abstract: The built environment is responsible for a significant portion of global waste generation. Construction and demolition (C&D) waste requires significant landfill areas and costs billions of dollars. New business models that reduce this waste may prove to be financially beneficial and generally more sustainable. One such model is referred to as the “Circular Economy” (CE), which promotes the efficient use of materials to minimize waste generation and raw material consumption. CE is achieved by maximizing the life of materials and components and by reclaiming the typically wasted value at the end of their life. This thesis identifies the potential opportunities for using CE in the built environment. It first calculates the magnitude of C&D waste and its main streams, highlights the top C&D materials based on weight and value using data from various regions, identifies the top C&D materials’ current recycling and reuse rates, and finally estimates a potential financial benefit of $3.7 billion from redirecting C&D waste using the CE concept in the United States. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019

During the delivery of healthcare services, hospital employees use enormous amounts of water, energy, and nonbiodegradable carcinogenic plastics. In the U.S., hospital staff generate an average of over 7,000 tons of waste per day at an average cost of $0.28 per pound for the disposal of regulated medical trash, which if efficiently managed or reduced, could result in substantial cost savings. Using the organizational learning and the transaction cost economics theories as the conceptual frameworks, the purpose of this qualitative case study was to explore strategies healthcare leaders used to minimize their waste management operational costs. Data were collected using semistructured interviews with 4 managers at a healthcare system in the Midwestern United States and reviewing financial documents as well as the participants' hospital website. Based on the thematic analysis, 4 primary themes emerged: (a) engaged leadership, (b) incorporate sustainability into the mission, vision, and values of the organization, (c) create an organizational culture of sustainability, and (d) innovation. Because society's health is largely dependent on the environment around them, these findings could assist hospital leaders in the implementation of cost-effective waste management strategies and contribute to positive social change.

The use of biomass as a potential feedstock for the production of liquid hydrocarbon fuels has been under investigation in the last few decades. This paper discusses a preliminary design and a feasibility study of producing liquid hydrocarbon fuels from biomass through a combined biochemical and thermochemical route. The process involves anaerobic digestion (AD) of the biodegradable portion of the biomass to produce methane rich gas. The methane rich biogas stream is purified by removing contaminants and upgraded to liquid hydrocarbon fuel in a gas to liquid facility (GTL) via thermochemical conversion route. The biogas conversion involves two major steps: tri-reforming step to produce syngas (a mixture of CO and H2), and Fischer-Tropsch Synthesis (FTS) step to convert the syngas to a spectrum of hydrocarbons. Separation and upgrading of the produced hydrocarbon mixture allows production of synthetic transportation fuels. AD is ranked as one of the best waste management options as it allows for: energy recovery, nutrient recovery, and reduction in greenhouse gases emission. A detailed process modeling of the process was carried out using ASPEN Plus process design software package. Data for the process was based on literature on AD combined with laboratory results on the biogas to liquid conversion process. The composition of the final liquid hydrocarbon from the ASPEN model has been compared to the composition of commercial diesel fuel, and results have shown good agreement. As a result, the most current commercial diesel prices were used to evaluate the potential revenue from selling the product in the open market. The total capital investment to construct the plant with a capacity of handling 100,000 ton per year of wet biomass is $16.2 million with a potential of producing 2.60 million gallons of diesel. The base case feedstock is corn stover. The annual operating cost to run the plant is estimated to be $8.81 million. An annual revenue from selling the diesel product is estimated to be $14.6 million taking into account a green energy incentive of $3.00/gallon of diesel sold. The net present worth at the end of the plant life is $8.76 million with a discounted cash flow of return of 26.2%. The breakeven cost of diesel is determined to be $4.34/gallon assuming no tipping fees are charged for handling the waste. Sensitivity analyses results concluded that the profitability of the process is most sensitive to variation in diesel selling price. Based on these results, it can be concluded that the process is profitable only if incentives are provided for renewable fuels due to the current low prices of fossil fuels.

