Τα υγρά απόβλητα των ελαιοτριβείων είναι το παραπροϊόν της παραγωγικής διαδικασίας του ελαιολάδου. Η γεωργική αυτή δραστηριότητα έχει ιδιαίτερη κοινωνική και οικονομική σημασία για το πληθυσμό των ελαιοπαραγωγικών χωρών, που βρίσκονται κυρίως στη περιοχή της Μεσογείου όπου παράγεται και το 95% περίπου της παγκόσμιας παραγωγής. Τεράστιες ποσότητες αποβλήτων παράγονται κάθε ελαιοκομική περίοδο και σε συνδυασμό με τα χαρακτηριστικά τους (υψηλή συγκέντρωση σε οργανικό φορτίο και φαινολικές ενώσεις), καθιστούν τα υγρά απόβλητα ελαιοτριβείου ένα δυσεπίλυτο πρόβλημα επικίνδυνα για την απευθείας διάθεσής τους στο περιβάλλον. Στόχος της παρούσας μελέτης, ήταν ο συνδυασμός μεθόδων επεξεργασίας των υγρών απόβλητων ελαιοτριβείου. Αρχικά, με την εφαρμογή αναερόβιας χώνευσης και στη συνέχεια με τη κλασματοποίηση των αναερόβιων εκροών σε ένα σύστημα, αποτελούμενο από φίλτρα και επιλεγμένες μεμβράνες. Η αναερόβια χώνευση των αποβλήτων πραγματοποιήθηκε με το ταχύρυθμο σύστημα του περιοδικού αναερόβιου αντιδραστήρα με ανακλαστήρες. Στη συνέχεια οι αναερόβιες εκροές διοχετεύθηκαν στο σύστημα υπερδιήθησης και αντίστροφης όσμωσης προκειμένου να γίνει η κλασματοποίησή τους.Η αύξηση του ρυθμού οργανικής φόρτισης έγινε με αύξηση στο ΧΑΟ της εισροής και με μείωση του υδραυλικού χρόνου παραμονής (ΥΧΠ). Με την αύξηση του ΧΑΟ στην εισροή επήλθε εκτροπή της διεργασίας και μηδενισμός στη παραγωγή βιοαερίου Το γεγονός αυτό ήταν αποτέλεσμα της συσσώρευσης πτητικών λιπαρών οξέων στο σύστημα. Αντιθέτως, με τη μείωση του ΥΧΠ η διεργασία ήταν σταθερή και οδήγησε στη μείωση του ΥΧΠ στις 3.75 ημέρες και αύξηση του ρυθμού οργανικής φόρτισης στα 8.9 gΧΑΟ/L/d επιτυγχάνοντας μία μείωση στο ΧΑΟ της εκροής της τάξεως του 72%. Η περαιτέρω επεξεργασία των εκροών με τις μεμβράνες οδήγησε στη παραλαβή τελικού διηθήματος με λιγότερο από 0.1 g/L ΧΑΟ. Η αναερόβια χώνευση υγρών αποβλήτων ελαιοτριβείου με το περιοδικό αναερόβιο αντιδραστήρα με ανακλαστήρες ήταν σταθερή ακόμα και σε υψηλούς ρυθμούς οργανικής φόρτισης. Με την κλασματοποίηση των εκροών, παρελήφθη ένα τελικό διήθημα υψηλής ποιότητας, κατάλληλο για άρδευση και επαναχρησιμοποίηση για την αρχική αραίωση του αποβλήτου πριν την αναερόβια χωνευση. / Olive mill wastewater is the by product of olive oil production. This agricultural activity with high social and economic impact on the population of olive-producing countries, are mainly located in the Mediterranean area which approximately 95% of the world’s olive oil production is derived. It is produced seasonally in large quantities by a large number of small olive mills and the combination of their characteristics (very high organic load and phenolic compounds) are the main difficulties in finding a solution for the management of these wastewaters, which are dangerous for the environment. The aim of this study was the combined treatment of olive mill wastewater. The anaerobic digestion of the olive mill wastewaters took place in a high rate system, the periodic anaerobic baffled reactor. Application of the membrane system aimed at purifying the anaerobic effluent.An increase in the organic loading rate was achieved by increasing the influent COD and alternatively by decreasing the hydraulic retention time (HRT). The first option caused process failure, since the volatile fatty acids accumulation resulted in negligible biogas production. In contrast, the second change led to stable operation that permitted the reduction of the HRT to 3.75 d and increase of the organic loading rate to 8.9 gCOD/L/d with satisfactory total COD removal 72%. Further purification in the membrane units resulted in a final permeate of less than 0.1 gCOD/L. The anaerobic digestion of olive mill wastewater in a PABR was stable even at high organic loading rates. Filtering and membrane fractionation of the anaerobic effluent resulted in a final permeate stream of high quality, suitable for irrigation and reuse for diluting the wastewater prior to anaerobic digestion.

