The human colon is an anaerobic environment densely populated with bacterial species, creating what is known as the human intestinal microbiome; an ecosystem imperative to physiological function with regards to metabolism of non-digestible residues, growth of cells and immune protection from invading organisms. As such, quantifying, and subsequently developing an understanding of the behaviour of this microbial population can be of great value. Unfortunately, because of the physical inaccessibility of many parts of the gastro-intestinal (GI) tract, routine experimentation with this environment is not practical. However, theoretical modelling techniques including in vitro and in silico simulation/experimental platforms provide a means by which further studying of intestinal microflora can be approached. Perfecting these theoretical models is an important step in further understanding colon microbiota. An existing in silico model of carbohydrate digestion in the colon, developed by Munoz-Tamayo et al. (2010) has been used as a platform for experimentation with the intention of of discovering features which may be removed and/or added to improve the performance and reliability of the design. The model is an adaptation of the waste-water engineering based mathematical model ADM1 (Anaerobic Digestion Model 1), developed to incorporate biochemical and environmental specifications as well as physical structures particular to the human colon. The model is then a system of 102-ordinary differential equation with 66 parameters.Simulations with the default model configuration as well as variations of input variables, namely dietary fiber consumption and system flow rate, were completed to study the effect on average biomass concentration, demonstrating significant sensitivity to input variables and an unexpected linearity based on the non-linearity of the original complex system. Simulations and further study suggest that advancements in in silico modelling of the colon rely on the development of a metric or scheme that can effectively compare mathematically generated data with that collected through traditional experimentation. Also, experimenting with various reactor configurations as a basis for mathematical modelling may prove simpler configurations capable of generating comparable data to more complicated designs which may then also be applicable to existing in vitro representations of the colon.

La valorisation des déchets par digestion anaérobie conduit à la production d’un résidu, appelé digestat, qui est composé de la matière organique non biodégradée et présente une forte teneur en azote ammoniacal et organique. De par cette richesse en azote, les digestats présentent un intérêt grandissant pour la substitution aux engrais minéraux. L’objectif de cette thèse est de comprendre les transformations de l’azote en digestion anaérobie afin de prédire la qualité azotée des digestats. Cette compréhension des processus de transformation de l’azote ouvrira la possibilité de dimensionner et piloter le procédé de digestion anaérobie pour une substitution optimisée des engrais minéraux par les digestats. Pour cela, deux approches ont été développées: (i) une approche compréhensive centrée sur la compréhension de la bioaccessibilité de l’azote organique en lien avec sa biodégradabilité, et la compréhension des transformations de l’azote en digestion anaérobie en conditions de laboratoire et pilote; et ; (ii) une approche numérique où les processus identifiés ont été intégrés à des outils de modélisation à bases statistiques et biocinétiques permettant de prédire les propriétés azotées des digestats en fonction des cocktails de substrats et du temps de séjour dans le digesteur. / Energetic recovery of waste by anaerobic digestion leads to the production of a residue called digestate, which is composed of non-biodegraded organic matter and has a high content of ammoniacal and organic nitrogen. Due to this high nitrogen content, digestates are growing interest for the substitution of mineral fertilizers. The objective of this thesis is to understand the transformations of nitrogen that occur during anaerobic digestion in order to predict the nitrogen quality of digestates. This understanding of nitrogen transformation processes will allows the design and management of anaerobic digestion plants aiming at the optimization of the substitution of mineral fertilizers by digestates. To this end, two approaches were used in this work: (i) an experiment approach focused on the understanding of the bioaccessibility of organic nitrogen in relation to its biodegradability, and the understanding of the transformations of nitrogen in anaerobic digestion under laboratory and pilot conditions; and; (ii) a numerical approach where previously developed knowledge has been integrated in statistical and biokinetic modeling tools to predict the nitrogen properties of digestates according to substrate cocktails and residence time in the digester.

