. Certain metal dealt with; sludge will be formed of the filters (see Fig. 4). parts are subject to very strict cleaning (discussed below), and the solution requirements; therefore, the reused so- will become unusable after a certain Membrane Filtration lution must be as clean as possible. time period. Most companies clean and Membrane filtration is the best Some level of on-site testing should be reuse the same solution for up to one means of mechanically separating dif- carried out to determine the best process. year before cleaning out the system. ferent constituents. Membranes can Table 111 shows the approximate Although membrane technologies can separate pm-size particles (microfiltra- costs associated with the implementa- actually clean the water to exceed tion), particles <0.1 pm in size or large tion of membrane technology for mass- municipal drinking water standards, molecules (ultrafiltration), and small finishing recycling. Initial capital costs these membrane types (nanofiltration molecules and dissolved metal (nan- include the membrane system, tanks, and reverse osmosis) are more expen- ofiltration and reverse osmosis). For pumps, solids dewatering equipment, sive to use and do not lend themselves the most part, companies have relied and installation. Operating costs in- to the recycling process where mi- on microfiltration and ultrafiltration for clude membrane/filter replacement, en- crofiltration and ultrafiltration are best cleaning and reusing finishing solu- ergy, and labor. Depending on the size employed. Over time, salts and metals tion. Because one of the primary of the operation and extent of automa- accumulate in the recycled solution to objectives is to recover as much soap tion in the system, costs can vary a point where the parts do not clean as possible, it is usually not necessary widely. If the operation is fairly small well. In some cases, where there are to make use of nanofiltration or reverse (400 gal/day), filter bags can be used long periods of inactivity, biological osmosis technologies, which would to dewater solids that are periodically growth creates an operational as well , separate out most of the soaps and are removed from the operation. Compa- as odor problem. Small doses of hydro- much more costly to operate. A typical nies with larger finishing operations gen peroxide usually eliminate this .* t“ process schematic for a recycling sys- have purchased filter presses, which problem. When the solution is ready to tem using membrane technology is can handle larger amounts of sludge be replaced, companies normally do one shown in Figure 5. and dewater at a faster rate than simple of two things: (1) depending on the Many Rhode Island companies are filter bags. . volume of recycled solution, a company currently using the process described in Regardless of the changes imple- may have a licensed hauler remove the Figure 5. Although the previously men- tioned techniques are certainly viable and less costly, membrane technology allows for much longer recycling peri- Finishing Clean ods. For example, Miniature Casting Operation Holding makes use of simple recycling without c Tank any filtration for several months. The water begins to become so contami- nated, however, that the parts no longer are clean after finishing. At this point, all of the recycled fluid is processed through a small ultrafiltration system. The solution is “recharged” and ready to be used for another 2-3 months of simple recycling (see Fig. 6). Other companies have also implemented simi- lar “hybrid” recycling programs where different filtration technologies are combined. Figure 5. Solution recycle using membrane technology.

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Plating Rate VI Temperature Plating Thickness VI Time

Uyemura International Corporation 2625 E. Cedar Street. Ontario, CA 91761 Tel: 19091 923~2294Fax: 19091 923 7643 36 Sheffield Street. Waterbury, CT 06704 Tel: 12031 754~1434Fax: 12031 753~0426 Clrcie 079 on reader information card Soap, -3 gallmanth manufacturing operations. Companies Tap water make-up that are able to mass finish “part on for evaporation- part” without media (very small metal -20 gallmanth parts, usually) end up with sludge that is pure in metal, and off-site reclama- Finished tion becomes even more attractive. Off-site reclamation becomes more Operatio” difficult if the metal portion of the sludge is of a mixed variety. The Make.up sludge may be a mixture of metals (every 10 weeks) because many companies manufacture ~~ different metal parts that are complex alloys. For example, brass contains zinc and copper; and some “white” levcry 10 weeks) metals contain a mixture of lead, 1 1 antimony, and tin.

