Anaerobic digestion of the Organic Fraction of Municipal Solid Waste (OFMSW) generates a mixture of methane (CH4), carbon dioxide (CO2) and water (H2O). Beyond the field capacity the water generated is collected and recirculated as leachate in Bioreactor Landfills (BLs.) Leachate recirculation has a profound advantage on biodegradation of the Organic Fraction of Municipal Solid Waste (OFMSW) in the landfills. Mature leachate from older sections of landfills (>20 years) and young leachate were blended prior to recirculation in the ratios 3/3 mature, 3/3 young, 1/3 mature-2/3 young and 2/3 old-1/3 young and their effect on biodegradation and biogas production monitored. In addition to analysis of the effect of blending old and new leachates, the study also analyses the effect of an open vs. a closed recirculation loop and the effect of organic loading rates of OFMSW in landfills. Data collected from initial batch tests supplement column bioreactors simulating bioreactor landfills with real world OFMSW from operational landfill facilities in Ontario, Canada. The results are conclusive that the biogas generation can be improved by up to 92% by blending the leachate in an open loop recirculation system as compared to a conventional closed loop system employed in landfills today.

Anaerobic digestion of the Organic Fraction of Municipal Solid Waste (OFMSW) generates a mixture of methane (CH4), carbon dioxide (CO2) and water (H2O). Beyond the field capacity the water generated is collected and recirculated as leachate in Bioreactor Landfills (BLs.) Leachate recirculation has a profound advantage on biodegradation of the Organic Fraction of Municipal Solid Waste (OFMSW) in the landfills. Mature leachate from older sections of landfills (>20 years) and young leachate were blended prior to recirculation in the ratios 3/3 mature, 3/3 young, 1/3 mature-2/3 young and 2/3 old-1/3 young and their effect on biodegradation and biogas production monitored. In addition to analysis of the effect of blending old and new leachates, the study also analyses the effect of an open vs. a closed recirculation loop and the effect of organic loading rates of OFMSW in landfills. Data collected from initial batch tests supplement column bioreactors simulating bioreactor landfills with real world OFMSW from operational landfill facilities in Ontario, Canada. The results are conclusive that the biogas generation can be improved by up to 92% by blending the leachate in an open loop recirculation system as compared to a conventional closed loop system employed in landfills today.

Leachate clogging in the Leachate Collection System (LCS) due to chemical precipitations and biofilms produced by microbial activities is a common phenomenon in any Municipal Solid Waste (MSW) landfill. This study focuses on quantifying the factors that impact the micro-environment of leachate; and microbial activities that help the precipitates to form and attach to the LCS. It also evaluates the performance of operational changes that have been implemented or the potential alternatives and recommends the possible measures to reduce the severity of clogging. A field scale side-by-side pipe network, and several laboratory setups were used in this study. Calcite is identified to be the predominant phase present in the precipitates using XRD/XRF analysis which, concur with the previous studies. Microbial growth and activities enhance the precipitation of CaCO3 in LCS. Clogging in LCS pipes can be controlled if not eliminated by continuous monitoring along with frequent cleaning with physiochemical processes. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Given the increase in nanomaterial (NM) use in consumer products and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology use is still in its early stages, there are currently no regulations pertaining to the disposal of NMs and their fate in MSW landfills is still unknown. Understanding the fate of NMs in MSW landfills is vital to ensure the proper handling of these novel materials from cradle to grave; such research will provide information on how these NMs can be safely introduced into the environment. This research seeks to understand the fate of NMs within waste environments by examining the interactions between NMs and landfill leachate components. The primary focus of this thesis is the effect of Zinc Oxide (ZnO) on biological landfill processes, solids aggregation, and chemical speciation of Zn in landfill leachate following the addition of crystalline, nanosized ZnO coated with triethoxycaprylylsilane. This research (1) observed the effects of coated ZnO on five-day biochemical oxygen demand (BOD5) and biochemical methane potential (BMP), (2) examined effects of solids aggregation on the fate of ZnO, (3) quantified the concentration of Zinc (Zn) by size fractions, and (4) modeled the chemical speciation of Zn in landfill leachate using Visual MINTEQ. No change in dissolved Zn was observed after coated ZnO was exposed to “middle-aged” leachate. Upon exposure to “mature” leachate there was an increase in dissolved Zn assumed to be a result of the dissociation of ZnO. Solids data supported the aggregation of particles in both middle aged and mature leachate. There was an increase in the Zn concentration in leachate fractions greater than 1500 nm presumably due to the dispersion of normally insoluble ZnO ii nanoparticles (NPs) following the interaction with humic acids (HA). ZnO did not inhibit anaerobic or aerobic processes in either middle aged or mature leachate, presumably due to the relatively low concentration of dissolved ionic Zn. Despite the observation of increased dissociation upon exposure to mature leachate, the presence of dissolved organic matter (DOM) may have hindered the ability for dissolved ionic Zn to become bioavailable. Fractionation, BOD5 and BMP tests, and chemical speciation modeling provided insight on the mobility of ZnO in landfills and the absence of inhibitory effects on landfill processes. Aggregation of ZnO NPs may prevent movement through traditional containment systems (i.e. geomembrane liners) due to the increased particle size. However, the increased dispersion suggests that ZnO NPs will be transported out of the landfill in the leachate, however biological treatment of leachate should be unaffected by the presence of ZnO. The bioavailability of Zn was not substantially affected by the presence of ZnO due to affinity of dissolved Zn for DOM. However, due to the heterogeneity of landfill leachate and the utilization of different NM coatings, it is challenging to predict the overall mobility of other NMs in a landfill.

