hohPublica :: Browsing by Person "Jungbluth, Thomas"

Browsing by Person "Jungbluth, Thomas"

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A full-scale study on efficiency and emissions of an agricultural biogas plant
(2013) Nägele, Hans-Joachim; Jungbluth, Thomas
In this study we focused on process engineering for the conversion of biomass, and utilization of the gas obtained by fermentation. Several topics regarding efficiency and emissions have been addressed by conducting intensive and long-term measurements. In detail, our objectives were (1) to conduct long-term measurements of the electric energy consumption of the biogas plant and its individual components and examination of energy-saving potentials; (2) to develop a method to measure mixing quality in the digester and to examine the mixing quality by measuring nutrient distribution in the digester with different agitator setups; (3) measure the influence of maintenance strategies on efficiency and emissions at long-term operation in practical application; (4) examine the efficiency of an external biological desulfurization plant under practical conditions to enhance biogas fuel quality. The results of electric energy measurement over a period of two years showed that a percentage of 8.5% (in 2010) and 8.7% (in 2011) of the produced electric energy was required to operate the biogas plant. The consumer unit agitators with 4.3% (in 2010) and 4.0% (in 2011) and the CHP unit with 2.5% (in 2010 and 2011) accounted for the highest electrical power demand, in relation to the electric energy produced by the CHP unit. Calculations show that the agitators consumed 51% (in 2010) and 46% (in 2011) of the total electric energy demand. The results stress the need for further research in the fields of substrate homogenization in biogas plants in order to reduce the demand for electric energy. Based on the results of electric energy consumption, follow-up studies have been conducted on nutrient distribution, which depends on agitator type and agitator regime. The investigation showed that significant differences in local concentrations of organic acids, which are not correlated to DM content, are found in dependence on agitator type and agitation regime. Measurements on electric energy consumption of the different agitator types verified that, depending on the agitator type, the saving potential rises up to 70%. The results for emissions and efficiency of the CHP unit confirm the fact that after readjustment of the air-fuel ratio (Lambda value), the emission values for NOx decline while CO increases. However, the emission-optimized operation mode leads to lower engine efficiency. The permanent measurements proved their legitimacy showing various emission deviations from the limiting values prior and post maintenance. In addition, the results show that by monitoring the lubricating oil quality, the oil change intervals can be maximized, while ensuring that engine performance is not endangered. This allows the operator to reduce maintenance expenditures while minimizing wear. To increase engine efficiency, the reduction of the lambda value combined with exhaust gas scrubbing and exhaust gas power generation is a promising approach. However, that would presuppose a permanent and almost total removal of H2S from the biogas. The fourth part of the study examined the technical and economic feasibility of a Fixed Bed Trickling Bioreactor (FBTB) for external biological desulfurization of biogas. In contrast to well-established biological methods to oxidize H2S, the FBTB allows removal of these from the biogas process, thus ensuring a constant low H2S concentration in the biogas. The FBTB showed H2S removal efficiencies (RE) of 98% at temperatures between 30-40°C. A major decline in RE in a range of 21-45% was observed when temperature in the FBTB dropped to a range of 5-25°C. The results revealed that different pH values of the percolation fluid and air ratios have little effect on RE. The practical use of the investigated FBTB system is an interesting technological alternative as disadvantages of internal biological desulfurization methods are being avoided. Due to high expenditures for operation resources and maintenance for FBTB operation during the research, a technical optimization is necessary to ensure economical operation. The results presented in this thesis show that the scientific instrument ?research biogas plant? is the ideal supplement to methods such as laboratory scale research and measuring programs. Research at full scale offers an entirely new opportunity to determine the interaction of process technique and process biology and to conduct long-term studies of gas utilization. Compared to measuring programs at commercial biogas plants, the research biogas plant has the advantage of being significantly better equipped with measurement technologies and that economic success is not the overall goal.
An expert system for planning and designing dairy farms in hot climates
(2008) Samer Mohamed, Mohamed; Jungbluth, Thomas
Planning and designing dairy farm facilities is a sophisticated work where a multitude of procedures should be carried out which requires time and efforts; moreover, making mistakes is also possible. Therefore, it is necessary to develop computer tools that have the ability to pre-process the data so as to produce value-added information, in order to accelerate analyses and to improve decision-making. Eleven simulation models were developed to plan and design several dairy farm facilities. Subsequently, an electronic spark map (decision tree) was developed for each simulation model, and then the simulation models were integrated into the relevant spark maps. Afterwards, C# language (C Sharp), which is an object-oriented programming language, was used to develop an expert system via the simulation models and the electronic spark maps. The developed expert system is able to plan and design several dairy farm facilities, e.g. housing system (corrals system), shade structure and roof material, concrete base, cooling system, milking parlor, forage storage, and manure handling system. Subsequently, it plans the farmstead layout, and it leads to implement the technologies, equipments, and machines required for performing several farm operations. Furthermore, it studies water and electricity requirements of the planned dairy farm and the available sources on site. Moreover, it calculates the capital investment and the fixed, variable, and total costs. Data of 6 dairy farms were used to carry out the expert system validation and evaluation. The differences between the actual and calculated values were determined and the standard deviations were calculated. The coefficients of variation range between 3% and 7%. The required input data are 358 thereof a multitude will be recommended by the expert system itself; consequently, it computes and displays 372 output data with the ability of saving and retrieving data. Besides, the system?s accuracy had been calculated using the actual and calculated values of the different outputs and it was found 98.6%. However, the system?s syntax includes 22106 lines. It can be concluded that the developed expert system can be used successfully for planning and designing dairy cow farms in hot climates.