Bayesian approaches to prediction and the assessment of predictive uncertainty in generalized linear models are often based on averaging predictions over different models, and this requires methods for accounting for model uncertainty. In this thesis we describe computational methods for Bayesian inference and model selection for generalized linear models, which improve on existing techniques. These methods are applied to the building of flexible models for gamma ray count data (data measuring the natural radioactivity of rocks) at the Castlereagh Waste Management Centre, which served as a hazardous waste disposal facility for the Sydney region between March 1978 and August 1998. Bayesian model selection methods for generalized linear models enable us to approach problems of smoothing, change point detection and spatial prediction for these data within a common methodological and computational framework, by considering appropriate basis expansions of a mean function. The data at Castlereagh were collected in the following way. A number of boreholes were drilled at the site, and for each borehole a gamma ray detector recorded gamma ray emissions at different depths as the detector was raised gradually from the bottom of the borehole to ground level. The profile of intensity of gamma counts can be informative about the geology at each location, and estimation of intensity profiles raises problems of smoothing and change point detection for count data. The gamma count profiles can also be modelled spatially, to inform the geological profile across the site. Understanding the geological structure of the site is important for modelling the transport of chemical contaminants beneath the waste disposal area. The structure of the thesis is as follows. Chapter 1 describes the Castlereagh hazardous waste site and the geophysical data, which motivated the methodology developed in this research. We summarise the principles of Gamma Ray (GR) logging, a method routinely employed by geophysicists and environmental engineers in the detailed evaluation of hazardous site geology, and detail the use of the Castlereagh data in this research. In Chapter 2 we review some fundamental ideas of Bayesian inference and computation and discuss them in the context of generalised linear models. Chapter 3 details the theoretical basis of our work. Here we give a new Markov chain Monte Carlo sampling scheme for Bayesian variable selection in generalized linear models, which is analogous to the well-known Swendsen-Wang algorithm for the Ising model. Special cases of this sampling scheme are used throughout the rest of the thesis. In Chapter 4 we discuss the use of methods for Bayesian model selection in generalized linear models in two specific applications, which we implement on the Castlereagh data. First, we consider smoothing problems where we flexibly estimate the dependence of a response variable on one or more predictors, and we apply these ideas to locally adaptive smoothing of gamma ray count data. Second, we discuss how the problem of multiple change point detection can be cast as one of model selection in a generalized linear model, and consider application to change point detection for gamma ray count data. In Chapter 5 we consider spatial models based on partitioning a spatial region of interest into cells via a Voronoi tessellation, where the number of cells and the positions of their centres is unknown, and show how these models can be formulated in the framework of established methods for Bayesian model selection in generalized linear models. We implement the spatial partition modelling approach to the spatial analysis of gamma ray data, showing how the posterior distribution of the number of cells, cell centres and cell means provides us with an estimate of the mean response function describing spatial variability across the site. Chapter 6 presents some conclusions and suggests directions for future research. A paper based on the work of Chapter 3 has been accepted for publication in the Journal of Computational and Graphical Statistics, and a paper based on the work in Chapter 4 has been accepted for publication in Mathematical Geology. A paper based on the spatial modelling of Chapter 5 is in preparation and will be submitted for publication shortly. The work in this thesis was collaborative, to a smaller or larger extent in its various components. I authored Chapters 1 and 2 entirely, including definition of the problem in the context of the CWMC site, data gathering and preparation for analysis, review of the literature on computational methods for Bayesian inference and model selection for generalized linear models. I also authored Chapters 4 and 5 and benefited from some of Dr Nott's assistance in developing the algorithms. In Chapter 3, Dr Nott led the development of sampling scheme B (corresponding to having non-zero interaction parameters in our Swendsen-Wang type algorithm). I developed the algorithm for sampling scheme A (corresponding to setting all algorithm interaction parameters to zero in our Swendsen-Wang type algorithm), and performed the comparison of the performance of the two sampling schemes. The final discussion in Chapter 6 and the direction for further research in the case study context is also my work.

This doctoral dissertation examines how the symbolic character of a relocated capital city influences and intersects with local conditions to shape the governance structure and relations in service delivery. The focus is on Abuja, the new capital city of Nigeria, and the sector studied is solid waste management. Abuja was planned to avoid the numerous problems facing other Nigerian cities. Contrary to the intention of government and planners, the city now houses the fastest growing slum in the country. There are various possible explanations for these outcomes but this study pays particular attention to the conception of Abuja as a symbol of national unity. The ‘good governance’ agenda is often promoted by the World Bank and donors as a way of handling the numerous challenges facing African governments, including service delivery. A major expectation of the agenda is that local governments manage the urban development process in conjunction with an array of institutions ranging from the private sector to community groups and households. An underlying notion is that of a minimalist national state. This is not the case in Abuja, where governance is conducted at higher levels and the municipal council remains largely invisible. This is manifested in solid waste management, where the municipal council has no jurisdiction over the sector. In addition, community groups and households play very minimal roles in the governance of services. Drawing on the concept of space and place, the study concludes that the types of institutions found and their roles and relations are shaped by the national function of the city and the local power relations. The study draws on primary and secondary data. Interviews were conducted with state officials, community leaders, households and interest groups, such as the private sector. Secondary data were obtained from government documents, studies and newspaper reports.

