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Adequate drainage and efficient rinsing of workpieces is necessary in order to keep hazardous metal solutions within the process, rather than escaping in the effluent. Increasing drainage time of flat, vertical parts from one to six seconds reduces drag-out by half. How the parts are racked also has an effect on drag-out, as do the viscosity and temperature of the process bath.

The addition of one closed loop rinse can significantly reduce the amount of metal in the effluent. Agitating the rinse bath or adding a second counter flowing rinse reduces the contamination even more.

1.7 COATING

Lead, chromium, zinc and barium are commonly added to paints for corrosion resistance. Cobalt, mercury, and cadmium are often added as well. These metals find their way into the various waste streams of paint manufacturing: empty bags and packages, baghouse dusts, spills, and equipment cleaning wastes. Toxic bag and package wastes can be reduced by segregation of hazardous and non-hazardous materials, use of recyclable plastic lined drums instead of paper bags, and implementation of water soluble packaging. Hazardous baghouse dust volumes can be reduced through use of paste pigments instead of dry powders, and through careful scheduling of baghouse hopper emptying. Hazardous waste streams due to spills and other inadvertent discharges can be minimized using dry cleaning methods, closing of floor drains, and better worker supervision and equipment maintenance. Equipment cleaning waste source reduction methods include use of mechanical devices and high pressure spray heads for mix tank cleaning, installation of Teflon lined tanks, and use of "pigs" for pipe cleaning. Paints containing hazardous metals can sometimes be replaced with more environmentally benign products. Yellow iron oxide, for instance, is used as a substitute for chrome yellow in traffic paints.

Recycling of pigment collected from baghouse dust is viable if the pigment is used in manufacturing low-grade paint. Wash solvent containing metals and other contaminants is sometimes reusable in place of virgin solvent, if employed for cleaning equipment producing the same type of paint.

Paint application generates wastes as well as paint manufacturing. Paint application wastes include empty paint containers, spent cleaning and stripping solutions, and paint overspray. Buying paint in containers of a size suitable for the application can reduce unused paint wastes. Segregating non-hazardous from hazardous waste streams is also important. Paint overspray can be reduced through operator training and proper handling of spray guns. Preventive maintenance of equipment and avoidance of reject paint applications can significantly reduce the wastes generated from stripping and reworking a job. Use of dry painting techniques such as powder coating is also a promising way of reducing wastes.

1.8 UTILITY SYSTEM MAINTENANCE

Utility systems for equipment and space heating and cooling frequently use heavy metal corrosion inhibitors in their heat transfer fluids. Chromate compounds are among the best corrosion inhibitors available. Nonchromate inhibitors that have proved to be feasible substitutes include polyphosphates, organophosphates, zinc, molybdates, and aromatic azoles. Some of these compounds have their own environmental impacts, however. Azoles, for instance, can be quite dangerous to human health.

1.9 FLUORESCENT AM) MERCURY VAPOR LAMP WASTE MANAGEMENT

Spent fluorescent lamps and mercury vapor lamps contain mercury in sufficient quantities to be considered hazardous wastes. Recycling facilities exist to recover the mercury content of these lamps.

1.10 WASTE SEGREGATION

Segregation of hazardous from nonhazardous waste streams, of one type of hazardous waste from another, and of liquid from solid waste can greatly facilitate waste management operations, and result in lower volumes of waste generated and reduced management costs.

1.11 MATERIAL HANDLING AND STORAGE

Safe material handling and storage of raw materials, products and waste, and the careful transfer of these from one area to another are essential in controlling waste generation. Methods of reducing the likelihood and waste generation impacts of spills and leaks include regular hazard assessment studies, proper design of storage tanks and process vessels, alarm systems for leaks and overflows, effective secondary containment systems, and implementation of a set of emergency procedures and spill cleanup actions.

1.12 MANAGEMENT PRACTICES

Management initiatives such as scheduling changes, better operating procedures, and in-house waste reduction programs can help to reduce the amount of wastes generated. Raising employee awareness of what is involved in waste minimization is important, since innovative ideas for constructive changes often come from the operators themselves. Waste minimization training programs for plant staff can be divided into three stages: prior to the job assignment; during on-the-job training; and training drills and safety meetings.

In conclusion, many opportunities exist to prevent the generation of metal waste streams, and to effectively recycle or treat them once they are generated. Source reduction methods that prevent pollution generation are of four types: alterations to processes, such as increasing drainage time in electroplating operations; input material modifications that include replacing toxic metal materials with less dangerous materials; improvements in institutional, procedural or administrative aspects of operation; and product changes such as replacing metal with non-metal products.