Auswirkungen der flexiblen Biogasproduktion auf die Effizienz von landwirtschaftlichen Biogasanlagen
(2020) Kress, Philipp; Jungbluth, Thomas
In future energy systems based on renewable energies, biogas plants can make a significant contribution to stabilizing the electricity grids. However, this requires demand-flexible and load-driven electricity production, which is only made possible by flexible biogas production with extremely versatile feed management. From the process engineering and process biology point of view, this demand-flexible operation represents a major challenge for the operation of biogas plants. Technically, this demand-flexible biogas production requires a complete utilization of the existing fermenter volume, which in turn requires an optimal mixing of the substrates in the fermenter. Similarly, a continuous high-resolution monitoring of the produced biogas composition is also necessary to detect process disturbances or overloads that begin at an early stage. The objective of this work was to test and optimize new measuring methods for the flow velocity measurement and the mixing quality in the biogas reactor. Furthermore, to achieve a high-resolution gas quality measurement, practical scale tests were conducted. From these results, conclusions about possibilities and limitations of a flexibilisation of the biogas production shall be derived. Stirring is one of the most important processes in biogas production. The power input was intended to generate turbulent flows and thus ensure uniform distribution of nutrients and homogeneous temperatures throughout the reactor and avoid sinking and floating layers. In order to be able to assess and optimize these mixing processes, investigations of flow velocities in the fermenter were carried out using a magnetic-inductive measuring system. Additionally, flow profiles were created as a function of the DM content and the viscosity of the fermentation substrate. At a DM content of 9.45% in the fermenter, the average flow velocity measured was 87.5 cm/s. The DM content and the viscosity of the fermenting substrate were also taken into account. This dropped to 0.96 cm/s with a DM content of 9.95%. For the further description of the mixing quality, spatially dissolved nutrient samples were taken from the entire fermenter to determine the biological parameters. It was proven that the punctual input of the solid biomass via the solid input leads to a locally increased DM content and increased concentrations of organic acids in the vicinity of the input. In contrast to the laboratory tests using the process tomography method, no zone was found in the fermenter at which process disturbances were present. Furthermore, in contrast to laboratory tests, no biologically inactive zones could be detected in the fermenter of the research biogas plant. In further investigations, a photoacoustic sensor with a newly developed measuring system for determining the methane and carbon dioxide concentrations of the biogas was installed, tested and optimized for the first time in a biogas plant in the field. The basic applicability of such a system in biogas plants could be demonstrated. The achieved data density was significantly higher than that of conventional devices with a very high precision of the measured values. Using this innovative measuring technique, a flexible substrate supply and its influence on the product gas quality was subsequently evaluated. Substrates with different degradation behavior and different specific methane yields were fed to the fermenter. The influence of the specific substrate used in biogas production was reflected in the biogas quality. In particular, the relation between the relative change in gas quantity and quality makes it possible to detect process changes at an early stage. The presented studies have created a basis that enables a demand-oriented biogas production: Even with high substrate quantities that are fed to the fermenter, a high mixing quality can be achieved in the fermenter with an appropriate design of the agitators, which also prevents local process overloads. The investigations prove that, despite very low flow rates, there is sufficient nutrient supply for the microorganisms. The newly developed sensors for determining the biogas composition provide measured values with high precision and high temporal resolution, so that possible process disturbances can be detected very early. The investigations contribute to optimizing future demand-oriented electricity production on the basis of demand-flexible feeding in biogas plants. As a result, biogas plants can fulfil an important system service in a renewable energy based grid by decentrally stabilizing the electricity supply.
Beurteilung nicht quantifizierbarer Verfahrensparameter von Feuchtgetreidekonservierungsverfahren mit der Nutzwertanalyse
(1989) Jungbluth, Thomas
In der Bundesrepublik Deutschland werden je nach Klimaregion zwischen 50 und 85 % der gesamten Getreidemenge in einem Zustand geerntet, der vor der Lagerung eine Konservierung notwendig macht. Berücksichtigt man zusätzlich, daß mehr als 50 % des geernteten Getreides in der tierischen Produktion veredelt werden, so ist zu erwarten, daß die sogenannten Feuchtkonservierungsverfahren zunehmend Bedeutung erlangen werden. Es war daher notwendig, die bekannten Verfahren zu beurteilen. An diesem Beispiel wird das Einbeziehen nicht direkt quantifizierbarer Parameter mittels einer Nutzwertanalyse vorgestellt.
