A nine month field and laboratory study was undertaken to measure, predict and model the variation of detected ammonia concentrations in landfill gas. An additional side study attempted to characterize organic trace contaminants found in landfill gas. The field project consisted of biweekly sampling of gas extraction wells from four Vancouver-area landfills for the analysis of NH₃-N in the gas and leachate. Methane and other common landfill gases were also analyzed. The wet chemical boric-acid sampling technique used in this study was estimated to have a ammonia gas recovery efficiency of 50 %. Other than a low recovery efficiency, problems encountered with this sampling technique was the high humidity and negative interferences inherent in the landfill gas. Laboratory analysis of the collected NH₃-N gas samples was by the automated phenate method, which could detect NH₃-N gas concentrations greater than 10 ppb. The NH₃-N concentrations in gas were found to exceed 600 ppb, but were more commonly in the 50 to 200 ppb range. In the statistical and graphical analysis, gas temperature and precipitation were found to correlate the most to the variation in ammonia gas concentration, while leachate ionic strength correlated strongest with most CH₄ % analysis. Prediction of both NH₃-N gas and CH₄ % by regression analysis was found to be suspect due to low R² values and non-normality of some data. Four different Henry's Law constants of ammonia gas were evaluated to help predict the concentration of NH₃-N in the gas phase. The combination of already measured NH₃-N leachate concentrations and Henry's Law constants yielded results that over and underpredicted measured NH₃-N gas data by 2000 fold or more. This leads the author to believe Henry's Law may not be applicable in a landfill environment due to non-equilibrium conditions coupling with various other reaction mechanisms. Comparison of landfill ammonia gas flux rates with total ammonia leachate flux rates in two of the four landfills yielded an insignificant gas flux rate of less than 0.03 % of the total leachate NH₃-N fluxes. The NH₃-N gas flux results were calculated from a spreadsheet emission model employing both convection and diffusion flow through the landfill cover. A comparison of the emission model results for the 20 ha Richmond landfill study area (3.862 kg/yr) compared favorably to the mass flux results determined from a simple gas generation mass balance model. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

No description available.

There is a requirement in the European Union to divert organic wastes from landfill because of the risk of methane emissions. One alternative is anaerobic digestion of organic wastes, such as food waste, to stabilise them whilst at the same time recovering the energy from them. One problem with this approach is that the high nitrogen content of food waste may lead to ammonia inhibition. A solution to this has been found for mesophilic digestion but had not been attempted in thermophilic digestion where ammonia toxicity is known to be more acute. The work was carried out in laboratory-scale semi-continuous digesters operated over long time periods to provide maximum opportunity for acclimatisation, and in duplicate to give an indication of reproducibility. A series of experimental runs were undertaken at thermophilic temperatures to assess the influence of trace element (TE) addition on the digestion process. These were carried out at organic loading rates (OLR) of 2, 3 and 4 g volatile solids (VS) l-1 day-1 against unsupplemented controls at OLR 2 g VS l-1 day-1. Although TE addition could offset the accumulation of VFA which occurred in response to an increasing concentration of total ammonical nitrogen (TAN), it could not prevent this. The high alkalinity resulting from ammonia, however, allowed the digesters to continue to produce methane until VFA had accumulated to high concentrations before eventual failure due to a rapid drop in pH. To determine the threshold inhibitory ammonia concentration in thermophilic digestion, one pair of digesters was run on synthetic low nitrogen food waste (low-N food waste) at an OLR 2 g VS l-1 day-1 and compared to a control pair running on domestic food waste at the same loading. All four digesters received TE supplementation. The digesters fed with low-N food waste showed consistently stable performance with pH ~7.4, IA/PA ratio ~0.4-0.5, SMP 0.39 l CH4 g-1 VS, 52-55% CH4, total VFA <500 mg l-1 and 88% VS destruction whereas the controls showed signs of failure after 112 days and irreversible VFA accumulation at a TAN concentration >3.5 g N l-1. One of the low N digesters was supplemented with urea slowly and one by a shock dose: both showed signs of VFA accumulation at TAN >2.5 gl-1 and, again, an irreversible trend in propionic acid build-up when TAN >4 g N l-1. Long term operation showed meta-stable conditions when the digesters were operated at TAN between 2.5 - 3.5g l-1 with oscillations in VFA (especially propionic acid) concentration. Mesophilic digestion at 37oC with TE addition showed very stable performance with pH ~8, IA/PA ≤ 0.3, SMP ~0.48 l CH4 g-1 VS, 55-60% CH4, total VFA < 300 mg l-1 and VS destruction ~75-78% with a final total ammonia nitrogen (TAN) concentration of 4.5 g N l-1. As the temperature in digesters was raised from 35 to 43 oC in 1oC steps a change in performance was noted when the temperature reached 40 oC. Above this temperature VFA concentrations rose above 4000 mg l-1 and biogas and methane production fluctuated. It is probable that the higher temperature increased the concentration of free ammonia nitrogen (FAN) to ~800 g N l-1 at the measured TAN concentration ~5.5-6.0 g N l-1 and this was sufficient be inhibitory even with TE dosing. Fluorescent in situ hybridisation (FISH) was used to identify the methanogenic populations in some of the trials over selected time periods. This showed changes in population structure both in relation to temperature (mesophilic or thermophilic) and also in response to increasing concentrations of TAN. At high TAN concentrations Methanomicrobiales was the dominant methanogenic group and under mesophilic conditions this proved to be extremely ammonia tolerant. A 14C radio-labelling assay confirmed the dominant pathway to methane formation was by the hydrogenotrophic route which reflected the known metabolic pathway of this methanogen. It was concluded that thermophilic digestion of source segregated domestic food waste would lead to instability and failure of the process unless measures were introduced to reduce the TAN concentration to < 3.5 g N l-1, and preferably to < 2.5 g N l-1. Keywords: Anaerobic digestion, food waste, biogas, VFA accumulation, ammonia inhibition, Fluorescent in situ Hybridisation (FISH).