Recycling of wastes is the preferable waste management method after source reduction opportunities have been exhausted. Recycling can be performed within the process itself, within the plant, or off-site, and can involve reuse of die entire waste stream, or recovery of a part of it. Recovery of the stream's metal content can be achieved through operations such as electrolytic recovery, reverse osmosis, and ion exchange.

Waste streams that cannot be further reduced at the source or recycled must be treated in a manner that reduces their toxicity and/or quantity. Of special importance are treatment methods for process solutions that keep sludge generation to a minimum.

SECTION 2.0 INTRODUCTION

2.1 FOCUS OF STUDY

This study focuses on source reduction, recycling and treatment strategies for safely reducing the environmental risk due to California's hazardous metal waste streams. This report is not intended to be a design manual for waste reduction. It is a compendium of ideas, and contains descriptions of-many useful methodologies. These descriptions are intended to stimulate the interest of waste generators and provide them with information they can use in developing waste reduction programs. The report also contains numerous references for help in following up on, and implementing, the ideas presented.

2.1.1 Listed Metals

Metals occurring frequently in waste streams that are listed by the California Code of Regulations (Title 22, Division 4, Article 9, Section 66699) as hazardous include the following:

0

Antimony

0

Arsenic

0

Barium

0

Beryllium

0

Cadmium

0

Chromium

0

Cobalt

0

Copper

o

Lead

o

Mercury

0

Nickel

0

Silver

0

Selenium

0

Vanadium

0

Zinc

As wastes, these metals are considered hazardous due to their toxicity to humans and the environment. They are all persistent in the environment, and tend to bioaccumulate in food chains. Most of these wastes are also listed by EPA (40 CFR) as hazardous and given a "D" designation due to their toxicity. Wastes resulting from electroplating and metal treating processes are given an "F' designation. EPA's F006 category designates wastewater treatment sludges from many electroplating operations.

22 INDUSTRIAL USE OF LISTED METALS

The above metals are used in many industrial processes. Cadmium, for instance, is plated onto fabricated metal parts to provide corrosion resistance, lubricity and other desirable properties; it is used in rechargeable batteries, television and fluorescent light phosphors, inorganic coloring agents for paint, plastic and printing ink, and as a catalyst. Applications of the metals listed above are detailed in Table 2-1, categorized by Standard Industrial Classification (SIC) codes. These industries are discussed further in Section 4.0.

23 METAL WASTE GENERATION

In the industries mentioned in Table 2-1, some of the metals find their way into the waste streams, either in their pure form or as part of some compound. The focus of this study is to examine effective ways of reducing that fraction of hazardous metals that end up as waste, using, in order of preference, source reduction, recycling and treatment strategies to accomplish this. The study approach is to identify and analyze the major activities, employed throughout California industries, that are responsible for most of the metal bearing wastes generated. By studying and understanding these activities, effective waste reduction strategies can be formulated.

The first step in this process is undertaken in Section 4.0, in which the industries mentioned in Table 2-1 are examined, and the activities that produce wastes are identified.

2.4 WASTE MANAGEMENT 2.4.1 REGULATORY TRENDS

The 1984 Hazardous and Solid Waste Amendments (HSWA) to the Resource Conservation and Recovery Act (RCRA) imposed new responsibilities on those who manage hazardous wastes. HSWA prohibits land disposal of untreated hazardous waste beyond specified dates, and directs EPA to develop treatment standards for those wastes. The State of California implementation of HSWA was in the form of the Hazardous Waste Management Act of 1986 (SB 1500), which required the Department of Health Services (DHS) to prohibit, on or before May 8, 1990, the land disposal of untreated hazardous wastes, and to establish treatment standards. Existing State regulations already provide Soluble Threshold Limit Concentration (STLC) values for 18 toxic metal constituents of waste. Metal wastes are also regulated under RCRA. For instance, electroplating waste sludges ("F006" wastes) must meet stringent treatment standards before they can be placed in land disposal units. A thorough description of standards on F006 and other metal wastes is contained in the Environment Reporter of May 27, 1988 (the full reference is listed at the end of this section).

