Burning Waste

Burning Waste has been practised around the world for decades. Burning waste can be carried out for various reasons such as, generating energy, and reducing the waste pile. The follwoing article talks about Inceneration, a method of burning waste.  

The Burning Waste

Fire has always held a fascination for humans, and it has been one of our most useful tools. Fire has provided warmth, cooked food, cleared forests lands, offered protection against marauding animals, and much more. Although garbage has probably been burned ever since humans discovered fire, it has been incinerated in a systematic manner for only about a century. Perhaps surprisingly, given its long history and obvious benefits, waste incineration is a topic that is both controversial and emotional. In this chapter we will discuss the advantages and disadvantages of incineration and how it can contribute to an integrated waste management program.

               Under proper conditions, incineration provides a number of benefits:

·         It greatly reduces the volume of waste that must go to disposal in landfills—a vitally important objective. In conventional municipal incinerators, the volume reduction ranges from 80% to 95%, with a mean of about 90%.

·         It can be used in conjuction with landfill mining to reclaim closed landfills and greatly extend the operating lifetimes of existing landfills.

·         The ash produced is relatively homogeneous and thus more suitable than raw waste for treatment such as solidification in concrete.

·         A relatively large proportion of the organic compounds, including putrescible and hazardous wastes, is destroyed: thus, there is a net reduction in the quantity of toxics.

·         Energy can be generated as a useful by product, which preserves nonrenewable fuels like natural gas, oil, and coal.

Fewer air pollutants are produced by burning waste than by burning coal or oil.

The use of incineration has been increasing in the United States since about the mid=1980s, and currently the country burns about 16% of its municipal wastes (EPA, 1994). This figure is significantly lower in Canada—about 4%—but it can be much higher overseas. For Example, Japan, which faced its waste disposal crisis in the 1950s, 20 years before the crisis reached North America, incinerates approximately 34% of its municipal garbage (Hershkowitz & Salerni, 1997). Most Japanese incinerators generate electricity. In Sweden, the government regards waste as a resource, not something to be squandered by landfilling; approximately 41% of its waste is incinerated  in 21 waste-to-energy incinerators, with almost all the energy being delivered to district heating systems ( Rylander, 1994 ). This energy corresponds to 4.5 terawatt-hours ( tera means 10 raised to the power 12 ), or 15% of the total district heating requirements in Sweden. There are more than 400 waste incinerators in the world.

The main drawback to incineration is that the process releases contaminants into the air, violating the principle of protecting health porate rigorous emission controls. There is considerable opposition by the public to the use of waste incinerators, at least partly because oider incinerators certainly caused air pollution. Modern waste-to-energy plants have largely overcome this deficiency by including improved combustion processes, better pollution control technology, and the production of a useful product, energy.

Opponents of incineration argue that contaminants are spread into the atmosphere where they cannot be controlled, instead of being contained in a landfill. Another disadvantage of an incinerator is that it is more costly to construct than a landfill; furthermore, all of the capital cost is incurred up front, whereas landfill capital costs are spread over the operating lifetime. Incinerator technology is far more sophisticated than that of a landfill, requiring more careful control and trained operators.

Design criteria for incinerators should ensure that:

·         Air will be supplied in the quantities needed for proper combustion.

·         Gases will be tempered and cooled to prevent damage to the refractories ( heat-resistant incinerator liner ) and to allow the gases to be treated.

·         Particulates and noxious substances will be removed from the flue gases.

·         Waste will be fed into the furnace and ash removed without allowing combustion products to escape.

·         A water treatment plant will be incorporated to process the water used in cooling the ash residues and flue gases.

·         The amount of maintenance and downtime for repairs will be minimized.