Beurteilung von Geruchsimmissionen aus der Tierhaltung
(2011) Gallmann, Eva; Jungbluth, Thomas
Odours from farm animal production can cause significant problems. It is therefore appropriate to develop suitable procedures for their assessment and limitation in the sense of immission control. The challenge comprises the objectification of the odours, bearing in mind that their effect is very individual, subjective and emotion-based. The resultant work offers a contribution towards the classification and further development of procedures for assessment of odours from farm animal production. The latest knowledge of the various aspects of measurement and evaluation of farm animal production odour immissions will be analysed in detail through ongoing literature assessment and from results of own investigations. The perceived nuisance effect relies on multiple stimulus-based variables associated with context and person. Measuring the associated effect can take place through psychometric surveys. Assessment of a significant nuisance effect within a group is conventionally based on the proportion of subjected persons that can be regarded as tolerable. Odours from farm animal production in particular are considered on the basis of investigations and data concerning odour components and their emission, transmission and immission. The extent of available data including results from own odour emission measurements give a high degree of scatter. This scatter is caused by the multiplicity of influences on emissions and also through the imprecision of measurements based on olfactometry. There are limitations on the extent to which reduction measures can be quantified. Dispersion modelling is an important tool for assessing odour immissions, but is also associated with limitations as shown by validation and sensitivity investigations. Particularly decisive are the appropriate illustration of the transmission and the choice and modification of the model structure and input parameters. The modelling of diffuse and varying sources near the ground surface remains a challenge. The consideration of cold air outflows is essential for immission assessment. The common odour threshold distances from pig and cattle production units determined via odour plume measurements are discussed using numerous trial results as examples. The results of own grid measurements at four locations are detailed, also with regard to the effect of a plausibility control, the variation of the odour hour criterion, and compared with dispersion calculations. Grid measurements help in the differentiated measurement of the immission situation. In the interpretation of absolute values, the imprecision area around the real value must be considered. The effect of immission reduction measures is hardly quantifiable nor able to be generalised. The knowledge is based, above all, on flow simulations and on experience. Main points of influence are the dilution of outflow air, the transmission conditions and the location circumstances. The immission hedonics from farm animal production odours were compared and recorded for own investigations and within the framework of a cooperative project “Odour assessment in agriculture“. The hedonic differences were not, however, nuisance-relevant as shown by evaluation of the exposition effect relationships within the same trial framework. The differences regarding type of farm animal are, however, relevant. The results from various epidemiological studies were thoroughly analysed because these were oriented on the assessment procedure for immissions and their effects. The starting point for assessing odour emissions from farm animal production can differ more through source-oriented distance rules or immission regulations for the limitation of odour hour frequency or odour concentration. Both points provide possibilities for recognition of animal type differences via factor weighting of animal mass, animal numbers or key immission figures. The assessment principle for distance standards that apply to all types of farm animals with factor weighting for source, transmission and immission parameters, or as empirical distance model, are explained and assessed based on examples from Switzerland, Austria and Germany. The methods and the establishment of factors are less well able to be appreciated as the degree of differentiation increases. The determinations within the odour immission guideline are compared with the regulations for odour exposition limits in the Netherlands, and in other countries. The suitability of the assessment bases and procedures for assessment are finally evaluated for assessment in practical conditions and recommendations for further developments suggested.
Beurteilung von neuen Futtergetreide-Feuchtkonservierungsverfahren mit biochemischem Wirkprinzip
(1988) Jungbluth, Thomas; Schneider, Gabriele; Fiedler, Ekkehard
Zur Feuchtgetreidekonservierung werden neben der Lagerung ganzer Körner im gasdichten Hochsilo zunehmend Verfahren wie Einlagerung von Getreideschrot unter Wasserzusatz im gasdichten Hochsilo und Einlagerung von Getreideschrot im Fahrsilo in der Praxis eingesetzt. Diese Verfahren sind noch weiter zu entwickeln.In praktischen Lagerungs- und Fütterungsversuchen zeigte sich, daß auch diese neueren Verfahren für die Konservierung grundsätzlich geeignet sind und ein hochwertiges Futter für Mastschweine erzeugt werden kann.
Biochemical composition of biomass and its impact on the prediction of the specific methane yield potential
(2017) Mukengele, Michael Mutombo; Jungbluth, Thomas
This thesis analyzes the biomass biochemical composition and its influence on the specific methane yield potential of energy crops. The influence of the ensiling technique and the specific methane yield potential gained using a batch-test scaled up to semi-continuous flow system were also assessed. The results show that through ensiling process the risk of over-estimating the specific methane yield potential was particularly high for silages of low DM content. Through ensiling up to 8.6% higher methane yield potential could be achieved. The impact was different depending on the maturity index of the crop material. The evaluation of the bioconversion efficiency in batch and semi-continuous flow digester showed that 80% to 87% of the theoretical methane yield potential could be recovered in a batch-test. By scaling up batch the bioconversion efficiency decreased of up to 19%. The investigation on maize showed that the absolute values of the biochemical crop traits and in-vitro estimates of digestibility for whole-crop were poor predictors for high specific methane yield potential (R² = 0.31 to 0.32). Other crops alternative to maize showed a wider variation range in specific methane yield potential. Reproductive crop fractions of lipid rich crops revealed higher specific methane yields reaching 0.455 mN³ CH4/ kg ODM in sunflower crown and 0.598 mN³ CH4/ kg ODM in rape seed. The stalk/stem fraction of these crops seemed to be the most limiting factor for degradability. Conversely, carbohydrates rich crops (rye and sorghum) showed methane yields slightly lower or equal to those of maize.