Nanotechnology is an increasing market. Engineered nanoparticles (NPs), materials with at least one dimension between 1 and 100 nm, are produced on a large scale. NPs are vastly used in industrial processes and consumer products and they are most likely discharged into wastewater treatment plants after being used. Activated Sludge is one of the most applied biological wastewater treatment processes for the degradation of organic matter in sewage. Activated sludge produces an excess of sludge that is commonly treated and stabilized by anaerobic digestion. Recent studies have found that NPs accumulate in the activated sludge; thus, there is a potential for the concentrations of NPs to magnify as concentrated waste sludge is fed into the anaerobic digestion process. For this reason, it is important to study the possible toxic effects of NPs on the microorganisms involved in the anaerobic digestion process and the approaches to overcome toxicity if necessary. The present work evaluates the toxic effect of NPs on anaerobic wastewater treatment processes and also presents approaches for toxicity attenuation. The first objective of this dissertation (Chapter III) was to evaluate the toxicity of high concentrations (1, 500 mg L⁻¹) of Ag⁰, Al₂O₃, CeO₂, Cu⁰, CuO, Fe⁰, Fe₂O₃, Mn₂O₃, SiO₂, TiO₂, and ZnO NPs to acetoclastic and hydrogenotrophic methanogens and the effect of a dispersant on the NPs toxicity to methanogens. The findings indicated that only Cu⁰ and ZnO NPs caused severe toxicity to hydrogenotrophic methanogens and Cu⁰, CuO, and ZnO NPs to acetoclastic methanogens. The dispersant did not impact the NPs toxicity. The concentrations of Cu⁰ and ZnO causing 50% of inhibition (IC₅₀) to hydrogenotrophic methanogens were 68 and 250 mg L⁻¹, respectively. Whereas the IC₅₀ values for acetoclastic methanogens were 62, 68, and 179 for Cu⁰, ZnO, and CuO-Cu NPs respectively. These findings indicate that acetoclastic methanogens are more sensitive to NP toxicity compared to hydrogenotrophic methanogens and that Cu⁰ and ZnO NPs are highly toxic to both. Additionally, it was observed that the toxicity of any given metal was highly correlated with its final dissolved concentration in the assay irrespective of whether it was initially added as a NP or chloride salt, indicating that corrosion and dissolution of metals from NPs may have been responsible for the toxicity. The second objective of this dissertation (Chapter IV) was to evaluate the Cu⁰ NP toxicity to anaerobic microorganisms of wastewater treatment processes. Cu⁰ is known to be toxic to methanogens; nonetheless, little is known about its toxic effects on microorganisms of upper trophic levels of anaerobic digestion or other anaerobic process used for nitrogen removal. This specific objective evaluated Cu⁰ NP toxicity to glucose fermentation, syntrophic propionic oxidation, methanogenesis, denitrification and anaerobic ammonium oxidation (anammox). Chapter IV showed that anammox and glucose fermentation were the least and most inhibited processes with inhibition constants (K(i)) values of 0.324 and 0.004 mM of added Cu⁰ NPs, respectively. The Ki values obtained from the residual soluble concentration of the parallel experiments using CuCl₂ indicated that Cu⁰ NP toxicity is most likely caused by the release of soluble ions for each one of the microorganisms tested. The results taken as a whole demonstrate that Cu⁰ NPs are toxic to a variety of anaerobic microorganisms of wastewater treatment processes. The third objective of this document (Chapter V) was to study the role of biogenic sulfide in attenuating Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Previous literature results and research presented in this dissertation indicated that the release of soluble ions from Cu and ZnO NPs cause toxicity to methanogens. In the past, the application of sulfide to precipitate heavy metals as inert non-soluble sulfides was used to attenuate the toxicity of Cu and Zn salts. Building on this principle, Chapter V evaluated the toxicity of Cu⁰ and ZnO NPs in sulfate-containing (0.4 mM) and sulfate-free conditions. The results show that Cu⁰ and ZnO were 7 and 14x less toxic in sulfate-containing than in sulfate-free assays as indicated by the differences in K(i) values. The K(i) values obtained based on the residual metal concentration of the sulfate-free and sulfate-containing assays were very similar, indicating that the toxicity is well correlated with the release of soluble ions. Overall, this study demonstrated that biogenic sulfide is an effective attenuator of Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Finally, the last objective (Chapter VI) of this dissertation was to evaluate the effect of iron sulfide (FeS) on the attenuation of Cu⁰ and ZnO toxicity to acetoclastic methanogens. FeS is formed by the reaction of iron(II) and sulfide. This reaction is common in anaerobic sediments where the reduction of iron(III) to iron(II) and sulfate to sulfide occurs. FeS plays a key role controlling the soluble concentrations of heavy metals and thus their toxic effects in aquatic sediments. This study evaluated the application of FeS as an approach to attenuate Cu⁰ and ZnO NP toxicity and their salt analogs to acetoclastic methanogens. Two particle sizes, coarse FeS (FeS-c, 500-1200 µm) and fine FeS (FeS-f, 25-75 µm) were synthesized and used in this study. The results showed 2.5x less FeS-f than FeS-c was required to recover the methanogenic activity to the same extent from the exposure to highly inhibitory concentrations of CuCl₂ and ZnCl₂ (0.2 mM). The results also showed that a molar ratio of FeS-f/Cu⁰, FeS-f/ZnO, FeS-f/Zn Cl₂, and FeS-f/CuCl₂ of 3, 3, 6, and 12 respectively, was necessary to provide a high recovery of methanogenic activity (>75%). The excess of FeS needed to overcome the toxicity indicates that not all the sulfide in FeS was readily available to attenuate the toxicity. Overall, Chapter VI demonstrated that FeS is an effective attenuator of the toxicity of Cu⁰ NP and ZnO NPs and their salt analogs to methanogens, albeit molar excesses of FeS were required.

