Case: Waste
Do you sort waste? Or do you throw everything in the municipal solid waste bin? Have you ever thought about what happens then? If it is not placed in landfill, which is increasingly being abandoned due to the highly negative impact on the environment, it is processed. However, municipal solid waste is more difficult to treat because it is composed of a variety of materials. An expert team, led by Vojtěch Pilnáček and Libuše Benešová from the Institute for the Environment, Faculty of Science, Charles University, therefore focused on the possibilities of making optimal use of biodrying technology
According to European legislation, there should be a gradual increase in prices per tonne of municipal solid waste (MSW) deposited in landfills until 2030. That year there should be a total ban on landfilling. However, given that MSW will, unfortunately, probably be with us for some time, it is necessary to focus our attention on the use of substitute methods and technologies for MSW management. Such methods should be more environmentally friendly and economically feasible. One promising possibility is known as biodrying of municipal solid waste.
challenges in its treatment than sorted waste.
Photo: K. Fraindová.
This method uses the heat generated by microbial aerobic decomposition of biodegradable waste components. The source of oxygen for aerobic decomposition is air blown into the appropriate substrate. At the same time, this air supports the drying of wet parts. However, when air is blown, the substrate also cools down, which negatively affects microbial decomposition. Optimising the intensity of the blown air is thus pivotal.
The basis for deciding that MSW biodrying technology will be tested in Czechia was Ms Benešová’s and Mr Černík’s visit to the West German city of Trier in the state of Rhineland-Palatinate. Accompanied by the operator, both were allowed to inspect one of the cutting edge facilities for biodrying municipal solid waste. After returning to Czechia, they assigned a topic for a diploma thesis, the aim of which was to verify the possibilities for using biodrying technology in our conditions. The author of the diploma thesis under the supervision of Ms Libuše Benešová was a student named Vojtěch Pilnáček.
Municipal solid waste was collected in a selected locality in Mníšek pod Brdy, which is likely to be proposed as the location for a mechanical-biological waste treatment facility in the future. The waste was then processed in accordance with the biodrying processing technology. The methodology and workflow were developed by the cooperating University of Aachen.
The basic requirement in the treatment is that part of the waste with low moisture content and high calorific value is sorted to enable further use of the product as a fuel. This can reach a calorific value comparable to, for example, brown coal. Thanks to the ingenious use of the assemblies of several air sorting devices and screening processes, light heating components and heavy waste components such as metals and inert materials are separated. This guarantees high quality fuel.
The resulting product has several advantages. For example, low moisture content prevents the risk of spontaneous combustion or decomposition processes accompanied by odours. At the same time, waste treated in this way meets the requirements of the EU Directive 1999/31/EC on the landfill of waste. In addition, operation is considerably simpler compared to conventional waste combustion in incinerators. Last but not least, it is also necessary to mention the production of certified fuel, which is already used by German plants in Dresden and Trier.
Mechanical-biological waste treatment represents a significant shift in the issue of waste management and its subsequent use. Although no mechanical-biological waste treatment facilities currently operate in our territory, Czechia can be considered a country with sufficient potential for their construction. Feasibility studies for such facilities are currently being prepared, but their implementation remains relatively problematic while other methods of waste management continue to be preferred. However, in connection with forthcoming legislation prohibiting the disposal of municipal waste in landfills without regulation, we can perhaps expect a positive change akin to that which has taken place in Germany or Austria.
Kateřina Fraindová
References:
Juniper (2005): Mechanical-biological treatment: a guide for decision makers, processes, policies and markets, Juniper Consultancy Services, UK.
Kočí, V., Trecakova, T. (2011): Mixed municipal waste management in the Czech Republic from the point of view of the LCA method. The International Journal of Life Cycle Assessment, Vol. 16, No. 2, pp. 113–124. doi: 10.1007/s11367-011-0251-4.
Tambone, F., Scaglia, B., Scotti, S., Adani, F. (2011): Effects of biodrying process on municipal solid waste properties. Bioresource technology, Vol. 102, No. 16, pp. 7443–7450.
Published:
Mar 07, 2022 09:25 AM
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