Theoretical and Methodological Aspects of Transition to a Circular Economy

Gabriela VACEKOVÁ^a, Michal PLAČEK^a, Jana SOUKOPOVÁ^b
a Faculty of Social Sciences, Charles University, Smetanovo nábřeží 6, 110 00 Praha 1, Czech Republic, e-mail: gabriela.vacekova@fsv.cuni.cz, michalplacek@seznam.cz
^b Faculty of Economics and Administration, Masaryk University^,, Lipová 41a, 60200 Brno, Czech Republic, e-mail: jana.soukopova@econ.muni.cz

The transition to a more circular society has been adopted as a guiding principle in several countries' policies. The present paper reviews the international definitional, theoretical and methodological approaches to the circular economy originating in the Western environment with a view to assessing their applicability in the (post-) transitional context of the Central and Eastern Europe and identifying the elements of their integrative conceptual core. The main finding is that scientific research on circular economy and circular business thinking takes two relatively independent directions (normative/positive), as it is grounded in two different methodological approaches. Furthermore, the paper provides definitional clarifications and policy implications for the Czech context, and shows that it is possible to use a starting point for further research on circularity that would not be based on dichotomous approaches but on integrity (holistic approach).

Key words: Circular Economy, Circular Business Thinking, Transformation Process, CEE

Development of operational functional sample of biotrickling filter with integrated heating of circulating liquid phase

Jiří HENDRYCH, Jiří KROUŽEK
University of Chemistry and Technology Prague, Technická 5, 166 28 Praha 6, Czech Republic, e-mail: Jiri.Hendrych@vscht.cz

Biotrickling is a relatively inexpensive and technically undemanding process for cleaning gas from various areas and industries. The subject of the research was the realization of three apparatuses for testing and operation of this technique. Initial system was a laboratory installation on which the key aspects of the process were tested. The findings were used in realization of compact model apparatus of biotrickling filter with classical and microwave heating of circulating liquid phase. The main part of the work is devoted to the description of this device. The final technical solution – up-scaled compact container unit installed at the biogas plant in the Central Bohemia region is briefly described.

Keywords: biofiltration; biotrickling; heating; container unit; biogas plant; construction

Observation of solid pollutants flowing during solid alternative fuel combustion

Nikola KANTOVÁ, Michal HOLUBČÍK, Jozef JANDAČKA, Alexander ČAJA
Department of Power Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitna 1, 010 26 Žilina, Slovakia, e-mail: nikola.kantova@fstroj.uniza.sk, michal.holubcik@ fstroj.uniza.sk, jozef.jandacka@ fstroj.uniza.sk, alexander.caja@fstroj.uniza.sk

The production of waste materials is big global problem. One of the waste treatment options is a combustion. Waste material has to be appropriately prepared and combusted with low formation of the emissions, such as solid pollutants also called particulate matter. This article deals with an observation of these solid pollutants flowing through the flue gas tract of small heat source during solid alternative fuel combustion. Solid alternative fuel is waste material formed by its separation and modification. Flue gas tract is optimized by three baffles for separation of particulate matter and realized on 3D model. CFD simulations are used for observation of flowing. The observation of particulate matter flowing during wood chips combustion is also described in this article. In the results, we can see comparison between solid pollutants flowing from combustion of solid alternative fuel and wood chips.

Keywords: solid pollutants, particulate matter, alternative fuels, waste material

Characteristics of PM₁₀, PM_2.5 and NO_x pollutants in urban environment

Dusan JANDACKA and Daniela DURCANSKA
University of Žilina, Faculty of Civil Engineering, Department of Highway Engineering, Univerzitná 8215/1, 010 26 Žilina, Slovak Republic, e-mail: dusan.jandacka@fstav.uniza.sk

