Metal Products and Machinery: Proposed Rule for Pretreatment and Effluent Guidelines

ENVIRONMENTAL QUALITY MANAGEMENT / Summer 2001 / 65

Metal Products and Machinery: Proposed Rule forPretreatment and Effluent Guidelines

Wade Miller

EPA’s proposal outlines technology-based effluent limits and pretreatment standards for waste-water discharges from facilities that manufacture, rebuild, repair, or maintain finished metalproducts, parts, or machines. © 2001 John Wiley & Sons, Inc.

On January 3, 2001, the U.S. Environ-mental Protection Agency (EPA) pro-posed new effluent limitation standardsfor the Metal Products and Machinery(MP&M) point-source category. The rulewould establish technology-based efflu-ent limits and pretreatment standards forwastewater discharges from both newand existing facilities that manufacture,rebuild, repair, or maintain finishedmetal products, parts, or machines.These manufacturing, rebuilding, andmaintenance activities occur in 18 indus-trial sectors, including:

• aerospace• aircraft• buses and trucks• electronic equipment• hardware• household equipment• instruments• job shops• mobile industrial equipment• motor vehicles• office machines• ordnance• precious metals and jewelry

© 2001 John Wiley & Sons, Inc.

• printed wiring boards• railroads• ships and boats• stationary industrial equipment• miscellaneous metal products

Not included in this proposal are themaintenance and repair of metal parts,products, or machines that occur only asancillary activities. All told, the MP&Mindustry is estimated to include almost89,000 facilities, 63,000 of which dis-charge wastewater. This article looks atthe proposed rule and attempts to pro-vide some insight into its applicabilityand impact.

BACKGROUNDEffluent limitations have previously

been established for 13 industries withoperations involving metal products andmachinery:

• electroplating (40 CFR, Part 413)• iron and steel manufacturing (40

CFR, Part 420)• nonferrous metals manufacturing (40

CFR, Part 421)

Wade Miller66 / Summer 2001 / ENVIRONMENTAL QUALITY MANAGEMENT

• ferroalloy manufacturing (40 CFR,Part 424)

• metal finishing (40 CFR, Part 433)• battery manufacturing (40 CFR, Part

461)• metal molding and casting (40 CFR,

Part 464)• coil coating (40 CFR, Part 465)• porcelain enameling (40 CFR, Part

466)• aluminum forming (40 CFR, Part

467)• copper forming (40 CFR, Part 468)• electrical and electronic components

(40 CFR, Part 469)• nonferrous metals forming and metal

powders (40 CFR, Part 471)

In 1986, EPA determined that a sig-nificant number of metals processingfacilities were not covered by effluentlimitations, but should be. Further analy-sis resulted in the decision to develop theMP&M point-source category.

The current MP&M proposal followsa 1995 proposal that the Agency did notfinalize (see 60 Fed. Reg. 28210). Theprevious proposal addressed some of thesame facilities covered by the currentproposed rule, but using a phasedapproach. Based on comments receivedon the 1995 proposal, EPA decided toestablish effluent guidelines for allindustrial sectors that would be includ-ed in the MP&M category (62 CFR 8726).

WHAT IS BEING PROPOSEDThe MP&M rule would establish

technology-based effluent limits andpretreatment standards for wastewaterdischarges from a wide range of indus-tries. These new rules would apply toboth new and existing facilities thatmanufacture, rebuild, repair, or maintainfinished metal products, parts, ormachines.

Discharge limits are being tightenedfor a number of metals, including man-ganese, molybdenum, tin, oil, and

grease, and total organic carbon. Somenew industries, such as machine shops,medical device manufacturers, andmaintenance facilities for trucks, buses,trains, and airplanes, are also beingbrought under the new rule. Circuitboard and metal finishing job shops willbe shifted from another discharge rule tothe MP&M rule and would see signifi-cantly tighter discharge limits.

As noted above, there are approxi-mately 89,000 MP&M sites in the UnitedStates, of which approximately 63,000discharge process wastewater. Thewastewater-discharging sites range insize from 10 employees to over 10,000employees; from discharge rates of lessthan 100 gallons per year to over 100million gallons per year. The number ofemployees at a site does not necessarilycorrespond with the discharge flow atthe site. The proposed regulations wouldcover facilities that discharge to surfacewater bodies and those that discharge tomunicipal treatment systems.

Some of the MP&M facilities arealready regulated under other cate-gories. Generally, the requirements forthese facilities will not change,although they may have to comply withthe MP&M requirements in addition tothose already imposed by other regula-tions. However, the Printed WiringBoard and the Metal Finishing JobsShops subcategories, currently subjectto the Electroplating and Metal Finish-ing Effluent Guidelines, will be subjectonly to the new MP&M category. Exhibit1 summarizes the impacts on the indus-trial sectors already covered by othercategories)

MP&M unit operations consist of:

• metal shaping operations• surface preparation operations• metal deposition operations• organic deposition operations• surface finishing operations• assembly operations

In 1986, EPA deter-mined that a signifi-cant number of met-

als processing facil-ities were not cov-

ered by effluent lim-itations, but shouldbe. Further analysis

resulted in the deci-sion to develop the

MP&M point-sourcecategory.

