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Abstract

In the constant pursue of the sustainability of socio-industrial systems, the definition of useful, reliable and informative, and at the same time simple and transparent, indicators is an important step for the evaluation of the circularity of the assessed systems. In the circular economy (CE) context, scientific literature has already identified the lack of overarching indicators (social, urban, prevention-oriented, etc.), pointing out that mono-dimensional indicators are not able to grasp the complexity of the systemic, closed-loop, feedback features of CE. In this respect, Emergy accounting is one of the approaches that have been identified as holding the potential to capture both resource generation and product delivery dimensions and therefore to provide an enhanced systems’ evaluation in a CE perspective.

Because of Emergy’s intrinsic definition and its calculation structure, Emergy-based indicators conceptually lend themselves very well to the evaluation and monitoring of circular processes. Additionally, Emergy has the unique feature of enabling the evaluation of systems that are not necessarily only technosphere systems, but also of technological systems which embed nature (techno-ecological systems).

The present paper gives a perspective on a set of Emergy-based indicators that we have identified as suitable to evaluate circular systems, and outlines the different perspective compared to the circularity indicators defined in the “Circularity Indicators Project” launched by the Ellen MacArthur Foundation.

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Authors and Affiliations

Antonino Marvuglia
Remo Santagata
Benedetto Rugani
Enrico Benetto
Sergio Ulgiati
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Abstract

Bioeconomy is an important element of the Polish economy and the basis of bioeconomy is innovative biotechnology. The development of bio-economy (especially in closed circuit) requires modern “bio” technology. The resignation of such elements in the economy as achievements of modern biotechnology – albeit possible – is associated with a significant increase in development costs and the loss of access to innovative technologies that are essential for the today and future economy of the country. It is necessary to gain public acceptance for the emerging market of bioproducts, bioservice and bioprocesses. Legislation ammendment supporting innovation in general, and bio domains in particular, is a necessity. The current state of Polish biotechnology is presented on the basis of detailed studies and published on the website of the Biotechnology Committee of the Polish Academy of Sciences: “Biotechnological centers in Poland – MAP OF POLISH BIOTECHNOLOGY”; on this page you will find as well this report (www.kbiotech.pan.pl).

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Authors and Affiliations

Ekspertyza Komitetu Biotechnologii PAN
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Abstract

Analytical relations, describing the electrical fields of cylindrical piezoceramic radiators with circular polarization as a member of the cylindrical systems with the baffle in the inner cavity, using the related fields method in multiply connected regions were obtained. Comparative analysis of the results of numerical experiments performed on the frequency characteristics of the electric field of the radiating systems for different modes of radiation allow to establish a number of subtle effects of the formation of the electric field of radiators.

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Authors and Affiliations

Aleksandr Leiko
Anatolii Derepa
Aleksandr Rasstrygin
Andrii Kosiakovskyi
Oksana Kocharian
Yaroslav Starovoit
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Abstract

Steel yielding arch support constructed of V profiles is commonly used to protect galleries and, in some cases, to reinforce or secure a shaft support. For this purpose, a closed, circular-shaped arch support is used, with arches overlapped by clamps that are typical for this type of construction. The support has high resistance to the impact of even (distributed over the entire surface of the support) load, however, as a result of significant deformation associated with a change in the radius of the curvatures, the support shows limited yielding capacity. This is due to the increase in resistance to slide on the locks, resulting from changes in the geometry of the ring caused by the rock mass. This article presents the results of research and analysis concerning the elements of the arch support with notches in arches. The research team tested the effect of the depth and location of the notches of the section’s flanges on the load impacting on the clamp’s bolts and the strength of the roof support. Moreover, the tests covered the influence of the number and location of clamps in a frictional joint on the change in the nature of work and yielding capacity. Finally, the research included both strength tests of the support’s elements, as well as strength analyses based on the finite element method.