Due to legislative pressures and the recent ban of trybutyl tin, alternative environmentally acceptable ship hull antifouling systems are required. This thesis uses a multidisciplinary approach to combine two disparate areas of research namely marine biology and surface engineering, to develop a novel natural product (NP) based antifouling system. The overall objective of this thesis is to transfer a natural marine biological defence mechanism into an engineered antifouling coating system. By combining natural product extraction and incorporation into a trial coating an extensive test programme was able to investigate the antifouling performance and address the issues of bringing this active area of research to the next technological readiness level. By using a stepwise approach to the development of the engineered solution, a suite of techniques were used to fully characterise a NP based system. The biological and surface engineering techniques adapted and developed are described here and their future use to evaluate a novel NP based antifoulant system is critically assessed. After an extensive literature review, an ethanol extract from the red seaweed Chondrus crispus was selected as the natural product source. NP specimens were harvested locally and also purchased as industrially processed dried algae. The industrially processed algae showed good antifoulant activity ( ≤ 25 μg mL-1) in laboratory bioassays and had a greater efficacy than the locally harvested samples highlighting its potential as an economically viable solution. The direct incorporation of the NP into a commercial control depletion polymer binder, allowed for the rapid development of characterisation techniques to evaluate the effects this had on the performance of the NP-binder matrix. The feasibility of a range of electrochemical techniques to measure corrosion potential, impedance, resistance and water uptake in the NP coating was critically assessed. A combination of open-circuit potential and electrochemical impedance spectroscopy provided a unique and rapid means to non-destructively measure the contribution of incorporated NPs to the degradation and water uptake of the binder film. Studies of biofilm growth were used to successfully measure community viability and structure using fluorescent staining and differential interference contrast microscopy. These techniques were found to be very informative on Southampton water marine biofilm community structure and were cross correlated by fourier transform infrared measurements. Resistance to biofouling was determined through field trials, an important testing platform for an antifouling system, and specifically trials which test the entire coated system including any primers and substrate preparation requirements. An initial NP antifouling performance greater than the booster biocide (Chlorothalonil) control was documented for one field trial over a period of the first 6 weeks. A key aspect was to determine the potential efficacy of NPs and their viability in a coating system. To achieve this, a range of standard and non-standard techniques were used to assess this novel combination of crude NP extract and commercial binder system. This work has shown that a limited antifoulant activity is achievable. By evaluating the effect of a NP on both the fouling community and a binder system this unique approach helps define key techniques to assess future NP antifoulants and identifies the optimisation required to increase their functionality.

