There is an estimated 20 million tonnes of slurry produced by 2 million dairy cows each year in the UK. The suitable treatment of dairy farm waste could address both environmental concerns and energy security. In this study, dairy farm waste was separated into liquid slurry and solid residues, and treated by Microbial Fuel Cells (MFCs) and pyrolysis to minimise the environmental impact and produce bio-energy products. The effective treatment efficiencies were achieved by using incubated slurry mixed with fresh slurry as the anodic solution in MFC reactors. Comparing MFCs with anaerobic digestion (AD) under anaerobic conditions, the highest COD removal efficiency (71 %) and total nitrogen removal efficiency (17%) were obtained in MFCs operated at 25°C and 30°C for 30 days, respectively. A higher working temperature (35°C) was found to benefit the degradation of total suspended solids (78%). The MFCs were also found to be effective for nutrient-rich solution treatment. Furthermore, the anodic solutions were pre-treated by BI-CHEM manure degrader, which could significantly benefit the bio-degradation of the TSS, COD and nitrogen removal and enhance power generation. The dairy farm solid waste was treated by pyrolysis to produce bio-oil and biochar. The highest oil yield of 51 % was obtained at 500°C. For a mixed feedstock of solid waste and bone chips (up to 15%), results suggested that co-pyrolysis could improve the biochar production yield and bio-oil quality. The optimal concentration of bone chips for oil yield was found to be 1 O~ and the optimal temperature was 500°C. The conversion technologies for dairy farm waste are discussed based on the results of the experiments in this study. The potential energy recovery of the whole treatment was 61%.

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Burgeoning global demand for fossil feedstock in the production of fuels and chemicals, coupled with rising costs of waste disposal routes are driving manufacturing industry to innovate towards greater resource efficiency. A desirable approach is the valorisation of industrial eo- products, including food waste. Food wastes is an underutilised resource with potential to be used as a raw material in a range of products including biofuel, thus avoiding conventional lower value treatment routes of animal feed use and composting and, better still, avoiding the environmentally and financially costly disposal routes of, incineration and landfill. This research, carried out under the framework of a Knowledge Transfer Partnership (KTP) between Brocklesby Ltd and the Green Chemistry Centre at the University of York, has delivered a number of protocols and methodologies to valorise biodiesel industry eo-products (glycerine) and food waste. The project focussed on bettering the production of used cooking oil-based (UCO) biodiesel: soapstock side streams were characterised with a number of analytical techniques (GC, GC-MS, ESI, IR, NMR and others) and optimisation protocols were developed which lead to the production of a higher grade glycerine eo-product with commercial value. The overall strategy of the project linked the quality of the eo-product (glycerine and food waste), with a number of chemistries and subsequent commercial applications. Amongst the chemistries attempted (esterifications, oligomerisation, hydrogenolysis, glycerol carbonate production and others) the use of a heterogeneous catalyst at low temperature (below 150°C) l-step reactions was prioritised. Some of the products (glycerol acetates) obtained showed potential for use as plasticisers in various applications. In addition, valorisation strategies for two Brocklesby-generated food eo/products (as liquid effluent and oil/fat rendering) were evaluated, in addition to alternative treatments anaerobic digestion for industrial liquid effluent and hydrothermal and microwave-assisted extraction for animal by-products.

Increasing environmental concerns coupled with increasing oil prices have led to bio- refmeries becoming attractive as a viable route for renewable energy from biowastes. This research focused on: three crucial steps in the production of value added intermediates in the biorefinery process: Hydrolysis of biomass waste producing sugars. Dehydration of sugar monomers producing furfural. Aldol condensation of furfural with acetone. The first step was concerned with the viability of the dilute acid hydrolysis of potato peel wastes to produce sugars. Acid concentrations and temperature were investigated to find optimum conditions. High phosphoric acid concentrations with low temperatures gave -the optimum yield of 55.2g sugars/lOOg of dry mass using 10% w/w phosphoric acid and a temperature of 408 K. The second step investigated the use of xylose for value added chemical production by catalytic dehydration to furfural, an aldehyde. To date, little was known about ." the exact reaction mechanism and kinetics involved. This work looked in detail at the reactions occurring within the liquid phase. A reaction mechanism was proposed and kinetic parameters estimated. The mechanism included isomerization of xylose to lyxose, dehydration of lyxose and xylose to furfural, fragmentation of furfural to organic acids, oligomerization of furfural to bi- and tridimensional furilic species, and complete dehydration of organic acids to carbonaceous deposits. Finally, the base catalysed aldol condensation of furfural with acetone was investigated. This reaction is a step in the production of bio-alkanes by lengthening the chain length so the resultant product is less volatile. Unlike sodium hydroxide used by comparative studies, charred dolomite as a novel solid base catalyst was employed. The properties of dolomite were studied using X-ray diffraction, scanning-electron-microscopy, thermo-gravimetric analysis, and were related to its catalytic activity. The reaction was found to be effectively catalysed by dolomite, attributed to the formation of hydroxyls within the catalyst when the charred dolomite is hydrated. ii

The rapidly increasing prices of petroleum fuels and potential shortages, have created a need for renewable fuels derived from organic waste products. The objective of this research project is to produce advanced multipurpose, continuous microwave biofuelslchemical reactors to utilise waste vegetable oils. The heat transfer efficiency of the reactor was studied using pure vegetable oils to establish the reactor design, operating temperatures and controls necessary to produce First Generation biodiesel by advanced microwave technology. Water modelling was used to scale up the reactors from 200 W to 1.2 kW and then subsequently to 2 kW. Once the initial continuous reactor was optimised, the work was repeated using various grades of waste cooking oils provided by Longma Clean Energy Ltd. In order to achieve the required conversion to give 96.5% methyl esters, these oils needed larger quantities of both catalyst and methanol to reduce the viscosity of the crude oil. The system was then modified to carry out microwave assisted methanol extraction of free fatty acids, with the addition of a decanter to allow continuous phase separation. This process produced no glycerol, was energy efficient and the free fatty acids that were removed, were recovered in the methanol distillation unit. In the future, the waste frictional heat from the diesel engine could be used to grow algae, the waste heat from the exhaust gases could be used to heat the distillation unit and the carbon dioxide could be biofixated by microalgae. An industrial prototype 1.2 kW microwave de-acidification unit has now been built at the Longma Clean Energy site at Hereford. There is a surplus of poor quality biodiesel glycerol that is currently regarded as a waste product. The novel continuous microwave unit which was developed from the biodiesel reactor has been used to acetyl ate the glycerol with acetone at below 50°C to produce acetals for use as fuel additives. An atmospheric/vacuum fractional distillation column will be required to recover the methanol or acetone and to distil the acetal from the unreacted glycerol, which is then recycled. The technology developed can utilise any waste cooking oils, acidic seed oils or fats as biofuels for combined heat and power generation or to convert them to biodiesel fuels. This research work is the basis of an integrated, green, low carbon, microwave based refinery. 2

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).