Incineration
These facilities tended to risk the health of the plant workers and the local environment due to inadequate levels of gas cleaning and combustion process control.
[citation needed] Incinerators reduce the solid mass of the original waste by 80–85% and the volume (already compressed somewhat in garbage trucks) by 95–96%, depending on composition and degree of recovery of materials such as metals from the ash for recycling.
Alternatively, at landfills, the volume of the uncompressed garbage can be reduced by approximately 70% by using a stationary steel compressor, albeit with a significant energy cost.
[5] A number of other European countries rely heavily on incineration for handling municipal waste, in particular Luxembourg, the Netherlands, Germany, and France.
In order to comply with this at all times, it is required to install backup auxiliary burners (often fueled by oil), which are fired into the boiler in case the heating value of the waste becomes too low to reach this temperature alone.
Controlled combustion, burn back prevention systems are essential as dust when suspended resembles the fire catch phenomenon of any liquid petroleum gas.
[18] The most publicized concerns about the incineration of municipal solid wastes (MSW) involve the fear that it produces significant amounts of dioxin and furan emissions.
The EPA announced in 2012 that the safe limit for human oral consumption is 0.7 picograms Toxic Equivalence (TEQ) per kilogram bodyweight per day,[20] which works out to 17 billionths of a gram for a 150 lb person per year.
Backyard barrel burning of household and garden wastes, still allowed in some rural areas, generates 580 grams (20 oz) of dioxins annually.
For this reason there is also a time element to the temperature exposure to ensure heating completely through the thickness of the fly ash and the volume of waste gases.
Fortunately, dioxin and furan compounds bond very strongly to solid surfaces and are not dissolved by water, so leaching processes are limited to the first few millimeters below the ash pile.
Modern municipal incinerator designs include a high-temperature zone, where the flue gas is sustained at a temperature above 850 °C (1,560 °F) for at least 2 seconds before it is cooled down.
For very small municipal incinerators, the required temperature for thermal breakdown of dioxin may be reached using a high-temperature electrical heating element, plus a selective catalytic reduction stage.
[25] Other gaseous emissions in the flue gas from incinerator furnaces include nitrogen oxides, sulfur dioxide, hydrochloric acid, heavy metals, and fine particles.
It may be avoided by decreasing the steam content by flue-gas condensation and reheating, or by increasing the flue gas exit temperature well above its dew point.
The efficiency of removal will depend on the specific equipment, the chemical composition of the waste, the design of the plant, the chemistry of reagents, and the ability of engineers to optimize these conditions, which may conflict for different pollutants.
[citation needed] Sulfur dioxide may also be removed by dry desulfurisation by injection limestone slurry into the flue gas before the particle filtration.
They receive and store the waste in an enclosed area with a negative pressure with the airflow being routed through the boiler which prevents unpleasant odors from escaping into the atmosphere.
Research studies have also assessed exposure to pollutants through blood or urine samples of residents and workers who live near waste incinerators.
[34][36] Findings from a systematic review of previous research identified a number of symptoms and diseases related to incinerator pollution exposure.
Specific pollutant exposures, such as high levels of nitrogen dioxide, have been cited in community-led complaints relating to increased emergency room visits for respiratory issues.
[41] For example Wheelabrator Baltimore in Maryland has been investigated due to increased rates of asthma in its neighboring community, which is predominantly occupied by low-income, people of color.
He began Robert Ross Industrial Disposal because he saw an opportunity to meet the hazardous waste management needs of companies in northern Ohio.
However, many of these projects have faced continued political opposition in spite of renewed arguments for the greenhouse gas benefits of incineration and improved air pollution control and ash recycling.
[76][77] In Sweden, about 50% of the generated waste is burned in waste-to-energy facilities, producing electricity and supplying local cities' district heating systems.
[79] Due to increasing targets for municipal solid waste recycling in the EU, at least 55% by 2025 up to 65% by 2035,[80] several traditional incineration countries are at risk of not meeting them, since at most 35% will remain available for thermal treatment and disposal.
[89] A permit has recently been granted[90] for what would be the UK's largest waste incinerator in the centre of the Cambridge – Milton Keynes – Oxford corridor, in Bedfordshire.
Emergency incineration systems exist for the urgent and biosecure disposal of animals and their by-products following a mass mortality or disease outbreak.
One-third of global meat exports (approx 6 million tonnes) is affected by trade restrictions at any time and as such the focus of Governments, public bodies and commercial operators is on cleaner, safer and more robust methods of animal carcass disposal to contain and control disease.
Large-scale incineration systems are available from niche suppliers and are often bought by governments as a safety net in case of contagious outbreak.
