1. Valorization of biomass through anaerobic digestion and hydrothermal carbonization : integrated process flowsheet and supply chain network optimizationSanja Potrč, Aleksandra Petrovič, Jafaru Musa Egieya, Lidija Čuček, 2025, izvirni znanstveni članek Opis: Utilization of biomass through anaerobic digestion and hydrothermal carbonization is crucial to maximize resource efficiency. At the same time, supply chain integration ensures sustainable feedstock management and minimizes environmental and logistical impacts, enabling a holistic approach to a circular bioeconomy. This study presents an integrated approach to simultaneously optimize the biomass supply chain network and process flowsheet, which includes anaerobic digestion, cogeneration, and hydrothermal carbonization. A three-layer supply chain network superstructure was hence developed to integrate the optimization of process variables with supply chain features such as transportation modes, feedstock supply, plant location, and demand location. A mixed-integer nonlinear programming model aimed at maximizing the economic performance of the system was formulated and applied to a case study of selected regions in Slovenia. The results show a great potential for the utilization of organic biomass with an annual after tax profit of 23.13 million USD per year, with the production of 245.70 GWh/yr of electricity, 298.83 GWh/yr of heat, and 185.08 kt/yr of hydrochar. The optimal configuration of the supply chain network, including the selection of supply zones, plant locations and demand locations, transportation links, and mode of transportation is presented, along with the optimal process variables within the plant.
Ključne besede: anaerobic digestion, hydrothermal carbonization, supply chain optimization, process flowsheet optimization, mathematical programming
Objavljeno v DKUM: 07.02.2025; Ogledov: 0; Prenosov: 7
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2. Modeling and optimization of anaerobic digestion technology : current status and future outlookTina Kegl, Eloisa Torres Jiménez, Breda Kegl, Anita Kovač Kralj, Marko Kegl, 2025, pregledni znanstveni članek Ključne besede: renewable energy, anaerobic digestion, biogas plant, mathematical models, optimization algorithms, products utilization
Objavljeno v DKUM: 31.01.2025; Ogledov: 0; Prenosov: 13
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3. Mathematical model-based optimization of trace metal dosage in anaerobic batch bioreactorsTina Kegl, Balasubramanian Paramasivan, Bikash Chandra Maharaj, 2025, izvirni znanstveni članek Opis: Anaerobic digestion (AD) is a promising and yet a complex waste-to-energy technology. To optimize such a process, precise modeling is essential. Developing complex, mechanistically inspired AD models can result in an overwhelming number of parameters that require calibration. This study presents a novel approach that considers the role of trace metals (Ca, K, Mg, Na, Co, Cr, Cu, Fe, Ni, Pb, and Zn) in the modeling, numerical simulation, and optimization of the AD process in a batch bioreactor. In this context, BioModel is enhanced by incorporating the influence of metal activities on chemical, biochemical, and physicochemical processes. Trace metal-related parameters are also included in the calibration of all model parameters. The model’s reliability is rigorously validated by comparing simulation results with experimental data. The study reveals that perturbations of 5% in model parameter values significantly increase the discrepancy between simulated and experimental results up to threefold. Additionally, the study highlights how precise optimization of metal additives can enhance both the quantity and quality of biogas production. The optimal concentrations of trace metals increased biogas and CH4 production by 5.4% and 13.5%, respectively, while H2, H2S, and NH3 decreased by 28.2%, 43.6%, and 42.5%, respectively.
Ključne besede: anaerobic digestion, batch bioreactor, methane production, model parameters calibration, active set optimization method, perturbation of model parameter, gradient based optimization, trace metals
Objavljeno v DKUM: 30.01.2025; Ogledov: 0; Prenosov: 3
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4. Ensiling, in vitro rumen digestion and soaking in slurry altered the germination capacity of Rumex obtusifolius seedsAnastazija Gselman, Maksimiljan Brus, 2023, izvirni znanstveni članek Opis: This study investigated whether the process of ensiling and in vitro digestion in rumen juice, as well as the response to soaking in pig or cattle slurry, affects the germination rate and germination energy of Rumex obtusifolius (broad-leaved dock) seeds. Seeds were subjected to different treatments (200 seeds each) in three experiments: (I) seed ensiling (8 weeks) followed by in vitro rumen digestion (24, 36 and 48 h); (II) the soaking of non-ensiled and ensiled seeds in cattle or pig slurry (2, 4 and 24 weeks); and (III) the in vitro rumen digestion (24, 36 and 48 h) of non-ensiled and ensiled seeds followed by soaking in cattle or pig slurry (24 weeks). The control treatment included untreated seed (0—non-ensiled seed; 0—no in vitro rumen digestion; and 0—no soaking in slurry). Germination tests (germination rate and germination energy) were then conducted in four replicates in the germination chamber under alternating day (20–35 °C for 14 h under light) and night conditions (17–20 °C for 10 h without light) at 75% relative humidity. Experiment I showed that ensiling significantly (p ≤ 0.001) reduced both the germination rate and germination energy of R. obtusifolius seeds. In addition, the length of in vitro digestion duration that the non-ensiled seeds were subjected to significantly (p ≤ 0.001) reduced their germination energy but not the total germination rate. However, the seeds that were subjected to the process of ensiling and in vitro digestion in the rumen lost their germination completely. The Experiment II investigated the effects of soaking non-ensiled seeds in slurry and showed that germination rates were comparable in pig and cattle slurry. Longer soaking times significantly reduced the germination rate, with no germination observed after 24 weeks. The Experiment III considered the combined effects of in vitro digestion and slurry soaking and showed that rumen digestion reduced the proportion of germinable seeds. Germination was inhibited in pig slurry, while in cattle slurry, a decreasing germination rate was observed with increasing digestion time.