Primeiramente, esse trabalho pretende esclarecer a importância de pesquisas em modelagem, simulação e controle nos processos de tratamento de efluentes e apontar o atraso do Brasil nesta área de pesquisa comparado ao avanço das iniciativas internacionais. O trabalho apresenta o problema específico da modelagem dos processos anaeróbios e propõe uma nova ferramenta de simulação de regime permanente para esses sistemas, desde digestores de lodo a reatores UASB. O simulador se baseia no ADM1 (Anaerobic Digestion Model No 1), modelo proposto pela IWA em 2002, e está implementado em C++. A intenção é disponibilizar livremente um software de simulação com o diferencial de uma metodologia e interface gráfica amigável, capaz de trazer para o dia-a-dia do profissional da área toda a sofisticação de uma modelagem mais completa, tanto do ponto de vista microbiológico como físico-químico. A metodologia proposta se mostrou muito eficiente para a obtenção da condição de regime permanente, fazendo com que a caracterização do afluente se tornasse a etapa limitante do processo de simulação. O método desenvolvido é tão eficaz que permite que sejam realizadas simulações com afluentes e reatores hipotéticos, tornando possível estudos desvinculados da necessidade de análises laboratoriais complexas ou fora do comum. / First, this work intends to show the importance of research in modeling, simulation and control of wastewater treatment processes, and to point the delay of our country (Brazil) in this subject, compared to the advance of the international initiatives. This work presents the specific problem of modeling the anaerobic digestion and proposes a new tool to simulate the steady state condition in anaerobic reactors. The simulator is based on the ADM1 (Anaerobic Digestion Model No 1), developed by IWA in 2002, and is implemented in C++. The intention is to give free access to a new simulation software with the advantages of better methodology and friendly graphical interface. This tool should be able to bring to the professionals all the sophistication of a more complete modelling in the microbiological and physical-chemical point of view. The developed methodology revealed itself to be very efficient for the attainment of the steady state condition. Consequently, it makes the characterization of the influent the critic stage of the simulation process. The developed method is so efficient that allows simulation studies to be carried out using hypothetical influents and reactors. Thus, it brings independence for simulation studies with no need of complex or unusual laboratorial analyses.

Primeiramente, esse trabalho pretende esclarecer a importância de pesquisas em modelagem, simulação e controle nos processos de tratamento de efluentes e apontar o atraso do Brasil nesta área de pesquisa comparado ao avanço das iniciativas internacionais. O trabalho apresenta o problema específico da modelagem dos processos anaeróbios e propõe uma nova ferramenta de simulação de regime permanente para esses sistemas, desde digestores de lodo a reatores UASB. O simulador se baseia no ADM1 (Anaerobic Digestion Model No 1), modelo proposto pela IWA em 2002, e está implementado em C++. A intenção é disponibilizar livremente um software de simulação com o diferencial de uma metodologia e interface gráfica amigável, capaz de trazer para o dia-a-dia do profissional da área toda a sofisticação de uma modelagem mais completa, tanto do ponto de vista microbiológico como físico-químico. A metodologia proposta se mostrou muito eficiente para a obtenção da condição de regime permanente, fazendo com que a caracterização do afluente se tornasse a etapa limitante do processo de simulação. O método desenvolvido é tão eficaz que permite que sejam realizadas simulações com afluentes e reatores hipotéticos, tornando possível estudos desvinculados da necessidade de análises laboratoriais complexas ou fora do comum. / First, this work intends to show the importance of research in modeling, simulation and control of wastewater treatment processes, and to point the delay of our country (Brazil) in this subject, compared to the advance of the international initiatives. This work presents the specific problem of modeling the anaerobic digestion and proposes a new tool to simulate the steady state condition in anaerobic reactors. The simulator is based on the ADM1 (Anaerobic Digestion Model No 1), developed by IWA in 2002, and is implemented in C++. The intention is to give free access to a new simulation software with the advantages of better methodology and friendly graphical interface. This tool should be able to bring to the professionals all the sophistication of a more complete modelling in the microbiological and physical-chemical point of view. The developed methodology revealed itself to be very efficient for the attainment of the steady state condition. Consequently, it makes the characterization of the influent the critic stage of the simulation process. The developed method is so efficient that allows simulation studies to be carried out using hypothetical influents and reactors. Thus, it brings independence for simulation studies with no need of complex or unusual laboratorial analyses.

