2. Waste-to-energy process

In the last few decades, the problems of carbon-containing materials reforming into synthesis gaseous fuel—mixture CO and H2—by means of plasma technologies were widely discussed in the scientific literature [1–14]. This syngas can be used for heat or electrical energy produc-

The European Commission (EC) has defined the European Union (EU) objectives in the energy sector by 2020 (20% less greenhouse gas emissions, at least 20% of the EU's energy resources renewable energy sources, a 20% reduction of primary energy consumption in the directive EU, COM (2008) 30) [15, 16]. To achieve these objectives, the Member States have to increase the share of renewable energy resources in electricity generation, fuel saving and waste management. At the same time, it should be taken into account about the most effective hazardous waste destruction technology such as a thermal treatment and gasification. Ukraine and Lithuania have approved the Community and follows the most important requirements and

It is well known that one of the most effective hazardous waste destruction technologies is a thermal treatment and gasification. However, there exist an entire group of substances any traditional treatment of which causes a threat to the environment and human health. Therefore, present research proposes to develop and implement plasma technology, which allows to remove all waste containing hazardous substances. Plasma decontamination technology of toxic materials allows to create a compact device, which can reliably neutralize all of types of hazardous waste. Such plasma device is characterized by a very high temperature, short reaction time, extreme activation energy, the ability to heat various gases, effective neutraliza-

Complete and safe hazardous waste (outdated medications, banned pesticides, plastic gears, pathological waste, container, etc.) removal method is high temperature (plasma) pyrolysis. It is already employed in many countries around the world: USA, Japan, France, Germany, Switzerland, Australia, etc. Many developing countries (India, China, Belarus, etc.) also seek to employ the plasma technology in this area. There is a shortage of detailed technology description in worldwide scientific literature because these research results some times are not made public. Medical wastes from hospitals, dental clinics and other health centers are collected and recycled in about 1500 large companies. Most of them are located in the USA,

The interest in plasma technology in the application of harmful substances neutralization processes is huge. For example, the Japanese medical waste management company recently implemented a large project, whose main goal is to transform the infected local medical waste

Environmental safety and technological advantages of plasma using plasma technology for this purpose are noted in many of the papers. However, the most important problem is their energy efficiency, because the efficiency of electricity generation to power the plasma torch (PT) is only about 30% [9]. Thus, in order to achieve the commercialization of such environmentally clean technologies, they need to simultaneously achieve high levels of their energy

efficiency. The solution of this problem is also dedicated by this work.

tion [13].

procedures of the EU.

166 Gasification for Low-grade Feedstock

tion and independence from fuel sources.

France, Great Britain and Japan [17, 18].

into useful products - glass, metal and syngas.

Modern technologies of the waste treatment are oriented on the processes of their gasification. It has three interrelated advantages. First of all, the temperature range at which the gasification processes are effectively carried out is quite high and usually exceeds 1000C. This automatically meets the requirements of the Directive 2000/76/EC [15], according to which the temperature should be maintained at 1100C in case of incineration of waste containing more than 1% wt. of halogenated organic substances under conditions of chloride. This is necessary for dioxins and furans which are formed at lower temperatures, to be effectively decomposed into HCl.

Second, each local volume of gas produced in the processing has to be kept at this temperature over time ≥2 s. In this case, maximum permissible emission of dioxins and furans to the atmosphere in the refinement products do not exceed 10<sup>10</sup> g/m3 [15]. This is very important as these compounds are among the most toxic ones. In addition, prolonged residence of reagents at high temperature ensures the completeness of gasification processes, and also allows accepting the assumption of equilibrium conditions when performing thermodynamic calculations.

Third, although gasification products must be cooled down quickly to avoid the reverse generation of dioxins and furans, the main energy is accumulated in chemical bonds. Even though syngas cooling leads to some losses of thermal energy, the share of which is small compared to the total energy content which consists of thermal and chemical energies.

Another problem appears when the waste contains in its composition heavy metals; using well known incineration for their utilization leads to formation of ash, which is itself a hazardous waste [19–21]. The latter environmental hazard is particularly dangerous in the case of recycling the sewage sludge of urban wastewater treatment plants [13].

The arc discharged plasma is an effective tool for many types of application including hazardous waste treatment. It is important to notice that there exist several unsolved problems in thermal treatment of sewage sludge area. During the combustion process, solid dispersed particles may be formed from the combustion products. Solid particles may penetrate into the human lungs and can cause serious illnesses. Incomplete combustion may also occur inside the furnace and form new chemicals that may appear to be more toxic than initial material. Therefore, flue gas is cleaned in multicyclones or fiber filters before discharge into the atmosphere. However, such types of filters are expensive and not very effective in the case of fine dispersed particulates. There does not exist means against newly formed hazardous chemicals at all. So the plasma treatment of exhaust combustion products is welcomed. Atmospheric pressure arc plasma is also a promising tool for the synthesis of catalytic coatings which could be successfully employed in the manufacturing of catalyst for flue gas treatment.