The present study aimed to investigate the methane yield from anaerobic digestion of a lignocellulosic substrate subjected to different pretreatments. The lignocellulosic forest residues materials were milled and then pretreated with the organic solvent NMMO (N-Methylmorpholine N-oxide) and/or the lignolytic enzymes laccase and versatile peroxidase at a dosage of 60 U g-1 total solids (TS) substrate. The amount of methane produced was studied in a biomethane potential assay with inocula from a thermophilic biogas reactor treating municipal waste. All samples were run in triplicates. Due to the large amount of samples, two biomethane potential assays were conducted: series 10 & 20 and series 30 & 40. The gas production results show that NMMO-treated forest residues yielded 130 NmL CH4 g-1 volatile solids (VS) substrate and the untreated forest residues yielded 95 NmL CH4 g-1 VS substrate for series 10 & 20. For series 30 & 40, both untreated and NMMO-treated forest residues yielded 140 NmL CH4 g-1 VS substrate. NMMO-treatment appears to be favourable and no advantages from the enzyme pretreatment could be seen in terms of gas yield. An analysis of the reaction fluid after the enzymatic treatment showed presence of phenols, an indication of successful lignin hydrolysis. / Studien avsåg att undersöka metanutbytet från anaerob nedbrytning med förbehandlad lignocellulosa som substrat. Lignocellulosamaterialet, i form av skogsavfall, maldes och förbehandlades därefter med det organiska lösningsmedlet NMMO (N-metylmorfolin-N-oxid) och/eller de lignolytiska enzymerna laccase och versatile peroxidas med dosen 60 U g-1 torrsubstanshalt (TS). Mängden producerad metan undersöktes i en biometanpotentialanalys med inocula från en termofil biogasreaktor, som behandlade hushållsavfall. Triplikat av varje prov användes för att öka den statistiska stabiliteten. På grund av det stora antalet prover genomfördes studien i två omgångar: Serie 10 & 20 samt serie 30 & 40. Resultaten visade att det NMMO-behandlade skogsavfallet gav 130 NmL CH4 g-1 organisk substans (VS) och det obehandlade skogsavfallet gav 95 NmL CH4 g-1 VS i serie 10 & 20. Både obehandlat och NMMO- behandlat skogsavfall gav 140 NmL CH4 g-1 VS i serie 30 & 40. Förbehandling med NMMO verkar vara fördelaktig medan enzymbehandling endast resulterade i en smärre ökning av gasproduktionen. En analys av vätskan efter enzymbehandlingen visade förekomst av fenoler, vilket visar på en lyckad ligninnedbrytning.

This study aims to undertake a comprehensive analysis of different waste management systems for the wastes produced in Östersund municipality of Sweden with an impact assessment limited to greenhouse gas emissions and their total environmental effects in terms of global warming potential, acidification potential, and eutrophication potential. A life cycle assessment methodology is used by integrating knowledge from waste collection, transportation, waste management processes and the product utilization. The analytical framework included the definition of functional unit, system boundaries, complimentary system design, waste management, and partial use of the energy. Three different municipal solid waste management scenarios, incineration, composting, and digestion were considered for the study. All wastes from Östersund municipality were classified into biodegradable and combustible and thereafter treated for energy and compost production. Greenhouse gas emissions and total environmental impacts were quantified and evaluated their corresponding benefits compared to three different types of marginal energy production system. The results showed that the major greenhouse gas carbon dioxide and nitrous oxide emissions are greater in composting scenario, whereas methane emission is greater in digestion scenario. Composting scenario that uses additional coal fuel has greater global warming potential and acidification potential compared to other scenarios. Composting scenario using wood fuel additional energy has greater eutrophication potential. The highest reduction in global warming potential is achieved when digestion scenario replace coal energy. The greater reduction in acidification and eutrophication potential achieved when digestion scenario replaced coal energy, and wood fuel respectively. Based on the assumptions made, digestion scenario appears to be the best option to manage solid waste of Östersund municipality if the municipality goal is to reduce total environmental impact. Although there may have plentiful of uncertainties, digestion and incineration scenario results are competitive in reducing environmental effects, and based on the assumptions and factors used for the analysis, the results and conclusions from this study appear to be strong. Key words: Solid waste, incineration, composting, digestion, total environmental effect, wood fuel, biogas.