Metal Products and Machinery: Proposed Rule for Pretreatment and Effluent Guidelines ENVIRONMENTAL QUALITY MANAGEMENT / Summer 2001 / 67

• dry-dock operations• specialized printed-wiring-board

operations• unit operations performed at steel-

forming and finishing sites

Some MP&M sites conduct only one ortwo of these operations, while othersconduct all of them. Typical operationsperformed at MP&M sites are listed inExhibit 2.

Exhibit 1. Clarification of Coverage by MP&M Category

Subcategory Proposing to continue to Proposing to continue to Proposing to cover under 40 CFR, Part 438 cover under 40 CFR, Part 413 cover under 40 CFR, Part 433 (Metal Products & Machinery)(Electroplating) (Metal Finishing)

General Metals Existing facilities that are Existing facilities that are All new and existing direct dischargers in thiscurrently covered by 413 AND currently covered (or new subcategory regardless of annual wastewater are indirect dischargers that facilities that would be covered) discharge volume and all new and existing introduce less than or equal to by 433 AND are indirect indirect dischargers in this subcategory with 1 million gallons per year into discharges that introduce less annual wastewater discharges greater than a POTW. than or equal to 1 million gallons 1 million gallons per year. (See 438.10)

per year into a POTW.

Metal Finishing Job None (See non-chromium None (See non-chromium All new and existing direct and indirect Shops anodizers) anodizers) dischargers under this subcategory. These

facilities would no longer be covered by 413 or 433. (See 438.20)

Non-Chromium Anodizers Existing indirect dischargers New and existing indirect Existing and new direct dischargers that only Facilities that perform that are currently covered by dischargers (not covered by perform non-chromium anodizing (or do not anodizing with chromium 413 AND that only perform 413) that only perform non- commingle their non-chromium anodizing or with the use of non-chromium anodizing (or chromium anodizing (or do wastewater with other process wastewater for dichromate sealants (or do not commingle their non- not commingle their non- discharge). (See 438.30)commingle their non- chromium anodizing chromium anodizing chromium anodizing wastewater with other process wastewater with other process wastewater with wastewater for discharge). process wastewater for wastewater from other discharge).MP&M subcategories) will be covered by 40 CFR, Part 438.

Printed Wiring Board None None All new and existing direct and indirect dischargers(Printed Circuit Board) under this subcategory. These facilities would no

longer be covered by 413 or 433. (See 438.40)

Steel Forming & Finishing N/A N/A All new and existing direct and indirect discharges under this subcategory as described. (See 438.50)

Oily Wastes N/A N/A All new and existing direct and indirect dischargers under this subcategory as described. (See 438.60). (This subcategory excludes new and existing indirect dischargers that introduce less than or equal to 2 million gallons per year into a POTW. Facilities under the cutoff are not and will not be covered by national categorical regulations.)

Railroad Line Maintenance N/A N/A All new and existing direct dischargers under this subcategory as described. (See 438.70). There are no national categorical pretreatment standards for these facilities.

Shipbuilding Dry Docks N/A N/A All new and existing direct dischargers under this subcategory as described. (See 438.80). There are no national categorical pretreatment standards for these facilities.

Source: EPA. (2000, December). Development document for the proposed effluent limitations, guidelines and standards for the metal products and machinery point sourcecategory, EPA-821-B-00-005, Table 1-1.


PROPOSED GUIDELINESThe following are types of waste-

water generated by the unit operations atMP&M facilities:

• hexavalent -chromium-bear ingwastewater

• cyanide-bearing wastewater• oil-bearing and organic-pollutant-

bearing wastewater• chelated-metal-bearing wastewater• general metal-bearing wastewater

Because MP&M facilities can haveprocesses that could cause them to becategorized under multiple sectors, EPAdetermined that a regulation based onindustrial sectors would create imple-mentation issues. Instead, the agencyconcluded that the wastewater generatedby MP&M facilities has similar treatabil-ity issues across all of the MP&M sectors.

Accordingly, EPA is proposing anumber of subcategories to account for

these similarities. These subcategoriesare General Metals; Metal Finishing JobShops; Non-Chromium Anodizing;Printed Wiring Board; Steel Formingand Finishing; Oily Wastes; RailroadLine Maintenance; and ShipbuildingDry Dock.

The General Metals subcategory is asort of catch-all for facilities that dis-charge metal-bearing wastewater, butwhich do not fit into the other subcate-gories. The General Metals subcategorymay include facilities from all of theMP&M industrial sectors, except theprinted-wiring-board sector. General-metals facilities typically perform manu-facturing or heavy rebuilding of metalproducts, parts, or machines.