Biofilter - Einfluß unterschiedlicher Filtermaterialien auf die Effektivität
(2000) Martinec, Milos; Hartung, Eberhard; Jungbluth, Thomas
Um den Einfluß des Filtermaterials auf die Effektivität von Biofiltern zu prüfen, wurden fünf verschiedene Filtermaterialien parallel an einem Mastschweinestall getestet. Die höchste Geruchsreduktion von etwa 81 % wurde bei den Filtermaterialien Biochips und Kokosfaser- Fasertorf festgestellt. Alle Filtermaterialien reduzieren zusätzlich die Emissionen von Ammoniak im Durchschnitt um etwa 9 bis 30 %. Biofilter mit Biochips wiesen deutlich niedrigere Strömungswiderstände und Stromverbrauch auf als die mit anderen Filtermaterialien. Geruchsemissionen aus der landwirtschaftlichen Nutztierhaltung können durch Biofilter um etwa 25 % bis 95 % reduziert werden. Hierbei warden die Ammoniakemissionen gleichzeitig auch teilweise reduziert (ca. 0 bis 35 %). Der Einsatz von Biofiltern ist aber bei ordnungsgemäßem Betrieb mit sehr hohen Betriebskosten verbunden (HARTUNG et al., 1997; HOPP, 1998; MANNEBECK, 1994). Deswegen werden Biofilter nur dann eingesetzt, wenn der Mindestabstand nach Richtlinien VDI 3471 (1986) und VDI 3472 (1986) oder TA-Luft (1986) unterschritten wird. Eine wesentliche Möglichkeit, Biofilter weiter zu optimieren, besteht in der Auswahl des Filtermaterials. Das Ziel der vorliegenden Untersuchungen war es, die Geruchsreduktion ausgewählter Filtermaterialien zu ermitteln. Des weiteren sollte der Einfluß des Filtermaterials auf die Höhe der Emissionsminderung von NH3, CO2, CH4, N2O, der Strömungswiderstand und der Stromverbrauch überprüft werden.
Biofilters - The Influence of Different Filter Materials on the Reduction Efficiency
(2000) Martinec, Milos; Hartung, Eberhard; Jungbluth, Thomas
The influence of five different filter materials on the reduction efficiency of biofilters has been investigated in parallel long-term measurements in a stall for fattening pigs. The greatest odour reduction (approximately 81%) was achieved with biochips and a mixture of coconut fibre and fi- bre peat as filter materials. All filter materials additionally reduce am- monia emissions by an average of about 9 - 30%. Biofilters with bio- chips caused considerably lower flow resistance and electricity con- sumption than filters with other materials. Biofilters allow odour emissions from farm animal husbandry to be re- duced by approximately 25 - 95%. Ammonia emissions also diminish to a certain extent (about 0 - 35%). However, very high operating expenses are attached to the use of biofilters if they are used properly (HARTUNG et al., 1997; HOPP, 1998; MANNEBECK, 1994). For this reason, they are used only when the minimum distance required by the VDI 3471 (1986) and VDI 3472 (1986) guidelines as well as the TA Luft (1986) (German Air Pollution Regulations) cannot be kept. The selection of the filter material provides a significant possibility to further optimize bio- filters.The present study was conducted to establish the odour reduction achieved by selected filter materials. Additionally, it was the goal of this research to examine the influence of the filter material on the reduction of the emission of NH3 , CO2 , CH4 , and N 2 O, as well as flow resistance and electricity consumption.
Biologische Wasserstoffmethanisierung in Hochdruck-Rieselbettreaktoren für Power-to-Gas-Konzepte
(2018) Ullrich, Timo; Jungbluth, Thomas
In order to achieve climate protection targets, intermittent and decentralised energy sources such as wind power and photovoltaics will be expanded in the future. However, the power grids are not designed for the large-scale expansion and connection of different decentralised and fluctuating generation plants. This represents a major challenge for grid stability and requires an increasing expansion of energy storage. Power-to-Gas technology, a process for converting electrical energy into chemical energy, will play a central role in this process. In this two-stage process, hydrogen is first produced by electrolysis, which then reacts with carbon dioxide to form methane. It can be stored and transported in the natural gas grid almost indefinitely and can be used flexibly in a wide variety of applications. In addition to the chemical-catalytic methanation of hydrogen, there is also the biological methanation process. Characteristic features are a flexible load change behaviour and a marked robustness regarding the educt gas composition. Compared to chemical-catalytic methanation, however, the gas flow rates are significantly lower, which is the greatest challenge of this process. For this reason, the aim of this work was to optimize the performance of trickle-bed reactors for biological hydrogen methanation. The focus was on improving the gas-liquid-mass-transfer as described in the literature, but not yet which has not yet been investigated in the context of this promising concept. In an automated and continuous test plant, the operating pressure was initially varied in stages of 1.5, 5 and 9 bar in the first publication. With increasing pressure, conversion rates were improved and gas quality increased by 34%. Furthermore, the circulation of the process liquid to the trickling bed of the reactors was paused for periods up to 1440 min in the second publication. As the circulation pause rose, there was a noticeable increase in all performance parameters with maximum methane contents > 97 Vol.-%. Finally, different temperature levels of 40 - 55 °C were also examined. In spite of the continuous increase in gas volumes in the three publications, the performance parameters increased again. Overall, the combined optimization measures more than doubled the output with an MFR of 4.28 ± 0.26 m3 m-3 d-1 to 8.85 ± 0.43 m3 m-3 d-1, while simultaneously increasing the methane content in the product gas. Periodical analyses of the process liquid, especially the acid concentrations, as well as the stable conversion rates indicated a stable biological process in all experiments. The tests were done with three identical reactors, underlining the high degree of reproducibility. It was noticeable that the microorganisms quickly adapted to the changing operating parameters within a maximum of 24 hours. The performance increases could thus be related to the successful increase in the gas-liquid-substance exchange rate and not to a changed microorganism concentration or selection. The studies have also revealed further optimisation potential. In particular, the properties of the process liquid with regard to pH and nutrient composition should be the subject of further investigations. Thus, the present study not only successfully demonstrated the goal of increasing performance; with stable and uncomplicated operation over several months and a wide range of operating parameters, it also demonstrated that trickle bed reactors for the biological methanation of hydrogen are a reliable, flexible and thus promising concept in the context of power-to-gas applications.
