Operations

Computer manufacturing
The manufacture of an average desktop computer and monitor uses more than ten times its weight in fossil fuels and chemicals according to Computers and the Environment: Understanding and Managing Their Impacts. In comparison, an automobile or refrigerator only requires one to two times its weight in fossil fuels. Details about manufacturing cathode ray tubes (CRTs) and liquid crystal displays (LCDs) are found in the Computer Display Industry and Technology Profile from EPA's Design for the Environment.

The main environmental impacts associated with computer production processes are--

• significant energy use in production and operation of computers
• possible long-term health effects on workers and communities from chemical exposure associated with microprocessor fabrication
• possible health impacts from exposure to brominated flame retardants and lead, plus other hazardous materials contained in computers and electronic products improperly disposed or improperly recycled

In general, pollution prevention techniques for the electronics and computer industry can be categorized as--

• process or equipment modifications
• raw material substitution or elimination
• waste segregation/separation/preparation
• recycling

Specific suggestions on pollution prevention in electronics manufacturing are found in the P2 Opportunities section of this topic hub.

Microprocessor fabrication
The invention of integrated circuits (ICs), about 1960, as replacements for discrete transistors using vacuum tubes, sparked a revolution in the electronics industry. They are currently used in all types of applications, from computers, to cellular phones, to washing machines.

Manufacturing microprocessors requires an ultra-clean environment. "Class one" cleanrooms contain no more than one speck of dust per cubic foot. Cleanrooms are 10,000 times cleaner than a hospital operating room, requiring huge air-filtration systems that completely change the air about ten times per minute, an obvious energy-efficiency opportunity.

Finished microprocessors are very complex, involving more than 250 steps. The manufacturing process allows mass production of reliable, complex designs at low cost. In 2006, chips can hold up to one million transistors per square millimeter.

Companies producing intermediate components and finished goods are frequently located physically near each other, to take advantage of recent innovations. As a result, some areas of the country have become centers of the electronics industry, such as "Silicon Valley" near San Jose, California. However, there are electronics manufacturing plants throughout the U.S. and the world.

Recycling and recovery operations
Recovery and reprocessing of e-waste includes refurbishment and repair of equipment for reuse, recovery of individual components for reuse, and recycling of individual materials. Obviously, reuse of intact equipment is the best option.

Whatever the end result, care must be taken to assure products are not mishandled and that toxic or hazardous materials are properly handled, in compliance with all regulatory requirements. Leaded glass and plastics are the most problematic materials to recycle.

Cathode ray tubes (CRTs) recycling typically manually separates plastic casings, circuit boards, and wiring. The metals and leaded glass are separated for recycling. Then the CRTs are crushed. A recycling study in Minnesota found that reusing leaded glass to make new CRT screens was twice as efficient as recovering lead via smelting. The phosphor lining (a very small quantity) on the CRT screen can be extracted for disposal to a proper landfill. Old television CRTs, manufactured in the 1960s or 1970s, may contain polychlorinated biphenyl (PCB) capacitors.

Plastics have been collected and separated for recycling in a study done in Minnesota. The Characterization and Processing of Plastics study found that the plastic used for TV housings was 54% of the consumer electronics waste stream, while computer plastics comprised 38%. About half of the plastic in the electronics was discarded and half sent for recovery. About 85% of the plastics processed were able to be recovered. High impact polystyrene (HIPS) was about 56% of the recovered plastic, acrylonitrile-butadiene-styrene (ABS) was 20%, and polyphenylene oxide (PPO) was 11%. The study found that post-consumer streams of engineering plastics can meet manufacturers' specifications for use in new products. The three main factors which will influence the value of recycled electronics plastics in the future commodity markets are

• the ability to sort engineering plastics by resin and grade
• the ability to meet new product specification standards with post-consumer streams of these plastics
• the ability to aggregate sufficient quantities to meet production schedules set by manufacturers

Circuit boards and some hard drives may be resold for use as operational parts. Otherwise, they are typically chopped into a powder and separated into fiberglass, metals, and precious metals using fire assay.