Indirect dischargers in the GeneralMetals subcategory (i.e., those discharg-ing to municipal treatment plants) areexcluded from these regulations if theirdischarges are less than or equal to 1 mil-lion gallons per year. This exemption is

Exhibit 2. Typical Unit Operations Performed at MP&M Sites

Unit Operation Name

1. Abrasive Blasting 24. Electroplating without Chromium or Cyanide2. Abrasive Jet Machining 25. Electropolishing3. Acid Treatment with Chromium 26. Floor Cleaning4. Acid Treatment without Chromium 27. Grinding5. Alkaline Cleaning for Oil Removal 28. Heat Treating6. Alkaline Treatment with Cyanide 29. Impact Deformation7. Alkaline Treatment without Cyanide 30. Machining8. Anodizing with Chromium 31. Metal Spraying9. Anodizing without Chromium 32. Painting - Spray or Brush10. Aqueous Degreasing 33. Painting - Immersion11. Assembly/Disassembly 34. Plasma Arc Machining12. Barrel Finishing 35. Polishing13. Burnishing 36. Pressure Deformation14. Chemical Conversion Coating without Chromium 37. Salt Bath Descaling15. Chemical Milling 38. Soldering/Brazing16. Chromate Conversion Coating 39. Solvent Degreasing17. Corrosion Preventive Coating 40. Stripping (paint)18. Electrical Discharge Machining 41. Stripping (metallic coating)19. Electrochemical Machining 42. Testing20 Electroless Plating 43. Thermal Cutting21. Electrolytic Cleaning 44. Washing Finished Products22 Electroplating with Chromium 45. Welding23. Electroplating with Cyanide 46. Wet Air Pollution Control

Source: EPA. (2000, December). Development document for the proposed effluent limitations, guidelines and standards for the metalproducts and machinery point source category, EPA-821-B-00-005, Table 1-2.


proposed to reduce the permitting burdenon municipal treatment systems. Theexclusion does not make a facility exemptfrom other pretreatment standards.

Facilities in the Metal Finishing JobShops subcategory must perform one ofthe following: electroplating; electrolessplating; anodizing; coating (chromating,phosphating, passivation, and coloring);chemical etching and milling; or printed-circuit-board manufacture. They alsomust own less than 50 percent of thematerials undergoing metal finishing.Printed-wire-board job shops are beingproposed for this subcategory based onthe unique economics of job-shop opera-tions. Facilities that would be in this sub-category are currently regulated under theexisting Metal Finishing or Electroplatingeffluent guidelines and standards.Facilities subject to the Metal-FinishingJob Shops subcategory would no longerbe covered by the effluent guidelines andstandards in 40 CFR 413 or 433.

The Non-Chromium Anodizing sub-category will include facilities that per-form aluminum anodizing without usingchromic acid or dichromate sealants.Anodizers that use chromic acid ordichromate would be in the GeneralMetals subcategory or, if they operate as ajob shop, in the Metal Finishing JobShops subcategory. Indirect dischargerswith non-chromium anodizing opera-tions would be excluded from the MP&Mcategorical pretreatment standards. Suchfacilities would still need to comply withMetal Finishing (40 CFR 433) pretreat-ment standards for their non-chromiumanodizing wastewater and the generalpretreatment standards at 40 CFR 403.

The Printed Wiring subcategory willcover wastewater discharges from themanufacture, maintenance, and repair ofprinted wiring boards. Printed-wiring-board facilities perform unique opera-tions, including applying, developing andstripping of photo resist, lead/tin solder-ing, and wave soldering. This subcategory

does not include job shops that manufac-ture, maintain, or repair printed wiringboards. These facilities will be coveredunder the Metal Finishing Job Shops sub-category. Facilities in this subcategory arecurrently regulated under the existingMetal Finishing or Electroplating effluentguidelines and standards. Facilities sub-ject to the Printed Wiring Board subcate-gory will no longer be covered by theeffluent limitations guidelines and stan-dards in 40 CFR 413 or 433.

The Steel Forming and Finishingsubcategory was established for facilitiesthat perform MP&M operations or coldforming operations on steel wire, rod,bar, pipe, or tube. This subcategory doesnot include facilities that perform thoseoperations on other base materials.Wastewater from steel forming and fin-ishing operations, regardless of whetherthese operations occur at a stand-alonefacility or at a steel manufacturing facili-ty, would be covered under this subcate-gory. Proposed revisions to the Iron andSteel regulations would exclude thosefacilities that EPA has determined to beregulated by the MP&M rule.

The MP&M Steel Forming andFinishing subcategory does not coverwastewater generated from any hot-steel-forming operations or from cold forming,electroplating, or continuous hot dipcoating of steel sheet, strip, or plates;these operations will be covered underthe Iron and Steel regulations.

When a steel manufacturing facilityperforms these MP&M steel forming andfinishing operations and commingles thewastewater for treatment with wastewaterfrom other non-MP&M unit operations,control authorities and permit writerswill need to set limits that account forboth the MP&M and the Iron and Steelregulations. Facilities that discharge theirMP&M steel forming and finishing waste-water separate from their iron and steelwastewater will have the appropriate lim-its applied to each waste stream.

