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The energetic and economic analysis of demand-driven biogas plant investment possibility in dairy farm
The Influence of Drying Sewage Sludge with the Addition of Walnut Shells on Changes in the Parameters and Chemical Composition of the Mixture
Evaluation of the Effects of Using the Giant Miscanthus (Miscanthus × Giganteus) Biomass in Various Energy Conversion Processes
The giant miscanthus (Miscanthus × giganteus) is one of the most essential energy plants. It also finds various alternative uses, including installing belts to prevent soil erosion. Biomass from such belts should be removed and rationally managed every year. The parameters of miscanthus biomass were investigated in terms of its suitability for combustion and anaerobic fermentation. Under the conditions of the experiment, miscanthus achieved a stable yield already in the second year of vegetation, mainly due to the high planting density. Energy parameters turned out to be typical for straw biomass (calorific value 18.06 MJ/kg). Relatively low ash melting temperatures (<1400 °C) and their chemical composition meant a high risk of contamination depositing on heating devices, which is often indicated as a shortcoming of biomass compared to hard coal. Miscanthus silage can be a valuable substrate for anaerobic digestion, but it requires a sufficiently early harvest, which affects the yield of biomass. The yield of energy in biomass obtained after drying plants was 163,623.6 MJ/ha. In contrast, the yield of energy from biomass collected in summer and processed into biomethane was much lower and amounted to 72,978.2 MJ/ha.
Analysis of Sewage Sludge Drying Parameters Using Different Additives
This paper describes the process of drying sewage sludge mixtures with the addition of various components: straw chaff, wood sawdust, ash, bark, wood chips, and walnut shells. The tests were conducted in two series: summer and autumn (with maximum insolation of 24.1 and 29.8 MJ∙m−2, respectively). Using a set of sensors with which the experimental station was equipped, the parameters of the environment (temperature, humidity, and insolation) and the parameters of the dried mixtures (temperature and humidity) were measured. Based on the results obtained, the influence of external factors on the parameters, time, and drying effect of the respective mixtures was analyzed. With the initial moisture content of the mixtures ranging from 41 to 79%, a final moisture content of 6 to 49% was obtained, depending on the components and drying conditions. It was found that the drying rate was most influenced by the amount of solar energy and the associated outdoor (maximum 29 °C and 19 °C) and indoor (maximum 33 °C and 24 °C) air temperatures, and in the second series, there was an additional effect of the temperature of the mixtures (maximum 30 °C), upon which the intensity of water evaporation depended. Straw chaff and walnut shells proved to be the best additives, for which the highest drying rates were obtained (max. 50 to 60% humidity drop). The possibility of using dried materials for agricultural and energy purposes was indicated. This approach is in line with the principles of sustainable development.
Sposób zwiększenia sprawności energetycznej biogazowni oraz układ do zwiększenia sprawności energetycznej biogazowni
Influence of Modification of the Plasticizing System on the Extrusion-Cooking Process and Selected Physicochemical Properties of Rapeseed and Buckwheat Straws
The article discusses the effect of modification of the plasticizing system of a single-screw extruder on selected physicochemical properties of rapeseed straw and buckwheat straw. A TS-45 single-screw extruder (ZMCh Metalchem, Gliwice, Poland) with an L/D = 12 plasticizing system was used for the process. The shredded straws were moistened to four moisture levels: 20, 25, 30 and 35% dry matter. Three different rotational speeds of the extruder screw were applied for the test cycle: 70, 90 and 110 rpm. The following characteristics were determined for the extrusion-cooking process: efficiency and specific mechanical energy. Selected physical properties were determined for the extrudates obtained in the process: water absorption index (WAI), water solubility index (WSI), bulk density, and the efficiency of cumulative biogas and cumulative methane production expressed on dry mass, fresh mass, and fresh organic mass basis. It has been proved that the modification of the plasticizing system had a significant impact on the course of the process and the tested physicochemical properties. An important factor confirming the correctness of the modification is the increase in biogas efficiency. After modification, the highest yield of cumulative biogas from the fresh mass was 12.94% higher than in the sample processed before modification.
An Analysis of the Physicochemical and Energy Parameters of Briquettes Manufactured from Sewage Sludge Mixtures and Selected Organic Additives
As a by-product of wastewater treatment, sewage sludge can be used for natural, agricultural, or energy purposes. One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural additives can be used to alter the structure of the sludge and accelerate the evaporation of water. This research aimed to evaluate the influences of different organic additives in sewage sludge mixtures on the physicochemical and energy parameters of briquettes. This research was carried out without thermal boosting in a 4 × 2.5 × 2 m plastic tunnel. The tunnel was equipped with three drying stations and control and measuring equipment. In two test series, sludge additives in the form of straw and lignocellulosic materials, sawdust, bark, woodchips, and walnut shells, were used. Briquettes were made from the resulting mixtures and then subjected to physical and chemical analyses. This research showed high variability in the contents of trace elements, nitrogen, and sulphur in relation to an increase in the amount of sludge in the briquettes, which, for the briquettes made from sewage sludge, was nearly twice as high as for the briquettes made from the mixtures. The results of the flue gas analysis for the briquettes with sawdust and wood chip additives were very similar. The briquettes made from sewage sludge with lignocellulosic materials (bark and wood chips) had fuel properties similar to woody biomass, with a calorific value and heat of combustion of 15–16 MJ/kg. Fibrous additives (straw) significantly increased the strength parameters of the briquettes, by more than 50% of the value. The compositions and properties of the mixtures affected the following briquetting parameters: temperature and compressive force. The briquettes made from sewage sludge and additives can be classified according to ISO 21640 as SRFs (solid recovered fuels). In most of the results, the net calorific value (NCV) was 3 to 4; the chlorine content (CL) was 2 to 1; and the mercury content (Hg) was 1. The sewage sludge mixtures facilitated the agricultural and energy use of the briquettes.
Gases Emissions during Composting Process of Agri-Food Industry Waste
The vegetable production is an important part of agriculture sector in every country. In Poland, vegetables and fruits production covering the area of no more than 3% of agricultural land, is more than 36% of plant production and 14–15% of the whole agricultural production. The study aim was to determine the management possibilities of the selected waste from vegetable production in composting process. Laboratory tests were carried out using the bioreactor set-up with capacity of 165 dm3, respectively, for each chamber. The composting process has been tested for the following mixtures: K1—cabbage leaves, tomato dry leaves + manure and slurry additive; K2—cabbage leaves, solid fraction from biogas plant + manure and straw additive; K3—cabbage leaves, onion husk + straw additive. In all three composts the thermophilic phase occurred which indicates that the process ran correctly. In each chamber, the temperature exceeded 70 °C and its maximum value during the experiment was 77.5 °C for K2 compost. The article discusses changes in O2, CO2, NH3 and H2S emissions during composting. The carbon dioxide concentration in the exhausted gas from analyzed composts and the ratio with oxygen they testify to the decomposition of raw materials in the composting process. The results showed that the agri-food waste can be a proper substrate for composting production. Due to legal regulations and the increase in prices of mineral fertilizers, the development of the compost market should be expected.