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Waste Disposal Techniques

One of the besetting problems of society is how to dispose of wastes in a safe and non-polluting way. Wastes are categorized into four main areas according to source: municipal, medical, industrial and hazardous. Other categorizations are by consistency into solid, liquid and sludge wastes; and by environmental danger into non-hazardous, hazardous and special wastes. Each category is disposed of in different ways according to its characteristics.

  1. Landfills

    • This technique entails burying waste in thin layers in a contained pit. Compacted layers are spread over by clean soil before adding another layer. About 90 percent of U.S. municipal wastes go to landfills. They are cost effective; 75 percent of their cost is involved in collection and transport of wastes to the landfill. After landfills are closed, the land is reused for other community purposes. The land has to be monitored for settling and the site must be properly planned and landscaped.

    Incinerators

    • Incinerators destroy 99.9 percent of the organic materials processed and reduce the refuse volume by half. Incinerators have a small footprint and can be operated in any weather. They are expensive to build and maintain, however, have a high energy requirement and can be a source of odors and vermin. Specially licensed incinerators dispose of medical wastes.

    Ocean Dumping

    • Oceans are contaminated with sewage, animal wastes from feedlots and agricultural operations, nutrient runoff from agricultural areas and industrial wastes--including petroleum products, hazardous wastes and thermal wastes from power plants and factories. Ocean dumping is convenient, inexpensive and still used in developing countries, but it overburdens the ocean and negatively affects ocean life.

    Open Dumping

    • Many developing countries still practice this unsanitary method. Refuse is not treated or managed and is a source of pathogens, diseases, odors and vermin. Runoff contaminates ground water and pollutes waterways and bodies of water.

    Recycling

    • Waste materials are sorted by waste type, with recyclable elements reprocessed into usable items. This applies mostly to municipal and industrial wastes. It is time-consuming and expensive, and separation of waste from recyclable materials can be difficult. Results can be impressive, however, as shown by data cited in Oberlin College's "Interesting Facts About Recycling," where in 2007 more than 56 percent of the paper consumed in the U.S. was recycled for reuse.

    Wastewater Treatment Plants

    • Processing sewage through wastewater treatment plants results in control of pathogens, vermin and run-off contamination from sewage. Processing the sewage is a multi-stage treatment, with the end goal being eliminating debris, particulate matter, organic material, disease-causing microorganisms and other pollutants from the waste, which is 99.94 percent water. The process is regulated closely.

    Land Farming and Composting

    • In this technique, organic wastes and some oilfield waste--if it meets certain limits of contamination levels--are spread in thin layers over ground surface, which is periodically plowed. This allows soil microbes to work on the wastes and biodegrade them.

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