The effect of preparation of biogenic sorbent on zinc sorption

The aim of this study is to prepare biogenic sulphides by using bacteria for the removal of zinc cations from their solutions. Theproduction was realized in a bioreactor under anaerobic conditions at 30 °C. Sorbents were prepared by sulphate-reducing bacteria indifferent nutrient medium modifications, under two modes of bacteria cultivation. Created precipitates of iron sulphides were removedfrom the liquid phase of the cultivation medium by filtration, dried and used for the sorption experiments

The Reclamation of Industrial Wastes Inclusive Sulphates by Sulphate-Reducing Bacteria

The objective of our study was to verify experimentally the possibility of using coal mine drainage and gypsum from the stabilizate (the final product from the combustion desulphurisation) as the source of sulphate for the cultivation of SRB with the prospect of: purging of mine waste waters inclusive sulphates, recycling of desulphurisation agent (limestone) and production of elemental sulphur from hydrogen sulphide. The results confirmed the theoretical assumptions on the use of gypsum, which forms the substantial component of stabilizate, as the source of sulphate for sulphate-reducing bacteria, which produce hydrogen sulphide in the process of bacterial reduction of sulphates. They also showed the possibility of recycling the desulphurisation agent limestone, as well as the realistic alternative of using stabilizate in the production of elemental sulphur which still represents an important raw material needed in chemical, paper or other industries

The degradation of lining of rotary furnaces in the production of zinc oxide

This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.

Identification of export potential in foreign trade: case of Slovakia in Kazakhstan

For small open economies such as Slovakia, foreign demand is a significant factor in economic growth. Since Slovakia acceded to the European Union, its exports have focused primarily on the EU internal market. Therefore, one of its goals is to diversify the territorial structure of foreign trade. Kazakhstan is the economic engine of Central Asia, which has made significant efforts in recent years to transform its economy. The aim of the case study of the Slovak Republic is to examine its export opportunities to Kazakhstan using selected onefactor indicators of competitiveness based on their mutual foreign trade. The imbalance in Slovakia-Kazakhstan’s foreign trade suggests sizable reserves. The work evaluates their foreign trade relations through indices of trade intensity, complementarity, and intra-industry trade. It identifies the export potential of Slovakia based on the concept of revealed comparative advantages and import significance of Kazakhstan in the examined period. In 2020, The export potential was used only at 2%, the export gap was 95,928mil. EUR and concerned 56 commodities at the level of HS 4 aggregation. Considering the geographical distance and costs, Slovakia should focus on the export of goods with higher added value

Neka svojstva prašine smrekovine dobivene procesom brušenja

This paper presents the research of selected properties of spruce dust generated from experimental sanding by a hand belt sander with two sanding models - along the wood fibres and perpendicular to the wood fibres in the radial direction. The experiment was carried out for the purpose of obtaining the basic characteristics of wood sanding dust – granularity, size and shape of individually formed particles, and bulk properties (bulk density, bulk angle, and tilt angle) that are important for suction, which is connected with the quality of living and working environments. The particles smaller than 100 micrometers are unsuitable for both environments, since they do not sediment in space at all or only partly, and they are characterized as airborne dust. The most harmful particles for humans are those smaller than 2.5 μm as they reach the lung alveoli. When sanding wood the finest particles are formed and therefore it is important to know the basic characteristics of sanding dust in order to deal with these problems effectively. On the basis of the mesh sieve analysis, we can state that in sanding perpendicular to the wood fibres the share of particles smaller than 100 μm is 76.94 % on average and along the wood fibres it is only 56.01 %. The structure, shape and size of particles were investigated by microscope. When using the longitudinal model of sanding, the fibrous elements were formed for the most part. When using the perpendicular model, isometric particles were predominantly formed in smaller fractions and particles of fibrous shape in larger fractions. The smallest particles were found in the following samples. When the perpendicular model of sanding was used, we have found the smallest particle in the investigated samples with the diameter of 1.68 μm, and when the longitudinal model of sanding was used, the particle with the diameter of 1.75 μm. Bulk density of spruce dust from the longitudinal model of sanding is 77.77 kg · m-3, while dust from the perpendicular model of sanding is 116.68 kg · m-3. Tilt angle of spruce dust in a longitudinal direction of sanding is 33.4°, and in a perpendicular direction it is 37.4°. Bulk angle for the perpendicular model of sanding is 48.7°, and for longitudinal model of sanding it is 48.3°. The obtained results have confirmed that the model of sanding at which wood dust was formed is a significant factor affecting properties of wood bulk material.U radu su istraživana neka svojstva prašine smrekovine dobivene ručnim eksperimentalnim brušenjem u dva smjera – u smjeru vlakanaca i okomito na njih, i to u radijalnom smjeru. Cilj istraživanja bio je odrediti osnovna obilježja čestica bruševine – granulaciju, veličinu čestica i oblike individualnih čestica, nasipna svojstva (nasipnu gustoću, nasipni kut i kut klizanja s kosine), koje su važne pri njihovu odsisavanju i za njihov utjecaj na kvalitetu općega i radnog okoliša. Za obje vrste okoliša štetno je postojanje čestica manjih od 100 μm, a s obzirom na to da se one teško talože ili se uopće ne talože, smatraju se lebdećim česticama. Najštetnije čestice za ljudski organizam jesu one manje od 2,5 μm jer dospijevaju do plućnih alveola. Uspješno rješavanje problema nastajanja najfinijih čestica bruševine moguće je uz poznavanje njihovih osnovnih obilježja. Granulometrijskom analizom bruševine nastale brušenjem okomito na drvna vlakanca izmjeren je udio od 76,94 % čestica manjih od 100 μm, a brušenjem u smjeru vlakanaca samo 56,01 %. Struktura, oblik i veličina čestica istražena je uz pomoć mikroskopa. Pri brušenju duž vlakanaca formirani su pretežno vlaknasti elementi. Pri brušenju okomito na vlakanca uglavnom su nastajale izometrične čestice u sitnijim frakcijama te čestice vlaknastog oblika u krupnijim frakcijama. Među česticama nastalim pri brušenju okomito na vlakanca izmjeren je najmanji promjer čestice od 1,68 μm, a pri brušenju uzdužno s vlakancima promjer 1,75 μm. Nasipna gustoća smrekove bruševine pri uzdužnom brušenju iznosi 77,77 kg/m³, odnosno 116,68 kg/m³ pri brušenju okomito na vlakanca. Kut klizanja s kosine bruševine nastale brušenjem u smjeru vlakanaca iznosi 33,4°, a kut klizanja bruševine nastale brušenjem okomito na vlakanca 37,4°. Nasipni kut za bruševinu nastalu brušenjem okomito na vlakanca iznosi 48,7°, a za bruševinu nastalu brušenjem uzdužno na vlakanca 48,3°. Dobiveni rezultati potvrdili su da smjer brušenja s obzirom na smjer vlakanaca ima značajan utjecaj na veličinu i svojstva usitnjenoga drvnog materijala

