Krzysztof Dziedzic

Impact of Selected Properties of Raw Material on Quality Features of Granular Fertilizers Obtained from Digestates and ASH Mixtures

Abstract The paper presents the results of research, the objective of which was to determine the impact of particle size distribution and density of digestates and ash on density and tensile strength of granular fertilizer obtained from mixtures of these substrates. Particle size distribution, absolute density, envelope density and porosity of substrates were determined. Granular fertilizers were made of clean substrates and their mixtures. Envelope density of the obtained granulates was within 0.81 - 1.88 g⋅cm-3. The determined compaction degree was within 3.65 - 10.12. While, the compaction index IS of granulates made of mixtures was within 0.5 - 0.55 and was lower in comparison to IS of granulates from digestates (0.6) and ash (0.76).

Analysis of Impact Of Biomass Added to RDF Oversize Fraction on Properties of Briquettes

Abstract The impact of biomass addition to the RDF oversize fraction on quality parameters obtained from this blend of briquettes produced under semi-industrial conditions was analysed. For the purposes related to the experiment four RDF mixtures with fragmented biomass of common willow Salix viminalis L., differing only with percentage participation of base elements, were prepared. The briquetting process was performed with the use of a semi-industrial briquetting machine at the determined compaction pressure of 47 MPa and a diameter of a sleeve (and a briquette at the same time) of 50 mm. Selected quality parameters of produced briquettes were determined, i.e. density, mechanical strength DU and compression strength. The best parameters were obtained for briquettes produced from the blend with a 50% share of willow (ρ=843.9 kg · m-3, DU=86.1%, Rc=0.46 MPa). The lowest parameters were in case of briquettes without biomass addition. Statistical analysis of research results indicates that biomass additions to RDF significantly affect the improvement of quality parameters of the obtained briquettes.

Agglomeration of Ash-Based Fertilizer Mixtures from Biomass Combustion and Digestate

The production of fertilizers based on high quality waste materials is a highly important problem in environmental protection, mainly due to the protection of natural mineral resources. In addition, the combination of organic and mineral raw materials makes these fertilizers innovative in the fertilizer economy. As the research material unique mixtures of mineral and organic substances mixture were used. The main components were ash from biomass combustion power plant in the Polaniec and the digestate from a biogas plant located in Piekoszow. Sulfur and phosphorite were used as components to enhance the fertilizer value of the tested prototype blends (variant A). There were also blends supplemented with urea (variant B) to add nitrogen to composition. During the tests the energy consumption of the granulation process was determined and the quality of the obtained granules was determined by specifying envelope density, bulk density and mechanical durability.

Prospects of Growing Miscanthus as Alternative Source of Biofuel

The paper presents the results of research work aimed at determining process parameters for production of quality briquettes from Miscanthus raw material. Raw material was obtained from southern Ukraine from the autumn harvest. The obtained results clearly indicate that adequate grinding, humidity reduction of less than 15% and application of agglomeration pressures above 37 MPa, results in obtaining satisfactory quality briquettes. Compliance with the developed technological assumptions should not in practice lead to technical problems that will have a significant impact on the dissemination of this activity in rural Ukraine.

Spread Mustard and Prospects for Biofuels

The paper presents research aimed to determine the potential of waste biomass from the processing of mustard. Raw material for research came from the central part of Ukraine. Studies have shown that mustard residues are a valuable raw material for the production of solid biofuels in the form of briquettes or pellets. Values of quality parameters (such as calorific value, durability, density) are comparable to those found in commercial solid biofuels. Analysis of ash content showed an increased content of mineral fractions, which were the source of plant surface impurities applied by atmospheric agents (rain, wind).

Conceptual Design of the RDF Granulation Line

The paper presents a concept of a technological line for the production of granulated fuel from RDF. The main assumption of the line is the complexity of processing a raw RDF with very variable input parameters (morphological and granulometric composition, proportion and type of impurities as well as variable moisture content) to a pellet with high quality parameters (specific density, mechanical durability). Based on an analysis of the raw material characteristics and preliminary research on the RDF granulation process, design guidelines and assumptions were proposed. This allowed to develop a block diagram including all technological operations which must be used to process raw material. For each operation a technical solution was proposed which best fulfills the stated assumptions. A vacuum transport system of raw material has been proposed to reduce the amount of fly dust generated during the production process. This system is equipped with a central filter from which the dust is driven for re-granulation. Such system, reduces production of waste byproducts. As the pelletizing unit, a developed by the authors pelletizer with modified dye was proposed. Thanks to this solution, the granulation process will proceed in the temperature about 100 °C. Beside recommended moisture content and fineness of the raw material, high temperature helps ensure the predetermined quality of pellets.