Biomethane production in an innovative two-phase pressurized anaerobic digestion system
(2015) Chen, Yuling; Jungbluth, Thomas
Generation of biogas from biomass through anaerobic digestion is receiving increasing attention. Over the past decade, the biogas industry has been developing rapidly in Germany, as well as the rest of the world. In Germany, biogas is generally used in a heat and power plant (CHP) for electricity and heat production. However, most biogas plants are located in a rural area, where heating demands are quite low. Except for biogas plant thermal control, a huge amount of cogenerated heat is often wasted. In order to increase the overall energy utilization efficiency, biogas can be alternatively converted to biomethane of natural gas quality and injected into existing gas grids. By making use of the mature gas transportation and storage systems, biogas production and end utilization can be temporally and spatially separated. Therefore, it is regarded as an efficient and flexible solution to energy issues. Nevertheless, in terms of this application, raw biogas requires, above all, gas purification and upgrading. Carbon dioxide content, in particular, must be reduced from 40–50% in the raw biogas to approximately 4% in the purified gas. Conventional technologies are generally expensive in investment and/or operation. Therefore, an economical option is desired. Within this research project, a two-phase pressurized anaerobic digestion system was developed. The innovative concept aimed to reduce the cost involved in biomethane conversion and injection into the natural gas grids by integration of biogas production, purification and compression in one system. It was expected that a great amount of carbon dioxide could be directly removed from the pressurized digester due to its high solubility. In addition, the methane-rich biogas could be produced at an elevated pressure which could meet the injection standard, and therefore could reduce or even avoid the expenses for further compression. In order to gain better understanding of two-phase pressurized anaerobic digestion, three major studies were conducted: - The pressure effects on two-phase anaerobic digestion - Effects of organic loading rate (OLR) on the performance of a pressurized anaerobic filter in two-phase anaerobic digestion - Effects of liquid circulation on two-phase pressurized anaerobic digestion By this means, the system performance could be examined and the technical feasibility and potential of the new concept could be explored. Moreover, an optimization of the process in a two-phase pressurized anaerobic digestion system could be realized. From both economic and ecological perspective, two-phase pressurized anaerobic digestion offers an interesting process option for biomethane production, making a great contribution to sustainable energy supply.
Demand-driven biogas production in anaerobic filters
(2017) Krümpel, Johannes; Jungbluth, Thomas
Fluctuating energy sources, namely wind turbines and photovoltaic, will be the mayor contributors to the increase in share of renewable energies. The intermittent energy supply by these sources poses challenges for the power grid and need to be counter balanced. A demand-driven energy supply by weather independent biomass conversion can offer these grid services. Flexible energy production from biogas has been identified as a vital approach to provide the grid with positive and negative balancing power. The two-staged anaerobic digestion may be especially suitable for demand orientated gas production due to the advantages of the anaerobic FIlters to withstand high organic loading rates and shock loading. Two staged anaerobic digestion is characterized by a spatio-temporal separation of acidification and methane production. A liquid rich in soluble products, such as volatile fatty acids, alcohols and sugars is produced in the first stage and and is subsequently converted to biogas in the second stage. The methanation stage as the main gas producing unit in such a system is in the focus of this research.The ability to react to sudden changes in demand might be influenced by substrate composition and controlled hydrolysis towards certain intermediates could improve the reaction times towards increased demand. It is therefore one focus of this research work to examine intrinsic methane production kinetics of common intermediates of anaerobic digestion. Other major questions are how fast the methane production can be adapted to sudden changes in demand and to what extent these adaptions are reproducible. It was therefore of interest to demonstrate the feasibility, reproducibility and the possible extent of demand-driven biogas production in anaerobic filters, with respect to changing substrate composition. Furthermore the evaluation of the process effciency based on carbon fluxes should be examined to unfold effects resulting from changing operational conditions. With a newly developed methodology, introduced in the publication "Kinetics of Biogas Production in Anaerobic Filters" kinetic parameters of methane production for individual volatile fatty acids (VFA) could be determined. The bandwidth of tested intermediates was broadened in the second research paper "Intrinsic Gas Production Kinetics of Selected Intermediates in Anaerobic Filters for Demand Orientated Energy Supply". It has been found that intermediates could be ordered according to their half-lives of methane production. The apparent order, beginning with the fastest was acetic acid >ethanol >butyric acid >iso-butyric acid> valeric acid> propionic acid> propanediol> lactic acid. However the mixture of these individual components administered as a naturally produced hydrolysate revealed the fastest methane production kinetics. Differences in the absolute values of determined kinetic parameters between the two experiments can be attributed to variations in organic loading rate (OLR), since degradation rates of a specific substrate are determined by substrate concentration. But also other parameters influence the absolute rate at which methane is produced, such as the concentration of products or unionized substrate itself, pH, nutrient availability, bioenergetics, temperature, inhibition, mass transfer and microbial population. In the third research paper "Demand-Driven Biogas Production in Anaerobic Filters "the previous findings have been put to the test by applying changes in OLR throughout the day and examining different substrate compositions with respect to the methane production rates. As demonstrated, the gas production followed the applied OLR with a distinctive expression of each change in the OLR. That marks the process as highly predictable and defined boundaries within safe operation of AD, in terms of VFA accumulation,can possibly be satisfied by process control. The inclusion of three reactors in the analysis emphasizes the repeatability and therefore the predictability of such an approach of operation. Feasibility and reproducibility of demand-driven biogas production by anaerobic filters could thus be demonstrated. It has been found that the hydrolysate composition has no significant influence on methane production kinetics for demand orientated gas production, since the maximum rate is limited by acetoclastic methanogenesis. The control of the hydrolysis should focus on high overall degradation, rather than towards the production of specific intermediates. A key factor in order to prevent large fluctuation in gas composition is alkalinity, specifically the provision of nitrogenous compounds is vital to maintain stable conditions. Anaerobic filters or attached biomass reactors in general seem to exhibit superior performance towards shock loading and are therefore especially suited for demand orientated gas production as they recover quickly from overloading.Formation of soluble microbial products (SMP) and extracellular polymeric substances (EPS) may be influenced or exaggerated by constantly changing HRT and OLR. Further research in order to evaluate the limits of safe operation is recommended as more extreme scenarios than the ones examined in this work are imaginable in practice.