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Authors and Affiliations

Marek Rotkegel
ORCID: ORCID
Łukasz Szot
Sławomir Fabich
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Abstract

The presented work focuses on the experimental investigation of a vibroacoustic metamaterial integrated into a spinning circular saw blade. Vibroacoustic metamaterials are a novel technology for broadband vibration reduction. Built from an array of local resonators, a broadband vibration reduction characteristic in the frequency domain (a so-called stop band) can be achieved. A design of a vibroacoustic metamaterial suitable for integration into a circular saw blade is developed and a numerical stop band prediction is performed. The resonators of the vibroacoustic metamaterial are integrated into the saw blade with a water jet cutting machine to create slots, forming flaps that are free to oscillate. The structural dynamic behavior of the saw blade with integrated vibroacoustic metamaterial is experimentally investigated on a rotor dynamic test bench and compared to that of a standard saw blade. The saw blades are excited by an automatic impulse hammer and the resulting out-of-plane vibrations are measured with a laser vibrometer at two different radii. Measurements are conducted at different rotational speeds up to 1800 rpm. Up to rotational speeds of 1000 rpm a stop band characteristic in the frequency range of 1900–2500 Hz is observed.
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Authors and Affiliations

Sebastian Rieß
1
ORCID: ORCID
William Kaal
1
ORCID: ORCID
Sven Herold
1
ORCID: ORCID

  1. Fraunhofer Institute for Structural Durability and System Reliability LBF, 64298, Darmstadt, Germany
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Abstract

Environmental protection is one of the objectives of the implemented concept of sustainable development and circular economy. The construction industry and its products (building objects) have a large contribution in negative influences, therefore all actions limiting them are necessary. One way of doing this is to apply substitution to existing unfavourable solutions, both in terms of construction and materials as well as technology and organization. The aim of the article was to determine the key factors conditioning the use of substitution at each stage of the investment and construction cycle, leading to environmental protection. The research paid attention to the use of substitute recycled products. The defined factors were subjected to a SWOT analysis and then, using the DEMATEL method, cause-andeffect relationships were identified that determine development in the application of substitution in the environmental context of sustainable and closed-cycle construction. The analysis was carried out by using a summative, linear aggregation of the values of the position and relationship indicators.
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Authors and Affiliations

Anna Sobotka
1
ORCID: ORCID
Kazimierz Linczowski
1
ORCID: ORCID
Aleksandra Radziejowska
1
ORCID: ORCID

  1. AGH University of Science and Technology in Cracow, Faculty of Civil Engineering and Resource Management, Department of Geomechanics, Civil Engineering and Geotechnics, Av. Mickiewicza 30, 30-059 Cracow, Poland
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Abstract

Municipal waste management has been an area of special interest of the European Commission (EC) for many years. In 2018, the EC pointed out issues related to municipal waste management as an important element of the monitoring framework for the transition towards a circular economy (CE), which is currently a priority in the economic policy of the European Union (EU). In the presented monitoring framework, 10 CE indicators were identified, among which issues related to municipal waste appear directly in two areas of the CE – in the field of production and in the field of waste management, and indirectly – un two other areas – secondary raw materials, and competitiveness and innovation. The paper presents changes in the management of municipal waste in Poland in the context of the implementation of the CE assumptions, a discussion of the results of CE indicators in two areas of the CE monitoring framework in Poland (production and waste management), and a comparison of the results against other European countries.