Restrictions on the land disposal of metal wastes have dramatically increased the cost of their management, and make it more attractive for manufacturers to implement measures that prevent the generation of those wastes, or recycle them once they are generated, rather

TABLE 2-1 CALIFORNIA INDUSTRIES THAT USE LISTED METALS

1 Sic 1

INOUSTRY

1CODES 1

1 10 I

Metal Mining

I 13 I

Oil and Gas Extraction

I 14 1

Nonmetaiiic Minerals, Except Fuets

1 15 1

General Coniractors/Builders

1 16 I

Heavy Const'uctlofi, except bldngs

I 1? 1

Contractors - Special Trade

1 1

Lumber and Wood Products

1 27 1

Publishing and Printing

1 28 1

Chemicals and Allied Products

1 29 1

Petroleum Relming

1 30 1

Rubber & Misc Plastic Products

1 32 1

Slone. Clay, and Glass Products

1 33 1

Primary Metals Industry

1 3« 1

Fabricated Metal Products

1 35 1

Machinery Except Electrical

! 36

Electric and Electronic Equipment

1 37 1

Transportation Equipment

1 38 1

Instruments and Related Products

1 39 1

Miscellaneous Manufacturing

1 46 1

Pipelines Except Natural Gas

1 49 1

Elec, Gas & Sanitary Services

1 76 1

Miscellaneous Repair Services

1

All EstaDi stents

|NUMBER | IN CALIF

1 METAL. 1 STLC(mg/l):

Antimony 15

Arsenic 5 0

Barium 100

Beryllium 0.75

Cadmium 1.0

Chromium VI: 5

Cobalt 80

5.0

Mercury 0.2

Nickel 20

Selenium 1.0

Silver 5

Vanadium 24

Zinc 250

I 123 I 1.038 I 325

X

X X X

I 14.563 I 2,533 I 28,536

X

X X

I 2,406 I 6,585 I 1.440

X

X X

X

X

X X

X

X

X

X

X

X

X X

X X

X

I 249 I 1.931 I 1.658

X X

X

X

X X

X

X

X

X

I 782 1 4,522 I 7,389

X

X

X

X X

X

X X

X

X X

X

X

X X

I 3.509 1 1.625 i 1,623

X

X

X X

X

X

X X

X X

X X

X X

X X

X

X X

X

i 1.370

X

X

X

1 6.140

X

I 110,550

Sources 1. County Bjsmess Patterns 1983 - CaMorma U S Dept. ot Commerce. Bureau ot the Census. Sept 1985

2 Mineral Facls and Problems 1985 edition Bureau of Mines Bulletin 675 U.S. Dept. 0' the Interior C

than seek ways to treat and dispose of them. Adding to this trend is the continuing liability that generators face for their wastes, even after they have shipped them to a disposal site.

A listing of State and Federal regulations applicable to the management of metal wastes is included in Appendix E.

2.4.2 WASTE MANAGEMENT HIERARCHY

The waste management hierarchy is an ordering of types of hazardous waste management options that is a function of each option's possible environmental impact (USEPA 1988, Wolf 1988). The option type at the top of the hierarchy -- source reduction ~ is considered by many to be the most-desirable. TTiis is because source reduction seeks to prevent or reduce the generation of hazardous waste within the industrial process itself, rather than attempting to manage waste after it is generated. Source reduction methodologies include: 1) substitution of different input materials that produce lower waste quantities and/or reduce their toxicities; 2) process changes that result in toxicity and/or waste quantity reductions; 3) changes in institutional, procedural or administrative aspects of operations (e.g. operators' training); 4) product changes, such as replacement of chromed metal automobile trim with plastic trim, whose manufacture does not generate metal wastes; and 5) combinations of processes that increase efficiency and eliminate certain wastes.

Recycling options are the next ones on the waste reduction hierarchy. They include both the more preferable on-site recycling of wastes at the facility that generates them, and offsite recycling. On-site recycling avoids the risks and economic costs of packaging and transporting hazardous substances. Off-site recycling is often performed at commercial recycling facilities.

Treatment of waste should be considered only after source reduction and recycling options are fully addressed. Treatment includes methods for separation of the metals fraction from the wastes stream. This typically involves neutralization, precipitation, filtration and drying operations. Waste treatment, although often desirable and necessary, is not considered to be a waste minimization option by the USEPA.

2.4.3 ENVIRONMENTAL BENEFITS OF A WASTE MINIMIZATION PROGRAM

The benefits of waste minimization can be understood in terms of environmental risk reduction. Risk reduction - the lessening of potential dangers to human health and the environment — includes both technology-based strategies, and those that involve organizational and management changes within a company (such as better training programs or segregation of waste streams). Whatever methods are used, waste minimization programs can benefit the environment by:

o preventing the generation of wastes, residues, and contaminants that, if released, could pose a threat;

o recycling and reusing wastes that are generated by feeding them back as input materials into industrial processes. Materials recycled often have significant economic value, and should be included in the cost analysis of the new process.

2.4.3.1 Requirements for Successful Programs

It must be stressed that management commitment to a waste minimization program is extremely important for its success. The identification of a "project champion" is often the critical factor in creating a successful program. The project champion is the one who will take it as his or her mission to see that effective waste minimization is implemented. In a large shop, the project champion might be a foreman, engineer or manager. In a small job shop, it is most often the owner/manager who spearheads the effort.

There is a continuum of activities that individual workers, groups within a plant, and the plant as a whole can engage in to reduce health and environmental risks. But in order for these activities to take place, an effective, well organized risk reduction program is essential.

To create a successful program, attention must be paid to the following steps: o Planning and Organization o Assessment of Needs o Selection of Attainable Goals o Implementation

Because a waste minimization program impacts many functional groups within a plant, the planning and organizational phase of the program needs to bring these groups together in an effective way. Although the complexity of the program depends on the size of the waste problems of the plant, it is critical to have a strong management commitment to support the program. The potential benefits from a serious waste minimization program that often convince management to lend their support include economic advantages, regulatory compliance, reduction in liabilities associated with generation and disposal of hazardous waste, improved public image, and reduced environmental impact (USEPA 1988).

Assessment of a company's waste minimization needs includes examining the content of and volume of hazardous waste streams it generates, and the processes or operations that generate them. The object of this step is to prioritize the needs of the company, based on environmental risk, liability, and economic criteria.

The assessment phase also includes identification of waste minimization methodologies that appear promising for solving the particular problems of the plant. Once the origins and causes of waste generation are understood, it is possible to identify possible ways to minimize waste in the assessed areas. Many of the ideas and knowledge on how to do this can come from plant staff with hands-on knowledge of the company's operations. This is supplemented through the use of the technical literature, and contacts with trade associations, state and local environmental agencies, consultants and equipment vendors.

Selection of the program's goals is done through analysis of the technical and economic feasibility of the waste minimization options identified. Technical evaluation determines whether a proposed option is possible to implement (i.e., is the necessary equipment and/

or expertise available), and whether it will work in a specific application. Economic analysis is conducted using standard measures of profitability such as payback period, return on investment and net present value.

Successful implementation of waste minimization methodologies depends on several factors, most notably obtaining the necessary funding. Waste reduction is generally accompanied by process efficiency improvements and cost reductions. Nevertheless, the company's capital resources may be tied up elsewhere. It is essential to know the level within an organization that has approval authority for capital projects, and to have a team that can present the financial, technical and environmental benefits in such a manner as to sell the project to management.

2.4.4 THE WASTE MINIMIZATION OPPORTUNITY ASSESSMENT

In order to aid companies and other organizations in creating effective waste minimization programs, the Environmental Protection Agency has developed a recommended procedure for identifying and implementing source reduction and recycling applications that includes the steps discussed in the previous section. They have published a detailed Waste Minimization Opportunity Assessment Manual (1988) that outlines this procedure in depth. The manual employs a series of worksheets that guide plant personnel through the process of identifying and evaluating promising waste minimization strategies. The manual also includes methodologies for analyzing the feasibility of potential options on economic and technical bases as well. An extensive opportunity assessment is a valuable, effective tool for choosing the best waste minimization strategies.

2.4.5 REFERENCES

Environment Reporter. May 27, 1988. "EPA Proposal for Land Disposal Restrictions, Treatments for First-Third Scheduled Wastes Under RCRA (53 FR 17578; May 17, 1988)." Volume 19, Number 4, pp. 106-154.

Wolf, K. May 1988. "Source Reduction and the Waste Management Hierarchy." Journal of the Air Pollution Control Association, vol. 38, No.5, p.681.

USEPA. April 1988. Waste Minimization Opportunity Assessment Manual. EPA/625/788-003. Environmental Protection Agency, Hazardous Waste Engineering Research Laboratory, Cincinnati, OH.

SECTION 3.0 REPORT ORGANIZATION

Section 2.0 identifies metals listed by the California Code of Regulations as hazardous in industrial waste streams. Section 2.0 also discusses the waste reduction hierarchy and waste management methods examined in the report.

Section 4.0 discusses the industries in California that generate the major share of hazardous metal wastes. Section 4.0 also identifies the operations and processes within these industries that generate the wastes.

Sections 5.0 through 9.0 detail the major metal-working operations, such as casting and electroplating, that generate the wastes. The sections analyze source reduction and recycling strategies for reducing these wastes, and also examine treatment methods for the wastes that are generated. Section 10.0 does the same for auxiliary manufacturing operations, including utility system maintenance and hazardous materials handling procedures. Section 11.0 discusses non-metal working processes that generate metal wastes, industry refinery processes and photo-finishing.

