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Equipment for Thickening Waste Water from Biogas Plants
Vondra, Marek ; Bébar, Ladislav (referee) ; Hoffman,, Pavel (referee) ; Stehlík, Petr (advisor)
This dissertation thesis deals with the development of technology which could tackle two major issues related to biogas plants. These issues concern the insufficient use of waste heat from biogas combustion and its subsequent processing. It also concerns the use of the fermentation residues which are formed in large quantities and whose use is restricted by law. Based on a literary search of separation methods, a vacuum evaporator was selected as the most suitable technology. Its advantages include its simple construction, operational reliability and robustness, low costs of thickening medium pre-treatment, potential for a quick commercial application and, especially, the chance to use a low-potential waste heat. A primary purpose of this technological unit is the reduction in the volume of fermentation residues. Other benefits include the efficient use of waste heat from a biogas plant, which would otherwise be wasted. Evaporators with a low consumption of electrical energy (which is a main product of a biogas plant) seem to be the best option for applications in the biogas plants. Three of these technologies were subjected to a more thorough analysis, which included the development of computational models and their quantification for conditions in a sample biogas plant. A one-stage evaporator with a forced circulation (680 – 712 kWhth/m3, 25.9 – 30.5 kWhel/m3) was evaluated as the least suitable option in terms of energy demands. The energy intensity of a three-stage evaporator with a falling film (241 – 319 kWhth/m3, 12.0 – 23.6 kWhel/m3) and a nine-stage flash evaporator (236 – 268 kWhth/m3, 13.6 – 18.4 kWhel/m3) is significantly lower. A multi-stage flash evaporator (MSF) was then chosen for development and will form the central focus of this thesis. The reasons for the choice are as follows: the low requirements on the heat transfer surface, good operational experience in the field of desalination, its simple construction, modularity and evaporation outside the heat transfer surface. A thorough technical-economic evaluation was also performed on the integration of the evaporator into the biogas plant. The main part of the work included the experimental development of a MSF evaporator prototype. The main objective of this development was to achieve a stable flow rate of the thickening liquid digestate fraction and the continuous formation of the distillate. This was not an easy objective to achieve, especially due to the properties of the liquid digestate, which has a non-newtonian characteristic and increased density and viscosity compared to water. The tendency of the liquid digestate to form foam was also the subject of analysis. The development of the evaporator and first successful operational test are described in the thesis in detail. This required the use of an anti-foaming product. A fully-developed prototype of the MSF evaporator allowed us to achieve continuous operation with a distillate production, reaching from 5 to 10 kg/h at a liquid digestate flow rate of 0.4–0.5 m3/h. The main drawback of this technology is the pollution of the distillate with ammonia nitrogen, and it is for this reason that the basic procedures of its subsequent elimination was selected for further analysis.
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The biomass production for enegetic use from permanent grasslands and influence of ferment fertilisation on permanent grasslands
HAŠKOVCOVÁ, Michaela
Permanent grassland in agricultural landscapes represents an important position in terms of biodiversity. Becoming a habitat of endangered plant species, they are rich in flowering plants and also provide wintering territories to many animals. The aim of this study is to assess the biomass production of grassland for energy recovery, describe ways to use herbaceous biomass and impact of digestate on species composition and productivity of grassland. The experiment was conducted on the land in the village Dmýštice, located in the county of Písek. The site of fertilization by digestate is located near the village of Novosedly, county Strakonice. On these lands there were monitored ecological conditions of grasslands, dates and intensity of their use, botanical composition, species diversity and biomass production. Furthermore, this thesis uses methods of preservation of harvested biomass and comparing fertilized and unfertilized plots. The obtained data were used to calculate the Simpson index species diversity, nutrient and water mode positions. The values were statistically processed.
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Humic substances as transport medium for plant nutrition
Vlková, Markéta ; Solná, Irena (referee) ; Klučáková, Martina (advisor)
This bachelor thesis treats about humic matters and their application in agriculture by means of hydrogels transport medium. It studies progressive releasing of substances, which could be used as more common nutrition for plants, prepared from superabsorbent polymers. Research was implemented in collaboration with industrial partners. The substances are synthetically made of sodium Lignohumate and mixture of industrial fertilizer called NPK. Released substances were characterized by using some methods. First, there were measured qualities, which didn’t specify released compounds, like swelling, conductivity, pH and absorption of hydrogels with different wavelengths. More details came with methods ICP-OES and ion chromatography. Hydrogels which contained both mixtures of matters written up, were studied in water solution for 5 weeks and every week all characterization were measured. From the results we can see that both of the mixtures decrease ability of hydrogel’s swelling, mainly NPK. Measuring of absorption showed that the most of the substances released from sodium Lignohumate were from hydrogels without NPK. By other measuring, we noticed realizing of potassium and phosphorus elements. The most of them were from hydrogels containing NPK. By measuring ion chromatography, we found chloride, phosphoric, sulfuric and nitric ions in solution.
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The behavior of superabsorbent polymers in artificial soils
Männlová, Adriana ; Smilek, Jiří (referee) ; Kratochvílová, Romana (advisor)
This bachelor thesis deals with the study of superabsorbent polymers for environmental and agricultural applications. Generally thessis preparations are to perform the funciton of irrigation ,so that thanks to its unique properties , can absorb water in tha rainy season and keep it arend the root system as long as possible. Superabsorbent polymers can also perform the fiction of fertilizer carries and thus ensure its gradual release. These gel structures were subjected to testing of their swelling in environments with different ionic strenght. Subsequently, in the long term monitored thein ability to trap water in the soil environment model.
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The apply digestate at operate of biogas plant agricultural type
ČÁPOVÁ, Aneta
Comparing inputs needed to operate biogas stations, this Bachelor paper focuses on the composition of digestate and on its use in five examined stations. The paper is split into two sections: theoretical and practical. The theoretical section, i.e. a summary of relevant literature, explains the basic concepts and other issues related to the biogas proper, biogas generating stations, substrates and digestates. The practical section deals with experimental data obtained from the five stations. The data were acquired through a questionnaire wherein the stations' operators described their facilities while specifying the parameters; substrates applied; methane yield figures; results of digestate analyses; and their methods of application.
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Denitrification in soils with different nutrient inputs
ŘÍHOVÁ, Gabriela
The aim of this thesis was to estimate denitrification activity in four agricultural soils which are managed differently regarding type and amount of fertilizers. Potential denitrification, soil respiration and denitrifying enzyme activity were determined in laboratory experiments. In additional experiment, the impact of changes in soil pH on denitrification characteristics was studied.
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Using of digestate of agricultural biogas stations
VERNER, Dušan
This work deals with problems of agricultural biogas stations with the focus on using of final product of anaerobic fermentation, digestate, on agricultural soil. It evaluates its fertilizing effect in comparison to industrial fertilizers. The results showed that the fertilizing effect can improve economy of growing plants, however it depends on quality of digestate, constitution of base input material and technology of processing. It is not possible to use digestate anytime, it depends on growing crops and its technology. Nevertheless digestate as a final product of anaerobic fermentation is an interesting fertilizer.
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