Το στράγγισμα από τους χώρους υγειονομικής ταφής απορριμμάτων (ΧΥΤΑ) περιέχει σύνθετους οργανικούς ρύπους, με αποτέλεσμα η επεξεργασία του να έχει αποκτήσει ιδιαίτερη σημασία στις μέρες μας. Εκτός από τις μεγάλες ποσότητες οργανικού υλικού μέσα στα στραγγίσματα υπάρχουν επίσης βαρέα μέταλλα, χλωριωμένα οργανικά ή ανόργανα άλατα και γενικά διάφορες ουσίες που μπορεί να ρυπάνουν τα επιφανειακά και υπόγεια νερά. Γι ‘ αυτό κατά την κατασκευή ενός ΧΥΤΑ πρέπει να εγκατασταθούν συστήματα συλλογής και επεξεργασίας των στραγγισμάτων, ώστε να αποφευχθεί το φιλτράρισμα τους μέσω του εδάφους και τους υπεδάφους και στη συνέχεια η περαιτέρω μόλυνση ρεμάτων ή γεωτρήσεων. Στην παρούσα εργασία θα ασχοληθούμε συγκεκριμένα με τον χαρακτηρισμό των στραγγισμάτων όσον αφορά το χημικά απαιτούμενο οξυγόνο (COD), το βιοχημικά απαιτούμενο οξυγόνο (BOD), τα συνολικά αιωρούμενα στερεά (TSS) καθώς και των λοιπών φυσικοχημικών παραμέτρων τους. Επιπλέον, παρουσιάζονται κάποιες προτάσεις για την απορρύπανση των στραγγισμάτων των ΧΥΤΑ που πρέπει να γίνεται πριν από την απόρριψη τους σε οποιαδήποτε περιοχή, όπως προ-επεξεργασία των στραγγισμάτων με ένα συνδυασμό φυσικοχημικών, αναερόβιων και υδρολυτικών διαδικασιών. Για την απομάκρυνση βαρέων μετάλλων (όπως Fe, Cd, Cr) καθώς και τη μείωση του COD, μπορεί να είναι αποτελεσματική η προ-επεξεργασία με πήξη-κροκίδωση. Στην παρούσα όμως διπλωματική εργασία για τη μείωση του COD χρησιμοποιήθηκε η Φωτοκαταλυτική Διαδικασία Αποδόμησης (Photocatalytic Degradation Process), η οποία περιλαμβάνει φωτοκαταλυτική επεξεργασία με τη χρήση υπεριώδους ακτινοβολίας (UV) και την προσθήκη καταλύτη οξειδίου του τιτανίου (TiO2) στο δείγμα του στραγγίσματος. Ακόμη, εναλλακτικά χρησιμοποιήθηκε η προσρόφηση με εξανθράκωμα (biochar), Σκοπός αυτών των διαδικασιών είναι η απομάκρυνση των ανθεκτικών οργανικών ενώσεων και ο αποχρωματισμός του στραγγίσματος. Με την ολοκλήρωση των διεργασιών ο αποχρωματισμός του στραγγίσματος επιτεύχθηκε με την ετερογενή φωτοκατάλυση και η σχετική μείωση των οργανικών ρύπων με τη χρήση του ροφητικού μέσου biochar. / Leachate from landfills contains complex organic compounds, a fact that makes its effective treatment a matter of crucial importance nowadays. Apart from high quantities of organic material, leachate also contains heavy metals, organic or anorganic chloride salts and various substances which can pollute surface and ground water. As a result, the construction of landfills must include leachate collection and treatment systems, in order to prevent its filtering through ground and underground, and subsequent pollution of streams, small rivers and wells. This thesis presents the characterization of a leachate sample and testes various decontamination techniques, which could to be executed before its disposal in any area. In particular, leachate pre-treatment can be performed with a combination of physical chemical, anaerobe and hydrolytic methods. In order to remove heavy metals (i.e. Fe, Cd, Cr) and reduce COD, pre-treatment can be effective using flocculation-coagulation. In this thesis a Photocatalytic Degradation Process was used to reduce COD, which consists of photocatalytic treatment using UV radiation and adding TiO2 to the leachate sample. Alternatively, adsorption process with biochar was also tested. The purpose of this process is the removal of persistent organic compounds and the discoloration of the leachate. With the completion of the processes the discoloration of the leachate was accomplished using heterogeneous photocatalysis and the relative reduction of organic pollutes using sorption materials (i.e. biochar).