Ključne besede: broad-leaved dock, in vitro rumen digestion, ensiling, pig and cattle slurry, seed germination
Objavljeno v DKUM: 05.04.2024; Ogledov: 308; Prenosov: 16
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5. Improvement of biogas production utilizing a complex anaerobic digestion model and gradient-based optimizationTina Kegl, Breda Kegl, Marko Kegl, 2024, izvirni znanstveni članek Opis: : Anaerobic digestion (AD) is a promising technology for renewable energy production from organic waste. In order to maximize the produced biogas quantity and quality, this paper deals with the optimization of the AD process in a CSTR bioreactor of a full-scale biogas plant. For this purpose, a novel approach was adopted coupling, a highly complex BioModel for AD simulation, and a gradient-based optimization method. In order to improve AD performance, the dosages of various types of biological additives, the dosages of inorganic additives, and the temperature in the bioreactor were optimized in three different scenarios. The best biogas quality was obtained using multi-objective optimization, where the objective function involves the following two conflicting objectives: the maximization of biogas production and minimization of the needed heating energy. The obtained results show that, potentially, the content of CH4 can be increased by 11%, while the contents of H2, H2S, and NH3 can be reduced by 30%, 20%, and 81% when comparing the simulation results with the experimental data. The obtained results confirm the usefulness of the proposed approach, which can easily be adapted or upgraded for other bioreactor types.
Ključne besede: additives, anaerobic digestion, approximation method, BioModel, complex substrate, gradient-based optimization, process conditions
Objavljeno v DKUM: 12.03.2024; Ogledov: 298; Prenosov: 30
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6. Optimizacija priprave proteinov krvne plazme z razgradnjo na peptide v raztopini za proteomsko analizo z masno spektrometrijo : diplomsko delo univerzitetnega študijskega programa I. stopnjeEva Zajšek, 2023, diplomsko delo Opis: V diplomskem delu sta predstavljena danes najpogostejša načina priprave vzorcev proteinov z razgradnjo na peptide za proteomsko analizo z masnim spektrometrom: SDS PAGE in stopenjska priprava v raztopini, ki vključuje denaturacijo, redukcijo, alkilacijo proteinov in njihovo cepitev na peptide s tripsinom.
Naš namen je bil skrajšati, poenostaviti in poceniti v znanstveni literaturi opisani protokol stopenjske priprave vzorcev proteinov v raztopini, vendar kljub temu ohraniti dobro razgradnjo proteinov in identifikacijo z masnim spektrometrom. V delu je tako podrobneje prikazana analiza optimizacije priprave vzorcev v raztopini: različni reagenti, različne koncentracije, združevanje korakov, dodajanje korakov, različne temperature in različno dolge inkubacije.
Rezultati kažejo, da protokola ne moremo skrajšati na račun časa inkubacije tripsina, vendar pa lahko to storimo z združitvijo korakov denaturacije, redukcije in alkilacije ter skrajšanim časom inkubacije teh korakov. Kot boljši alkilacijski reagent se je v primerjavi z jodoacetamidom (IAM) zaradi manjšega števila neželenih modifikacij izkazal kloroacetamid (CAM), za oba reagenta pa je primerna koncentracija pod 10 mM. Ugotovili smo, da dodaten korak prekinitve alkilacije z ditiotreitolom (DTT) zaradi prihranka časa in kemikalij ni primeren, saj ne zmanjša števila neželenih modifikacij. Povzeti protokol smo nekoliko pocenili z zamenjavo alkilacijskih reagentov, saj je kloroacetamid (CAM) cenejši in ga je na voljo za več eksperimentov, sicer pa ceno celotnega eksperimenta določa predvsem poraba tripsina, čigar cena znaša okrog 2,23 EUR za 1 μL.
