Department of microbiology microbial food technology group a diploma in quality assurance in microbiology diploma



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Methods of disposal

Integrated waste management


Integrated waste management using LCA (life cycle analysis) attempts to offer the most benign options for waste management. For mixed MSW (Municipal Solid Waste) a number of broad studies have indicated that waste administration, then source separation and collection followed by reuse and recycling of the non-organic fraction and energy and compost/fertilizer production of the organic waste fraction via anaerobic digestion to be the favoured path. Non-metallic waste resources are not destroyed as with incineration, and can be reused/ recycled in a future resource depleted society.

Plasma gasification


Plasma is a highly ionized or electrically charged gas. An example in nature is lightning, capable of producing temperatures exceeding 12,600 °F (6,980 °C). A gasifier vessel utilizes proprietary plasma torches operating at +10,000 °F (5,540 °C) (the surface temperature of the Sun) in order to create a gasification zone of up to 3,000 °F (1,650 °C) to convert solid or liquid wastes into a syngas. When municipal solid waste is subjected to this intense heat within the vessel, the waste’s molecular bonds break down into elemental components. The process results in elemental destruction of waste and hazardous materials.[2]

According to the U.S. Environmental Protection Agency, the U.S. generated 250 million tons of waste in 2008 alone, and this number continues to rise. About 54% of this trash (135,000,000 short tons (122,000,000 t)) ends up in landfills and is consuming land at a rate of nearly 3,500 acres (1,400 ha) per year. In fact, landfilling is currently the number one method of waste disposal in the US. Some states no longer have capacity at permitted landfills and export their waste to other states. Plasma gasification offers states new opportunities for waste disposal, and more importantly for renewable power generation in an environmentally sustainable manner.[3]


Landfill


Disposing of waste in a landfill involves burying the waste, and this remains a common practice in most countries. Landfills were often established in abandoned or unused quarriesmining voids orborrow pits. A properly designed and well-managed landfill can be a hygienic and relatively inexpensive method of disposing of waste materials. Older, poorly designed or poorly managed landfills can create a number of adverse environmental impacts such as wind-blown litter, attraction of vermin, and generation of liquid leachate. Another common byproduct of landfills is gas (mostly composed of methane and carbon dioxide), which is produced as organic waste breaks down anaerobically. This gas can create odour problems, kill surface vegetation, and is agreenhouse gas.



A landfill compaction vehicle in action.



Design characteristics of a modern landfill include methods to contain leachate such as clay or plastic lining material. Deposited waste is normally compacted to increase its density and stability, and covered to prevent attracting vermin (such as mice or rats). Many landfills also have landfill gas extraction systems installed to extract the landfill gas. Gas is pumped out of the landfill using perforated pipes and flared off or burnt in a gas engine to generate electricity.
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