Facilities subject tothe Metal-FinishingJob Shops subcate-gory would nolonger be coveredby the effluentguidelines and stan-dards in 40 CFR 413or 433.


The Oily Wastes subcategory wascreated as a catch-all for MP&M facilitiesthat discharge only oil-bearing waste-water and that do not fit into any of theother MP&M subcategories. Facilities inthis subcategory must discharge waste-water only from alkaline cleaning for oilremoval; aqueous degreasing; corrosionprevention coating; floor cleaning; grind-ing; heat treating; impact deformation;machining; pressure deformation; sol-vent degreasing; testing (e.g., hydrostat-ic, dye penetrant, ultrasonic, magneticflux); painting; steam cleaning; and laun-dering. Facilities in this subcategory arepredominantly machine shops or main-tenance and repair shops.

Corrosion prevention coating isdefined as the application of removableoily or organic solutions to protectmetal surfaces against corrosive envi-ronments. Corrosion preventive coat-ings include petroleum compounds,oils, hard dry-film compounds, solvent-cutback petroleum-based compounds,emulsions, water-displacing polar com-pounds, and fingerprint remover andneutralizers. Corrosion preventive coat-ing does not include electroplating,painting, and chemical conversion coat-ing (including phosphate conversioncoating) operations.

Additionally, indirect dischargersthat would fall into the Oily Wastes sub-category are excluded from the MP&Mregulations if they discharge less than 2million gallons per year of MP&Mprocess wastewater.

The Railroad Line Maintenance sub-category was developed to cover facili-ties that routinely clean and maintainrailroad engines, cars, car-wheel trucks,and similar parts or machines. Facilitiesin this subcategory discharge wastewaterfrom only those unit operations thatwould fall under the MP&M operationsthat EPA defines as oily operations,stormwater clean-up, and washing offinal products. Railroad line mainte-

nance facilities are similar to facilities inthe Oily Wastes subcategory in that theyproduce oil-bearing wastewater and donot perform MP&M operations that gen-erate wastewater, which would requiretreatment to remove metals.

Railroad manufacturing facilities orrailroad overhaul or maintenance facili-ties are not included in this subcategory.Indirect discharges from railroad linemaintenance facilities are excluded fromthe MP&M regulations.

The Shipbuilding Dry Dock subcate-gory was created to specifically coverMP&M process wastewater generated atdry docks, graving docks, building ways,marine railways, and lift barges at ship-building facilities. This subcategory willcover only process wastewater generatedand discharging from MP&M operationsinside and outside ships.

Process wastewater generated atother locations at a shipyard would notbe covered under this subcategory, butwill likely be covered under other sub-categories of the MP&M regulations.Additionally, three other water streamswill be excluded from the ShipbuildingDry Dock subcategory: flooding water,dry-dock ballast water, and stormwater.These wastewaters will be coveredunder EPA’s stormwater general permit,state stormwater permits, or individualstormwater permits. Indirect dischargesfrom dry docks and similar structureswill be excluded from the MP&M rule.

For the priority and nonconvention-al organic pollutants listed in Exhibit 3,EPA is proposing an approach similar tothe one used in the Metal FinishingEffluent Guidelines (40 CFR, Part 433). Alist of organic pollutants, called the totalorganics parameter (TOP), was devel-oped using the list of organic prioritypollutants and other nonconventionalorganic pollutants that met EPA’s pollu-tant-of-concern criteria for this rule.

Of the nonconventional organiccompounds on the MP&M list of pollu-

A list of organicpollutants, calledthe total organicsparameter (TOP),

was developedusing the list of

organic priority pol-lutants and othernonconventional

organic pollutantsthat met EPA’s pollu-tant-of-concern cri-

teria for this rule.


tants of concern, only those that areremoved in appreciable quantities by thetreatment technologies in two or moresubcategories are being proposed for reg-ulation. EPA is also proposing to allow

the use of an indicator parameter tomeasure the presence of organic pollu-tants in MP&M process wastewater.Facilities can monitor for the organicpollutants specified in the TOP limit, or

Exhibit 3. Remaining Pollutants Considered for Proposed Regulation for the Metal-BearingSubcategories