We carried out a series of measurements at various measuring stations (five measuring stations) in Žilina, Slovakia, during different measuring seasons. The main objective was to find out the characteristics of particulate matter (PM10 and PM2.5) and nitrogen oxides (NOx) pollutants in urban environment of Žilina City. In particular, the concentrations of pollutants, the distribution of particulate matter, the relationship of particulate matter and nitrogen oxides, the content of selected chemical elements in the particulate matter fraction were examined. A varied behavior of the particulate matter and nitrogen oxides with respect to the measurement station and the measurement season was found. Significant changes in the concentrations of particulate matter and nitrogen oxides are caused not only by primary sources (e.g., road traffic in the city of Žilina), but mainly by the negative events (combination of air pollution sources and meteorological conditions). Maximum 24-hours concentrations of particulate matter PM and nitrogen oxides NOx were measured during the winter season at the measuring station on Komenského street: PM10 114.9±15.6 µg/m3, PM2.5 84.5±20.6 µg/m3 and NOx 95.6±51.2 µg/m3. There were some measuring stations with a higher proportion of course fraction PM2.5-10 or fine fraction PM2.5 in Žilina City. The relationship was analysed between PM10 and NOx. Differences in the concentrations of investigated chemical elements contained in the PM were found. The coarse fraction PM2.5-10 was mainly represented by the chemical elements Mg, Al, Si, Ca, Cr, Fe, and Ba and the fine fraction PM2.5 was represented by the chemical elements K, S, Cd, Pb, Ni, and Zn.

Keywords: particulate matter, nitrogen oxides, urban air pollution, chemical composition of particulate matter

Paulownia Wallachia  and its biogas potencial

Michaela PLEKANCOVÁ, Lucia IVANOVÁ, Petra SZABOVÁ, Hela RUTZKÁ, Igor BODÍK
Department of Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovakia, e-mail: plekancova@stuba.sk

The aim of this work was to determine the biogas potential of the fast-growing plant Paulownia Wallachia. The work dealt with the monitoring of biogas production in a long and a short term, when the plant was used in its fresh and ensiled form.

The substrate was tested in the short term by methanogenic tests at different substrate to anaerobic sludge ratios.The experimental part consists also from a monitoring of the operation of mixed anaerobic reactors in mesophilic conditions, which were operated at a volumetric load of 1 g Xorg/l.d. The organic substrate was dosed into the reactors from October 2018 to December 2018, and different chemical parameters were analyzed on weekly basis. The results showed a favorable increase in biogas production, which stabilized after approximately 30 days. Based on the results of this work it is clear that Paulownia Wallachia has a biogas potential and it is a suitable alternative for biogas production in the world and Slovakia as well. The plant can produce more than 120 m³ of biogas per one tonne of raw substrate with about 55 % methane portion in biogas.

Keywords: Paulownia Wallachia; mesophilic anaerobic digestion; biogas

Influence of temperature on biogas production from fermentation residues

Martin ŠOTNAR
Mendel University in Brno, Zemedelska 1, 613 00 Brno, Czech Republic, e-mail: martin.sotnar@mendelu.cz

The fermentation residue from the biogas plant has the potential for residual biogas production. This biogas and methane production was tested during 180 days at 41 °C, 27 °C and 16 °C. Most of the biogas was produced by sample A with temperature regime of 41 °C, where the specific productionof this sample was 152.9 ⨯ 10^-3 m³ · kg^-1. The same sample produced at 41 °C volume of 86.4 ⨯ 10^-3 m³ · kg^-1of methane. A statistically significant difference was found between the specific biogas and methane production of all test variants. Furthermore, the production of biogas and methane, depending on temperature, was interleaved by a second degree polynomial. The polynomial equations for biogas can be written in the form Y = (-42,927 ± 38,349) + (5,223 ± 2,9566) · X (-0,0181 ± 0,0510) · X², (R² = 0,957) and for methane Y = (- 26.85 ± 27.94) + (2.3296 ± 2.1541) · X (0.0033 ± 0.0372) · X², (R² = 0.939). These equations allow the subsequent determination of cases of roofing and heating of specific storage wells to the fermentation residue with respect to the test duration of 180 days. The theoretical electricity production by the cogeneration unit using the average methane production for 180 days of the test, generated at 41 °C, overall 70 685.0 kWh.