Development of Innovative Ventilation Systems for Fattening Pigs : Part I - Method and First Results
(2004) Häußermann, Angelika; Hartung, Eberhard; Jungbluth, Thomas
The aim of the above named project at the Institute of Agricultural Engi- neering (University Hohenheim) is to develop and to test several innova- tive ventilation systems. The investigations focus on an improved indoor air quality, the reduction of environmentally toxic and greenhouse gases from animal husbandry and the technical use of additional housing and animal parameters to control the indoor air climate within the scope of Precision Livestock Farming. To reach this aim experimental work is done for more than one year in the Hohenheim research facility for fat- tening pigs. The experimental pig facility is subdivided in two compart- ments and features two different feeding systems. For the investigations the research facility was upgraded according to current animal welfare requirements. Furthermore the climate control was equipped with a high pressure water fogging system for humidifying and cooling the air. Addi- tional control parameters which influence the degree and the reaction of the ventilation rate in different ways and which starts e.g. the water fog- ging, are the animal activity and the CO 2 -indoor concentration in the compartment. Based on a continuous data collection with high temporal resolution over four fattening periods, data on the indoor air climate and the emission as well as further side effects are recorded within rotating ventilation strategies in the two compartments. In a following step the emissions of NH3 , CO2 and CH 4 are calculated including the background concentration and the exhaust air concentration of each gas, the water vapour cross sensitivity of the gas analysers and the ventilation rate measured simultaneously. Due to the developed innovative experimental design the evaluation of the control strategies encloses different influenc- ing factors like seasonal effects, measuring sections, the feeding systems, the compartments or the effect on the indoor air climate. Part I of the three-part proceedings explicates mainly the developed experimental lay- out, the operating mode of the control strategies, their technical realisa- tion and the approach of the investigation including the data logging sys- tem. Furthermore the practical functionality of the control strategies is described and pictured within the first selected results. The figures com- pare the indoor temperatures, the ventilation rates and the CO2 -indoor concentrations of both compartments, featuring different ventilation con- trol strategies at the same time. The first results indicate the effectiveness of the different ventilation control strategies. When finishing the practi- cal research work in early summer 2004, the final evaluation of the com- pleted data-set is scheduled subsequently.
Dynamics of Odour Release from a Pig Stall - Part 2 : Results of Parallel Measurements with Olfactometry and the ?EURoeElectronic Nose?EUR?
(2002) Brose, Gregor; Hartung, Eberhard; Jungbluth, Thomas
The heavily fluctuating operating conditions in pig husbandry due to cli- matic and biological changes (alterations of temperature and air flow ra- te between day and night as well as between summer and winter, increa- sing animal mass during the fattening process, etc.) exert a significant in- fluence on the amount of actual odour emission. The examination pro- gramme of the presented project comprised the measurement of seasonal (fattening course), daytime-related, and short-term (feeding) dynamic ef- fects of odour release, as well as the identification of potential factors which influence the amount of odour emitted. Parallel to “classic” olfac- tometry, an “electronic nose” with a chemosensor array of ten metal oxide sensors was employed. The largest odour emissions are measured on hot summer days, while the lowest emissions were determined on cold winter days. On the one hand, the sensor signals of the “electronic nose” exhibit considerable differences on days with large air flow rate alterati- ons. On the other hand, continuous measurement with the “electronic nose” allows changes in the gas- and odorant composition of the exhaust air during the feeding times to be shown. From the measurement results, recommendations for odour sampling, the consideration of seasonal odour emission fluctuations in odour spreading calculations, and the use of “electronic noses” for the evaluation of odour emissions have been derived.
Dynamik der Geruchsfreisetzung aus einem Schweinestall - Teil 2 : Ergebnisse der parallelen Messungen mit der Olfaktometrie und der 'elektronischen Nase'
(2002) Brose, Gregor; Hartung, Eberhard; Jungbluth, Thomas
Die stark wechselnden Betriebsbedingungen in der Schweinehaltung durch klimatische und biologische Veränderungen (Temperatur- und Volumenstromänderungen zwischen Tag und Nacht sowie Sommer und Winter, zunehmende Tiermasse während der Mast, etc.) haben einen erheblichen Einfluss auf die Höhe der tatsächlichen Geruchsemission. Das Untersuchungsprogramm des vorgestellten Projektes umfasste die Messung jahreszeitlicher (Mastverlauf), tageszeitlicher und kurzfristiger (Fütterung) dynamischer Effekte der Geruchsfreisetzung sowie die Identifikation potentieller Einflussfaktoren auf die Höhe der Geruchsemission. Parallel zur ?EURzklassischen?EURoe Olfaktometrie wird eine ?EURzelektronische Nase?EURoe mit einem Chemosensor-Array von zehn Metalloxid-Sensoren eingesetzt. Die höchsten Geruchsemissionen werden an heißen Sommertagen, die niedrigsten an kalten Wintertagen ermittelt. Die Sensorsignale der ?EURzelektronischen Nase?EURoe zeigen zum einen deutliche Unterschiede an Tagen mit großen Volumenstromveränderungen. Zum anderen ermöglicht die kontinuierliche Messung mit der ?EURzelektronischen Nase?EURoe Veränderungen in der Gas- und Geruchsstoffzusammensetzung in der Abluft während der Fütterungszeiten aufzuzeigen. Aus den Messergebnissen werden Empfehlungen für die Geruchsprobenahme, für die Berücksichtigung jahreszeitlicher Schwankungen der Geruchsemission in Geruchsausbreitungsrechnungen und für den Einsatz von ?EURzelektronischen Nasen?EURoe zur Beurteilung von Geruchsemissionen abgeleitet.
Einsatz von Spurenelementen bei der Vergärung von nachwachsenden Rohstoffen in Biogasanlagen
(2014) Vintiloiu, Anca; Jungbluth, Thomas
The operational agricultural biogas plants in Germany are fed mainly with renewable raw materials. During substrate addition, several micro and macro elements enter the digester. These elements are essential nutrients for the methanogens. If their concentration is too low, the production of biogas can be disrupted. A large number of agricultural biogas plants use therefore commercially available trace element solutions to optimize the process and to achieve higher methane yields. When the fermentation is complete, the digestate containing these trace elements (mostly heavy metals) is spread on fields as fertilizer. The amounts added to the biogas process should be kept as low as possible in order to minimize the environmental damage. The purpose of this study was to investigate the cause of trace elements deficiency in renewable raw materials fed biogas plants. It was also tested whether the chelation of the nutrients could increase their bioavailability for microorganisms and thus lead to a reduction of the amounts needed for the stabilization of the fermentation process. The effect of the complexing agent ethylenediaminetetraacetic acid (EDTA) on the bioavailability of metal ions was tested. The sole addition of EDTA to an undersupplied substrate increased the methane yield by up to 32 %. When trace elements were also added, their amounts could be reduced by up to 75 % with no negative consequences for the fermentation process. EDTA is a persistent chelating agent and so it was further tested, whether readily biodegradable chelating agents (ethylenediaminedisuccinic acid (EDDS) and iminodisuccinic acid (IDS)) could have the same effect. During the investigation, IDS had a high statistically significant positive effect on the bioavailability of the metal ions, which exceeded the effect of EDTA. IDS represents therefore a good alternative to EDTA. The bioavailability of the metal ions in the digester was increased by the use of complexing agents, which made the reduction of the trace elements amounts needed to compensate for substrate-related deficiency symptoms possible. This reduces the pollution on the agricultural land on which the digestate is used as fertilizer.
Energy Recovery of Animal Waste by Pyrolysis
(2006) Beck, Jürgen; Schmalzbauer, Ralf; Jungbluth, Thomas
Animal excrements contain a considerable amount of energy, which is additionally enlarged by adding litter ma- terial. Therefore dried animal manures are traditional fuels in numerous countries, where no firewood is available. The thermal utilization of animal waste could therefore be an interesting, cost-effective, and above all complete solu- tion for the excess manure. Simultaneously it serves to tap a new energy-yielding source, which has up to now been only incompletely utilized by anaerobic digestion for methane generation. To obtain the heating values of fae- ces, urine, litter substrates and solid manures for further alternative forms of utilization, extensive laboratory inves- tigations were conducted with adiabatic calorimetry. With the exception of urine the substrates showed on average net calorific values of about 20,000 kJ kg . The study was-1 completed by the evaluation of the net calorific values of the pyrolysis products from the laboratory pyrolysis plant at the Institute for Sanitary Engineering, Water Quality and Solid Waste Management of Stuttgart University.
