Fly ashes are among the coal combustion products (CCPs) which are harmful to the environment. Researchers from three Polish universities are searching for innovative methods to process and safely use this type of waste. Their solutions are expected to contribute to a several-percent increase in the reuse of these harmful substances, once properly processed, in various sectors of the economy, including construction, agriculture or environmental engineering.
By establishing the FUNash Consortium, researchers from the Lublin University of Technology (LUT), the AGH University of Science and Technology in Kraków (AGH) and the University of Warsaw (UW) have joined forces to conduct the research. The project has received PLN 21 million in funding from the Foundation for Polish Science under the TEAM-NET programme.
“Each year Polish power plants and thermal power plants generate approx. 4 million tonnes of fly ashes. Around 60% of these are managed and reused – mainly in concrete and cement production, but also for land stabilisation during road construction, and in mines, where they serve as flooring materials or are utilised in borehole liquidation. However, large amounts of fly ashes are still dumped at landfills, polluting the environment. Some of these materials, as fine particles, are blown into the air, contributing to smog formation. Moreover, landfill sites occupy much space that could be used for other purposes, while producers are forced to bear substantial costs related to dumping and environmental charges. For these reasons, the utilisation of fly ashes appears much more beneficial than dumping,” stressed Prof. Wojciech Franus, Ph.D. Eng., from the Faculty of Civil Engineering and Architecture at the Lublin University of Technology , who is the FUNash project leader.
New methods of reusing fly ashes are also needed in view of the fact that increasingly large quantities of these CCPs cannot be used as concrete or cement additives due to their specific mineral composition, which results from more restrictive regulations and modernisations of the coal combustion processes employed in power plants. So, what are the new ways of utilising fly ashes from energy production?
Biocement in restoration of monuments
Fly ashes can be used as precursors for the synthesis of various functionalised materials, including synthetic zeolites, zeolite-carbon composites and zeolite-carbon-vermiculite composites. Certain bacterial strains, e.g. producing calcium carbonate, could then be added to these mineral substrates displaying specific physiochemical properties, in order to obtain innovative and microbiologically modified materials that could be used in construction, e.g. for biocement production. And biocement is excellent for stone surface damage repairs (including in objects of cultural and historical value). However, in order for it to be utilised on a wider scale, efficient technologies need to be developed, allowing the use of fly ashes as precursors for the synthesis of functionalised materials. At the FUNash Consortium, this task has been taken on by one of the teams from the Lublin University of Technology. Another team operating within LUT will develop mineral-microbiological hybrids, and test the possible ways of their utilisation in the construction industry.
Remediation of polluted waters, soils and air
The project will deliver another innovative solution involving modification of ash-based materials to transform them into sorbents to remove specific types of water, wastewater and soil pollution, including metals, metalloids, radionuclides, antibiotics, pesticides and herbicides. This task will be performed by the research team at the Faculty of Geology, Geophysics and Environmental Protection of the AGH University of Science and Technology. The research team established within the Faculty of Biology at the University of Warsaw will also focus on eliminating environmental pollutants by means of ash-based products. “The novelty of this solution lies in the use of fly ash conversion products as carriers for microorganisms stimulating bioremediation of waters, soils and air. The materials obtained from ashes will be enriched with organic waste substances (e.g. whey or molasses). This will be followed by settling bacteria on the materials. Through such a combination, bacterial action will be more stable and efficient, and the biofiltration process will stand a better chance of success. A similar method will be used in waste treatment plants, where denitrifying bacteria will be settled on functionalised materials derived from fly ashes,” said Prof. Wojciech Franus.
Innovative fertilizers and biofertilizers
Another important innovation delivered by the project will be the impregnation of the functionalised materials obtained from ashes with nitrates, sulphates and phosphates in order to develop an original technology of producing mineral-organic fertilizers with lignite additives. This stage of research work, which will be conducted at the AGH University of Science and Technology, will also involve developing new formulas for mineral-organic fertilizers to be used with those plant species which are predominant in European cropping patterns. The FUNash researchers will also develop biofertilizers. Biologists from the University of Warsaw are also planning to use ash-based materials as carriers for microorganisms stimulating plant growth, accelerating the composting process or suppressing the development of plant pathogens, which will allow natural elimination of phytopathogens without the need to resort to pesticides that are dangerous to the environment. The researchers have already succeeded in selecting and testing some bacterial and fungal strains which could be used in the proposed biofertilizers. These include cold-adapted strains suitable for our climatic zone.
Six independent research teams, having various competences and scientific experience, will be established for the purposes of the FUNash project. These teams will closely cooperate with each another and exchange their research results, which may lead to developing novel solutions of a truly unique character. The principal objective of the FUNash project is to establish a cross-institutional federation (LUT + AGT + UW) to render services and provide new technologies and solutions based on fly ashes. “Such services will be dedicated to various sectors of the economy, serving as the first-ever comprehensive approach to fly ash reuse,” stressed Prof. Wojciech Franus. The researchers are estimating that the wide range of products and technologies will contribute to increasing fly ash reuse in Poland by 3-5%.
The TEAM-NET programme
The TEAM-NET programme for the Foundation for Polish Science provides funds for interdisciplinary research implemented through a network of cooperating research teams led by prominent and experienced scientists. As well as facilitating the implementation of innovative research in Poland, the programme aims to strengthen supra-regional cooperation between research establishments, and to develop competencies in the use of available infrastructure and research services. The competition rules stipulate that the budget of each research project can amount to PLN 3.5 million per team, for a period of 36 months. The financing can be granted for a period from 36 to 48 months.
A call for proposals for the TEAM-NET competition was opened in October 2018, and in March 2019 the Foundation for Polish Science announced its results. A total of 39 project proposals were submitted, of which 11 received funding for a total amount exceeding PLN 201 million.
The TEAM-NET competition has been conducted by the FNP using EU funds from the European Regional Development Fund as part of the Smart Growth Operational Programme.
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The photo shows zeolite –a mineral obtainable from fly ashes