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1.
Valorization of biomass through anaerobic digestion and hydrothermal carbonization : integrated process flowsheet and supply chain network optimization
Sanja Potrč, Aleksandra Petrovič, Jafaru Musa Egieya, Lidija Čuček, 2025, original scientific article

Abstract: 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.
Keywords: anaerobic digestion, hydrothermal carbonization, supply chain optimization, process flowsheet optimization, mathematical programming
Published in DKUM: 07.02.2025; Views: 0; Downloads: 1
.pdf Full text (2,71 MB)

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Mathematical model-based optimization of trace metal dosage in anaerobic batch bioreactors
Tina Kegl, Balasubramanian Paramasivan, Bikash Chandra Maharaj, 2025, original scientific article

Abstract: 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.
Keywords: anaerobic digestion, batch bioreactor, methane production, model parameters calibration, active set optimization method, perturbation of model parameter, gradient based optimization, trace metals
Published in DKUM: 30.01.2025; Views: 0; Downloads: 2
.pdf Full text (4,66 MB)

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Improvement of biogas production utilizing a complex anaerobic digestion model and gradient-based optimization
Tina Kegl, Breda Kegl, Marko Kegl, 2024, original scientific article

Abstract: : 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.
Keywords: additives, anaerobic digestion, approximation method, BioModel, complex substrate, gradient-based optimization, process conditions
Published in DKUM: 12.03.2024; Views: 298; Downloads: 27
.pdf Full text (7,33 MB)
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5.
Building of mini digester for mesophilic anaerobic digestion
Bogomir Muršec, Peter Vindiš, 2009, professional article

Abstract: 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.
Keywords: mini digester, mesophilic anaerobic digestion, organic wastes
Published in DKUM: 11.07.2017; Views: 1779; Downloads: 116
.pdf Full text (493,38 KB)
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6.
Biogas as a renewable energy source
Matjaž Ošlaj, Bogomir Muršec, 2010, review article

Abstract: 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.
Keywords: anaerobic digestion, biogas, manure, renewable energy
Published in DKUM: 11.07.2017; Views: 1786; Downloads: 113
.pdf Full text (194,11 KB)
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