Entwicklung innovativer Lüftungssysteme für Mastschweine : Teil I - Methode und erste Ergebnisse
(2004) Häußermann, Angelika; Hartung, Eberhard; Jungbluth, Thomas
Ziel des Projektes am Institut für Agrartechnik der Universität Hohen-heim ist die Entwicklung und der Test innovativer Lüftungssysteme für die Mastschweinehaltung. Schwerpunkte der Untersuchungen bilden die Verbesserung der Stallluftqualität, eine Minderung klima- und umweltrelevanter Emissionen aus der Tierhaltung und die technische Verwendung zusätzlicher Stall- und Tierparameter zur Steuerung des Stallklimas im Rahmen von Precision Livestock Farming. Hierfür werden Versuche über ein Jahr (Hauptuntersuchungen) im Versuchsstall für Mastschweine der Universität Hohenheim in zwei Abteilen und bei zwei verschiedenen Fütterungssystemen durchgeführt. Der Versuchsstall wurde für die Untersuchungen entsprechend aktueller Anforderungen modernisiert und die Stallklimaregelung mit einer zusätzlichen Hochdruckbefeuchtung zur Luftfeuchteregulierung und Luftkühlung ausgestattet. Als zusätzliche Regelgrößen, die die Höhe und die Reaktion des Volumenstromes sowie den Einsatz der Befeuchtung in unterschiedlicher Weise beeinflussen, kommen die Tieraktivität und die CO2-Innenraumkonzentration im Abteil zum Einsatz. Die Datenerfassung erfolgt kontinuierlich in Langzeitmessungen über vier Mastdurchgänge mit hoher zeitlicher Auflösung. Es werden Stallklima- und Emissionsdaten sowie weitere Randparameter bei wechselnden Stallklimaregelkonzepten in den beiden Abteilen erfasst. Die an-schließende Berechnung der Emissionen von NH3, CO2 und CH4erfolgtunter Einbeziehung der Hintergrund- und Abluftkonzentrationen der einzelnen Gase, der Wasserdampfquerempfindlichkeiten der Messgeräte und des zeitgleich über kalibrierte Messventilatoren erfassten Abluftvolumenstromes. Die Bewertung der Regelkonzepte schließt durch die weiterentwickelte statistische Versuchsplanung den Einfluss der jahres-zeitlichen Effekte, der Messabschnitte, der Fütterungssysteme und der Abteile sowie die Auswirkung auf das Stallklima mit ein. Teil I der mehr-teiligen Veröffentlichung erläutert weitestgehend den entwickelten Versuchsplan, die Funktionsweise der Regelkonzepte und deren technischen Umsetzung sowie die methodische Vorgehensweise der Messwert-erfassung. Weiterhin ist die Funktion der Regelkonzepte im praktischen Versuchen anhand erster ausgewählter Ergebnissen dargestellt, die zeit-parallel die Innenraumtemperaturen, Volumenströme und CO2-Innenraumkonzentrationen der beiden Abteile bei unterschiedlicher Stallklimaregelung vergleichen. Die ersten Ergebnisse zeigen, dass die Funktionsweisen der einzelnen Lüftungsvarianten, bzw. Lüftungsregelkonzepte den an sie gestellten Anforderungen entsprechen. Der Ab-schluss der praktischen Untersuchungen und die anschließende Gesamt-auswertung der erfassten Daten ist für Sommer 2004 vorgesehen.
Entwicklung und Erprobung eines Online-Messsystems für Biogasanlagen auf Basis der Nah-Infrarot-Reflexionsspektroskopie (NIRS)
(2013) Stockl, Andrea; Jungbluth, Thomas
Due to the EU?s and Germany?s political goals of expanding the use of renewable energy sources, the utilization of biomass for energy supply is expected to continue growing in the coming years. Consequently, the efficiency of biogas plants will have to be improved further. This applies both to raising the energy yield from the input materials and exploiting the full potential of the technical installations. During the four phases of the anaerobic digestion (AD) process, volatile fatty acids such as acetic and propionic acids are produced as intermediates. These compounds can be used as indicators of the function and stability of the digestion process. So far, volatile fatty acids have to be determined by sampling the digester content and analyzing the sample in the laboratory (e.g., by gas chromatography). It is thought that by using near-infrared-reflection spectroscopy (NIRS) for online measuring, the management and control of biogas plants could be facilitated, considerably. This was to be investigated in a project funded by the Baden-Württemberg Ministry of Rural Areas and Consumer Protection within the ?research platform on bioenergy? Baden-Württemberg?. In this study, a NIR-measurement system was calibrated for determining the concentration of volatile fatty acids in two semi-continuously operated, bench-scale digesters at mesophilic and thermophilic temperature level. For each of the two digesters, one NIR-sensor was calibrated for acetic and propionic acid, and a second one for total acid equivalents. The experimental studies were divided into three stages. The chapters of this research work consist of three peer-reviewed papers that describe these experiments.
Entwicklung, Implementierung und Bewertung eines IT-Systems zur Prozessdokumentation und -unterstützung in der landwirtschaftlichen Nutztierhaltung
(2010) Kuhlmann, Arne; Jungbluth, Thomas
In livestock farming, the use of automation technology is common. Automation technology is able to perform sub-processes, whereby the farmer is supported in his daily work. The data produced by this technology is usually monitored manually. The same applies to the collection of process parameters such as resource consumption and climate data. Therefore overall process monitoring and process documentation require high workload. Caused by structural change and the demand for food safety and traceability, livestock farming needs to introduce information technology. This document is dealing with the topics collection, storage, usage and exchange of data on farms and in their environment using the example of pig fattening. A stable for fattening pigs was used to analyse the conditions, requirements and implementation options for achieving the objectives process documentation and process support. Based on the conclusions drawn, a prototype was developed, that focuses on the full integration of all technical components in the stable using communication and data standards. Besides the presentation and evaluation of the system, concrete benefits for science and practice are presented using selected examples. Furthermore possibilities for improvements regarding the used technologies and standards are pointed out.

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