Τα απόβλητα των ελαιοτριβείων αποτελούν ένα από τα σημαντικότερα περιβαλλοντικά προβλήματα της Μεσογείου, λόγω της άκριτης διάθεσης τους. Είναι χαρακτηριστικό ότι, περίπου το 95% της παγκόσμιας παραγωγής ελαιόλαδου παράγεται από μικρές, οικογενειακές επιχειρήσεις Μεσογειακών χωρών. Στόχος της παρούσας διατριβής ήταν η βιοτεχνολογική αξιοποίηση των αποβλήτων των ελαιοτριβείων για την αναερόβια παραγωγή υδρογόνου. Ειδικότερα, μελετήθηκε η δυνατότητα παραγωγής υδρογόνου σε μεσόφιλες συνθήκες από το ημι-στερεό υπόλειμμα διφασικών ελαιοτριβείων (ελαιοπολτός ή olive pulp) και από τα υγρά απόβλητα τριφασικών ελαιοτριβείων (OMW) με χρήση μικτής αναερόβιας καλλιέργειας μικροοργανισμών. Τα απόβλητα αραιώθηκαν με νερό βρύσης σε αναλογία όγκων 1:4 αντίστοιχα, ώστε να καταστεί δυνατή η βιολογική επεξεργασία τους. Πειράματα σε αντιδραστήρες τύπου CSTR κατέδειξαν ότι, η συνεχής μεσόφιλη αναερόβια παραγωγή υδρογόνου είναι εφικτή τόσο από αραιωμένο ελαιοπολτό (1:4) όσο και από αραιωμένο απόβλητο OMW (1:4). Η απόδοση της συνεχούς διεργασίας σε υδρογόνο από αραιωμένο ελαιοπολτό (1:4) προσδιορίστηκε μικρότερη από τη μέγιστη θεωρητική απόδοση (4 mol H2/mol γλυκόζης που καταναλώθηκε) πιθανότατα λόγω της αρνητικής επίδρασης της μερικής πίεσης του υδρογόνου. Στα πλαίσια αξιοποίησης των πειραματικών αποτελεσμάτων της παρούσας διατριβής το μαθηματικό μοντέλο αναερόβιας χώνευσης ADM1 τροποποιήθηκε κατάλληλα, ώστε να καταστεί δυνατή η περιγραφή της αναερόβιας παραγωγής υδρογόνου. Αρχικά, όλες οι κρίσιμες παράμετροι του μοντέλου προσδιορίστηκαν από τα πειραματικά δεδομένα της συνεχούς αναερόβιας παραγωγής υδρογόνου από αραιωμένο ελαιοπολτό (1:4), ενώ πειράματα διαλείποντος έργου πραγματοποιήθηκαν για την επαλήθευσή τους. Προκειμένου να εξεταστεί η εγκυρότητα του τροποποιημένου μοντέλου και η δυνατότητα αξιόπιστης περιγραφής της αναερόβιας παραγωγής υδρογόνου από απόβλητα ελαιοτριβείων, το μοντέλο χρησιμοποιήθηκε για την περιγραφή της αναερόβιας επεξεργασίας του αραιωμένου αποβλήτου OMW (1:4) με στόχο την παραγωγή υδρογόνου. Στη συνέχεια, αναπτύχθηκαν και εφαρμόστηκαν μέθοδοι προεπεξεργασίας του αραιωμένου ελαιοπολτού (1:4) (φυσικοχημικές μέθοδοι και ενζυμική υδρόλυση) με κύριο στόχο την αύξηση της συγκέντρωσης των διαλυτών υδατανθράκων του, ενώ στις περιπτώσεις που αυτό επιτεύχθηκε, διερευνήθηκε η επίδραση τους στην απόδοση της διεργασίας σε υδρογόνο. Η προσπάθεια αυτή βασίστηκε στο συμπέρασμα που προέκυψε από πειράματα διαλείποντος έργου, σύμφωνα με τα οποία, οι αδιάλυτοι υδατάνθρακες συνεισέφεραν ελάχιστα στην αναερόβια παραγωγή υδρογόνου με την εκατοστιαία κατά βάρος περιεκτικότητα τους να αντιστοιχεί περίπου στο 50% της περιεκτικότητας του αποβλήτου σε ολικούς υδατάνθρακες. Μεταξύ των φυσικοχημικών μεθόδων που εφαρμόστηκαν (προσθήκη αλκαλικού μέσου, οζονισμός, επεξεργασία με ατμό) ως βέλτιστη μέθοδος επιλέχθηκε η επεξεργασία με ατμό (1 bar, 121oC) για 60 min, καθώς οδήγησε στο μεγαλύτερο ποσοστό αύξησης των διαλυτών υδατανθράκων (περίπου 26% επί της αρχικής τους συγκέντρωσης), με το μικρότερο δυνατό οικονομικό κόστος, αυξάνοντας την απόδοση της διεργασίας σε υδρογόνο περίπου κατά 45% (εκφρασμένη ως mL Η2/g διαλυτών υδατανθράκων που καταναλώθηκαν). Τα εμπορικά διαλύματα ενζύμων Celluclast 1.5L (διάλυμα ενδο-β-γλυκανάσης) και Novozyme 188 (διάλυμα β-γλυκοσιδάσης) χρησιμοποιήθηκαν για την ενζυμική υδρόλυση του αραιωμένου ελαιοπολτού (1:4). Συμπερασματικά, πειράματα διαλείποντος έργου κατέδειξαν ότι, η απόδοση της αναερόβιας διεργασίας παραγωγής υδρογόνου από αραιωμένο ελαιοπολτό (1:4) καθίσταται βέλτιστη με την προσθήκη μόνο Celluclast 1.5L σε συγκέντρωση 50 FPU/g αδιάλυτων υδατανθράκων υποστρώματος και σε αναλογία όγκων υποστρώματος/μαγιάς μικροοργανισμών (S/X) ίση με 1 σε διεργασία ενός