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Gorenje Surovina d.o.o., in collaboration with the University of Maribor (UM), has successfully completed its environmental protection project called "RRPO 2013: Building a pilot reactor for drying and disinfecting of urban and/or industrial sludge from purification plants". The project consisted of developing a technologically and economically efficient device for drying of non-hazardous sludge. The project offers a promising solution to an increasing problem in terms of environmental protection because of the potential use of such technology in industry.

Following one year of intensive research, analyses and testing, the experts of Gorenje Surovina (GS), a company for comprehensive waste management, in collaboration with the Faculty of Electrical Engineering and Computer Science (FERI), Faculty of Mechanical Engineering (FS), and Faculty of Natural Sciences and Mathematics (FNM) designed and produced a pilot vacuum reactor for drying mud under negative pressure by means of a low-temperature heating medium. "Being a socially responsible company, we put our best efforts into close cooperation with the University with a view to research and develop practical and useful environmental solutions," says the GS director Jure Fišer. He adds: "We are proud to have developed together a pilot device and to have defined technical as well as economic parameters for the development of an industrial device." The device will enable the rationalization of costs of urban and/or industrial sludge as well as the minimisation of the sludge disposal. "A rotary vacuum paddle dryer has been selected, operating in batch mode. This is an optimum concept design of a reactor for drying and disinfecting the sludge in purification plants," explains dr. Janez KRAMBERGER of FS, head of the mechanical part of the project. Prof. dr. Riko ŠAFARIČ of FERI, head of the project at UM, adds: "This is an important technological achievement, a breakthrough in environmental protection and a product of Slovenian know-how."


The project was initiated because non-hazardous sludge is showing to be an ever increasing environmental protection issue. "More and more sludge is produced every year because of increasingly stricter legislation in the area of environmental protection, population growth, greater population density and consequently a larger number of water purification plants. In Slovenia, the capacity of the sludge processing does not meet the current needs which is why the export share is rising," explains dr. Janez Ekart, head of the project of GS. The sludge is a raw material or energy-generating product that can be used – after proper treatment – as a fertiliser, raw material for composting, building material, soil or as an alternative fuel. "One of the most frequently used preparation processes for further or final utilisation is drying," explains Prof. Šafarič.

"By means of a reactor, we were able to achieve a significant drop in the level of the sludge humidity, a decrease of pathogens and an increase of its calorific value," says prof. Andrej Šorgo of FNM, head of microbiological research in the project.  With an acceptable energy consumption per kilogram of dried mud, economic efficiency of the device was also achieved. The success of the project is a result of the complementarity of various scientific disciplines and the industry, as highlighted by dr. Suzana Žilić Fišerof the Institute for Media Communications (FERI): "Each new technical solution in ecology has to consider wide environmental consequences. We understand the importance of informing wider public that has to be involved in an altered paradigm of waste processing tackled by the state, while the companies in this sector need to consider public interest."


The project has been co-financed by the Republic of Slovenia and the European Union (EU) provided by the European Regional Development Fund. The funds have been obtained through a public tender for promoting research and development projects in problematic areas with high unemployment from 2013 to 2015 – RRPO 2013. "The estimated maximum financing from this title amounts to EUR 152,497.50. Most funds for the completion of the project starting in November 2013 have been provided by GS's own funds. It is of paramount importance that we have our own physical chemistry laboratory for the analysis of combustible material and waste in liquid and solid state in Tezno," explains mag. Tadej Krošlin, head of development of GS. He shares the opinion that the patent, result of this project, illustrates the potential use of this kind of technology in industry: "Key conditions have to be met for this kind of technology to have economic viability. This is why we are searching for solutions for further research and development projects in this area with potential users and co-investors."

Maribor, 21 April 2015

For more information, please visit: Surovina projekti

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