In Poland, tasks related to the implementation of municipal waste management from July 1, 2013 are the responsibility of the municipality, which is obliged to ensure the conditions for the system of selective collection and collection of municipal waste from residents, as well as the construction, maintenance and operation of regional municipal waste treatment installations (RIPOK). The municipality is also committed to the proper management of municipal waste, in accordance with the European waste management hierarchy, whose overriding objective is to prevent waste formation and limiting its amount, then recycling and other forms of disposal, incineration and safe storage. The study analyzed changes in the value of two selected CE indicators, i.e. (1) the municipal waste generation indicator, in the area of production and (2) the municipal waste recycling indicator, in the area of waste management. For this purpose, statistical data of the Central Statistical Office (GUS) and Eurostat were used. Data has been presented since 2014, i.e. from the moment of initiating the need to move to the CE in the EU. In recent years, there has been an increase in the amount of municipal waste generated in Poland as well as in the EU. According to Eurostat, the amount of municipal waste generated per one inhabitant of Poland increased from 272 kg in 2014 to 315 kg in 2017. It should be noted that the average amount of municipal waste generated in Poland in 2017 was one of the lowest in EU, with a European average of 486 kg/person. Poland has achieved lower levels of municipal waste recycling (33.9%) than the European average (46%). The reason for Poland’s worse results in the recycling of municipal waste may be, among others, the lack of sufficiently developed waste processing infrastructure, operating in other countries such as Germany and Denmark, and definitely higher public awareness of the issue of municipal waste in developed countries. Municipal waste management in Poland faces a number of challenges in the implementation of GOZ, primarily in terms of achieving the recycling values imposed by the EC, up to a minimum of 55% by 2025.

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Authors and Affiliations

Marzena Smol
Joanna Kulczycka
Agnieszka Czaplicka-Kotas
Dariusz Włóka
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Abstract

The concept of a Circular Economy assumes that the value of products, materials and resources is to be maintained in the economy for as long as possible to ultimately reduce waste generation to a minimum. In this concept, raw materials are repeatedly put into circulation many times, often passing from one branch of industry to another. So energy, water, metal ores, oil, gas, coal and others, and wherever possible, their replacement with renewable resources (wind and solar energy, natural resources). It is important, and this is the essence of the Circular Economy, the maximum re-use of scarce materials and raw materials from already produced and used products. This concept has found the support of the European Commission and activities in this area will successively be implemented through appropriate legal acts of the European Union. The need to implement solutions in the field of minimizing the consumption of raw materials, materials and energy or reducing waste production is also felt by consumers and industry. The packaging industry is particularly interested in implementing the concept of a Circular Economy. Due to the dynamic growth of the packaging market, which in 2017 reached around EUR 9.6 billion in Poland (data from the Polish Chamber of Packaging) and the increasing amount of post-consumer waste, it is necessary to introduce solutions limiting the consumption of raw materials and energy throughout the product life cycle.

The aim of the article is to present current practices regarding the reduction of the negative impact of packaging on the environment and the indication of directions for the implementation of the Circular Economy concept in the packaging industry.

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Authors and Affiliations

Agnieszka Kawecka
Agnieszka Cholewa-Wójcik
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Abstract

The circular economy model is based on several priority areas, including biomass and bio-based products. Focusing on them and their use should certainly take their cascading into account use, including how energy from waste from the wood industry is managed. Biomass is one of the most frequently used renewable energy sources in Poland, and in the European Union it satisfies 6% of primary energy. The CE (Circular Economy) model assumes that the reuse, processing and regeneration of a product requires less resources and energy, and is more economical than conventional material recycling, as low quality raw materials. The current model of waste management must take energy recovery into account, without which it is impossible to close the balance sheet of management of many groups of waste. This is also important from the economic point of view. Chemical energy, which is contained in a large part of waste, can be used for energy purposes, including the production of electricity and heat. Reducing the use of raw materials is the most effective environmental approach to solving the waste problem. However, this requires reducing the extraction and consumption of materials, challenging existing production and consumption patterns. In the circular economy model there is a huge difference in approach to recycling leading to new products that create transport and production, new jobs and possible GDP (Gross Domestic Product) growth. The aim of the study is to analyze the use of waste from the wood industry and to present possible solutions for its cascade use, taking the currently implemented circular economy model (CE) into account.

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Authors and Affiliations

Natalia Generowicz
ORCID: ORCID
Zygmunt Kowalski
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Abstract

Prof. Anna-Katharina Hornidge of the German Development Institute (DIE) draws on a systems-theory perspective to show how politicians, voters, companies and countries can be addressed to take climate change and environmental challenges of the future seriously.
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Authors and Affiliations

Anna-Katharina Hornidge
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Abstract

The purpose of this study is to find the value of the discharge coefficient (Cd) on a sieve with a circular perforated plate so that it can be used for application in the field. The method used is to make a physical model test of the screen weir in the laboratory with a width of 40 cm and a length of 797 cm, then the screen is made variations in the diameter of the hole 6, 8, 10 and 12 mm, flowrate Q = 453–4 481 cm3∙s–1 and the slope of the screen θ = 20–45°. The result was quite ef-fective, the sediment did not enter above the screen and did not clog the screen even the catch was quite good about 80% of the screen rods. The discharge coefficient (Cd) is directly proportional to the square value of the number Froude (Fr), the slope of the screen (θ) and the ratio of distance, diameter of the screen (a:d) and inversely proportional to the value of the specific energy square (E). From modelling the average value of the discharge coefficient (Cd) between 0.1–2.75 with NSE = 0.71, MAE = 0 and RMSE = 0.12.

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Authors and Affiliations

Nanang S. RizalL
Mohammad Bisri
Pitojo T. Juwono
Very Dermawan
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Abstract

The aim of our research is to gain understanding about material flow related information sharing in the circular economy value network in the form of industrial symbiosis. We need this understanding for facilitating new industrial symbiosis relationships and to support the optimization of operations. Circular economy has been promoted by politics and regulation by EU. In Finland, new circular economy strategy raises the facilitation of industrial symbiosis and data utilization as the key actions to improve sustainability and green growth. Companies stated that the practical problem is to get information on material availability. Digitalization is expected to boost material flows in circular economy by data, but what are the real challenges with circular material flows and what is the willingness of companies to develop co-operation? This paper seeks understanding on how Industry 4.0 is expected to improve the efficiency of waste or by-product flows and what are the expectations of companies. The research question is: How Industry 4.0 technologies and solutions can fix the gaps and discontinuities in the Industrial Symbiosis information flow? This research is conducted as a qualitative case study research with three cases, three types of material and eight companies. Interview data were collected in Finland between January and March 2021. Companies we interviewed mentioned use-cases for sensors and analytics to optimize the material flow but stated the investment cost compared to the value of information. To achieve sustainable circular material flows, the development needs to be done in the bigger picture, for the chain or network of actors, and the motivation and the added value must be found for each of them.
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Authors and Affiliations

Anne-Mari Järvenpää
Vesa Salminen
Jussi Kantola
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Abstract

Mining wastes are by-products generated during search, excavation and processing, both physical and chemical, of ores and other minerals. In 2017, wastes from group 01 constituted 60% of total wastes produced in Poland. According to the statistical data, approximately 92% of the waste generated during the excavation and processing of hard coal is economically reused. 30% of this waste used in industry and nearly 70% is used for the reclamation of the degraded industrial areas. At present, there is a tendency in the E uropean Union to shift from a linear economy to the Circular E conomy. The goal is to maintain economical value of the resources, among others, by their reuse in a productive way, which at the same time eliminates waste. One of the industrial branch where the ideals of a Circular E conomy can be implemented is the mining industry. Mining wastes may form one of the sources of anthropogenic minerals, as they belong to alternative aggregates. Deposits of anthropogenic minerals are considered sources of valuable raw materials which guarantee that the products made on their basis will be of high quality. The article presents the results of physico-chemical tests, the leachability of contaminations and phytotoxicity tests carried out on the basis of the selected mining waste in light of a Circular E conomy.

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Authors and Affiliations

Monika Czop
Amanda Kościelna
Karolina Żydek
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Abstract

In these times of the climate crisis surrounding us, the improvement of technologies responsible for the emission of the largest amounts of greenhouse gases is necessary and increasingly required by top-down regulations. As the sector responsible to a large extent for global logistics and supply chains, the fuel sector is one of the most studied in terms of reducing its harmful impact. The development of the next generations of fuels and biofuels, produced by companies using increasingly modern, cleaner and sustainable technologies, is able to significantly reduce the amount of greenhouse gases released into the atmosphere. In this case, the most effective solution seems to be the use of closed loops. Due to their low, often zero emission balance and the possibility of using waste to produce materials that can be reused, a circular economy is used in many sectors of the economy, while ensuring the emission purity of technological processes. One of the innovative solutions proposed in recent years is the installation created as part of the BioRen project, implemented under the Horizon 2020 program. The cooperation of European institutes with companies from the SME sector has resulted in the creation of an experimental cycle of modern technologies for the production of second-generation biofuels. The project involves the processing of municipal solid waste into second-generation drop-in biofuels. The entire process scheme assumes, in addition to the production of biofuels, the processing of inorganic fractions, the production of carbon material for the production of thermal energy, and the simultaneous treatment of wastewater.
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Authors and Affiliations

Piotr Jan Plata
1
ORCID: ORCID
Agnieszka Nowaczek
2
ORCID: ORCID

  1. Chemistry Department, Warsaw University of Technology, Warsaw, Poland
  2. Mineral and Energy Economy Research Institute, Polish Academy of Sciences, Kraków, Poland
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Abstract

The growing increase in the use of cars and transportation in general is causing an increase the emission of pollutants into the atmosphere. The current European Union regulations impose the minimization of pollution through the use of automotive catalytic converters on all member countries, which stops toxic compounds from being emitted into the atmosphere thanks to their contents of platinum group metals (PGMs). However, the growing demand for cars and the simultaneous demand for catalytic converters is contributing to the depletion of the primary sources of PGMs. This is why there is now increasing interest in recycling PGMs from catalytic converters through constantly developing technologies. There are newer and more sustainable solutions for the recovery of PGMs from catalytic converters, making the process part of a circular economy (CE) model. The purpose of this article is to present two innovative methods of PGM recovery in the framework of ongoing research and development projects.
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Authors and Affiliations

Natalia Generowicz
1
ORCID: ORCID
Agnieszka Nowaczek
1
ORCID: ORCID
Leszek Jurkowski
2
Iakovos Yakoumis
3

  1. Mineral and Energy Economy Research Institute Polish Academy of Sciences, Kraków, Poland
  2. Unimetal Recycling sp. z o.o., Trzebinia, Poland
  3. MONOLITHOS Catalysts and Recycling Ltd, Athens, Greece
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Abstract

This article investigates the possibilities of the recovery of raw materials at the Kraków–Płaszów municipal wastewater treatment plant (WWTP). The materials include sand coming with raw sewage and delivered by septic tankers, after cleaning sewage systems. Following the Regulation of the Minister of Climate (January 2020), sand from grit chambers is classified in the waste catalog as waste, with the code of 19 08 02. (Journal of Laws of 2020, item 10). The purchase of very efficient units has optimized the grit chamber operation and minimized the amount of waste generated as well as being an odor nuisance. The paper presents a mass balance for sand collected at the WWTP. Due to the use of new sand separators, the amount of this waste has been reduced by 28%. The paper presents the sieve curves of sand collected at the wastewater treatment plant and during the cleaning of sewage wells, as well as for sand mixtures. The sand mixture was prepared to allow some variations in the grain size characteristics of the sand. The graining differentiation indexes and curvature indexes were calculated. In addition, in laboratory tests, the leachability of heavy metals and the content of dry matter (DM) and dry mineral matter (DMM) were determined. The laboratory tests confirmed the reduction of organic solids to a level below 3% of dry weight; the content of heavy metals remained below the level of detection. The experiments confirmed that sand from the WWTP can be used as fine-grained aggregate in the production of concrete.
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Authors and Affiliations

Justyna Górka
1
ORCID: ORCID
Dominika Poproch
2 3
ORCID: ORCID
Małgorzata Cimochowicz-Rybicka
1
ORCID: ORCID
Bartosz Łuszczek
4
ORCID: ORCID

  1. Faculty of Environmental Engineering and Energy, Cracow University of Technology, Kraków, Poland
  2. Doctoral School, Cracow University of Technology, Kraków, Poland
  3. Krakow Water, Kraków, Poland
  4. Kraków Water, Kraków, Poland
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Abstract

The circular economy (CE) has been a European Union (EU) priority since 2014, when first official document on the CE was published. Currently, the EU is on the road to the transformation from a linear economy model to the CE model. In 2019, a new strategy was announced – the European Green Deal, the main goal of which is to mobilize the industrial sector for the CE implementation. The CE assumes that the generated waste should be treated as a secondary raw material. The paper presents an analysis of the possibility of using selected groups of waste for the production of fertilizers. Moreover, an identification of strengths and weaknesses, as well as market opportunities and threats related to the use of selected groups of waste as a valuable raw material for the production of fertilizers was conducted. The scope of the work includes characteristics of municipal waste (household waste, food waste, green waste, municipal sewage sludge, digestate), industrial waste (sewage sludge, ashes from biomass combustion, digestate) and agricultural waste (animal waste, plant waste), and a SWO T (strengths and weaknesses, opportunities and threats) analysis. The fertilizer use from waste is determined by the content of nutrients (phosphorus – P, nitrogen, potassium, magnesium, calcium ) and the presence of heavy metals unfavorable for plants (zinc, lead, mercury). Due to the possibility of contamination, including heavy metals, before introducing waste into the soil, it should be subjected to a detailed chemical analysis and treatment. The use of waste for the production of fertilizers allows for the reduction of the EU’s dependence on the import of nutrients from outside Europe, and is in line with the CE.
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Authors and Affiliations

Marzena Smol
1
ORCID: ORCID
Dominika Szołdrowska
1
ORCID: ORCID

  1. Mineral and Energy Economy Research Institute, Polish Academy of Sciences, Kraków, Poland
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Abstract

In Poland, the mineral sector generates 110–130 million tons of wastes annually (in the last 20 years), and metal ore mining alone was responsible for 31.2 million tons of wastes in 2017. The slags deposited at the Polkowice were investigated. This waste may be a potential source of many valuable metals (Zn, Pb, Cu, Sb, Sn, Se). The tailings dump in Polkowice contains approximately 80,000 tons of slag. The material contains primary phases formed by pyrometallurgical processes and secondary phases, which are the result of transformation of primary components. The primary phases are represented by sulfides: sphalerite [ZnS]; wurtzite [(Zn,Fe)S]; pyrite [FeS2]; sulfates: beaverite-(Zn) [Pb(Fe3+ 2Zn)(SO4)2(OH)6]; palmierite [(K,Na)2Pb(SO4)2]; oxides and hydroxides: goethite [Fe3+O(OH)]; wüestite [FeO]; hematite [Fe2O3]; magnetite [Fe2+Fe3+ 2O4]; chromian spinel [Fe2+Cr3+ 2O4]; silicates: petedunnite [Ca(Zn,Mn2+,Mg,Fe2+)Si2O6]; quartz [SiO2]; and microcline [KAlSi3O8]. Additionally, SEM -BSE observations revealed that oxidized native metals (Cu, Pb, As) and metal alloys and semi-metals appear. The slag consists mainly of SiO2 (13.70–20.60 wt%), Fe2O3 (24.90–39.62 wt%) and subordinately of CaO (2.71–6.94 wt%) and MgO (1.34–4.68 wt%). High contents are formed by Zn (9.42–17.38 wt%), Pb (5.13–13.74 wt%) and Cu (1.29–2.88 wt%). The slag contains trace elements Mo (487.4–980.1 ppm), Ni (245.3–530.7 ppm), Sn (2380.0–4441.5 ppm), Sb (2462.8–4446.0 ppm), Se (168.0–293.0 ppm). High concentrations are formed by toxic elements, such as e.g. As (13 100–22 600 ppm) and Cd (190.5–893.1 ppm). It is estimated that the tailings dump has accumulated about 80,000 t of slag, which may contain about 10,000 t of Zn, about 6,700 t of Pb, and 1,500 t of Cu.
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Authors and Affiliations

Karol Zglinicki
1
ORCID: ORCID
Krzysztof Szamałek
2
ORCID: ORCID
Anna Czarnecka-Skwarek
2
ORCID: ORCID
Katarzyna Żyłka
2 1

  1. Polish Geological Institute – Polish Research Institute, Warszawa, Poland
  2. University of Warsaw, Warszawa, Poland
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Abstract

The alternative waste fuels have a significant share in the fuel mix of the cement industry in Poland. The conditions inside cement kilns are favorable enough for environmentally-friendly use of waste fuels. In the article, the authors discuss the current situation concerning the use of alternative fuels in Poland, from difficult beginning in the 1990s to the present time, different kinds of fuels, and the amounts of used fuels. The use of fuels in Poland is presented against the global and EU consumption (including Central European countries and companies). The increased use of waste-derived fuels, from the level of about 1% at the end of the 1990s to the present level of about 70%, allowed for the limitation of waste storage, including avoidance of greenhouse gas emissions and consumption of conventional energy sources; those effects also contributed to the implementation of the sustainable development and circular economy conceptions. The experiences of the cement plants worldwide prove that the use of waste fuels is ecological and economical. The examples showed in the article confirm that cement plants are greatly interested in using waste fuels from waste, as they invest in the infrastructure allowing to store bigger amounts of waste and dose them more efficiently. Thus, the cement industry has become an important element of the country’s energy economy and waste management system.
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Bibliography

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Authors and Affiliations

Alicja Uliasz-Bocheńczyk
1
ORCID: ORCID
Jan Deja
2
ORCID: ORCID
Eugeniusz Mokrzycki
3
ORCID: ORCID

  1. AGH University of Science and Technology, Faculty of Civil Engineering and Resource Management, Poland
  2. AGH University of Science and Technology, Faculty of Materials Science, and Ceramics, Poland
  3. Mineral and Energy Economy Research Institute of the Polish Academy of Sciences, Poland
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Abstract

In this work, steady flow-field and heat transfer through a copper-water nanofluid around a rotating circular cylinder, dissipating uniform heat flux, with a constant non-dimensional rotation rate varying from 0 to 5 was investigated numerically using a finite-volume method for Reynolds numbers from the range 10–40. Furthermore, the range of nanoparticle volume fractions considered is 0–5%. The variation of the local and the average Nusselt numbers with Reynolds number, volume fractions, and rotation rate are presented for the range of conditions. The average Nusselt number is found to increase with increasing the nanoparticle volume fractions and decrease with increasing value of the rotation rate.

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Authors and Affiliations

Rafik Bouakkaz
Abded El Ouahed Ouali
Yacine Khelili
Salhi Faouzi
Ilyes Tiauiria
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Abstract

The theoretical estimation of sound absorption coefficient of a surface may give very different results. This will depend on the type of sound field assumed in the theoretical model used for the estimation of its sound absorption coefficient. Absorption coefficients for normal and diffuse sound fields are widely known, although they may be far from the absorption values given by an absorbing material when it is finally installed inside a room or enclosed space, where a sound field closer to a spherical wavefront is more likely to be found. This work presents a theoretical study, which is addressed at obtaining a mathematical expression to calculate the sound absorption coefficient for a variable range of incidence angles, called αs. The presented method uses a circular sound field incidence as an approximation to a spherical incidence. The estimation of this coefficient αs is based on obtaining the incident and reflected sound fields for a surface located facing a lineal source. The advantage of this calculation method over others lies on its capability to give results for circular, normal and random wave incidence depending on the range of incidence angles considered in the calculation.

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Authors and Affiliations

Sergio Alfio Yori
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Abstract

The rapid, high increase in production costs and prices of mineral fertilizers leads to a reduction in their use by farmers, while fertilizer manufacturers consider the use of alternative raw materials and reducing the energy consumption of fertilizer production processes. Given these circumstances, special attention is warranted for suspension fertilizers. The manufacturing of suspension fertilizers is simplified and less energy intensive in comparison with solid fertilizers. This is achieved by omitting certain production stages such as granulation, drying, sifting, which usually contribute to more than half of the production costs. This paper presents the production procedure of suspension fertilizers tailored for cabbage cultivation, utilizing alternative raw materials such as sewage sludge ash and poultry litter ash. The final products are thoroughly characterized. The obtained fertilizers were rich in main nutrients (ranging from 23.38% to 30.60% NPK) as along with secondary nutrients and micronutrients. Moreover, they adhere to the stipulated standards concerning heavy metal content as outlined in the European Fertilizer Regulation. A distribution analysis has showed that suspension fertilizers contain nutrients in both liquid and solid phases. This arrangement facilitates their easy availability for plants and subsequent release upon dissolution in soil conditions. To assess process consistency, the production of the most promising fertilizer was upscaled. A preliminary technological and economic analysis was also conducted. The method of producing suspension fertilizers using alternative raw materials is a simple waste management solution offering nutrient recycling with the principles of circular economy. This approach not only encourages nutrient recycling but also curtails reliance on imported raw materials.
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Authors and Affiliations

Katarzyna Gorazda
1
Halyna Kominko
1
Anna K. Nowak
1
Adam Wiśniak
1

  1. Cracow University of Technology, Poland
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Abstract

Failures that occurred in the last few decades highlighted the need to raise awareness about the emergent risk related to the impact localised degradation phenomena have on embankments. Common interventions aimed to improve embankments, such as the reconstruction of the damaged area or the injection of low-pressure grouts to fill fractures and burrows, may cause the weakening of the structure due to discontinuities between natural and treated zones. Moreover, since such repair techniques require huge volumes of materials, more sustainable solutions are encouraged. At the same time, the textile and fashion industries are looking for sustainable waste management and disposal strategies to face environmental problems concerned with the voluminous textile waste dispatched to landfills or incinerators. The use of soil mixed with textile waste in embankment improvement has been investigated to identify an effective engineering practice and to provide a strategy for the circular economy of textiles. Preliminary laboratory tests have been conducted on soil specimens collected from the Secchia River embankment, Northern Italy, to define the appropriate mixture proportions and to compare physical properties and hydro-mechanical behaviour of natural and treated soils. The results show that an appropriate fibre content offers manageable and relatively homogeneous mixtures. The indluence on soil consistency is mainly due to the textile fibre hydrophilic nature. The addition of fibres reduces the maximum dry density and increases the optimum water content. At low stress levels, the compressibility and hydraulic conductivity appear higher, however macro voids produced during sample preparation may alter the findings.
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Authors and Affiliations

Chiara Rossignoli
1
ORCID: ORCID
Marco Caruso
2
ORCID: ORCID
Cristina Jommi
1 3
ORCID: ORCID
Donatella Sterpi
1
ORCID: ORCID

  1. Politecnico di Milano, Department of Civil and Environmental Engineering, Piazza Leonardo da Vinci, 32, Milan, Italy
  2. Politecnico di Milano, Testing Lab for Materials, Buildings and Civil Structures, Milan, Italy
  3. Delft University of Technology, Faculty of Civil Engineering and Geosciences, Delft, The Netherlands
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Abstract

In this article, a 3D printed rectangular dielectric resonator antenna which is capable of polarization reconfiguration has been designed. Dielectric resonator is composed of environment friendly and biodegradable material, which is Polylactic Acid. In the proposed model, the polarization can be switch from a linear to a circular by changing the state of a switch, electonically. The antenna switch between two different polarizations: Linear polarization during OFF STATE and Lefthand circular polarization during ON STATE. The proposed 3D printed dielectric resonator antenna is designed to operate in Cband of microwave spectrum, with a broad effective bandwidth (overlapped impedance bandwidths of both states) of 14.542% with centre frequency at 5.845GHz and peak gain 5.5dBi. Further, validated simulated results with experiment and both results are in good agreement.
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Authors and Affiliations

Maganti Apparao
1
Godi Karunakar
1

  1. Department of Electronics and Communication Engineering, Gitam Institute of Technology, GITAM Deemed to be University, Visakhapatnam, India

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