σταδίου. Τέλος, μελετήθηκε η επίδραση της προσθήκης του ενζύμου Celluclast 1.5L στην απόδοση της συνεχούς διεργασίας παραγωγής υδρογόνου από αραιωμένο ελαιοπολτό (1:4) στον αντιδραστήρα τύπου CSTR. / Olive mill wastes constitute one of the most important environmental problems of Mediterranean region, because of their thoughtless disposal. It is characteristic that, approximately 95% world’s olive oil production is derived from small, familiar enterprises which are mainly located in Mediterranean countries. The biotechnological exploitation of olive mill wastes for anaerobic hydrogen production was the aim of this thesis. In details, the possibility of hydrogen production from semi-solid residue derived from two-phase centrifugation process (olive pulp) and olive mill wastewater derived from three-phase centrifugation process (OMW) was examined with mixed anaerobic cultures under mesophilic conditions. The wastes were previously diluted with tap water (1:4), in order to be susceptible for biological treatment. Various experiments in CSTR type reactors showed that, the continuous mesophilic anaerobic hydrogen production is feasible from diluted olive pulp (1:4) and diluted OMW (1:4) as well. The potential of hydrogen production from diluted olive pulp (1:4) was lower than the maximum theoretical potential (4 mol H2/mol consumed glucose) probably due to the negative effect of partial pressure of hydrogen. The anaerobic digestion model No 1 (ADM1) was properly modified in order to describe the anaerobic hydrogen production. All the model’s critical parameters were determined by fitting the experimental data of continuous anaerobic hydrogen production from diluted olive pulp (1:4), while batch experiments were conducted for their verification. In order to examine the validity and the reliability of the modified model for the description of anaerobic hydrogen production from various types of olive mill wastes, it was also tested in the case of diluted ΟMW (1:4) anaerobic treatment. Pretreatment methods of diluted olive pulp (1:4) were developed and evaluated (physicochemical methods and enzyme hydrolysis) targeting to the increase of soluble carbohydrates available concentration, while in the cases where this was achieved the effect on hydrogen potential was investigated. This attempt was based on the conclusion derived from batch experiments, indicated that, the non-soluble carbohydrates contribute to anaerobic hydrogen production only to a very small extent, with their concentration correspond approximately to 50% of waste content in total carbohydrates. Among the physicochemical methods that were applied (addition of alkaline solution, ozonation, treatment with steam), the treatment with steam (1 bar, 121oC) for 60 min was selected as the optimum method, because the achieved increase in soluble carbohydrates concentration was the highest (about 26%) with the least economic cost. The potential of anaerobic hydrogen production was increased approximately 45% (expressed as mL H2/g soluble carbohydrates consumed). Two commercial enzyme solutions, Celluclast 1.5L (endo-β-glucanase) and Novozyme 188 (β-glucosidase), were used for the enzymatic hydrolysis of diluted olive pulp (1:4). Conclusively, the potential of anaerobic hydrogen production from diluted olive pulp (1:4) was optimum with the addition of Celluclast 1.5L (50 FPU/g non soluble carbohydrates from substrate) and substrate/mixed culture volume ratio (S/X) equal to 1 in one stage process (Simultaneous Saccharification and Fermentation, SSF) Finally, enzyme (Celluclast 1.5L) was added into the CSTR-type reactor in order to determine the effect in the potential of anaerobic hydrogen production from diluted olive pulp (1:4).