The degradation of lining of rotary furnaces in the production of zinc oxide

This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.

Ikonoborecké spory VIII. - IX.století v historické a teologické perspektivě

Ikonoborecké spory VIII. století v historické a teologické perspektivě Иконоборческие споры VIII -IX столетий в философской и богословской перспективе PhD. Marina Luptáková Tento dizertáční projekt předkládá problématiku ikonoboreckých sporů VIII - IX století ve filosofické a teologické perspektivě, přičemž samotný spor je interpretován jako spor především dogmatický. Sledované jsou origenistské kořeny ikonoborectví, role smyslového vnímání v kontemplativním poznání a také metódy a prostředky ikonomalby jako vyjádření teologie ikony, která právě byla rozpracována v důsledků ikonoborecké polemiky.HTF - Katedra historické teologie a církevních dějinHussite Theological FacultyHusitská teologická fakult

Fytoextrakce umělých sladidel z vodných roztoků

Umělá sladidla jsou v současné době široce využívána jako potravinová aditiva. V lidském organismu jsou jen omezeně metabolizována a vylučována jsou cestou renální exkrece. Obrovská množství těchto nebiogenních látek potom kontaminují komunální odpadní vody. Účinnost současných čistíren odpadních vod se udává např. pro cyklamat 99 % a pro sacharin 90 % a uvedené sloučeniny se považují za dobře rozložitelné, byla nalezena rezidua těchto látek v povrchových vodách i podzemních vodách. V případě acesulfamu K nedochází v čistírnách odpadních vod k eliminaci prakticky vůbec. Při dlouhodobém působení je z hlediska biologických studií možnost vzniku rakoviny, ovlivnění gastrointestinálního traktu, či paradoxně zvyšování hmotnosti. V práci byla experimentálně studována možnost fytoextrakce sacharinu a acesulfamu K v "in vitro" podmínkách s použitím kultivarů slunečnice roční (Helianthus annuus), kukuřice seté (Zea mays) a řepky olejky (Brassica napus). Experimenty byly vyhodnocovány pomocí úbytku studované substance - sacharinu a acesulfamu K v kultivačním mediu dle Murashiga a Skooga. Bylo prokázáno, že použité rostliny jsou schopny extrahovat testovaná sladidla a během pěti až sedmidenní kultivační periody bylo extrahováno 30 - 60 % přidaného acesulfamu K a 50 - 60 % sacharinu, v závislosti na použitém...The artificial sweeteners are currently worldwide used as food additives. In human organism they are only partially metabolized and then renally excreted. The big amounts of these abiogenic compounds contaminate municipal wastewaters. The efficiency of cleaning process in the sewage treatment plants (STP) is usually for cyclamate about 99 % and saccharine cca. 90 %. Acesulfame K is in STP practically not eliminated. Although most of artificial sweeteners are considered as good degradable, the residues were found in both surface waters and groundwaters. At long-term treatment can these compounds exhibited biological effect such as cancer genesis, gastrointestinal effects and/or surprisingly body mass increasing. The phytoextraction of saccharine and acesulfame K was experimentally studied by using of "in vitro" cultivated plants Helianthus annuus, Zea mays, and Brassica napus. The phytoextraction was monitored as decrease in medium concentration of tested substance in Murashige-Skoog cultivation medium. It was shown, that used species are able to extract tested substances and during 5 to 7 days 30 - 60 % of acesulfam K and 50 - 60 % of saccharine amounts disappear from cultivation medium depending of used plant species. The best extraction ability was observed at Helianthus annuus cultivars - 0.1...Katedra organické chemieDepartment of Organic ChemistryPřírodovědecká fakultaFaculty of Scienc

Exploitation of bioremediation in the environment protection

Soils and waters contaminated with toxic metals pose a major environmental problem that needs an effective and affordable technological solution. Many areas remain contaminated with no remediation in sight because it is too expensive to clean them up with available technologies. Bioremediation may provide an economically viable solution for remediation of some of these sites. The bioremediation is an application of the biological treatment to the cleanup of hazardous chemicals and is an example of the environmental biotechnology. The aim of this paper is to give a theoretical and practical view concerning the possibility of the bioremediation exploitation in the environment protection. This paper includes some results of the bioremediation of the acid mine drainage by sulphate-reducing bacteria