Bluberries (Vaccinium sp.) are rich in polyphenols that are responsible for lowering the risk of developing several chronic degenerative diseases. However, the effect of food matrix interactions on the bioaccessibility and bioavailability of polyphenols is not well understood. In this research free and complexed polyphenols found in blueberry extracts were characterized and their antioxidant activity as well as antiproliferative activities against colon cancer cells (HT-29) and normal colon cells (CRL-1790) were evaluated. The blueberry food matrix and different carbohydrate-rich synthetic matrices were characterized and their biological activities assessed alone and in complexed state with polyphenols. The degradation of polyphenols during their transit through the gastrointestinal tract (GIT) was evaluated using an in vitro digestion model. Biological activities of blueberry polyphenols and their parent metabolites produced during colonic fermentation were estimated by in vitro antioxidant assays and cell proliferation analysis using HT-29 and CRL-1790 cell lines. HPLC analysis revealed the presence of 7 phenolic compounds and 13 anthocyanins in all samples. Although the concentration of the polyphenols varied among the samples, free and complexed polyphenols showed significant antioxidant and antiproliferative activities. Polyphenol complexes were analyzed using transmission electron microscopy (TEM) revealing the presence of electron dense complexes ranging from 100 – 200 nm. Pectinase treatment disrupted the structure of the complexes, suggesting the pectin nature of the polyphenol complexes. The antioxidant- and antiproliferative activities of the blueberry food matrix alone was below 10% compared to almost 90% and 70% of free and complexed polyphenols, respectively. Polyphenols and anthocyanins were highly stable during simulated gastric digestion step with approximately 93% and 99% of recovery, respectively. The intestinal digestion process decreased the polyphenol- and anthocyanin- contents by 49% and 15 % respectively. During colonic digestion, the complex polyphenol mixtures were degraded to a limited number of phenolic compounds. Only acetylated anthocyanins were detected in low amounts after the colonic digestion process. After simulated colonic digestion, the isolated catabolites showed lowered antioxidant activity and cell growth inhibition potential. Understanding the interactions that occur among polyphenols and different food matrices may help to produce more stable foods with better bioavailability. / The National Council of Science and Technology of Mexico (CONACYT)

La cellulose et ses dérivés sont utilisés dans un vaste nombre d’applications incluant le domaine pharmaceutique pour la fabrication de médicaments en tant qu’excipient. Différents dérivés cellulosiques tels que le carboxyméthylcellulose (CMC) et l’hydroxyéthylcellulose (HEC) sont disponibles sur le commerce. Le degré de polymérisation et de modification diffèrent énormément d’un fournisseur à l’autre tout dépendamment de l’origine de la cellulose et de leur procédé de dérivation, leur conférant ainsi différentes propriétés physico-chimiques qui leurs sont propres, telles que la viscosité et la solubilité. Notre intérêt est de développer une méthode analytique permettant de distinguer la différence entre deux sources d’un produit CMC ou HEC. L’objectif spécifique de cette étude de maitrise était l’obtention d’un profil cartographique de ces biopolymères complexes et ce, par le développement d’une méthode de digestion enzymatique donnant les oligosaccharides de plus petites tailles et par la séparation de ces oligosaccharides par les méthodes chromatographiques simples. La digestion fut étudiée avec différents paramètres, tel que le milieu de l’hydrolyse, le pH, la température, le temps de digestion et le ratio substrat/enzyme. Une cellulase de Trichoderma reesei ATCC 26921 fut utilisée pour la digestion partielle de nos échantillons de cellulose. Les oligosaccharides ne possédant pas de groupements chromophores ou fluorophores, ils ne peuvent donc être détectés ni par absorbance UV-Vis, ni par fluorescence. Il a donc été question d’élaborer une méthode de marquage des oligosaccharides avec différents agents, tels que l’acide 8-aminopyrène-1,3,6-trisulfonique (APTS), le 3-acétylamino-6-aminoacridine (AA-Ac) et la phénylhydrazine (PHN). Enfin, l’utilisation de l’électrophorèse capillaire et la chromatographie liquide à haute performance a permis la séparation des produits de digestion enzymatique des dérivés de cellulose. Pour chacune de ces méthodes analytiques, plusieurs paramètres de séparation ont été étudiés. / Cellulose and its derivatives are used in a wide range of applications, including the pharmaceutical industry for the manufacturing of medicines as inactive additives. Various cellulosic derivatives such as carboxymethylcellulose (CMC) and hydroxyethylcellulose (HEC) are readily available for such use. The degree of polymerization and modification differs from one supplier to the other, according to the origin of the cellulose and its process of chemical modification, conferring on them different physico-chemical properties, such as viscosity and solubility. Our interest is to develop an analytical method that can distinguish between different sources of a given CMC or HEC product. The specific objective of this master’s study was to obtain a fingerprint of these complex biopolymers by developing an enzymatic digestion method to produce smaller oligosaccharides that could be separated by simple chromatographic methods. The digestion was studied as a function of various parameters, such as the composition of the hydrolysis solution, the pH, the temperature, the duration of digestion and the substrate/enzyme ratio. A cellulase enzyme from Trichoderma reesei ATCC 26921 was used for the partial digestion of our samples of cellulose. Since these oligosaccharides do not possess a chromophore or fluorophore, they can’t be detected either by absorbance or fluorescence. It was thus necessary to work out the labeling method for oligosaccharides using various agents, such as 8-aminopyrene-1,3,6-trisulfonic acid (APTS), 3-acetylamino-6-aminoacridine (AA-Ac) and phenylhydrazine (PHN). Finally, the use of capillary electrophoresis and high performance liquid chromatography allowed the separation of the enzymatic digestion products of the cellulose derivatives (CMC and HEC). For each of these analytical separation techniques, several parameters of the separation were studied.