Energy recovery by waste incineration has a double function as waste treatment method and supplier of electricity and/or heat, thereby linking the systems of energy and waste management. Both systems are undergoing great changes, mainly due to new regulations. Important regulations within waste management in Sweden are a ban on landfill of combustible waste and organic waste, and a tax on landfill of waste. New waste incineration facilities are being built in order to increase capacity to meet these demands. The aim of this thesis is to investigate impacts on Swedish district heating systems of increased use of waste as a fuel in economic and environmental terms, the latter mainly by assessing emissions of carbon dioxide. Of importance is the influence of various policy instruments. To highlight the connection between the energy and waste management systems and how these influence each other is another goal, as well as the function of district heating systems as user of various waste heat supplies. An important assumption for this thesis is a deregulated European electricity market, where the marginal power production in the short term is coal condensing power and in the long term natural gas based power, that affects the conditions for combined heat and power in district heating systems. The method used is case studies of three Swedish municipalities that utilise waste in their district heating systems. In two papers, the scope is broadened from the energy utility perspective by comparing the energy efficiency of energy recovery and material recovery of various fractions, and the effect of including external costs for CO2 as well as SO2, NOx and particles. The ambition is that the results can be part of the decision making process for energy utilities and for policy makers in the energy sector and waste management. It is economically advantageous to use waste as a fuel in the energy sector and regulations in the waste management sector and high taxes on fossil fuels contribute to profitability. Waste incineration plants are base suppliers of heat because they derive revenue from receiving the waste. Economic conditions for waste incineration are altered with the introduction of a tax on incinerated municipal waste. A conflict may arise between combined heat and power production in district heating systems and waste incineration, since the latter can remove the heat sink for other combined heat and power plants with higher efficiencies. Combined heat and power is the main measure to decrease carbon dioxide emissions in district heating systems on the assumption that locally produced electricity replaces electricity in coal condensing plants. It can be difficult to design policy instruments for waste incineration due to some conflicting goals for waste management and energy systems. Comparing the energy efficiency of material recovery and energy recovery is a way to assess the resource efficiency of waste treatment methods. From that perspective, if there is a district heating system which can utilise the heat, biodegradable waste and cardboard should be energy recovered and plastics and paper material recovered. To put costs on environmental effects, so called external costs, is a way to take these effects into regard in traditional economic calculations, but the method has drawbacks, e.g. the limited range of environmental effects included and uncertainties in the monetary valuation of environmental effects.

The Wider Caribbean Region does not have a regional waste management strategy. An integrated approach to waste management throughout the region would benefit many economic sectors, safeguard people’s health and improve environmental quality. Numerous studies, above all a project conducted in 1994 by the World Bank, pointed out that one of the main reasons why such strategy has not been developed yet lies in the scarce availability of data in the waste management sector. Through on field researches and the analysis of institutional reports, the objective of the present study is defining the reasons that led and still underpin such scarcity. Furthermore, the study proposes a new methodology of data collection and improvements to one of the mathematical model that is used to estimate waste quantities in ports. The purpose of the paper is to find an integrated solution to a double challenge: waste abundance and energy scarcity, with focus on ship generated waste management.

Reduction is the best way of handling the issue of food waste, however, considering the difficulties of achieving reduction, a collection of waste for a potential decrease was established. The thesis consist of an examination between two subjects, the issue of food waste and the waste management system of collecting food waste to produce biogas, where the main focus is upon the municipality of Stockholm. The purpose of the study was to analyze the issue of food waste and connect it to the process of collecting food waste to produce biogas, and examine the potential benefits and conflicts between these two topics. The aim was also to investigate the process possibilities and functionality, and how the procedure is operating in the municipality of Stockholm. Besides a litterature study, four interviews were conducted with respondents from authorities and the municipality. The results show that the process of collecting food waste to produce biogas is a great procedure. It is a good alternative for the environment and generates to a substitute towards fossil fuel. However, whether the process is a benefit for the issue of food waste seems to be rejected. There are also difficulties of apprehending the connection between the two subjects, since they are seen as topics that lie collaterally to each other. In the municipality of Stockholm, the process function within the section of restaurants, however, it is not that fortunate within households. The factors of simplicity, profitability and trust are the main features threatening the success of the process of collecting food waste to produce biogas. One may presume that the goal/requirement firsthand is to focus upon reduction of food waste. However, there seems to be a shift from consuming less (reduce the waste) to consuming differently (reuse the waste) nowadays, hence the process of collecting food waste to produce biogas is central.

The bioreactor landfill is an emerging concept for solid waste management that has gained significant attention in the last decade. This technology employs specific operational practices to enhance the microbial decomposition processes in landfills. However, the unsupervised management and lack of operational guidelines for the bioreactor landfill, specifically leachate manipulation and recirculation processes, usually results in less than optimal system performance. Therefore, these limitations have led to the development of SMART (Sensor-based Monitoring and Remote-control Technology), an expert control system that utilizes real-time monitoring of key system parameters in the management of bioreactor landfills. SMART replaces conventional open-loop control with a feedback control system that aids the human operator in making decisions and managing complex control issues. The target from this control system is to provide optimum conditions for the biodegradation of the refuse, and also, to enhance the performance of the bioreactor in terms of biogas generation. SMART includes multiple cascading logic controllers and mathematical calculations through which the quantity and quality of the recirculated solution are determined. The expert system computes the required quantities of leachate, buffer, supplemental water, and nutritional amendments in order to provide the bioreactor landfill microbial consortia with their optimum growth requirements. