Modeliranje in večnamenska optimizacija pridobivanja energije in koristnih produktov iz organskih odpadkov na osnovi anaerobne razgradnje : doktorska disertacija

slovenian

doktorska dela

2022

anaerobic digestion   calibration of model parameters   CO2 supply network   gradient-based optimization algorithm   mechanistically inspired model   nanotechnology

Univerza v Mariboru, Fakulteta za kemijo in kemijsko tehnologijo

Technologies utilizing anaerobic digestion play an important role in reducing waste and greenhouse gas emissions into the atmosphere while simultaneously delivering energy from renewable sources. It is a complex and multifaceted topic addressed in this doctoral dissertation.This dissertation focuses on the development of a new mechanistically inspired BioModel for numerical simulation and optimization of the anaerobic digestion process of organic waste. Special attention is devoted to the determination of unknown or hard-to-determine parameters of the proposed BioModel. Novelties in the field of modeling and optimization of both, BioModel parameters and the anaerobic digestion process, represent the original contribution of this dissertation to science. These novelties are related to: (i) consideration of daily variable composition of input complex substrate and daily variable process conditions in the bioreactor; (ii) modeling of carbohydrates, lipids and proteins degradation by 3 types of hydrolytic enzymes and 13 different types of acetogenic, acidogenic and methanogenic bacteria, where various inhibitors that inhibit the growth and activity of individual bacterial species play an important role; (iii) modeling of dissociation-association, precipitation and liquid-gas mass transfer; (iv) consideration of the following biogas composition: CO2, CH4, H2, H2S, NH3 and water vapor; (v) determination of current pH without time consuming iterations; (vi) introduction of temperature and pH-dependent parameters; (vii) modeling of biological and inorganic additives activity; (viii) development of a new active set optimization procedure for parameter calibration; (ix) introduction of a gradient-based algorithm into all optimization processes. The complete computer code for modeling and optimization of the anaerobic digestion process was developed in-house in the C programming language. For the further use of CO2 from biogas and some other point sources, a conceptually simplified model was developed for the optimization of combined CO2 supply network and capture and utilization technologies by using the mixed-integer non-linear programming approach. For the further use of CH4 from biogas as a fuel in dual-fuel diesel engines, a critical analysis of the impact of the use of nanoparticles as fuel additives has been made. An analysis of nanoparticles usage as adsorbents for the removal of metals from wastewater is also presented with the aim of enabling possible removal of heavy metals and nutrients from liquid digestate.The results of numerical simulations of the anaerobic digestion process confirm the reliability of the newly developed BioModel and the efficiency of both, the newly developed procedure for parameter calibration and the engaged gradient-based optimization algorithm. Based on the research in the field of further processing of products of the anaerobic digestion process, we can conclude that an appropriate combination of anaerobic digestion technology, CO2 capture, storage and utilization, and nanotechnology, can contribute to the reduction of environmental pollution.

07.08.2023