Waste tyre pyrolysis – Impact of the process and its products on the environment

Abstract

The constant development of the automotive industry causes a steady growth in the production of tyres, which have to be utilized properly after their lifespan. Pyrolysis is considered a promising solution, providing many advantages for the environment in comparison with traditional waste management methods. The pyrolysis of waste tyres was undertaken at three different temperatures (400, 500 and 600 °C) and subsequently the products obtained were investigated in the context of their influence on environmental components such as the atmosphere, hydrosphere, soil and biosphere. Special attention was focused on the sulfur-containing compounds and heavy metals. Additionally, ultimate and proximate analyses were made and the organic composition of the liquid fraction was checked. The concentration of heavy metals in pyrolysis oils and chars were, in general, very low and this allows their further usage to be considered safe for the environment and human health. Additionally, the presence of valuable chemicals such as limonene, toluene and xylene enhance the profitability of the process as well as saving natural resources. On the other hand, the high concentration of sulfur-containing compounds in pyrolytic gas and oils makes their usability dependent on desulfurisation processes. However, the very high energy content (calorific value) in all three products encourages their industrial application.