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You are here: EPA Home » DfE » Alternatives Assessments

Off - Site Recycling

7.1 General

Off-site recycling is a commonly used alternative for PWB manufacturers as a means of managing spent etchant solutions and wastewater treatment sludges. Widespread implementation of this option reduces the quantity of wastes being disposed of in landfills. The PWB survey gathered information regarding the types of wastes sent to off-site recycling firms, quantities, destinations, and associated costs. These data are presented and discussed in this section.

A summary of data related to off-site recycling of spent process solutions, including etchants, is presented in Exhibit 7-1. Nearly all respondents reported using off-site recycling for disposing of spent process baths. A summary of data related to off-site recycling and disposal of wastewater treatment sludges is presented in Exhibit 7-2. Nearly ninety percent (90%) of those who provided data concerning the destination of their sludges indicated that they ship the sludges to recycling facilities rather than landfills.

Respondent
ID
Waste
Description
Source Quantity
(per year)
Available
Cost Data
Name of
Recycle Company
Distance to
Recycle Company
(miles)
279 cupric chloride etch 11,000 gal 5.54 $/gal Phibro Tech 40
279 cupric chloride etch rinses 6,000 gal 5.45 $/gal Phibro Tech 40
3023 ammoniacal etch 199,450 gal 0.50 $/gal Macdermid 75
3470 ammonia etch etch 18,000 gal nr - nr nr
3470 gold plate bath plate 60 gal nr - nr nr
6710 D001/D002 sulfuric/ peroxide 440 gal 1.96 $/gal US Filter Rec. 40
6710 D002 ammoniacal etch 8,000 gal 1.52 $/gal Phibro Tech 350
25503 cupric chloride etch 2,000 gal 0.25 $/gal Old Bridge 3,300
29710 D002/D004 etch 98,000 lb nr - Macdermid 768
29710 F005/D001 paint 1,536 lb nr - Safety-Kleen 100
29710 D001 solder wave 2,721 lb nr - Safety-Kleen 100
29710 D001 hot air solder lev. 1,482 lb nr - Safety-Kleen 100
32482 gold plating gold plate 100 gal nr - Advanced Chem 120
33089 ammoniacal etchant etch 60,000 lb 0.29 $/lb. US Filter Rec. 225
33089 tin/lead solder strip 6,000 lb 0.40 $/lb. US Filter Rec. 225
36930 etchant etch 60,000 gal 4,000 $/yr Phibro Tech 400
36930 microetch etching/cleaning 6,000 gal 9,600 $/yr - nr
37817 flux hot air leveler 200 gal 230 $/drum Entech Managt. 150
37817 etchant etch 23,000 gal nr - Dexter nr
37817 resins cadines 15 ft3 160 $/drum Entech Managt. 150
37817 acid sludge waste catch drains 200 gal 230 $/drum Entech Managt. 150
41739 D002 ammoniacal etch 17,000 gal 18,060 $/yr Phibro Tech 400
41739 F007 gold bath 25 gal 3,000 $/yr Technic 800
41739 D008 solder bath 20,000 lb nr - Alpha Metals 800
42692 ammoniacal etchant etch 52,883 gal nr - Old Bridge 400
42751 cupric chloride inner layer etch 83,700 gal nr - Norris Environ. 1,000
42751 ammoniacal etchant outer layer etch 32,050 gal nr - Phibro Tech 1,200
43694 ammoniacal etchant etch 35,000 gal nr - S. Cal Chem 30
43841 D002 etch 13,700 gal 38,000 $/yr Phibro Tech 500
43841 D001 oil/glycol 220 gal 2,000 $/yr Safety Kleen 1,500
43841 class 55 board scrap 38,000 lb 7,000 $/yr SIMCO 1,000
44486 NH etchant Cu etch 255,370 lb nr - Phibro Tech 200
44486 peroxide/sulfuric tin strip 49,911 lb 18,135 $/yr Phibro Tech 200
44486 flux HAL 32,292 lb 16,000 $/yr Hydrite 90
44486 acid Ni Ni plate 195 lb 683 $/yr PhibroTech 200
44657 D002/D008 etch 6,300 gal nr - Hubbard Hall nr
133000 etchant etch 40,000 gal 0.20 $/gal Macdermid 150
237900 ammoniacal etchant etch 50,000 gal 0.10 $/gal S. Cal Chem 370
237900 acid nitric solder strip 2,000 gal 4.60 $/gal Norris 370
237900 acid solder strip 1,000 gal 5.00 $/gal Norris 370
237900 acid plating 1,400 gal 4.80 $/gal Norris 370
358000 etchant etch 70,000 gal 0.11 $/gal Old Bridge, NJ 600
358000 tin stripper tin stripper 1,800 gal 3.18 $/gal Republic 200
462800 spent copper etch 1,419,393 lb 26,000 $/yr1 Phibro Tech 40
462800 acid rinse water etch 349,020 lb 0.05 $/lb Envirite 30
462800 copper sludge etch/microetch 12,854 lb 0.00 $/lb Phibro Tech 40
462800 spent flux hot air leveling 4,400 lb 0.91 $/lb AKA Industrial 55
502100 sludge etch 1,000 gal nr - nr nr
946587 D002 Cu sulfate plating 7,500 gal 0.12 $/lb Learonal 980
947745 etchant etching 3,960 gal 0.06 $/lb Phibro Tech 250
947745 stripper rack strip 1,200 lb 0.29 $/lb Encycle 250
953880 D002 etch 15,000 gal nr - Phibro Tech 600
955099 etchant ammoniacal etch 65,000 gal nr - Macdermid 280
955099 CuSO4 plating 12,000 gal 2.00 $/lb Phibro Tech 400
955099 solder HASL 22,000 lb 1.10 $/lb1 Dexter 50
955703 etchant etch 45,000 gal 0.18 $/lb Phibro Tech 25
955703 solder oil HAL solder 1,300 gal 0.40 $/lb DK 20
955703 tin strip tin strip 5,000 gal 0.37 $/lb Phibro Tech 25
955703 flux HAL solder 800 gal 0.40 $/lb Romic 70
959951 gold tab plate 50 gal nr - Electrochemicals nr
959951 silver film processor 250 gal nr - Electrochemicals nr
959951 ammonia etch 15,840 gal nr - Phibro Tech nr
965874 etchant etch 15,800 gal 0.30 $/gal Phibro Tech 600
36930A etchant etching 4,200 gal nr - Phibro Tech 400
T1 gold deep gold nr - nr - Learonal nr
T1 ammonical etch inner/outer etch nr - nr - Phibro Tech nr
T2 etchant Cu chloride etch 18,500 gal 3.68 $/gal Phibro Tech 7
T2 etchant ammoniacal etch 33,000 gal nr - Phibro Tech 7
T2 tin strip tin strip 9,000 gal 3.45 $/gal Encycle, TX 450
T2 nitric acid rack strip 660 gal 4.09 $/gal Encycle, TX 450
T3 etchant etch 8,000 gal nr - S. Cal Chemical 10
T3 nitric acid rack strip 1,000 gal 5.36 $/gal Great West. Chem 10
1 Income from recycled process fluid.
nr = no response
Exhibit 7-1. Off-Site Recycling of Spent Process Fluids (continued on nest page)

