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Influence of electrolysis on the degradation of dye water solutions
Olexová, Barbora ; Možíšková, Petra (referee) ; Kozáková, Zdenka (advisor)
The basic subject of this thesis is to investigate the influence of electrolysis on degradation of organic dyes in aqueous solutions. Electrolysis is a physically-chemical process, during which - under the influence of direct current - chemical reactions proceed inside the system. By choosing efficient conditions it is possible to achieve fundamental changes in the structure of organic compound’s molecules and on the basis of that for example their gradual degradation. This effect can be used in the process of wastewater treatment. The main task of the thesis is to analyse the influence of variously chosen chemical and physical conditions on the rate of degradation of azo dyes, which is the largest group of organic dyes used in industry and from this reason in great amounts contained both in mill residues and sewage water. Azo dyes have been selected for this experiment for their good solubility in water. Other advantage is that their degradation is accompanied by visible decoloration of the solution and their concentration in solution can be easily determined by UV-VIS spectrometry. Concretely two direct azo dyes - C.I. Direct Blue 106 and C.I. Direct Red 79 - have been chosen. The experiment was carried out in a simple reactor consisted of a bath with a stirrer into which two electrodes were installed and attached to the source of direct voltage. Every series of measurement proceeded at constant current which values were varied in range from 100 mA to 1 000 mA. The electric voltage ranged from 7 V to 22 V. Several samples were taken away from the solution during the experiment and the decrease of dye concentration was evaluated in every series. This evaluation validated the hypothesis that the dyes contained in the solution really degraded. This process was also connected to the expected bleaching of the solution. Decoloration of aqueous solution of dye is caused by disruptions in the structure of the dye molecule which is loosing its characteristic sections that cause colourfulness (a conjugate system of double bonds and presence of appropriate substitutes). A total amount of measured series was 16 with various input conditions (Fe and Pt electrodes, electrolytes NaCl, Na2SO4, and NaNO3 and their different concentrations, different current values) which more or less influenced the rate of degradation of investigated substances. It was found out that the blue dye is more likely to be electrolytically degraded. Chemical structure of its molecules, which is smaller and less branched than molecules of the used red dye, could be the source of that. The greatest degradation of the blue one proceeded at two chosen maximum values of constant current 800 mA and 1 000 mA. It could be assumed that current enhancement through the system induces higher dye concentration decrease. Degradation of the blue dye proceeded faster by using electrodes made of stainless steel than the platinum electrodes. The most suitable electrolyte was shown to be sodium chloride. When higher concentration (or conductivity) of electrolyte was used higher efficiency of degradation process was observed.
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Determination of Economic Efficiency of the Public Contruction Project
Šafář, Vít ; Witala, Lukáš (referee) ; Korytárová, Jana (advisor)
Bachelor’s thesis is focused on evaluating the economic efficiency of the construction project of sewerage treatment plant. The first part contains a presentation of the basic concepts of financial statements describes the assessment methods and, more generally, the issue of wastewater treatment. The second part deals with the practical applications of evaluation of economic efficiency. The aim is to analyze the specific project in Kunštát na Moravě.
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Phosphorus recycling - need or urgency
Holba, Marek ; Došek, M. ; Škvoran, O. ; Matysíková, J. ; Plotěný, K. ; Maršálek, Blahoslav
Phosphate policy is tightly connected with effective solutions in agriculture, but also with its removal from water environment where excessive concentration of phosphorus is not welcomed since it causes water bloom and worsening og surface water quality. Phosphate ores will be depleted soon and therefore recacling technologies should be introduced into practice in near future. Struvite - slow-release fertilizer seems to be good commodity for farmers. Struvite is usually responsible for clogged pipes in the wastewater treatment area. Therefore, several technologies of its recycling is recently being developed, esp. from reject water stream. Struvite crystallization, its production control and scale-up of technology from lab-scale through pilot-sclae to full-scale is technological challenge in the near future.
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Wastewater Treatment Using House Sewage Treatment Plants {--} Hygienic Aspects and Usage in the Czech Republic
FIŠEROVÁ, Alena
Constructed wetlands (CWs) originate from natural wetlands and are used for waste water treatment as an alternative to conventional treatment. This thesis was aimed at providing a literary summary of the types of house sewage water treatment plants and constructed wetlands used in the CR and abroad, of their hygienic aspects, functionality, treatment efficiency, expensiveness and the possibilities of their use in the conditions of the CR and their advantages and disadvantages. It also deals with a proposal of a suitable type of house CW for the conditions of the CR and a list of the necessary steps in construction of a house CW. Quite similar systems are being used for house sewage treatment in the Czech Republic and abroad {--} mostly septic tanks, ground mounds, constructed wetlands, active treatment plants and biodiscs. Alternative water treatment methods are generally not suitable for buildings having (now or in the future) the possibility of connection to municipal sewerage systems. They are on the other hand suitable for buildings not connected to sewerage systems or for seasonal objects, remote places and holiday houses with seasonal waste water production. A system with horizontal subsurface flow is mostly used as a CW in the Czech Republic. This CW type ensures sufficient removal of organic contamination and insoluble substances, but the efficiency of nitrogen and phosphorus removal is relatively low. However it is fully sufficient in the instance of low PE numbers, as the loading rate is usually low and the concentration of contaminants in the output water meets the prescribed limits. Foreign researches show that hybrid systems combining horizontal flow with vertical flow and with recirculation are more suitable for improving efficiency of nitrogen removal. Systems with vertical flow and intermittent waste water dosage showing particularly good results in ammoniac removal are also suitable for nitrogen removal. Special materials with higher iron, aluminium or calcium content are most suitable as filling of a constructed wetland or as additional filters or for improvement of phosphorus removal from waste water as they are able to reach efficiency of up to 90 %. In my thesis I came to a conclusion that a CW with horizontal subsurface flow is the most suitable type of house constructed wetland treatment for the conditions in the CR, mainly because it is the most frequently used and thus best proven CW type with sufficient efficiency of treatment for the substances required by standards.
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