Municipal Waste Anaerobic Digestion in Poland

The objective of the paper was to analyse the current state and possibilities of municipal waste anaerobic digestion in Poland. The article shows the main legal and technological aspects that determine the circumstances of implementing this technology in Poland. So far in Poland only a few anaerobic digestion plants are operating, what in comparison to other European countries (e.g. Germany) is a poor result. The main way to deal with waste in Poland is landfilling which can be in many ways dangerous for the environment. The EU law have put pressure on Polish waste management systems for which anaerobic digestion technology can play significant role. This work analysis anaerobic digestion from legal and economical point of view together with predictions of potential as waste management option and renewable energy source. The biogas market has been presented from the perspective of market players. Conclusions show why in the current situation development of Polish anaerobic digestion infrastructure is right.

Influence of Plant Biomass Added to Sewage Sludge on the Product Energy Potential

The authors of this study aimed at evaluating the influence of plant biomass added to sewage sludge on the product energy potential. In order to improve its physical properties, sewage sludge was mixed with wheat straw, sawdust, and bark of conifers. Materials with a natural water content were mixed at 1:1 weight ratio on a dry matter basis. The scheme of the experiment was as follows: sewage sludge without any additions (SS), sewage sludge + wheat straw (SS + WS), sewage sludge + sawdust (SS + S), sewage sludge + bark (SS + B). The moisture of materials, the contents of volatile matter, combined carbon, heat of combustion and calorific value were determined in the study. The addition of plant biomass to sewage sludge reduced the moisture content and increased the volatile matter content compared to sewage sludge without such addition, in which case the variation was relatively low. For the studied mixtures, larger variations were observed in relation to the ash and combined carbon contents. The highest contents of ash and combined carbon were found in the mixture of sewage sludge and bark. The highest value of heat of combustion was determined in the mixture of sewage sludge and sawdust (14,000 J g−1). Calorific values of the mixture of sewage sludge and wheat straw and sewage sludge and bark were 13,640 J g−1 and 11,540 J g−1, respectively, and were higher by more than 40% on the average compared to the calorific value of sewage sludge without any additions.

Analysis of MSW Potential in Terms of Processing into Granulated Fuels for Power Generation

Due to its morphological composition which includes mostly combustible material (plastics, paper, textiles, etc.), municipal solid waste is potentially a valuable raw material for use in power generation. On the other hand, content of incombustible fraction (glass, metal, rocks, etc.) reduces its value, particularly when solid municipal waste must be processed into the form of granulate as in case of co-combustion with coal in pulverized-fuel or fluidized-bed boilers. The process of granulation reduces also the costs of logistics processes such as transport, storage and handling. That is why the research carried out in the framework of “EkoRDF—an innovative manufacturing technology of alternative fuel from municipal waste for power and heating plants—a key component of the Polish waste management system” financed by Polish Centre for Research and Development (GEKON Programme) aimed at determining the MSW potential not only in terms of use in power generation, but mainly from the point of view of technologies of converting the waste into granulated fuels for power generation units. The test material comprised oversize and undersize fractions of municipal solid waste obtained from four sources (sorting plants). The morphological and grain-size analyses were carried out, and the parameters important from the point of view of power generation were determined (moisture content, calorific value, volatile matter content, ash content). The impact of those parameters on key stages of RDF production from waste (drying, comminution and granulation) were analysed. The analysis led to determination of acceptable raw material parameters for use in production of fuel granulates dedicated to burning in power generation units.

Analysis of Mechanical Dewatering of Digestate

Abstract Technology of processing of agricultural raw material and production residues from agri-food industry often requires their dewatering. Digestate is one of such materials i.e. the mass remaining after the bio-gasification process, which has great hydration (above 85%). The objective of the research was to know the impact of dewatering on the change of water content in digestate from biogas in Piekoszów. A mechanical dewatering process was carried out and reflected the conditions of operation of screw presses for dewatering of plant raw materials, whose screen internal diameter is 160 mm. Knowing the impact of pressure on the dynamics of raw material moisture decrease will allow modelling of the operation of industrial devices with similar operation parameters. Thus, a research on the dewatering process with the use of pressure within 0.58-2.91 MPa and slotted screens with meshes size of 0.1; 0.2 and 0.3 mm were carried out. The analysis of the obtained results indicates that an effective process of dewatering of the investigated digestate takes place at the working pressure to 1.74 MPa regardless the applied screen. Further increase of pressure does not cause a significant decrease of moisture in the investigated material.