Respondent
ID
Quantity (lbs) Percent
Solids
Recycle or
Dispose
Cost
($/yr)2
Cost
($/lb) 2
Company Distance
to Site
(miles)
279 nr nr nr nr nr nr nr
29710 nr nr nr nr nr nr nr
31838 nr nr nr nr nr nr nr
36930 nr nr nr nr nr nr nr
43694 nr nr nr nr nr nr nr
237900 nr nr nr nr nr nr nr
358000 nr nr nr nr nr nr nr
955703 nr nr nr nr nr nr nr
3470 10,000 75 nr nr nr nr nr
965874 5,000 15 nr nr nr nr nr
25503 1,200 95 unknown 720 0.60 Norris Env 30
42692 200,000 40 unknown 85,000 0.43 S. Water Treat. Co 300
273701 300 50 D 200 0.67 US Filter Rec. nr
36930A 181 50 D nr nr US Filter Rec. 30
33089 80,000 35 D 48,000 0.60 US Filter Rec. 225
502100 3,000 75 R nr nr nr nr
959951 33,190 50 R nr nr Cyprus Miami nr
T2 58,000 25 R nr nr Encycle, TX 450
44486 nr nr R nr nr Foreman Metals 20
462800 12,854 98 R 0 0 Phibro Tech 40
T1 260,000 80 R 35,000 0.13 Encycle, TX 1,500
41739 42,000 65 R 6,000 0.14 Encycle, TX 600
107300 400,000 60 R 60,000 0.15 WRC 222
740500 1,700,000 36 R 275,000 0.16 WRC 1,500
55595 140,000 40 R 22,880 0.16 Envirite 400
42751 250,000 48 R 39,375 0.16 WRC nr
133000 160,000 60 R 27,000 0.17 WRC 300
947745 9,600 80 R 1,875 0.20 Encycle, TX 250
3023 320,000 41 R 68,000 0.21 WRC 375
946587 308,000 53 R 63,150 0.21 WRC 1,000
955099 220,000 48 R 50,000 0.23 WRC 500
32482 14,000 65 R 4,000 0.29 WRC nr
44657 8,200 30 R 3,000 0.37 WRC 750
953880 120,000 35 R 48,000 0.40 WRC 300
43841 10,000 26 R 7,800 0.78 WRC 500
6710 18,000 nr R 25,000 1.39 WRC 850
37817 1,000 95 R 1,500 1.50 NE Chemical Co 400
T3 10,000 80 R 20,000 2.00 Encycle, TX 1,800
1 Unit is ft3.
2 Some variation in costs among respondents may be due to inclusion or omission of analytical fees (sometimes referred to as material profile fees).
nr = no response
Exhibit 7-2. Off-Site Recycling/Disposal of Wastewater Treatment Sludge

7.2 Off-site Recycling of Spent Process Baths

By far, the most commonly reported spent process fluid that is sent off-site for recycling is spent etchant, particularly spent ammoniacal etchant. Spent ammoniacal etchant is created at a rate of roughly 1 gallon per 30 surface square feet of inner- and outer-layer panels. On-site regeneration of ammoniacal etchant is not widespread. One respondent reported installing solvent extraction technology for the purpose of on-site regeneration of ammoniacal etchant and copper recovery in 1994 (see Section 6.2.4). The reason that spent etchant is a popular waste for off-site recycling is due mostly to its high copper concentration, which is typically 150 g/l Cu (i.e., 15% Cu). Etchant that is sent off-site is processed to recover the copper and regenerate the etchant for reuse. Eighty-three percent (83%) of the respondents who completed the off-set recycling section of the survey reported that they send spent ammoniacal etchant off-site for recycling. Costs associated with ammoniacal etchant recycling were provided in several different types of units and varied widely, but in general, it was clear that etchant recycling represented a major portion of overall recycling costs. One respondent (ID# 462800) reported an income from off-site recycling of their spent cupric chloride etchant ($26,000 annually).

Waste products other than etchant are less frequently sent off-site for recycling by the survey respondents. The next most commonly shipped waste product is tin and/or tin-lead stripping solutions. These solutions are listed by 20% of the respondents who completed this section of the survey form. Like etchant, spent stripping solutions have a high metal concentration that makes it a viable candidate for recycling. Also, stripping solutions are generated in relatively high volumes, furthering the economics of off-site recycling. For example, ID# 44486 reported shipping 49,911 lb of tin strip and ID# T2 reported shipping 9,000 lb of tin stripper). In comparison, these quantities are equivalent to approximately 20% to 30% of their etchant volume sent off-site.

Flux, solder dross from the hot-air-solder-level process, and other lead-bearing solutions are shipped off-site for recycling by 20% of the respondents. However, the quantities of these materials that are shipped are relatively small. One exception was ID# 41739, who reported shipping 20,000 pounds of solder bath to an off-site recovery facility. Tin-lead plating baths generally have a long life-span (several years) and disposal of the solution is an unusual event. For this reason, it is believed that with this particular case, shipment was a one-time event. For example, the facility may have replaced their tin-lead plating bath with a tin-only solution or needed to dispose of a bath due to irreversible contamination.

Micro-etchants are shipped off-site for recovery by only 8% of the respondents. Spent micro-etchants typically contain copper concentrations of 15 to 30 g/l Cu (i.e., 1.5 to 3.0% Cu). Other respondents reported electrowinning these solutions on-site, or treating them with conventional precipitation.

Gold- and silver-bearing wastes are sent off-site by 15% of the respondents. Gold electroplating baths (usually gold cyanide) have a long life-span, and not surprisingly, the reported volumes were all 100 gallons or less. Solutions containing gold may include spent gold electroplating bath, or the contents of drip or drag-out tanks on the gold plating line. Silver is present in film developing fluids that may be reclaimed on-site (electrowinned), shipped off-site for metal reclamation, or combined with other waste streams and treated conventionally.

Ten percent (10%) of the respondents indicated that spent rack stripping solution is shipped off-site. Plating racks are typically coated with a non-conductive substance to prevent electroplating from occurring on the rack surface itself. Due to use, this coating may degrade and plating can accumulate on the rack, especially near the clamps and contact points. This unwanted copper deposit is removed in a stripping solution such as dilute nitric acid. The volume of spent stripping solution can be significant. Respondent T3 shipped 1,000 gallons of nitric acid rack stripper off-site at a cost of more than $5 per gallon. By comparison, this volume is equivalent to 12.5% of the etch volume shipped by the same respondent.

7.3 Wastewater Treatment Sludge

A very high percentage of respondents (88% of those providing data) indicated that they send their wastewater treatment sludge to off-site disposal facilities rather than to landfills. This percentage appears to be particularly high when compared to the 31% of plating shops that use this method for disposal (based on results presented in ref. 1).

The average and median unit costs for off-site recovery of sludge are $0.48/lb and $0.21/lb, respectively. In general, the lower costs experienced by some respondents compared to others were due to larger-size shipments and shorter distances to the recycling sites, both of which reduce transportation costs. However, in some cases, differences in unit costs may be the result of other factors. For example, ID#'s 133000 and 953880 ship similar quantities of sludge the same distance to the same recycling company.m The unit cost of the off-site recycling for the two PWB manufacturers varies significantly ($0.17/lb vs $0.40/lb). One difference between the sludges shipped by these respondents is the percent solids. ID# 133000 is shipping a much dryer sludge (60% solids compared to 35% solids for ID# 953880). The dryer sludge will have a greater recovery value. By drying sludges PWB manufacturers can also reduce transportation costs since drying reduces the volume of the sludge. The sludge drying technology and its impact on sludge volume are discussed in Reference 1.

A discussion of off-site recycling, including descriptions of processes used by recycling companies, is presented in Reference 1.


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