All text pertaining to law and regulations contained within this report are provided for general information only. That information is not reliable for use as a legal reference. The generator must contact the appropriate legal sources and regulatory authorities for up-to-date regulatory requirements, and their interpretation and implementation.
This study identifies and examines source reduction, recycling, and treatment strategies for reducing California's metal-bearing waste streams. All of the strategies examined are alternatives to land disposal of the wastes. The methodologies stressed in the report are those that prevent the generation of hazardous wastes. Pollution prevention is preferable to "end-of-the-pipe" treatment or recovery.
The waste minimization strategies identified in this report are both technical and organizational. Technical options include changes in raw materials and manufacturing processes, and frequently involve equipment modifications. Organizational changes involve scheduling and purchasing modifications, upgrading of personnel skills through training programs, and better process documentation procedures.
The importance of the firm commitment of a plant's management to the creation of a successful waste minimization program cannot be stressed enough. A critical factor in this commitment is the finding of a "project champion", a person who will dedicate his or her efforts to obtaining the necessary funding, management directives, equipment, materials and/or personnel training necessary to implement effective waste minimization
Metals frequendy occurring in the state's waste streams include cadmium, chromium, lead, arsenic, zinc, copper, barium, nickel, antimony, beryllium, mercury, vanadium, cobalt, silver, and selenium. These metals are toxic to humans and other organisms, are persistent in the environment, and can bioaccumulate in food chains. They are typically used by businesses in many industrial categories, as shown in Table 2.1-1.
A large number of industrial processes employ metals. A relatively small number generate most of California's metal-bearing wastes. These processes include: foundry activities, surface cleaning and stripping, surface treatment, including chromating and passivating, electro- and electroless plating, draining and rinsing, and coating operations. Auxiliary operations, such as utility systems maintenance and hazardous material handling procedures also can generate wastes. Other activities that generate metal waste include petroleum refining, printed circuit board manufacturing, photofinishing and printing. Promising waste minimization strategies for these industrial activities are summarized below.
Wastes generated in metal casting operations include those picked up by air pollution control devices, hazardous slags, and spent casting sands. Source reduction methods for hazardous wastes from the operation of baghouses, scrubbers and other emission control systems include: 1) using "cleaner" scrap metal for the casting that does not contain lead, cadmium, zinc, or other hazardous metals, and 2) use of induction furnaces that emit less dust and fumes than electric arc furnaces. Baghouse dust can also be recycled back into the process, and zinc and other salable contaminants can be recovered. When flue dusts cannot be recycled and must be treated, the aim is to stabilize the hazardous components such as lead and cadmium, or remove them through precipitation.
Source reduction of hazardous slag generation can be accomplished by using low sulfur raw materials for casting, use of desulfurization agents, altering product requirements to allow a higher sulfur content, or improved process controls. Slags can also be recycled to the furnace. Treatment of slag piles with water sprays often creates air pollution problems. This can be avoided by using a quench tank to treat the slag, and sometimes adding an oxidizing agent to the tank as well.
Casting sands can often be reclaimed through washing and scrubbing techniques for removal of metal fines. Foundry sands can also be used as a construction material.
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