Ključne besede: proteomika, SDS PAGE, in-solution-digestion, reagenti, masna spektroskopija, priprava vzorcev
Objavljeno v DKUM: 31.03.2023; Ogledov: 649; Prenosov: 55
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7. Building of mini digester for mesophilic anaerobic digestionBogomir Muršec, Peter Vindiš, 2009, strokovni članek Opis: Anaerobic digestion is the biological degradation of organic material in the absence of air andmayimply environmental benefits with regard to waste treatment, pollution reduction, energy production, and improvements in agricultural practices. Ananaerobic digester is a system that harnesses this natural process to treat waste, produce biogas that can be converted to heat and electricity and anaerobic digestate, a soil improving material. The paper presents the building of a mini digester for mesophilic anaerobic digestion.With the mini digester the amount of biogas production (methane) from different organic wastes is observed. The basic structure is made of stainless steel, on which other components are fixed. The most important components are the eudiometers, pump and heater with thermostat, fermenters, thermometer and barometer. The experiment is made according to DIN 38 414, part 8. After building of a mini digester some experiments with different organic materials are made.
Ključne besede: mini digester, mesophilic anaerobic digestion, organic wastes
Objavljeno v DKUM: 11.07.2017; Ogledov: 1779; Prenosov: 118
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8. Biogas as a renewable energy sourceMatjaž Ošlaj, Bogomir Muršec, 2010, pregledni znanstveni članek Opis: Renewable energy technology does not simply produce energy, heat and transport fuel, but also offers the opportunity to live in the footsteps of a reasonable future development. In Europe and other industrialized regions, the main reason for the development of renewable energy is the environment, in particular the concern in relation to global climate change and the need to improve security and diversity of energy supply. In the developing countries, they promise a new hope for renewable primary energy supply in regions without conventional energy and provide an opportunity for sustainable development. Productionof "green energy" from biogas, which is among the renewable energy sources, promises an environmentally less damaging way of obtaining energy by reducing CO emissions into the environment and reduces energy dependence on imported energy sources. Biogas production is of major importance for the sustainable use of agrarian biomass as renewable energy source.
Ključne besede: anaerobic digestion, biogas, manure, renewable energy
Objavljeno v DKUM: 11.07.2017; Ogledov: 1786; Prenosov: 113
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9. In vitro selection and characterization of new probiotic candidates from table olive microbiotaCristian Botta, Tomaž Langerholc, Avrelija Cencič, Luca Cocolin, 2014, izvirni znanstveni članek Opis: To date, only a few studies have investigated the complex microbiota of table olives in order to identify new probiotic microorganisms, even though this food matrix has been shown to be a suitable source of beneficial lactic acid bacteria (LAB). Two hundred and thirty eight LAB, belonging to Lactobacillus plantarum, Lactobacillus pentosus and Leuconostoc mesenteroides species, and isolated from Nocellara Etnea table olives, have been screened in this survey through an in vitro approach. A simulation of transit tolerance in the upper human gastrointestinal tract, together with autoaggregation and hydrophobicity, have been decisive in reducing the number of LAB to 17 promising probiotics. None of the selected strains showed intrinsic resistances towards a broad spectrum of antibiotics and were therefore accurately characterized on an undifferentiated and 3D functional model of the human intestinal tract made up of H4-1 epithelial cells. As far as the potential colonization of the intestinal tract is concerned, a high adhesion ratio was observed for Lb. plantarum O2T60C (over 9%) when tested in the 3D functional model, which closely mimics real intestinal conditions. The stimulation properties towards the epithelial barrier integrity and the in vitro inhibition of L. monocytogenes adhesion and invasion have also been assessed. Lb. plantarum S1T10A and S11T3E enhanced trans-epithelial electrical resistance (TEER) and therefore the integrity of the polarized epithelium in the 3D model. Moreover, S11T3E showed the ability to inhibit L. monocytogenes invasion in the undifferentiated epithelial model. The reduction in L. monocytogenes infection, together with the potential enhancement of barrier integrity and an adhesion ratio that was above the average in the 3D functional model (6.9%) would seem to suggest the Lb. plantarum S11T3E strain as the most interesting candidate for possible in vivo animal and human trials.
Ključne besede: antibiotics, bacteria pathogen, cell metabolism, olives, probiotics, digestion
Objavljeno v DKUM: 19.06.2017; Ogledov: 1573; Prenosov: 359
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