Anaerobinis dumblo pūdymas - tai procesas, kurio metu dalis biomasėje esančių organinių junginių dėl įvairių rūšių mikroorganizmų veiklos yra suardomi. Vykstant šiam procesui, irstančios organinės dalelės verčiamos į biodujas – atsinaujinantįjį energijos šaltinį. Tačiau anaerobinis dumblo pūdymas gali sutrikti dėl įvairių inhibitorinių medžiagų. Norint reikiamą nuotekų išvalymo laipsnį užtikrinti pagal bendrąjį fosforą, naudojamas cheminis fosforo šalinimo būdas, kurio metu į nuotekas įterpiamos Al arba Fe metalų druskos. Šio darbo tikslas ‒ nustatyti, kaip skirtingos aliuminio ir geležies koncentracijos veikia anaerobinio stabilizavimo procesą ir išgaunamų dujų kiekį. Darbui atlikti buvo naudojamas standartinis anaerobinio pūdymo W8 (Armfield Ltd, UK) modelis. Tyrimu nustatyta, kad pūdant dumblą, į kurį buvo dozuota Fe druska, išsiskyrusių biodujų kiekis ml/d buvo artimas kontrolinio pūdytuvo reikšmėms, o pūdant dumblą, į kurį buvo dozuotos Fe ir Al druskos, biodujų ml/d išsiskyrė iki 30 % daugiau, nei palyginus su dumblu, į kurį druskos nebuvo dozuotos. Dozuojant metalų druskas ir esant padidėjusiai pūdytuvo apkrovai bepelenėmis sausosiomis medžiagomis, taip pat buvo nustatyta, kad sumažėja bepelenių sausųjų medžiagų suskaidymo efektyvumas iki 5—12 %. Nepaisant sumažėjusio bepelinių sausųjų medžiagų suskaidymo, biodujų m3/kgBSM suskaidytų padidėjo net iki 43 % pagal vidutines reikšmes. Išanalizavus tyrimų rezultatus pateiktos išvados ir rekomendacijos. Darbą sudaro šios... [toliau žr. visą tekstą] / Anaerobic sludge digestion is a process in which part of organic compounds existing in biomass are destroyed of various microorganisms. In this process volatile solids (VS) are converted into biogas – renewable energy source. Anaerobic digestion can be impaired in presence of inhibitors. Chemical phosphorus removal when Al and Fe metals salts are added to wastewater is used to reach the degree of waste water treatment by total phosphorus. Objective of this work was to investigate impact of different aluminium and iron doses on anaerobic digestion process and biogas produced. The work was carried out using standard anaerobic digestion model W8 (Armfied Ltd. UK). Research showed that biogas produced from Fe-dosed sludge was close to biogas production from un-dosed sludge and during digestion of Al-Fe-dosed sludge biogas ml/d production was 30% higher that from control. The efficiency of volatile solids destruction decreased 5-12% during dosing of metal salts. Biogas production from VS destructed was approx. 43% higher by average values when metal salts were dosed into sludge. The composition of biogas was not measured during research. Conclusions and recommendations are presented.

