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To date, microwave radiation has been successfully used to support the chemical hydrolysis of organic substrates in the laboratory. There is a lack of studies on large-scale plants that would provide the basis for a reliable evaluation of this technology. The aim of the research was to determine the effectiveness of using microwave radiation to support the acidic and alkaline thermohydrolysis of lignocellulosic biomass prior to anaerobic digestion on a semi-industrial scale. Regardless of the pretreatment options, similar concentrations of dissolved organic compounds were observed, ranging from 99.0 ± 2.5 g/L to 115.0 ± 3.0 in the case of COD and from 33.9 ± 0.92 g/L to 38.2 ± 1.41 g/L for TOC. However, these values were more than twice as high as the values for the substrate without pretreatment. The degree of solubilisation was similar and ranged between 20 and 28% for both monitored indicators. The highest anaerobic digestion effects, ranging from 99 to 102 LCH4/kgFM, were achieved using a combined process consisting of 20 min of microwave heating, 0.10–0.20 g HCl/gTS dose, and alkaline thermohydrolysis. For the control sample, the value was only 78 LCH4/kgFM; for the other variants, it was between 79 and 94 LCH4/kgFM. The highest net energy gain of 3.51 kWh was achieved in the combined alkaline thermohydrolysis with NaOH doses between 0.10 and 0.20 g/gTS. The use of a prototype at the 5th technology readiness level made it possible to demonstrate that the strong technological effects of the thermohydrolysis process, as demonstrated in laboratory tests to date, do not allow for positive energy balance in most cases. This fact considerably limits the practical application of this type of solution.

The objective of the present study was to determine the effectiveness of biogas production during methane fermentation of wastewaters originating from the dairy, tanning and sugar industries, by means ofrespirometric measurements conducted at a temperature of 35 degrees C. Experiments were carried out with the use of model tanks of volume 0.5 dm3. A high production yield of biogas, with methane content exceeding 60%, was achieved in the case of the anaerobic treatment of wastewaters from the dairy and sugar industries. A significantly lower effect was observed in the case of tanning wastewaters. The effectiveness of the fermentation process decreased with increasing loading of the tanks with a feedstock of organic compounds. By loading a model tank with this feedstock, the effectiveness of treatment ranged from 62.8% to 71.4% residual chemical oxygen demand for dairy wastewaters and from 57.9% to 64.1% for sugar industry wastewaters. The efficiency of organic compound removal from tanning wastewaters was below 50%, regardless of the method applied.

Abstract The use of algae as a potential substrate in biogas production processes has been discussed sporadically, therefore this manuscript provides an overview of reference data published so far on that matter. The goal of this review is to present possibilities of applying algae biomass for biogas production purposes and to determine the effectiveness of the fermentation process of algae belonging to various taxonomic groups, originating from various biocenoses and characterized by different morphology and properties. Finally, this work reports on methods and technological solutions for algae biomass production as well as impediments and opportunities stemming from algae biomass use in biogas production technologies.

The search for a balance between the energy-related challenges of the future and providing nutritional security has resulted in the development of a market for biofuels of successive generations. The larger their portion in biofuel production, the less the prices of agricultural products will increase. The use of algae, cyanobacteria and aquatic plants in the production of liquid fuels is an alternative. The aim of this study was to determine the effect of thermal hydrolysis on degradation of polysaccharides contained in biomass of cyanobacteria Arthrospira platensis and to assess the effectiveness of ethanol production from preconditioned biomass. The study is aimed at the selection of the most advantageous parameters of thermochemical hydrolysis to reach the experiment variant with the best effects, degree of polysaccharide degradation and effectiveness of alcohol fermentation. The experiment was divided into two stages; in stage I, the possibility of obtaining fermentable sugars by hydrothermal and chemical treatment of the substrate was tested. Stage II involved an assessment of the effectiveness of the pretreatment methods to produce bioethanol in alcohol fermentation. Yeast used in industrial ethanol production-Saccharomyces cerevisiae As4-was used in the alcohol fermentation. The results have shown that the temperature of 150 °C was the most beneficial for the process of thermohydrolysis, and the mash in the microwave-heated sample contained the highest concentration of alcohol (0.97 g/l), which is 98% more than in the control mash and 37% more than in the conventionally heated sample.

AbstractThe influence of ultrasonic pretreatment with specific energy input ranging from 25 to 550 kJ/kg volatile solids on the mixture of Sida hermaphrodita (L.) Rusby mixed with cattle manure disintegration and subsequent anaerobic digestion was assessed. The pretreatment process led to significant increase in the biomass solubility by 21.9% as chemical oxygen demand and enhanced biogas yield by 157% (567.1 L biogas/kg volatile solids) when the specific energy input was from 200 to 550 kJ/kg. However, only pretreatments where ultrasound was applied at 25–50 kJ/kg led to positive net energy gain, indicating that the biomass processing with this method does not always compensate the energy consumption for irradiation.

Abstract Biogas production from lignocellulosic biomass e.g. animal manures and agricultural residues may play a fundamental role as renewable energy sources. Many pretreatment methods can be used to prepare these substrates for biogas production. In this study, hydrodynamic cavitation and ultrasound were used for agricultural residues pretreatment to enhance its biomethanization. A small-scale study allowed to assess biogas productivity and energy efficiency for agricultural biogas plant (ABP) with/without cavitation-based pretreatment of cattle manure and wheat straw. Hydrodynamic cavitation pretreatment (HCP) and ultrasonic pretreatment (UP) significantly enhanced biogas production to 430 and 460 L methane/kg volatile solids (VS), respectively. The final net energy output of ABP/ABP-UP/ABP-HCP was respectively 56/52/61 kWh/d (p

Hydrodynamic cavitation was recently applied as a biomass pretreatment method. Most of the studies which used hydrodynamic cavitation were applied to pretreated sugarcane bagasse or reed. High biomass yield of Sida hermaphrodita points out the necessity of studies on its effective pretreatment before methane fermentation, especially because its “wood-like” characteristics could present different disintegration properties than other lignocellulose biomass. Thus, the aim of the study was to investigate the influence of duration of hydrodynamic cavitation on lignocellulose composition in Sida hermaphrodita silage, and the assessment of disintegrated biomass as a substrate for methane fermentation. The study showed a slight decrease in lignin, cellulose, and hemicellulose content in biomass after hydrodynamic cavitation, which resulted in a higher content of carbohydrates in the liquid fraction of disintegrated substrates. Methane production was 439.1 ± 45.0 L CH4/kg total solids (TS) from the substrate disintegrated for 20 min. However, the most effective time for methane production was hydrodynamic cavitation of the substrate for 5 min. At this pretreatment duration, the highest values for chemical oxygen demand (COD), total organic carbon (TOC), and carbohydrate reduction were also noted. The study proved that hydrodynamic cavitation applied for 5 min allowed obtaining an energy profit of 0.17 Wh/g TS. The studies on a laboratory scale indicated that the technology of hydrodynamic cavitation of Sida hermaphrodita could be economically applied for methane fermentation on a large scale.

The study aimed to determine the effect of the load cell model anaerobic load of organic substances contained in the whey acidic fermentation kinetics of transformation. Specified rate of biogas production and the amount and composition of the product gas quality sludge anaerobic metabolism. The highest yield of biogas rate of 945 ml was obtained during the application of the load of 4.0 g / l, the ratio of production rate of 0.25 k 1 / d Biogas production rate increased with the increase of the initial charge of organic compounds introduced into the digester and the model was in the range from 96.3 to 236.5. Biogas composition analysis revealed that the highest concentration of methane was obtained at a load of 1.0 g / l