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

Objetivo: Comparar el nivel de conocimiento y aplicación de medidas de bioseguridad en estudiantes de pregrado y egresados de la carrera de odontología del periodo 2013-2018 de una universidad privada peruana. Materiales y Métodos: Estudio piloto descriptivo de tipo transversal observacional, siendo la población los estudiantes de pregrado y egresados de la carrera de odontología de una universidad privada peruana. Se tomó una muestra de 32 estudiantes de pregrado y 32 egresados de odontología de la misma institución, evaluándose el nivel de conocimiento mediante una encuesta autoaplicable y el nivel de aplicación de las medidas de bioseguridad por medio de una ficha observacional. El análisis univariado se obtuvo mediante frecuencias absolutas y relativas; para el análisis bivariado se utilizó la prueba de Chi-cuadrado y prueba exacta de Fisher. (p≤0.05) Resultados: El conocimiento sobre medidas de bioseguridad de los alumnos de pregrado y egresados es de nivel regular, con valores de 40.6% y 46.8% respectivamente, el 34.37% de alumnos de pregrado y el 25.56% del grupo de egresados obtuvieron un buen nivel de aplicación de las medidas de bioseguridad. Se encontró diferencias estadísticamente significativas entre el nivel de conocimiento de los alumnos de pregrado y egresados. (p= 0.001). Conclusión: Los grupos de pregrado y egresados en referencia al conocimiento en medidas de bioseguridad, obtuvieron el nivel de regular, y lo que respecta a la aplicación de medidas de bioseguridad, ambos grupos lograron el nivel de bueno. / Objective: Compare the level of knowledge and application of biosafety measures in undergraduate and graduate students of the 2013-2018 dental career of a Peruvian private university. Materials and Methods: A descriptive, observational cross-sectional pilot study, with the population being undergraduate and graduate students of the dental career of a Peruvian private university. A sample of 32 undergraduate students and 32 graduates of dentistry from the same institution were taken, assessing the level of knowledge through a self-applying survey and the level of application of biosecurity measures through an observational record. Univariate analysis was obtained by absolute and relative frequencies; The Chi-square test and Fisher's exact test were used for the bivariate analysis. (p≤0.05) Results: The knowledge on biosecurity measures of undergraduate and graduate students is of a regular level, with values ​​of 40.6% and 46.8% respectively, 34.37% of undergraduate students and 25.56% of the group of graduates obtained a good level of application of biosecurity measures. Statistically significant differences were found between the level of knowledge of undergraduate and graduate students. (p = 0.001). Conclusion: Undergraduate and graduate groups in reference to knowledge in biosecurity measures, obtained the level of regular, and with regard to the application of biosecurity measures, both groups achieved the level of good. / Tesis

No description available.

No description available.

No description available.

Construction and Demolition (C&D) wastes are materials produced in the process of construction, renovation, or demolition of structures (buildings and roads). It also includes materials generated as a result of natural disasters (EPA, 2009). Preliminary estimates from the U.S. Environmental Protection Agency (EPA) show that the nation generated more than 160 million tons of building related C&D wastes in 2003. Also, Pennsylvania Department of Environmental Protection (PADEP) estimated that in 2005, Pennsylvania disposed over 2.25 million tons of C&D wastes in its municipal and C&D landfills (PADEP, 2009).Though previous studies have shown that it is cost-effective and environmentally friendly for contractors or construction managers to recycle C&D wastes rather than disposing them in landfills, these previous studies, however, paid little or no attention to detailed cost of recycling C&D wastes in a particular geographical area or region as compared to the availability of market for recycled materials or monetary value of the recycled materials. Hence, the objective of this study was to develop a mathematical model that helps stakeholders in construction business to evaluate the potential cost of recycling C&D waste components in their geographical area or region, and the potential revenue from the recycled materials. The model developed in this thesis will enable private companies or individuals to identify, invest and participate in the recycling of C&D waste components that yield good profits in their region or area. It will also enable Government to identify, sponsor or provide incentives for the recycling of C&D waste components that yield no or less profit in order to reduce environmental pollution and generate jobs. A case study is conducted in Pennsylvania to test the model developed in this thesis and the test has been successful. Based on the mathematical model and logic structure for selecting C&D waste components for recycling, drywall, roofing shingles and wood are identified as the components whose recycling will yield good profit and thus may not need government's support or incentives. Moreover, C&D waste components such as concrete, brick, block and asphalt, have been identified as components whose recycling will not be profitable enough and therefore would require government's support or incentives. The result of the case study also shows that the quantity of non-ferrous metals in C&D wastes are very small and their recycling will not yield any significant profit. / Civil Engineering