A better understanding of how dietary fibres impact the bioavailability of fat-soluble nutrients and nutraceuticals is required. The purpose of this research was to determine the influence of guar gum (GG) on the transfer processes impacting beta-carotene (BC) bioaccessibility (transfer to the aqueous phase) from an oil-in-water emulsion using an in vitro model simulating gastric and duodenal digestion. Canola oil emulsions (1.5 % soy protein isolate, 10 % canola oil and 0.1 % all trans BC, D4,3~160 nm) were prepared by microfluidization (40 MPa, 4 passes) and exposed, in the presence of 0.0, 1.0, 1.5, 2.0, or 4.0 % GG, to conditions representative of the stomach and duodenum in the fed state. Lipolysis, BC bioaccessibility, digestate apparent viscosities, droplet size, and bile acid (BA) binding were studied. With increasing concentration of GG, digestate viscosity was increased and lipolysis and bioaccessibility were decreased (P<0.05). Peak lipolysis was 56.2% vs. 21.6% for emulsions containing 0.0 % vs. 4.0 % GG, respectively. BC bioaccessibility was also lower in the presence of GG (i.e. 29.7 vs. 6.98 % for 0.0 vs. 4.0 % GG respectively). Thus, the presence of GG impacted digestive processes central to BC absorption. The impact of GG may be related to increased digestate viscosity entrapping mixed micelles or BAs and decreasing diffusion leading to decreased lipolysis and BC bioaccessibility. / NSERC, CFI

No description available.

In this project, by adding selected co-substrates and by incorporating optimum pre-treatment strategies, four experimental phases were conducted to assess the enhancement of biogas production from anaerobic co-digestion using wastewater treatment plant sludge as the primary substrate. In the first phase, the feasibility of using municipal organic wastes (synthetic kitchen waste (KW) and fat, oil and grease (FOG)) as co-substrates in anaerobic co-digestion was investigated. KW and FOG positively affected biogas production from anaerobic co-digestion, with ideal estimated substrate/inoculum (S/I) ratio ranges of 0.80-1.26 and 0.25-0.75, respectively. Combined linear and non-linear regression models were employed to represent the entire digestion process and demonstrated that FOG could be suggested as the preferred co-substrate. The effects of ultrasonic and thermo-chemical pre-treatments on the biogas production of anaerobic co-digestion with KW or FOG were investigated in the second phase. Non-linear regressions fitted to the data indicated that thermo-chemical pre-treatment could increase methane production yields from both FOG and KW co-digestion. Thermo-chemical pre-treatments of pH=10, 55°C provided the best conditions to increase methane production from FOG co-digestions. In the third phase, using the results obtained previously, anaerobic co-digestions with FOG were tested in bench-scale semi-continuous flow digesters at Ravensview Water Pollution Control Plant, Kingston, ON. The effects of hydraulic retention time (HRT), organic loading rate (OLR) and digestion temperature (37°C and 55°C) on biogas production were evaluated. The best biogas production rate of 17.4±0.86 L/d and methane content 67.9±1.46% was obtained with thermophilic (55°C) co-digestion at HRT=24 days and OLR=2.43±0.15 g TVS/L•d. In the fourth phase, with the suitable co-substrate, optimum pre-treatment method and operational parameters identified from the previous phases, anaerobic co-digestions with FOG were investigated in a two-stage thermophilic semi-continuous flow co-digestion system modified to incorporate thermo-chemical pre-treatment of pH=10 at 55°C. Overall, the modified two-stage co-digestion system yielded a 25.14±2.14 L/d (with 70.2±1.4% CH4) biogas production, which was higher than that obtained in the two-stage system without pre-treatment. The positive results could provide valuable information and original contribution to justify full-scale investigation in a continuing research program and to the field of research on anaerobic co-digestion of municipal organic wastes. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-09-20 09:00:09.719