Priority Metals

Cadmium LeadChromium NickelCopper SilverCyanide Zinc

Nonconventional Metals

Manganese TinMolybdenum

Conventional Pollutants

Oil and Grease (as Hexane Extractable Material, or HEM) Total Suspended Solids

Other Nonconventional Pollutants

Amenable Cyanide Total SulfideTotal Organic Carbon

Priority Organic Pollutants

1,1,1,-Trichloroethane Di-n-Butyl Phthalate1,1-Dichloroethane Di-n-Octyl Phthalate1,1-Dichloroethylene Dimethyl Phthalate2,4-Dimethylphenol Ethylbenzene2,4-Dinitrophenol Fluoranthene2,6-Dinitrotoluene Fluorene2-Nitrophenol Isophorone4-Chloro-m-cresol Methylene Chloride4-Nitrophenol n-NitrosodimethylamineAcenaphthene n-NitrosodiphenylamineAcrolein NaphthaleneAnthracene PhenanthreneBenzyl Butyl Phthalate PhenolBis(2-Ethylhexyl) Phthalate PyreneChlorobenzene TetrachloroetheneChloroethane TolueneChloroform Trichloroethylene1-Methylfluorene Biphenyl1-Methylphenanthrene Carbon Disulfide2-Isopropylnaphthalene Dibenzofuran2-Methylnaphthalene Dibenzothiophene

Nonconventional Organic Pollutants

3,6-Dimethylphenanthrene n-HexadecaneAniline n-TetradecaneBenzoic Acid p-Cymene

Source: EPA. (2000, December). Development document for the proposed effluent limitations, guidelines and standards for the metalproducts and machinery point source category, EPA-821-B-00-005, Table 7-10.


they can monitor for total organic carbon(TOC) and meet the TOC limit.

MP&M industries use many differenttypes of technologies to control and treatwastewater, including both in-processpollution prevention technologies andend-of-pipe treatment and disposal tech-nologies. EPA has classified the mostprevalent technologies used into fourtiers of an environmental managementhierarchy:

• Tier I: source reduction technologies• Tier II: recycling technologies• Tier III: end-of-pipe treatment tech-

nologies• Tier IV: disposal technologies

EPA evaluated the performance oftechnologies used by the MP&M indus-try and identified ten technology optionsfor the MP&M industry subcategories.Exhibit 4 shows the options for each sub-

Exhibit 4. Technology Options by Subcategory

Treatment or Source General Metals, Metal Finishing Job Shipbuilding Dry Reduction Technology Shops, Printed Wiring Boards, Steel Dock and Railroad

Forming and Finishing, and Non- Line Maintenance Chromium Anodizing Subcategories Oily Waste Subcategory Subcategories

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 7a Option 8a Option 9 Option 10

Chemical Precipitation • • • •Gravity Clarification for Metal

Hydroxide Removal • •Microfiltration for Metal

Hydroxide Removal • •Emulsion Breaking and

Gravity Separation for Oil Removal • • • •

Ultrafiltration for Oil Removal • • • •Emulsion Breaking and DAF

for Oil Removal • •Alkaline Chlorination for

Cyanide Removal • • • •Hexavalent Chromium

Reduction • • • •Reduction/Precipitation of

Chelated Metals • • • •Contract Hauling of Organic

Solvent-Bearing Wastewater • • • • • • • • • •Countercurrent Cascade

Rinsing • • • • •Centrifugation and Recycling

of Painting Water Curtains • • • • •Centrifugation and

Pasteurization to Extend Life of Water Soluble Machining Coolants • • • • •

DAF: Dissolved air flotationaEPA evaluated this option for Shipbuilding Dry Dock and Railroad Maintenance Subcategories along with Options 9 and 10.

Source: EPA. (2000, December). Development document for the proposed effluent limitations, guidelines and standards for the metal products and machinery point sourcecategory, EPA-821-B-00-005, Table 9-4.


category and the technologies used toestablish effluent limitations and stan-dards. These options are described inExhibit 5.

REGULATORY IMPLEMENTATIONEPA is proposing that existing facil-

ities comply with the MP&M pretreat-ment standards within three years fromthe date the rule becomes final. Besidesallowing facilities time to construct sys-tems for treatment, municipal systemswill need time to develop permits orother control mechanisms for theirindustrial users. New sources will needto comply with the standards at thetime discharge commences. In addition,this proposed rule completely replacesthe Phase I proposal, published on May30, 1995.

LIMITS AND STANDARDSEPA is proposing concentration-

based limits for all subcategories exceptthe Steel Forming and Finishing subcat-egory, which will use production-basedlimits. Permit writers and controlauthorities would be authorized to usetheir best judgment to decide when it ismost appropriate to implement mass-based limits in lieu of concentration-based limits. MP&M facilities that areusing good pollution prevention andwater conservation practices may wantto request mass-based limits.

For the Steel Forming and Finishingsubcategory, limitations are expressed inpounds per 1,000 pounds of product.The mass limitation is derived by multi-plying an effluent concentration by anappropriate wastewater volume deter-mined for each forming or finishingoperation and expressed in gallons perton of product. In order to convert theproposed effluent limitations and stan-dards expressed as pounds per 1,000pounds of product to a monthly averageor daily maximum permit limit, the per-mitting authority would use a produc-

tion rate with units of tons per day. Fouralternatives are being explored by EPAfor establishing permit effluent limita-tions and standards:

• Alternative A. This alternative is thebasis for the current proposal. Itretains the essential requirements ofthe rule under which EPA currentlyregulates Steel Forming andFinishing facilities. The followingprotocols would be added for permitwriters and control authorities:1. For similar, multiple production

lines with process waters treatedin the same wastewater treat-ment system, the reasonablemeasure of production will bedetermined from the combinedproduction of the similar pro-duction lines during the sametime period.

