engleski

The possibility of ash disposal generated during the waste incineration into deep wells

Thermal waste treatment generates a certain amount of waste with different characteristics, which should be permanently and safely disposed of in compliance with social, economic and legal obligations. In terms of quantity the most important is incinerator bottom ash, which quantity ranges from 25-30% of the total incinerated waste. Bottom ash is generally classified as non-hazardous or inert waste, provided well-led incineration technological process and uniform and known composition of the incoming waste. Many important types of waste is called filter ash generated in the process of purification of flue gases. It occurs in 3-5% of the amount of incoming waste (depending on the technology of incineration) and represents - hazardous waste that must be permanently disposed. In European practice, incineration plants dispose it in hazardous waste landfills, but technical possibilities to dispose it into deep geological formations is cheaper, technically simple and safe. In Croatia we have ideal possibilities for storing such waste in depleted oil and gas wells at the depths ranging from 1, 500-4, 000 m. Wells selection depends on the integrity of the wellbore, and the flow injection can be controlled in real time by using modern monitoring methods. Geologic formations in which such waste can be stored are covered by the impermeable cap rock and bed rock and are free of vertical regional faults, which prevent waste migration into the aquifer containing potable water. Such suitable wells can be found in almost all our Counties. The purpose of this paper is to familiarise the expert community with the possibility of ash disposal into suitable geologic formations using modern technology which has already been used for several decades in developed countries, particularly in the USA and Canada, and show its development in our country. This technology enables permanent and safe disposal of large quantities of hazardous waste from petroleum, chemical, pharmaceutical, food and other industries, and in Croatia it is successfully applied for disposal of waste generated during oil and gas exploration and production activities. To sum up, as new experience from international and Croatian petroleum practice shows incinerator ash can be disposed of into suitable geological formations in an environmentally friendly manner and in line with set national environmental strategy and EU directives. Injection of residual waste into wells represents a safe and permanent manner of disposal of waste from our living environment – the biosphere.

waste incineration; filter ash; waste disposal

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