Section 12.0 provides an overview of State and Federal regulation of hazardous metal wastes.

The waste reduction descriptions in this report are organized by industrial process. For instance, if the reader wants to find information on how to reduce metal wastes from an electroplating operation, refer to Section 7.0. Waste reduction methodologies are divided into three groups within each section: source reduction, recycling, and treatment. Each section contains evaluations of individual methods. Also, at the end of each section is a table listing all of the different waste reduction strategies that are discussed, where to find those discussions, and references in the literature that provide additional information on the strategies.

SECTION 4.0

INDUSTRIAL HAZARDOUS METAL USE AND WASTE GENERATION

4.1 INDUSTRY SUMMARIES

The ore mining group includes industries engaged in mining, mine development, and metallic ore exploration, as well as ore dressing and beneficiating mills. Operations at these mills include crushing, grinding, washing, drying, sintering and leaching the ore, as well as gravity separation and flotation operations.

Metal-bearing wastes are generated by mining operations largely as a result of acid mine drainage. Tailings piles generated both directly from the mining itself, as well as from milling processes, frequently contain pyrite (iron sulfide). When mixed with rainwater or process water sulfuric acid is formed. This acid leaches many minerals, including heavy metals, out of the tailings. Because of this situation, acid mine drainage frequently contains concentrations of cadmium, lead, chromium, antimony, arsenic, zinc, copper, cobalt, nickel, and other metals. Mine tailings are generated from operations in hydrothermal environments such as the Sierra Nevada Mountains region. The tailings generally contain significant pyrite, and so are susceptible to acid drainage. Some tailings also can contain galena (lead sulfide), which generates acid drainage containing silver, cadmium and antimony. Milling processes enhance the potential for acid drainage, because they produce finely ground tailings with large total surface area, and very reactive because of the chemical processes they have been subjected to.

While mining processes generate metal-bearing wastes, mining wastes are outside of the current hazardous waste regulatory scope. For further information on this, refer to the current amended version of the Resource Conservation and Recovery Act (RCRA), PL 94580, Subtitle C, Section 3001 -"Identification and Listing of Hazardous Waste."

4.1.2 THERMAL METALWORKING (SIC 332, 335, 336, 346)

This group includes industries engaged in manufacturing ferrous and nonferrous castings, in rolling, drawing and extruding operations, in forging, stamping, and metal heat treating. Iron, steel, and nonferrous casting operations are performed in "job" shops as well as those captive to another industry, that use the castings in products such as stoves, furnaces, plumbing fixtures, motor vehicles, machinery, etc. Nonferrous foundries manufacture castings from aluminum, brass, bronze and other metals.

Rolling and drawing results in the production of ingot, rods, plates and sheets, tubing, and wire. Forging and stamping operations are used to make such diverse products as chains, crankshafts, bottle caps, automobile wheels and fenders, hub caps and other parts. Heat treating operations involve annealing, brazing, shot peening, tempering and other operations. Hazardous metal-bearing waste streams are generated from air emission controls (e.g., baghouse wastes), furnace slag, and spent quench oils.

4.1 J FABRICATED METAL PRODUCTS (SIC 34)

Included in this category are establishments engaged in fabricating ferrous and nonferrous metal products such as cans, tools, cutlery, general hardware, structural metal products, ordnance and other products. Forgings and stamping (SIC 346), while technically in this group, are categorized in the thermal metal working section above.

Fabrication of metal parts and products involves operations such as machining, stripping and cleaning, surface preparation (anodizing, passivating, etc.), plating and other coating operations. Stripping and cleaning generate wastes that bear metals removed from the workpieces themselves. Stripping sludges from chrome plating shops, for instance, often contain chrome from old plating layers. Spent etchants also contain metals. Surface treatment and plating operations use many different hazardous metals, including cadmium, chromium, lead, silver, copper, nickel, and zinc. Spent plating baths, dragout from the baths, and contaminated rinse water contain high concentrations of these metals.

4.1.4 PAINT MANUFACTURING (SIC 2851)

Paint manufacturing industries make paints for architectural uses, product coatings (e.g. automotive, machinery, furniture, and container coating) and for many special applications involving high temperatures, resistance to severe environmental conditions, or other requirements. Paint compositions frequently include pigments and additives that contain heavy metals such as lead, zinc, and mercury. There are 215 paint manufacturing facilities in California (USEPA 1986), generating wastes containing approximately 130 tons per year of toxic metals (data from Wapora (1975) was used for this estimate).

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