Page 448 - Solid Waste Analysis and Minimization a Systems Approach

426 ELECTRONICS, SEMICONDUCTORS, AND OTHER ELECTRICAL EQUIPMENT

As shown in the table, the recycling rate for this sector is approximately 39 percent.
As derived from the solid waste evaluation model discussed in Chap. 12, the equation
that estimates the annual waste generation per year per employee for this sector can
be calculated from the following:

Tons of solid waste generated per year = 2.29 × number of employees − 0.83
× solid waste disposal cost per ton
− 56.31 if the company is ISO 140001 certified
+ 126.6

33.3 Constraints and Considerations

Due to their hazardous material contents, electronic and electric equipment waste
may cause environmental problems during the waste management phase if it is not
properly pretreated. Many countries have drafted legislation to improve the reuse,
recycling, and other forms of recovery of such wastes so as to reduce disposal. The
waste streams generated from electric and electronic manufacturing, being a mixture
of various materials, can be regarded as a resource of metals, such as copper, aluminum,
and gold. Effective separation of these materials based on the differences on their
physical characteristics is the key for developing a mechanical recycling system.
Therefore, an in-depth characterization of this specific material stream is imperative.
Major hazardous components in waste electric and electronic equipments and their
description:

■ Batteries—Heavy metals such as lead, mercury, and cadmium are present in
batteries.
■ Cathode ray tubes (CRTs)—Lead in the cone glass and fluorescent coating cover
the inside of panel glass.
■ Mercury-containing components, such as switches—Mercury is used in thermo-
stats, sensors, relays, and switches (e.g., on printed circuit boards and in measuring
equipment and discharge lamps); it is also used in medical equipment, data trans-
mission, telecommunication, and mobile phones.
■ Asbestos waste—Asbestos waste has to be treated selectively.
■ Toner cartridges, liquid and pasty, as well as color toner—Toner and toner car-
tridges have to be removed from any separately collected waste electrical and elec-
tronic equipment (WEEE).
■ Printed circuit boards—In printed circuit boards, cadmium occurs in certain com-
ponents, such as surface mounted device (SMD), chip resistors, infrared detectors,
and semiconductors.
■ Polychlorinated biphenyl (PCB)–containing capacitors—PCB-containing capaci-
tors have to be removed for safe destruction.
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■ Liquid crystal displays (LCDs)—LCDs of a surface greater them 100 cm have to
be removed from WEEE.