2. For process wastewater treat-ment systems where multipleproduction lines are commin-gled in the same treatment sys-tem, the reasonable measure ofproduction will be determinedfor each production line duringthe same time period.

• Alternative B. This alternative wouldestablish multi-tiered limits and pre-treatment standards. Permit writersand control authorities currently usetheir best judgment for establishingmultitiered permits. In situationswhere a single set of effluent limita-tions or standards is not appropriatefor the permit’s entire period, atiered permit/control mechanismmay be established. One set of limitswould apply for periods of averageproduction, along with other setsthat take effect when there are signif-icant changes in the average produc-tion rate. Predictable changes inlong-term production with a greaterthan 10 to 15 percent deviation rangewould warrant consideration of a

Four alternativesare being exploredby EPA for estab-lishing permit efflu-ent limitations andstandards.


Exhibit 5. Technology Options for the MP&M Industry Subcategories

Option 1This option includes segregation of wastewater streams, preliminary treatment steps as necessary (including oil removal using oil-water separation bychemical emulsion breaking), chemical precipitation using either sodium hydroxide or lime, and sedimentation using a clarifier. Preliminary treatmenttechnologies are described as follows:• Oil-Bearing Wastewater—Alkaline cleaning wastewater and water-based metal-working fluids typically contain significant amounts of oil and

grease. Pretreatment is recommended to remove oil, grease, and organic constituents in these waste streams. Chemical emulsion breaking fol-lowed by gravity separation of oil and water is recommended for removing these pollutants.

• Cyanide-Bearing Wastewater—The MP&M industry generates wastewater that may contain significant amounts of cyanide, such as plating andcleaning wastewater. Preliminary treatment to destroy the cyanide must be performed. Alkaline chlorination with sodium hypochlorite or chlorinegas can be performed to accomplish the pretreatment.

• Hexavalent-Chromium-Bearing Wastewater—Wastewater that may contain hexavalent chromium may be generated by operations in the MP&Mindustry, including acid treatment, anodizing, conversion coating, and electroplating. Because hexavalent chromium does not form an insolublehydroxide and is not treated by chemical precipitation and sedimentation, this wastewater requires chemical reduction of the hexavalent chromiumto trivalent chromium. Trivalent chromium forms an insoluble hydroxide and is treated by chemical precipitation and sedimentation. Sodiummetabisulfite or gaseous dioxide is typically used as a reducing agent for hexavalent-chromium-containing wastewater.

• Chelated-Metal-Bearing Wastewater—Electroless plating and some cleaning operations generate water that contains significant amounts ofchelated metals. Wastewater containing chelated metals requires chemical reduction to break the metal–chelate bond or reduce themetal–chelate complex to an insoluble state so that it can be removed during chemical precipitation. Sodium borohydride, dithiocarbomate,hydrazine, and sodium hydrosulfite are typically used as reducing agents.

• Organic-Solvent-Bearing Wastewater—Most solvent degreasing operations using organic solvents employ contract haulers for off-site recycling.EPA believes that this is the most effective means for reducing this waste stream.

After pretreatment of the segregated streams, chemical precipitation and gravity clarification remove total and dissolved metals. Segregation ofwastewater streams, preliminary treatment, and final chemical precipitation and gravity sedimentation is widely used throughout the metals industryfor effective removal of pollutants from MP&M wastewater streams.

Option 2Option 2 builds on Option 1 through the addition of pollution prevention, recycling, and water conservation methods that allow for the recovery andreuse of materials. Specific in-process pollution prevention, recycling, and water conservation methods include:• Countercurrent cascade rinsing for all flowing rinses;• Centrifugation and recycling of painting water curtains; and• Centrifugation and pasteurization to extend the life of water-soluble machining coolants.

EPA based the best practicable control technology (BPT), best conventional pollutant control technology (BCT), and best available technology (BAT)proposed effluent limitations guidelines and the proposed pretreatment standards for existing sources on Option 2 for existing direct dischargers inthe General Metals, Metal Finishing Job Shops, Printed Wiring Board, and Steel Forming and Finishing subcategories. Although EPA proposed effluentlimitation guidelines and new source performance standards for new direct dischargers in the Non-Chromium Anodizing subcategory, EPA did not pro-pose pretreatment standards for new sources in this subcategory.

Option 3This option differs from Option 1 by replacing the chemical emulsion breaking and oil/water separator with an ultrafilter for the removal of oil andgrease. A microfilter, rather than a clarifier, follows the chemical precipitation. Ultrafiltration allows water and small solute species to pass through asemi-porous membrane under pressure while emulsified oils are retained by the membrane and recovered as concentrate. Microfiltration uses apressure-driven membrane process to separate wastewater constituents based on size and shape. Using an applied pressure difference across amembrane, solvent and small solute species pass through the membrane and are collected as permeate. Larger constituents such as flocculatedmetal hydroxide particles generated during chemical precipitation are retained by the membrane and recovered as a concentrated solids slurry.

