Waste management and recycling, Slides of Waste Management

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E-Waste Management

Module: 5

~Dr. Jyothi C. Abbar

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• (^) Waste management are the activities and actions

required to manage waste from its inception to its

final disposal. This includes the collection,

transport, treatment and disposal of waste,

together with monitoring and regulation of the

waste management process.

• (^) Waste can be solid, liquid and gases and each type

has different methods of disposal and management.

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Effects of e-waste on human health:

• E-waste can be toxic, contains various types of toxic metals (lead, mercury, nickel, cadmium, lithium etc.), which can get accumulated in the environment, in the soil, air, water. This can cause a long term damage in the environment. Humans rely on air to breathe, so when that air fills with toxins, it can affect a person’s respiratory system.
• (^) It also contains biodegradable materials. Their disposal techniques are also harmful for the environment and living beings. For example, open-air burning and acid baths being used to recover valuable materials from electronic components release toxic material leaching into the environment. Exposure to these can also cause damage to the human body.

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• (^) The improper disposal of lead acid batteries and alkaline batteries also causes contamination of toxic chemicals with the soil and water. Lead may get into the blood, kidneys and even the nervous system and show adverse effects.
• (^) When a pregnant woman is exposed to such harmful substances, it can affect the development and health of her unborn child. Adverse health effects to the child include stillbirth, premature birth and low birth weight.

Powerpoint Templates E-Waste Disposal Methods of treatment & disposal:

• (^) Landfilling : A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. By this the technique, the e-waste are to be disposed scientifically, so that the soil and water resources doesn’t get effected in the nearby area.
• (^) Incineration (decomposing the waste material by burning) and pyrolysis (heating at high temperature and decomposing the product)
• (^) Recycling and Reuse: The electronic waste are required to be recycled and reused in a scientific way. It involves dismantling, processing and end processing. Reuse involves direct second hand use.

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• (^) Plastic Waste : Products made from plastics such as keyboards, casing, front or rear panel. Miscellaneous parts encased in plastics – disposed by shredding & melting method.
• (^) Printed Circuit Board Waste: Used in electronic parts such as motherboard, TV internal circuits, etc.– disposed by Desoldering & open burning, to remove metals.
• (^) Lead acid batteries and alkaline batteries should be disposed properly, so that the toxic metals, harmful chemicals like acid and base should not get contaminated with air and water sources.

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Hydrometallurgy method:

There are certain metals such as copper (Cu), silver (Ag) and gold (Au) are extracted by dissolving the concentrated e-waste in some suitable reagent and then rescuing the metal from the solution by treatment with some more electropositive metal. The use of cyanide in gold leaching has been a useful, but dangerous technique of metal extraction. This extraction process involves the chemical reaction between the pulverized e- waste and sodium cyanide, which produces a soluble gold cyanide solution that allows for easier extraction of the precious metal. 4 Au + 8 NaCN + 2H 2 O --------> 4 Na[Au(CN) 2 ] + 4NaOH

Powerpoint Templates Then the solution containing Gold cyanide complex is treated with zinc powder. As zinc is more electropositive than Au, it results in the precipitation of pure Au. 2Na[Au(CN) 2 ] + Zn  Na 2 [Zn(CN) 4 ] + 2 Au