With many landfills reaching their limits and public concern about environmental problems caused by incorrect waste disposal, incineration has become an attractive option for waste disposal. Incineration is not a complete substitute for landfill, but it can reduce the amount of landfill.
Incineration is the decomposition or destruction of organic matter in the presence of oxygen and heat. Incineration serves several purposes:
The main advantages of incineration are:
- It can greatly reduce the weight and volume of waste going to landfills;
- It can eliminate hazardous organic waste or organic waste that can produce harmful substances when degraded;
- It can eliminate organic compounds that can contaminate inorganic products;
- Incinerators can Sterilization. This is because the high temperatures generated during incineration can kill pathogens that may be present in infectious waste. Pathogens can cause organic living diseases.
- Energy can be generated, such as heat recovery in steam production
- Incinerators can treat pathological or other wastes produced by animals or people. The public is repulsed by the treatment or even the sight of these wastes and, at a minimum, finds it difficult to accept.
Incineration dates back as far as the origins of civilization. As we can see in early cities, incineration has been used for thousands of years to reduce the amount of waste. Today there are many types of incinerators: fixed bed chamber, multi-bed chamber, fluidized bed, grate, and rotary. The rotary furnace was invented in England in 1885 for cement production and is now used worldwide as an incinerator for industrial and hazardous waste.
Environmental concerns
If the public didn't believe incineration was environmentally sound, they certainly wouldn't accept it as a method of waste disposal. None of the public's primary concerns are really necessary: pathogens are killed inside the incinerator; the amount of ash burned is acceptable; and harmful air pollutants do not spill out of the oven. This section will introduce a few terms in incineration that are important to understanding these issues.
Killing pathogens
Pathogens are those organisms present in the waste that can cause infectious diseases.
The high temperatures generated in an incinerator kill pathogens in infectious waste. There is no reliable information on the conditions under which an incinerator kills all pathogens. But what is known is that temperature and residence time are critical. If pathogens are spilling out of the incinerator, then the following reasons for insufficient residence time and temperature are likely.
1. Incinerator charging before the operating temperature has risen
2. Failure to preheat the fireproof lining
3. Temperature fluctuations caused by intermittent use
4. Air flow rates exceeding the design value, resulting in shorter residence times
5. Overfilling of the incinerator
6. Waste with too high a moisture content
Others Some factors, such as: the type of fireproof lining, the number of burners and cloth position, the accuracy of the temperature control equipment, etc., will affect the killing of pathogens. The killing of pathogens in the ash is equally dependent on temperature and residence time.
Air Pollutant Concerns
Concerns about the environment are centered on the incinerator and its major pollutants. These pollutants include:
-Particulate matter;
-Hydrogen chloride gas;
-Toxic heavy metals;
-Organic compounds;
-Carbon monoxide;
-Sulphur oxides; and
-Nitrogen oxides.