Option 4Option 4 includes the technologies presented in Option 3 plus the in-process flow control and pollution prevention technologies of Option 2. EPA basedthe new source limitations and standards on Option 4 for the General Metals, Metal Finishing Job Shops, Printed Wiring Boards, and Steel Formingand Finishing subcategories.

Option 5Effluent limitations for Option 5 are based on end-of-pipe chemical emulsion breaking followed by gravity separation using an oil/water separator.Breaking the oil/water emulsion requires the addition of treatment chemicals such as acid, alum, and/or polymers to change the emulsified oils or cut-ting fluids from hydrophilic colloids to aggregated hydrophobic particles. The aggregated oil floating on the surface of the water can be removed usinga coalescing plate oil/water separator.

Option 6Option 6 uses the Option 5 technologies plus in-process flow control and pollution prevention technologies to allow the recovery and reuse of materi-als from the waste stream. Option 6 technologies include the same recycling and water conservation technologies found in Option 2. EPA based theeffluent limitations and guidelines and pretreatment standards for the Oily Wastes subcategory on Option 6.

Option 7Option 7 is based on end-of-pipe ultrafiltration. Ultrafiltration removes oil droplets ranging from 0.002 to 0.2 microns and is expected to generate a con-centrated oil phase that is 2 to 5 percent of the influent volume.


tiered or multitiered permit/controlmechanism.

• Alternative C. For the Steel Formingand Finishing subcategory, EPA isalso considering including a defini-tion of “production.” The modifieddefinition for use in developing thepermit/control mechanism would bethe average daily operating rate forthe year with the highest annual pro-duction over the past five years. Formultiple similar-process units dis-charging to the same wastewatertreatment system with one compli-ance point, the year with the highestannual production over the previousfive years would be determined onthe basis of the sum of annual pro-duction for each process dischargeline. Based on the highest produc-tion year’s average daily operatingrate, the daily production rateswould be calculated independentlyfor each line using total annual pro-duction and annual operating hoursfor each line.

• Alternative D. EPA is consideringestablishing production-based month-ly average effluent limitations andstandards in combination with dailymaximum concentration-based efflu-ent limitations and standards. Underthis alternative, the maximum month-ly average NPDES permit and pre-

treatment control mechanism massbasis requirements would be deter-mined using the production-basedstandards in combination with a rea-sonable measure of actual production,such as Alternative C. The daily max-imum requirements would be in theform of effluent concentrationsinstead of daily maximum produc-tion-based mass effluent limitationsand standards.

In an effort to reduce the monitoringburden placed on facilities, EPA is pro-posing to allow indirect dischargers inthe MP&M category to apply for a waiv-er. The facility would need to certify thatit does not use or generate a given pollu-tant at the site and that any amount ofthe pollutant found in the wastewaterstreams is a result of background levelsin the intake water. This certificationwould need to be based on samplingdata and technical information on theprocesses involved.

The monitoring waiver would applyonly to monitoring requirements andwould not exempt the facility from meet-ing the numerical limits in the permit.The industrial user would still need tomonitor for the specified pollutants aspart of the Baseline Monitoring Reportand the 90-day Compliance Report.These reports and the technical informa-

Exhibit 5. Technology Options for the MP&M Industry Subcategories (continued)

Option 8Option 8 includes the use of ultrafiltration plus the pollution prevention and water alternatives from Option 2. EPA is not proposing Options 7 or 8; how-ever, it did use these alternatives in the evaluation of the Shipbuilding Dry Dock and Railroad Line Maintenance subcategories.

Option 9Option 9 is an end-of-pipe option that involves chemical emulsion breaking followed by DAF to remove flocculated oils. Breaking the oil/water emul-sions requires adding treatment chemicals such as acid, alum, and/or polymers to change the emulsified material from a hydrophilic colloidal disper-sion to aggregate hydrophobic particles. In the DAF tank, air bubbles created as a result of a rapid pressure drop attach to the aggregated oil particlesand pull them to the surface of the tank. A scraping mechanism can then be used to collect the oil and solids from the surface.

Option 10This option includes the technologies provided in Option 9 plus the recycling and reuse technologies presented in Option 2. EPA based the effluent lim-itations guidelines and pretreatment standards for the Shipbuilding and Dry Dock and Railroad Line Maintenance subcategories on Option 10. EPA didnot propose pretreatment standards for new or existing sources in the Shipbuilding Dry Dock and Railroad Line Maintenance subcategories.


tion supplied from the facility would beused as the basis for granting or refusinga monitoring waiver.