Keywords: anaerobic fermentation, fermentation residue, methane 

The application of treated wastewater for the irrigation of fast-growing trees - field experiments on constructed wetland

Michal ŠEREŠ^a,b, Miloš ROZKOŠNÝ^c, Hana HUDCOVÁ^c, Pavel ŠALANDA^a,b, Petra INNEMANOVÁ^a,b, Pavel SEDLÁČEK^c
a DEKONTA, a.s., Dřetovice 109, 273 42 Stehelčeves, Czech Republic, e-mail: michal.seres@dekonta.cz
^b Institute for Environmental Studies, Faculty of Science, Charles University, Benátská 2,128 01 Prague 2, Czech Republic
^c TGM Water Research Institute, Mojmírovo nám. 16, 612 00 Brno, Czech Republic

Due to the progressive decrease in precipitation in the Czech Republic, the need for the irrigation of agricultural crops is steadily increasing. It is proposed that the problem of a lack of water resources might be partially solved via the reuse of treated wastewater (WW) in certain agricultural sectors however there is a very little known about the possible advantages or disadvantages of such sources of water. For this purpose, a semi-operated irrigation field was established at Hostětín in the Zlín region of the Czech Republic which was subsequently planted with willow cuttings (Salix viminalis L.). The plants were irrigated by means of two different water sources – wastewater from the local municipal treatment plant and local groundwater. During the 2018 and 2019 growing seasons, we observed the significantly enhanced growth of the wastewater irrigated willows – biomass yield was of 6.6 and 31.3 t/ha respectively under wastewater irrigation conditions, while only 1.0 and 1.8 t/ha was produced under fresh water irrigation conditions. The biomass quality was assessed via calorific values and showed lower gross and net calorific values for the wastewater irrigated willow biomass, i.e. 18.5 and 17.2 MJ/kg of dry matter respectively compared to 19.2 and 17.9 MJ/kg. However, the overall high yields of the biomass more than compensated for this disadvantage. This study confirmed the hypothesis that wastewater can be used in agricultural areas in which it does not endanger either public health or the environment.

Keywords: Wastewater reuse, drop irrigation, constructed wetlands, fast-growing trees

Waste reduction through using modern methods of construction

Marcela SPIŠÁKOVÁ, Mária KOZLOVSKÁ
Technical University of Košice, Civil Engineering Faculty, Vysokoškolská 4, 042 00 Košice, Slovakia, e-mail: marcela.spisakova@tuke.sk, maria.kozlovska@tuke.sk

The construction industry in Slovakia has been relying heavily on traditional construction technology. Buildings are usually constructed by the conventional cast in-situ methods. Recently, the modern methods of construction (MMC) are more apply for its performance improvement in construction, improvement of economic, environmental and social aspects of construction. The aim of submitted paper is to describe the waste reduction potential of using modern methods of construction which was determined through a questionnaire survey. The primary step of survey was to find out the state of awareness in professional public about the MMC and determine the importance level of particular factors for the selection of construction technology. Subsequently, based on expert opinions or professional experiences, the respondents evaluated the potential of waste reduction through the MMC using and identified the construction processes which may contribute to significantly reduce construction and demolition waste. The conclusion of paper is focused on the results comparison of this research and similar foreign research in this issue.

Keywords: modern methods of construction, construction and demolition waste, reduction, potential, questionnaire survey

Seldom Used By-product from Trimming Cement-bonded Particleboard Shows Potential for Modifying Building Materials Composition

Tomas MELICHAR, Jiri BYDZOVSKY, Amos DUFKA
Brno University of Technology, Faculty of Civil Engineering, Veveri 331/95, 602 00 Brno, Czech Republic, e-mail: melichar.t@fce.vutbr.cz, bydzovsky.j@fce.vutbr.cz, dufka.a@fce.vutbr.cz

The paper presents the suitability of an alternative raw material for use in cement-bonded particleboards. It focuses upon those trimmings produced as by-product when these boards are cut to size. The research aims to determine how this seldom used by-product might be reconstituted for use in a modified matrix. It was also determined the optimal particle size of these trimmings. The properties of the tested materials were analyzed after 90 days of curing. Given the intended purpose of the raw material as cement bonded particle boards, special conditions of higher temperature and humidity were set for the first stages of curing. The investigation involved the testing of physical-mechanical properties (DTA, XRD) including analyzing microstructure (SEM).