I takt med att städerna växer ökar belastningen på de kommunala avloppsreningsverken. Käppalaförbundet förutspår att antalet anslutna personekvivalenter till Käppalaverket kommer att öka med över 160 % under de kommande tre decennierna. En ökad belastning leder till en större mängd slam som måste behandlas. Detta görs idag med stabilisering genom mesofil rötning samt efterföljande avvattning och hygienisering. Samtidigt finns ett behov av hållbara energikällor i samhället, dit avloppsreningsverken bidrar genom tillhandahålla energirik biogas som biprodukt från rötningen.  Utrötningsgraden är beroende av slammets uppehållstid i rötkammaren och uppehållstiden kommer att bli kortare i takt med att belastningen ökar. Termofil rötning har identifierats som ett möjligt alternativ till inköp av ytterligare rötkammarvolym då metoden har rapporterats ge en snabbare stabilisering och därmed ett likvärdig resultat med kortare uppehållstid. Dessutom finns indikationer för att termofil rötning kan producera en större mängd biogas per enhet organiskt material i jämförelse med mesofil rötning. För att utreda huruvida Käppalaförbundet kan åtnjuta dessa fördelar har ett termofilt rötningsförsök bedrivits i pilotskala.  Pilotanläggningen bestod av en 5 m³ rötkammare som matades semikontinuerligt med 65 mass% primärslam och 35 mass% överskottsslam. Försöket inleddes med en temperaturövergång från en mesofil ymp till termofila betingelser, följt av att processen tilläts acklimatisera. Processen drevs därefter under tre uppehållstider med en längd på 18 dygn vardera. Samtliga driftparametrar härleddes i den mån det var möjligt från fullskalig slambehandling på Käppalaverket. De experimentella resultaten jämfördes med simuleringsresultat baserade på den matematiska modellen Anaerobic Digestion Model No. 1. Temperaturövergången och acklimatiseringen utfördes med framgång. Vid referensbelastningen var utrötningsgraden 54.4 % och den specifika metanproduktionen var 0.221 Nm3 CH4/kgVS, vilket var otillräckligt för att överträffa den mesofila, fullskaliga processen. Försöket indikerade att proteiner bryts ned lättare i en termofil process. Vidare observerades avtagande processtabilitet och försämrade avvattningsegenskaper hos rötresten. / As cities grow, the load on the municipal wastewater treatment plants increases. The Käppala Association predicts that the number of population equivalents connected to the Käppala Wastewater Treatment Plant will increase by over 160 % in the coming three decades. An increased load leads to a larger amount of sludge that must be treated. This is done today with stabilization through mesophilic anaerobic digestion and subsequent dewatering and hygienization. At the same time, there is a need for sustainable energy sources in society, to which wastewater treatment plants contribute by providing energy-rich biogas as a by-product from the anaerobic digestion. The degree of digestion is dependent on the retention time of the sludge in the digester and the retention time will become shorter as the load increases. Thermophilic anaerobic digestion has been identified as a possible alternative to the investment of additional digester volume as the method has been reported to provide a faster stabilization and thus an equivalent result with a shorter retention time. In addition, there are indications that thermophilic anaerobic digestion is able to produce a larger amount of biogas per unit of organic material in comparison with mesophilic anaerobic digestion. To evaluate whether the Käppala Association can enjoy these benefits, a thermophilic anaerobic digestion experiment has been conducted on a pilot scale. The pilot plant included a 5 m³ digester which was fed semi-continuously with 65 mass% primary sludge and 35 mass% waste activated sludge. The experiment began with a temperature transition from a mesophilic inoculum to thermophilic conditions, followed by allowing the process to acclimatize. The process was operated thereafter for three retention times with a length of 18 days each. All process parameters were derived as far as possible from the full-scale sludge treatment at Käppala Wastewater Treatment Plant. The experimental results were compared with simulation results based on the mathematical model Anaerobic Digestion Model No. 1. The temperature transition and acclimatization was performed successfully. At reference load, the degree of digestion was 54.4 % and specific methane production was 0.221 Nm3 CH4/kgVS, which was not enough to overcome the mesophilic full-scale process. Indications pointed towards proteins being more easily digested in a thermophilic process. Furthermore, deteriorating process stability and dewaterability of the digestate was observed.