SUMMARY OF POLLUTION PREVENTIONAPPROACHES loop filter Periodic sludge 4 removal for off site Figure 7 summarizes the available rcelamatiD“ pollution prevention options for mass- levcry 10 weeks1 finishing operations. Once modifica- tions have been made to the unit Figure 6. Present vibratory recycle operation at Miniature Casting Corp. (Cranston, R.I.). operation, in-process recycling meas- ures can be implemented. The final waste materials (Le., sludge and unusa- entire working volume (some compa- inevitably produced. The avoidance of ble finishing solution) either have to be nies recycle only a couple hundred chemical treatment reduces potential treated and/or disposed of. In any case, gallons of solution), or (2) dump the waste, hazardous materials handling, the amount of waste materials gener- solution into an already existing waste- and disposal costs. Optimizing finish- ated will be reduced substantially water pretreatment facility. How often ing times and the type of media through the implementation of pollu- the solution has to be changed varies employed in the process will help to tion prevention measures. from company to company; the average minimize the generation of waste cycle appears to be about a year. In any sludge. The solids that are removed ECONOMICS case, the volume of waste is reduced from in-process recycling programs The implementation of pollution- significantly. Sludge is periodically re- consist mostly of media and some 1 prevention techniques can incur costs moved from the operation and must be metal of the type@) found in the parts that cover a wide range: from minimal managed accordingly. to be cleaned. In some cases, the labor costs for simple process modifi- removed sludge can be returned to the cations to tens of thousands of dollars Sludge Handling metal supplier for reclamation. Some for membrane filtration equipment. Although certain steps can be taken companies are able tn return the sludge Most companies base equipment pur- to ensure that the amount of sludge that is removed from the recycling chases on cost-effectiveness and pay- generated is minimized through proc- process to their metal supplier along back. For example, if it is determined ess modification, some solid waste is with scrap metal that is left over from that a particular company’s operation requires $10,000 in equipment pur- Table IV. Economic Analysis of Pollution Prevention Project chases, the company would like to see annual or biannual savings of at least Cost Before, $ Cost After, $ $10,000. These savings may come in the Capital equipment including membrane system, tanks, form of disposal cost reductions, soap/ ~ pumps, and filterslhousing 0 5,500 chemical purchase savings, and water/ Annual operating costs (estimated) sewer fee reductions. Table IV summa- SoaD 1.526 1no.. rizes the economic savings achieved at Mineral spirits 1,015 0 one company where a payback was -~~ ~ Cartridge lilters 1,189 400 obtained in less than one year. Membrane replacement 0 300 ~~__ ~ Energy negligible negligible In some cases, however, because of Labor 4.742 1.700 regulatory pressure, companies are re- Water 161 0 quired to implement pollution-control Sewer fees 300 0 Analytical tests 224 20 equipment. Material recovery and the Tdal 9,157 2,500 minimization of environmental dis- charge are the best approaches to deal-

22 METAL FiNiSHiNG NOVEMBER 1994 All possible process modifications have been implemented: - input material replacement Printed Circuits - optimization of aoaplwater use Handbooks

In-Process Recycling edited by C.E Coombr, JK - simple settling hardcover $74.5 0 - coarse filtration - membrane filtration This excellent handbook is a complete reference for all topics in printed circuits manufactur- ing. It addresses both technical Off site reclamation concepts and common everyday or disposal of sludge -onsite treatment & disposal or problems. Furthermore, the - onsite disposal I I handbook considers all aspects of fabrication processing, Figure 7. Summary of pollution-prevention sequence. Send Orders to: METAL FINISHING ing with compliance problems (in-proc- Rhode Island (URI). His position is funded Three University Plaza ess recycling) as liabilities can he by the Pollution Prevention Program of the Hackensack, NJ 07601 significantly reduced immediately. Rhode Island Department of Environ- mental Management. Since 1989, he has For falter sewice, Acknowledgments provided technical assistance to many R.I. companies in the area of waste reduction Funding used to support the research Call (201) 487-3700 and pollution prevention. He received his or FAX your order to and testing was provided by the US. bachelor’s and master’s degrees from Dart- Environmental Protection Agency and mouth College and his Ph.D. from URI. He (201) 487-3705 the Rhcde Island Department of Envi- is a member of the American Institute of ronmental Management. Chemical Engineers. Most of his hack- All hak crderr must be prepaid. NY. NJ and MA rezidenra add nppmpriae mlez QI. PIrae include ground centers around membrane filtration $1.00 shipping and handling for delively of rarh Biography processes, especially for oiliwater separa- bmk via UPS fn addmsse in the US.: SX.00 for tion. He spent three years at Smbom- earh bwk for Air Pnml Pmi rhipmem m Canada: and $20.00for each kmk for Air Parcel Pwf ship Eugene Park is currently working as a Donaldson in Wrentham, Mass., as a mem m 811 other mmnfiiez. Research Professor at the Chemical Engi- process engineer in oiVwater separation neering Department of the University of prior to coming to URI in 1989. MF

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METAL FINISHING NOVEMBER 1994 23