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Number of results: 16
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Abstract

In literature as well as in the university debate, we can observe the increase of interest regarding converting agricultural residues into energy. Furthermore, the energy and climate policies have encouraged the development of biogas plants for energy production. One of the most significant reasons of this escalation is that this technology may be both convenient and beneficial. The produced biogas is not only supposed to cover the energy demand like heat and electricity, the resulting digestate has the prospect of a beneficial fertilizer and can thereby influence the energy management plans. This technology is widely introduced to countries, which have large income from agriculture. Not only does this reduce the use of industrial fertilizers, but also finds use for agricultural residues. One of the countries of this type is Vietnam, which is the fifth largest exporter of rice in the world. Over 55% of greenhouse gas emission in Vietnam comes from agriculture. Using innovative technologies such as biogas, may decrease this value in near future. It may also contribute to more sustainable agriculture by decreasing traditional fields burning after the harvesting period. The goal of this research paper is to estimate the possible production of biogas from rice straw to cover the energy demand of the rice mill. Four possible scenarios have been considered in this paper, the present situation and where electricity, energy or both were covered by biogas from agricultural residues. An attempt was made to answer the question whether the amount of biogas produced from agricultural residues is enough for both: electricity and energy supply, for the rice mill. If not, how much rice straw must be delivered from other sources, from which rice is not delivered to the rice mill. The base of the assumptions during the estimation of various values were statistics from FAO and other organizations, secondary sources and data from the existing rice mill in Hậu Mỹ Bắc B in Mekong delta in Vietnam.
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Abstract

The paper presents results of the field tests on membrane biogas enrichment performed with the application of mobile membrane installation (MMI) with the feed stream up to 10 Nm3/h. The mobile installation equipped with four hollow fibre modules with polyimide type membranes was tested at four different biogas plants. Two of them were using agricultural substrates. The third one was constructed at a municipal wastewater plant and sludge was fermented in a digester and finally in the fourth case biogas was extracted from municipal waste landfill site. Differences in the concentration of bio-methane in feed in all cases were observed and trace compounds were detected as well. High selectivity polyimide membranes, in proper module arrangements, can provide a product of high methane content in all cases. The content of other trace compounds, such as hydrogen sulphide, water vapour and oxygen on the product did not exceed the values stated by standard for a biogas as a vehicle fuel. The traces of hydrogen sulphide and water vapour penetrated faster to the waste stream enriched in carbon dioxide, which could lead to further purification of the product – methane being hold in the retentate (H2O > H2S > CO2 > O2 > CH4 > N2). In the investigated cases, when concentration of N2 was low and concentration of CH4 higher than 50%, it was possible to upgrade methane to concentration above 90% in a two-stage cascade. To performsimulation ofCH4 andCO2 permeation through polyimide membrane,MATLABwas used. Simulation program has included permeation gaseous mixture with methane contents as observed at field tests in the range of 50 and 60% vol. The mass transport process was estimated for a concurrent hollow fibre membrane module for given pressure and temperature conditions and different values of stage cut. The obtained results show good agreement with the experimental data. The highest degree of methane recovery was obtained with gas concentrating in a cascade with recycling of the retentate.
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Abstract

The present paper describes a cycle, which may be applied in sewage treatment plants as a system to convert biological waste into process heat and electricity. In sludge stabilization processes anaerobic fermentation acts as the source of methane, which can be used then to generate heat and electric current in gas turbines. Products of high-temperature oxidation can be utilized in organic Rankine cycles to generate electric power. Waste heat is used for heating the fermenting biomass. Energy balance equations mentioned in the thesis: organic Rankine cycle, regenerative gas turbine engine, anaerobic sludge stabilization system.
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Abstract

The world in 21st century is facing the problem of growing energy consumption while the supply of fossil fuels is being reduced. This resulted in the development of research into the use of renewable energy sources and development of new technologies for energy production. In Polish conditions the development of agricultural biogas plants finds its legitimacy in the document developed by the Ministry titled "Trends in agricultural biogas plants in Poland in 2010-2020”. The purpose of this study was to investigate the influence of the weather conditions and the degree of nitrogen fertilisation on yield of reed canary grass (Phalaris Arundinacea L.) and to determine their susceptibility to anaerobic digestion, and usefulness of the production of biogas. Carried out experiments showed that increasing nitrogen fertilisation (from 40 to 120 kg N/ha) linearly increased canary grass green biomass yield from 32 to 46.3 t/ha. However, the highest biogas yield 126 m3/ha was obtained when 80 kg N/ha was applied.
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Abstract

Two systems of hydraulic mixing in a vertical cylindrical anaerobic digester: standard and modernised are discussed in the paper. Numerical investigations that were carried out are focused on a study of hydrodynamic processes in an aerobic digester using two various systems of hydraulic mixing as well as on analysis of the efficiency of methane fermentation process accomplished under different geometric parameters of an anaerobic digester and systems of hydraulic mixing.
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Abstract

The article focuses on selected aspects of the technical and economic analysis of the 0.8 MW agricultural biogas plant. The electrical power, generated in a cogeneration system, fed power to the neighbouring overhead power grid, Węgrów – Sokołów Podlaski, while the heat energy recovered from combustion gases and liquids cooling the engine was used to heat digesters, a residential building, drying room and farm buildings. The planned annual production equals c.a. 6400 MWh per year given the 8000 h of engine operation. The substrates used as input for the digestive chambers were as follows: fermented maize, pig slurry and liquid digestate pulp.
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Abstract

The aim of the article is to present the issue of risk and related management methods, with a particular emphasis on the conditions of investment in energy infrastructure. The work consists of two main parts; the first one is the theoretical analysis of the issue, while the second discusses the application of analysis methods on the example of the investment in an agricultural biogas plant. The article presents the definitions related to the investment risk and its management, with a particular emphasis on the distinction between the risk and uncertainty. In addition, the main risk groups of the energy sector were subjected to an analysis. Then, the basic systematics and the division into particular risk groups were presented and the impact of the diversification of investments in the portfolio on the general level of risk was determined. The sources of uncertainty were discussed with particular attention to the categories of energy investments. The next part of the article presents risk mitigation methods that are part of the integrated risk management process and describes the basic methods supporting the quantification of the risk level and its effects – including the Monte Carlo (MC), Value at risk (VaR), and other methods. Finally, the paper presents the possible application of the methods presented in the theoretical part. The investment in agricultural biogas plant, due to the predictable operation accompanied by an extremely complicated and long-term investment process, was the subject of the analysis. An example of “large drawing analysis” was presented, followed by a Monte Carlo simulation and a VaR value determination. The presented study allows for determining the risk in the case of deviation of financial flows from the assumed values in particular periods and helps in determining the effects of such deviations. The conducted analysis indicates a low investment risk and suggests the ease of similar calculations for other investments.
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Abstract

This paper shall present and explain the key aspects related to the issue of combined heat and power generation (CHP – Combined Heat and Power or Cogeneration). The cooperation with the water treatment plant launched allowed a closer look at the described technology as well as allowed the analyses and survey. The survey on the efficacy of the selected components of the cogeneration system was based on two cogeneration units fuelled with biogas produced in the sewage fermentation.
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Abstract

The article describes problems related to intensification of energy production at a sewage treatment plant. The authors analyze anaerobic co-digestion of sludge from a water treatment plant and sewage treatment plant. The authors proposed a methodology of the research and analyzed the preliminary results, which showed that co-digestion of sewage and water sludge enhanced biogas production. The authors hope that the results of the study will provide a basis for development of methodology for sludge control and disposal.
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Abstract

The aim of the study was to develop an effective treatment of post-digestion liquors highly-loaded with biogenic and organic substances. The scope of the research project encompassed: mesophilic anaerobic digestion of waste activated sludge (WAS) as well as the treatment of post-digestion liquors, coming from the most appropriate HRT value of 25 days, in the process of ammonium magnesium phosphate (struvite) precipitation targeted at ammonia nitrogen binding and a subsequent reverse osmosis (RO) process. It was established that the method combining chemical precipitation and high-pressure filtration ensures a high degree of contaminants removal allowing for a direct release of treated liquors into the natural reservoir. However, in order to decrease the residual NH4+ concentration (6.1 mg NH4+/dm3) in the purified post-digestion liquors below the level allowing for a direct release to the natural reservoir, it turned out to be necessary to apply increased molar ratio of magnesium and phosphates (Mg:NH4+: PO43-= 1.5:1:1.5).
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Abstract

Nine phyto-ashes from the biomass combustion of birch (Betula), oak (Quercus), red oak (Quercus rubra), horbeam (Carpinus), pine (Pinus sylvestris), poplar (Populus), maple (Acer), oilseed rape straw (Brassica napus) and wheat straw (Triticum aestivum) were blended with a biogas digestate at 1:1 mass ratio to give nine organic-mineral soil improvers. The concept of the research was to outline an eco-friendly and low cost soil improver for remediating degraded lands. These (i.e. phyto-ashes, improvers and the biogas digestate) were applied (0, 5, 10, 20, 40 t·ha-1) to a soil metallurgically contaminated with Cu, Zn, Pb and Cd. Of several tested parameters, pH changes revealed that organic-mineral soil improvers may efficiently replace (linear R2>0.90****, P<0.001) phyto-ashes in soil remedial goals. Buffering properties expressed by the cation exchange capacity (CEC) improved progressively: 29, 52, 71, 100% (phyto-ash treatments) and: 18, 37, 44, 73% (improvers treatments) for the rates 5, 10, 20, 40 t·ha-1, respectively as referred to the control CEC. The Dynamic Remediation Efficiency (DRE) indices for Cu, Zn, Pb, Cd revealed metal-specific geochemical reactions initiated by phyto-ashes, improvers and biogas digestate. The rates 5.0–10.0 t·ha-1 for phyto-ashes and about 20 t·ha-1 for improvers [1:1, i.e. Phyto-ash:Biogas digestate] are recommended. For biogas digestate, the rates 10–20 t·ha-1 were found more efficient.
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Abstract

The paper describes practical results of four-year laboratory studies completed to estimate technically feasible conditions of upgrading an existing sludge disposal system. A minimization of sludge mass and volume together with an energy recovery improvement were main goals of these activities. The way from lab studies and simulations to full scale investments has been shown with a special emphasis on application of respirometric procedure being applied by authors. Proposed was authors’ procedure for an estimation of a digestion time prediction for sludge of specific composition. Investigations completed at existing wastewater treatment plant resulted in practical implementation to be used during the design of upgrading and extension of the digestion and energy recovery system at the plant. It was proved that proposed changes provide close to optimum conditions for process performance and the application of proposed calculation procedures was adopted by design team
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Abstract

The substrates to biogas production in anaerobic digestion, except plant materials, can also be animal feces and manure. It should be highlighted that Poland is one of leaders in the European Union in animal breeding. However, there is no precise data in the literature on the potential of biogas production from animal feces in this country. The aim of the paper was to analyze the biogas production potential from manure in Poland. The aim of work included anaerobic digestion research following materials: cow manure, pig manure, poultry manure and sheep manure. In the next step, based on the obtained results of the biogas yield, energy potential calculations were made. The methane yield for the investigated feedstock materials in the batch culture technology was performed following the internal procedures developed based on the adapted standards, i.e. DIN 38 414-S8 and VDI 4630. Animal wastes were obtained from the Agricultural Experimental Stations of Poznan University of Life Sciences (Poznan, Poland). On a base of achieved results it was concluded that tested substrates have a high energy potential (approx. 28.52 GWh of electricity). The largest potential for electricity production was found in chicken manure (about 13.86 GWh) and cow manure (about 12.35 GWh). It was also shown which regions of Poland have the best chance for development of agriculture biogas plants (Wielkopolskie and Mazowieckie voivodships) and where the potential is the least (Lubuskie and Opolskie voivodeships).
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Abstract

Sapropel deposits are widely distributed around the globe. In the Americas area they are adjacent to the Great Lakes region, in Europe sapropel deposits can be spotted in the territory of Scandinavia, France, Switzerland, Germany, Poland, Belarus, Russia and in the northern regions of Ukraine. Use of sapropel as a fertilizer can enhance high and stable yields of crops. However, despite the proven effectiveness of long-term practical researches in this area, nowadays sapropel is almost not used. One of the reasons - lack of developed processing methods of extraction and processing, including dehydration. Material properties as an object of interaction with the working bodies, change of their settings in the processing are crucial in the choice of technologies, development, bringing up to the necessary parameters and subsequent use. Sapropel high humidity (95-98%) is one of the main factor that determines the quality of its properties after the interaction with working bodies. However, in the process of decreasing, in interaction with oxygen, there are significant changes in physical and mechanical properties of sapropel. Decisive in the direction selection process of lake sapropels’ use in the economic sector is their moisture exchange and thermodynamic parameters. The complexity of setting the water apart, if freshly extracted sapropels possess only 15-20% of it, shows their strong water-retaining capacity. The above mentioned phenomenon proves the need for their use as an organic fertilizer during the crops growing, as superficial loss of moisture in the soil creates a new global problem. On the basis of deep analysis of the sapropels’ properties, the authors suggest three areas of freshly extracted lake sapropel application in mixtures with leafy part of the crops: in biogas production with its further use as an organic fertilizer; making a compost mixture of organic origin which physical and mechanical properties are approximate as that of the soil; alternative solid fuels in the form of briquettes.
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Abstract

Sewage sludge (municipal, or industrial) treatment is still a problem in so far that it is not satisfactorily resolved in terms of cost and final disposal. Two common forms of sludge disposal are possible; the first being direct disposal on land (including agriculture) and the second being incineration (ash production), although neither of these methods are universally applied. Simplifying the issue, direct sludge disposal on land is seldom applied for sanitary and environmental reasons, while incineration is not popular for financial (high costs) reasons. Very often medium and large wastewater treatment plants apply anaerobic digestion for sludge hygiene principles, reducing the amount to be disposed and for biogas (energy) production. With the progress in sewage biological treatment aiming at nutrient removal, primary sludge has been omitted in the working processes and only surplus activated sludge requires handling. Anaerobic digestion of waste activated sludge (WAS) is more difficult due to the presence of microorganisms, the decomposition of which requires a relatively long time for hydrolysis. In order to upgrade the hydrolysis effects, several different pre-treatment processes have already been developed and introduced. The additional pre-treatment processes applied are aimed at residual sludge bulk mass minimization, shortening of the anaerobic digestion process or higher biogas production, and therefore require additional energy. The water-energy-waste Nexus (treads of) of the benefits and operational difficulties, including energy costs are discussed in this paper. The intensity of pre-treatment processes to upgrade the microorganism’s hydrolysis has crucial implications. Here a low intensity pre-treatment process, alkalisation and hydrodynamic disintegration - hybrid process - were presented in order to achieve sufficient effects of WAS anaerobic digestion. A sludge digestion efficiency increase expressed as 45% biogas additional production and 52% of the total or volatile solids reduction has been confirmed.
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