Uncertainty about anaerobic digestion process stability is the main issue preventing more widespread use of the process as a source of energy recovery in wastewater treatment facilities. The overall objective of this research was to study the feasibility of enhancing biogas production inside wastewater facilities using co-digestion of municipal sludge with bakery waste. Another objective was to improve the stability index and a mathematical model that can be useful tools to predict the process stability of municipal sludge digestion alone, and when it is mixed with bakery waste, as a substrate for microorganisms. Experiments were conducted in three phases. In phase 1, a full-scale anaerobic digester at Central Weber Sewer Improvement District, Ogden, UT, receiving a mixture of primary and secondary sludge, was monitored for one hundred days. Chemical oxygen demand (COD), and volatile solids (VS) mass balances were conducted to evaluate the stability of the digester and its capability of producing methane gas. The COD mass balance accounted for nearly 90% of the methane gas produced while the VS mass balance showed that 91% of the organic matter removed resulted in biogas formation. Other parameters monitored included: pH, alkalinity, VFA, and propionic acid. The values of these parameters showed that the digester was running under stable steady state conditions. At mesophilic temperature, the stability index was determined and equal to 0.40 L (CH4)/ g(ΔVS) In phase 2, the feasibility of adding BW to MS was tested in batch reactors scale. The biogas production was enhanced and the digester was stable until the range of 37- 40% of BW to 63-60% of MS. The ADM1 coefficients were modified to accurately predict the digester performance. The modified model outputs (pH, VFA, and methane) were within acceptable ranges when compared with the observed data from the batch reactors. In phase 3, the feasibility of MS and BW were tested using an Induced Bed Reactor (IBR) with a 50:50% ratio of MS:BW (COD basis). The process was stable during different hydraulic retention times and the ADM1 was modified to predict the stability of the process in the IBR.

Der Ausbau von erneuerbaren Energien hat seit 2000, durch die Einführung des Erneuerbaren Energien Gesetzes, auch im Bereich Biomasse zu einem stetigen Ausbau von Biogasanlagen geführt. Seit ca. 2014 stagniert der Ausbau, aufgrund einer Neuauflage des EEGs, in dem einige Subventionierungen wegfallen. Aus diesem Grund liegt der Fokus momentan u.a. auf der Optimierung von Biogasanlagen und der Minimierung von Störungen (Über- oder Unterfütterung, Temperaturschwankungen, Rührwerksausfall, etc.). Eines dieser Störfaktoren ist der Mangel von Spurenelementen, der häufig beim Einsatz von nachwachsenden Rohstoffen auftritt. Häufig führt dieser Mangel zu einem niedrigen pH-Wert, einem hohem FOS/TAC Verhältnis sowie einer reduzierten Methanausbeute. Bleibt solch ein Mangel unentdeckt, kann es zu einem vollständigen Prozessabsturz innerhalb der Biogasanlage kommen. Die mathematische Beschreibung von anaeroben Prozessen erfolgt bereits seit ca. 40 Jahren und bildet den Biogasprozess mittlerweile sehr gut ab, sodass auf einige Störfaktoren rückgeschlossen werden kann. Durch eine Vielzahl existierender Modelle hat die IWA Task Group ein allgemeingültiges Modell zum anaeroben Abbau entwickelt, das Anaerobic Digestion Model No. 1 (Batstone et al. 2002). Aufbauend auf dem ADM1 sind weitere Modell-erweiterungen entwickelt worden. Eine Übersicht über diese Modelle ist in (Donoso-Bravo et al. 2011) zu finden. Bisher gibt es allerdings noch keinen Modellansatz zur Beschreibung der Spurenelemente innerhalb des ADM1 bzw. dessen Erweiterungen. Die vorliegende Arbeit beschäftigt sich mit dem Einfluss der Spurenelemente auf den Biogasprozess, insbesondere im Falle einer Mangelsituation. Dabei gab es zwei Hauptziele. Das erste Hauptziel der vorliegenden Arbeit war eine mathematische Beschreibung der Umwandlungsprozesse von Spurenelemente sowie deren unterschiedliche Bindungsformen bereitzustellen. Diese Beschreibung sollte als Modellerweiterung an ein vorhandenes Modell zum anaeroben Abbau angebunden werden. Mit Hilfe dieses Modells sollte sowohl der Konzentrationsverlauf