Thesis (Ph. D.)--Oregon State University, 1998. / Printout. Includes bibliographical references (leaves 266-285). Also available on the World Wide Web.

A severe shortage of many, to mankind, valuable elements are to be expected in the near future. Therefor is it of utmost importance to find these deposits and a way to refine the elements with as little negative effect on the environment as possible. One deposit of valuable elements such as U, V, Mo and Sr are the so called alum shale. Alum shale is a variety of sulfidic black shale which is rich in pyrite, FeS2, and organic carbon. Primary due to its contents of hydrocarbons and uranium the alum shale has been mined at different sites throughout Sweden. One of these sites was Kvarntorp in the region of Närke. The shale which had have its contents of hydrocarbons extracted through dry distillation was dumped into a heap that is now known as Kvarntorpshögen. The remaining hydrocarbons that this processed material still contain are to this day (2011) warm, with temperatures up to some hundred degrees Celsius. Due to this heat, infiltration of rainwater is held at a minimum. What no one knows however; is for how long Kvarntorpshögen will remain warm. Once it cools; many toxic elements will leak into the surrounding environment due to natural weathering caused by precipitation and frost wedging. The study also included a heating treatment of 70°C which is a temperature that the material of Kvarntorpshögen may be capable of generating by itself. This is assumed to be a good temperature for weathering processes; because it increases the kinetics of chemical reactions but also allows the presence of water. The results of this study shows that summer will be the season that contributes the most to the leaching of elements, of which some are toxic. Newly exposed surfaces of various shale materials often contain elements that is easily leached by water. Once this coat is washed away however, further leaching of that element decreases. Exceptions from this pattern in some shale products were shown by for example vanadium and molybdenum. The digestion data show that the completely processed shale, which makes up the majority of Kvarntorpshögen, still have a high content of rare and valuable elements. Making Kvarntorpshögen itself interesting for extraction processes in the future.

Thesis (Ph. D.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed January 28, 2008) Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 126-130). Also available via the Internet.

Application of microwave (MW) radiation followed by aeration (A) for the purpose of ammonia removal from both synthetic solutions and landfill leachate was investigated in this study. Four sets of experiments: water bath (WB), microwave (MW), sequential microwave/aeration process (MW+A), and sequential water bath/aeration process (WB+A) were conducted using synthetic solution. MW and MW+A tests were applied on the landfill leachate as well. For each test, either 100 mL of synthetic solution or landfill leachate was used. All the tests were conducted with three replicates in batch scale. For both economic and safety concerns, the samples’ temperature were maintained below the boiling point. One-way ANOVA tests and T-tests were conducted to analyze the differences of ammonia removal efficiencies among different methods. Both thermal and non-thermal effects for the sequential microwave/aeration process were investigated. Factorial design and response surface methodology (RSM) were applied to evaluate and optimize the effects of pH, MW energy level and microwave power output. Results confirmed that the sequential microwave/aeration process was an effective approach for removal of ammonia from aqueous systems. Maximum ammonia removal of 81.7 % for synthetic solution and 70% for landfill leachate was achieved by applying 7.8 KJ MW energy output/L sample and 10 minutes aeration. When apply the sequential microwave/aeration process to synthetic solution, at optimum condition of pH 10.5, 7.8 KJ MW energy output/L sample and 10 minutes aeration time, the contribution of thermal process was 39%, while 61% for non-thermal processes (33% for aeration and 28% for EMF). Statistical analysis of synthetic solution tests data using RSM showed that ammonia removal efficiency strongly depended on pH and MW energy output. R square of 0.941 indicates that observed results fitted well with the model prediction. Optimum pH and MW energy output level for ammonia removal was 11 and 7.8 KJ MW energy output/L sample respectively, and under this condition, maximum ammonia removal efficiency predicted for synthetic solution was 76.3%.