Keywords: Cuttings from cement-bonded particleboards formatting, cement, modification, physico-mechanical parameters, microstructure.

Influence of Dust Waste Containing a Silicate Matrix and Organic Filler on Properties of Cement Composites

Tomas MELICHAR, Jiri BYDZOVSKY
Brno University of Technology, Faculty of Civil Engineering, Veveri 331/95, 602 00 Brno, Czech Republic, e-mail: melichar.t@fce.vutbr.cz, bydzovsky.j@fce.vutbr.cz

The paper presents research into the evaluation of properties of cement composites modified by the dust waste from machining cement-bonded particleboards. The possibility of a partial replacement of cement by the mentioned dust (up to 8%) was considered. Dust parameters were modified. The properties of cement composites were analyzed after 28 and 90 days of ageing under laboratory conditions. Cement composites based on cement matrix and inorganic aggregates did not contain any other additives or admixtures. The research has brought about beneficial outcomes. Parameters well compared to the reference material can be reached by a very simple modification of dust properties in case of materials modified by such dust (as a cement substituent).

Keywords: Dust from processing cement-bonded particleboards, by-product, waste, modification of composition, alternative raw material, cement composite, parameters.

Building system with a high content of recycled materials based on micronized concrete

Zdeněk PROŠEK^a, Jan TREJBAL^a, Pavel TESÁREK^a, George KARRA´A^ba
Czech Technical University in Prague, Faculty of Civil Engineering, Thákurova 7, 166 29 Praha 6, Czech Republic, e-mail: zdenek.prosek@fsv.cvut.cz
^b Lavaris s.r.o., Areál Šroubáren 43, 252 66 Libčice nad Vltavou, Czech Republic

The presented paper describes a utilization of waste concrete of fraction equal to 0/4 mm. So far, effective application of such fines has not been solved in technical practice. Such a material can be homogenized and even mechanically activated using high-speed micro-milling. It can be consequently used for example during production of complex new wall masonry systems. The paper continues on results that have been published in WASTE FORUM 2/2018. The first part contains characterization of milled recyclate originated from supporting columns from demolished reinforced concrete structure. The second one focuses on a design of composition of mixtures to be used for construction system containing high amount of recycled materials. This system includes lightweight masonry blocks, construction adhesives, and plasters. The specific surface area was determined by using laser granulometry. The next part of the paper describes the production of test specimens and their consequent mechanical testing. Modulus of elasticity was determined by means of a nondestructive impulse resonance method, while tensile and flexure strengths were examined by macroscopic destructive tests. The microstructure of the material was observed using a scanning electron microscopy. The series of experiments was closed by measuring of thermal parameters using heat flow.

Keywords:  Circular economy, Construction and demolition waste, Waste concrete, Recycling, Micro-milled concrete, Masonry system, Silicate composite

Motivation of citizens of the Slovak Republic to separate municipal waste

Michal STRIČÍK, Monika BAČOVÁ, Monika ČONKOVÁ
Faculty of Business Econimics of the University of Econimics in Bratislava with seat in Košice, Tajovského 13,  041 30 Košice, Slovakia

The paper evaluates the attitudes and activities of citizens regarding the perception of environmental issues and the management of municipal waste, focusing on the factors of motivation and involvement in the field of sorting and management of municipal waste. It also analyzes the impact of citizens' belonging to different categories on the attitudes and activities of respondents in order to distinguish segments of citizens with characteristic thinking and behavior, for which an incentive campaign, management or legislative specifications can be individually tailored. Based on the results of a questionnaire survey conducted in 2018 within the Slovak Republic and a long-term study of the issue, we propose relevant measures that would contribute to a gradual reduction of municipal waste generation and intensify the level of its sorting. Among the most important factors, according to the survey, that motivate citizens to a higher level of municipal waste separation, are especially education and training in this area, legislative sanctions for those who do not sort municipal waste and financial motivation of those who separate municipal waste.

Keywords: waste recovery, municipal waste sorting, sustainable development, citizens' motivation