als auch die durch die Spurenelemente verursachten Auswirkungen auf den Biogasprozess abgebildet werden. Das zweite Hauptziel war die Validierung des Modells durch parallel durchgeführte Laborversuche an Reaktoren zur Untersuchung des Spurenelementmangels. Mit Hilfe der Laborversuche sind die Auswirkungen eines Spurenelementmangels nachgewiesen worden. Dabei zeigte sich nach ca. 3 Monaten Laufzeit ein reduzierter pH-Wert, ein ansteigendes FOS/TAC Verhältnis sowie eine verzögerte Biogasproduktion. Ein vollständig stabiler Prozess hat sich erst durch die Zugabe aller Spurenelemente wieder eingestellt. Gleichzeitig hat die erneute Zugabe der Spurenelemente in die Testreihen nach dem Mangel zu einer starken Schaumbildung geführt. Die mathematische Beschreibung der Umwandlungsprozesse von Spurenelemente erfolgt als eigenständiges Modell und kann an beliebige Modellansätze integriert werden. In der Arbeit ist dafür das ADM1da ausgewählt worden, um eine Beschreibung der anaeroben Prozesse zu integrieren. Gleichzeitig beinhaltet das ADM1da die Beschreibung von Mischsubstraten, sodass mit dem entwickelten Modellansatz zu jedem Substrat die spezifische Spurenelementkonzentration angegeben werden kann. Das neu entwickelte Modell beinhaltet drei wesentliche Schritte: (1) den Abbau des Substrates, indem die Spurenelemente gebunden sind, (2) die Freisetzung der Spurenelemente in den Gärschlamm und (3) die Umwandlung der einzelnen Spurenelement-Bindungsformen untereinander. Dabei sind in dem Modellansatz vier Fraktionen bezüglich der Spurenelemente integriert: (a) freie (bioverfügbare) bzw. leicht gebundene Ionen, (b) adsorbierte Ionen, (c) in Biomasse gebundene SE und (d) ausgefällte SE. Die Beschreibung einzelner Reaktionen sowie die Umwandlungen innerhalb der verschiedenen Fraktionen erfolgt über die Petersen-Matrix.:Danksagung I Inhaltsverzeichnis II Abbildungsverzeichnis IV Tabellenverzeichnis IX Abkürzungsverzeichnis XI 1 Einleitung 1 2 Kenntnisstand 4 2.1 Allgemeiner Aufbau Biogasanlagen 4 2.2 Grundlagen des anaeroben Abbaus 6 2.2.1 Biologische und chemische Prozesse 7 2.2.2 Einflussfaktoren 10 2.3 Spurenelemente 14 2.3.1 Bedarf und Folgen auf den Gärprozess 14 2.3.2 Bioverfügbarkeit von Spurenelementen 16 2.3.3 Quellen – Substrate und Zuschlagstoffe 17 2.4 Anaerobmodelle 18 2.4.1 Allgemein 18 2.4.2 ADM1 – mathematische Beschreibung der wichtigsten Prozesse 20 2.4.3 Weiterentwicklungen des ADM1 Modells 22 2.4.4 Verbesserungsmöglichkeiten am ADM1 Modell 24 2.4.5 Modellierung der Spurenelemente 26 3 Wissenschaftliche und experimentelle Methodik 29 3.1 Versuchsanlage 29 3.2 Versuchsdurchführung 31 3.3 Analysemethoden/Messtechnik 35 4 Auswertung und Diskussion der Laborversuche 38 4.1 Substratzugabe 38 4.2 Kontrollreihe 39 4.3 Testreihen mit Mangel an Spurenelementen 45 4.4 Spurenelementkonzentration innerhalb der Reaktoren 60 4.5 Test auf Signifikanz 64 5 Modellierung des Biogasprozesses unter Berücksichtigung der Spurenelemente 70 5.1 Mathematische Beschreibung des entwickelten Modellansatzes 70 5.2 Anknüpfung an das ADM1da 77 5.3 Programmtechnische Umsetzung/Implementierung 79 5.4 Anwendung des Modells anhand einer Biogasanlage 80 5.4.1 Simulation der Biogasanlage 80 5.4.2 Monovergärung von Maissilage 84 5.4.3 Substratmix zur Vermeidung eines Mangels 88 5.5 Anwendung des Modells anhand des Laborreaktors 93 5.5.1 Vergleich der Simulations- und Messdaten der Kontrollreihe 96 5.5.2 Vergleich der Simulations- und Messdaten der Testreihe 103 6 Zusammenfassung 122 7 Literaturverzeichnis 129 8 Anhang 138 8.1 Laborergebnisse Testreihe 138 8.1.1 Biogasmenge 139 8.2 Boxplot 140 8.2.1 Mangelphase 140 8.2.2 Rückführphase 141 8.3 Massenbilanzen 141 8.4 Vergleich Simulation/Messdaten – Kontrollreihe 142 8.4.1 pH-Wert 142 8.4.2 Biogasmenge 143 8.4.3 Methangehalt 143 8.5 Vergleich Simulation/Messung Testreihe 144 8.5.1 Spurenelemente 144 8.5.2 pH-Wert 146 8.5.3 FOS/TAC Verhältnis 147 8.5.4 Biogasmenge 148 8.5.5 Methangehalt 149