The certification for the waiverwould be submitted at the same timethat indirect dischargers submit periodiccontinued compliance reports. The mon-itoring waiver would be similar to thewaiver in the proposal entitled“Streamlining the General PretreatmentRegulations for Existing and NewSources of Pollution” (64 Fed. Reg.39564, July 22, 1999). If EPA promul-gates the final Pretreatment Streamliningregulations, a waiver specific to MP&Mfacilities would be unnecessary.

EPA is proposing three alternativesto allow flexibility in monitoring organicpollutants:

• The facility must meet a limit for thetotal of a list of specific organic pol-lutants.

• The facility must meet a numericallimit for TOC as an indicator param-eter.

• The facility must develop and certifythe implementation of an organicmanagement plan.

In meeting the organic pollutantcompliance limits, facilities would berequired to monitor only for those TOPchemicals that would reasonably bepresent. For compliance purposes, pol-lutants not reasonably present would becounted as zero in the TOP limit.

Facilities can monitor for the organicpollutants specified in the TOP list todemonstrate compliance with the TOPlimit, or they can meet the TOC limit.TOC was chosen as an indicator parame-ter because of its ability to measure alltypes of organic pollutants.

The use of an organic managementplan would consist of specifying: thetoxic and nonconventional organic com-pounds used at the facility; the disposalmethods used; the procedures in place

for ensuring that organic pollutants donot routinely spill or leak into the waste-water, or that minimize the amount oforganics used in the process; the proce-dures in place to manage the oxidation-reduction potential during cyanidedestruction to control the formation ofchlorinated organic by-products; and theprocedures in place to prevent the exces-sive usage of dithiocarbamates whentreating chelated wastewater. The facili-ty would need to certify that the proce-dures specified in the plan are beingimplemented.

EPA is proposing a total cyanidelimit for the General Metals, MetalFinishing Job Shop, Printed WiringBoard, and Steel Forming andFinishing subcategories. The monitor-ing point for this requirement would bebased on total cyanide found in thewastewater directly after cyanide treat-ment and before the wastewater is com-bined with any other effluent water.Samples may be taken from the finaleffluent when authorized by the permitauthority and when the limits include adilution ratio.

For the Metal Finishing Job Shopssubcategory, EPA is considering a pollu-tion prevention alternative that takesinto consideration the activities andachievements of the National MetalFinishing Strategic Goals Program(SGP). The Metal Finishing SGP is a per-formance-based, voluntary program thatincludes commitments by the industryto meet multimedia environmental tar-gets and substantially reduce pollutionfrom their operations. Pollution reduc-tions would be beyond what is requiredfor compliance. Indirect dischargers inthe Metal Finishing Job Shops subcate-gory, with approval from the permittingauthority, could demonstrate compli-ance with specified pollution preven-tion and water conservation practices inlieu of meeting the MP&M regulationrequirements.

Facilities can moni-tor for the organic

pollutants specifiedin the TOP list to

demonstrate com-pliance with the

TOP limit, or theycan meet the TOC

limit. TOC was cho-sen as an indicatorparameter because

of its ability tomeasure all types of

organic pollutants.


CONCLUSIONThe January 3, 2001, proposal for the

MP&M category pretreatment standardsapplies to process wastewater generatedfrom existing or new industrial sitesengaged in manufacturing, rebuilding, ormaintenance of metal parts, products, ormachines to be used in one of the fol-lowing industrial sectors: aerospace; air-craft; buses and trucks; electronic equip-ment; hardware; household equipment;instruments; job shops; mobile industri-al equipment; motor vehicles; officemachines; ordnance; precious metalsand jewelry; printed wiring boards; rail-roads; ships and boats; stationary indus-trial equipment; and miscellaneousmetal products. These facilities manu-facture, maintain, and rebuild metalproducts under more than 200 differentstandard industrial classification (SIC)codes. This proposal represents EPA’ssecond attempt to provide effluent limi-tations and guidelines for facilities oper-ating in these sectors.

While facilities already regulatedunder existing pretreatment guidelineswill continue to be regulated under those

rules, some operations will need to com-ply with the new MP&M standards. ThePrinted Wiring Board and the MetalFinishing Job Shops subcategories willbe particularly affected by this proposedrule.

EPA’s proposal includes a number offlexible monitoring and compliancemeasures, including use of best manage-ment practices and the option for facili-ties to choose technologies for pollutionprevention that will best address theoperational discharges for each facility.Treatment technology options primarilydistinguish between operations that gen-erate metallic pollutants and those thathave organics and oils in the wastewaterstreams.

INFORMATION SOURCESUnited States Environmental Protection Agency. (2000,

December). Development document for the proposedeffluent limitations: Guidelines and standards for themetal products and machinery point source category(EPA-821-B-00-005).

United States Environmental Protection Agency. (2001,January 3). Effluent limitations guidelines, pretreat-ment standards, and new source performance stan-dards for the metal products and machinery pointsource category, proposed rule. 66 Federal Register,424–558.

Wade Miller is an environmental scientist with Environmental Strategies Corporation in Minneapolis.

Metal Products and Machinery: Proposed Rule for Pretreatment and Effluent Guidelines

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