Page 655 - Materials Chemistry, Second Edition

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626 Waste Management Practices: Municipal, Hazardous, and Industrial
and new equipment is manufactured in its place, virgin resources are extracted, additional energy is
required, valuable resources are wasted, and air and water pollution are generated.

22.2 MAJOR TYPES OF ELECTRONIC EQUIPMENT
Several major types of electronic equipment are found in the MSW streams in all U.S. states. These
items and their significance are described below.

22.2.1 PERSONAL COMPUTERS
About half of the U.S. households own a PC. Most businesses have at least one compared with
larger businesses having many computers and peripherals (e.g., modems, scanners, and printers).
The composition of each component will vary significantly from others. Similarly, the recycling
processes and economics of each component differ markedly. When a PC is resold, recycled, or
scrapped, most recyclers and ‘demanufacturers’ (see below) will break it down into: (1) monitors;
(2) central processing units CPUs (including components such as circuit boards, hard drives, and
chips); and (3) peripherals (Florida DEP, 2002).

22.2.2 COMPUTER MONITORS
The monitor is the housing for the cathode-ray tube (CRT). The CRT is the ‘picture tube’ that pro-
duces the image on the monitor screen. The primary concern associated with monitors is the pres-
ence of lead (Pb) in the CRT.

22.2.3 COMPUTER CENTRAL PROCESSING UNITS

The CPU is the component that actually performs the computing. CPU components that possess
value for recycling and demanufacturing include circuit boards, hard drives, memory chips, micro-
processor chips, and video cards. These components contain a range of precious metals.

22.2.4 COMPUTER PERIPHERALS
Peripherals are devices needed to operate a computer such as the keyboard or mouse; that perform
additional functions such as printers, scanners, and modems; or cables that connect the different
parts of the computer.

22.2.5 HANDHELD AND DESKTOP TELECOMMUNICATIONS EQUIPMENT (TELEPHONES, FAX
MACHINES)
This category of equipment includes desk telephones, fax machines, portable telephones, and com-
munication radios. These products are found in most homes and businesses.
PCs, televisions, and desktop or handheld telecommunications equipment like cellular phones
and fax machines possess components or materials having a negative or zero net value when recy-
cled. The net value is defined as the value of recovered components or materials, minus the cost to
recover the materials.

22.2.6 MAINFRAME COMPUTERS AND HIGH-END TELECOMMUNICATIONS EQUIPMENT
Mainframe computers are composed of a large and powerful central computer with a number of
workstations, each consisting of a monitor and keyboard which access the mainframe via automated
servers. High-end telecommunications equipment consists of switching equipment for a building or
company-wide telephone equipment, and equipment used in commercial audio, video, or telephone
applications.