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Thesis (Master of Environmental Management)--Cape Peninsula University of Technology, 2018. / Fresh water is a renewable resource, but it is also finite, especially given environmental impacts from anthropogenic activities. Globally, there are countless signs that untreated industrial discharge into fresh watercourses is one of the main causes of ecosystem degradation. Poultry slaughterhouse wastewater (PSW) amongst the main pollutants of fresh water sources. In recent years, the world’s pre-eminent researchers have developed innovative wastewater treatment processes to treat the large quantity of wastewater generated as well as to manage the environmental health concerns arising from PSW discharged into the environment. Furthermore, increasing wastewater treatment capital costs and the implementation of increasingly rigorous government legislation to mitigate environmental pollution whilst minimizing fresh water source contamination, requires that wastewater such as PSW, be adequately treated prior to discharge. In order to assist the small-scale poultry producers in South Africa (SA), process simulation for a small-scale poultry slaughterhouse wastewater treatment plant was proposed using Sumo Wastewater treatment plant (WWTP) simulation software. Sumo is an innovative and most versatile wastewater simulation package on the market. The simulator is capable of modelling treatment plants of unlimited complexity, focusing largely on Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), nitrogen and phosphorus removal; with digester, and side streams design options, being available. Considering the possible advantages in modelling and ongoing studies of implementing wastewater treatment to increase water management, anaerobic digestion of high strength wastewater such as PSW, warranted this research study. Model development from the simulation included the evaluation of numerous design options to assist small scale poultry producers, to have a variety of designs to choose from in their PSW WWTP designs. With the aid of Sumo, two models were designed in this study, namely a single-stage and a two-stage anaerobic digestion without a recycle. The PSW used as feed was obtained from a local poultry slaughterhouse (Western Cape, South Africa). Both model designs predicted the reduction of the organic matter (COD, BOD5) total suspended solids (TSS), and volatile suspended solids (VSS) in the PSW. The digester for the single stage anaerobic digestion system modelled was set to operate at steady state for 150 days under mesophilic temperature (35 ˚C) with a solid retention time (SRT) of 25 days. The COD, TSS, VSS and BOD removal efficiencies reached a maximum of 64%, 77%, 84%, and 94%, respectively, at an organic load rate (OLR) of 143.6 mg COD/L/day. A minute increase in the ammonia (NH3) and phosphate (PO3- 4) concentration was observed once the simulation was completed. As for the two-stage anaerobic digestion system, both digesters were set to perform at mesophilic temperatures (35 ˚C) and a SRT of 13 days in the first digester and 25 days in the subsequent digester. The two-stage anaerobic digestion showed better performance in comparison to the single-stage anaerobic digestion system. The COD, TSS, VSS and BOD5 removal efficiencies reached a maximum of 69%, 79%, 85%, and 96%, respectively, at an at an OLR of 143.6 mg COD/L/day. A similar trend regarding phosphate and ammonia removal was noticed in the two-stage anaerobic digestion, suggesting a tertiary treatment system to be in place for further treatment. Although, the two-stage anaerobic digestion demonstrated adequate performance, for the purpose of this study, the single-stage was the process recommended for PSW treatment, as it is less costly and will be suitable for small scale poultry producers; albeit biogas production is much higher when digesters are connected in series. The PSW treatment modelling for this study was successfully employed with the resultant effluent being compliant with the City of Cape Town (CCT) wastewater and industrial effluent by-law discharge limits. Although, both the PO3- 4 and NH3 were suggested to require further monitoring. Therefore, the poultry slaughterhouse from which the PSW was obtained will be able to safely discharge the treated wastewater proposed in this research into local water bodies, i.e. rivers in the Western Cape, SA; however, the treated PSW will not be suitable for re-use as process water.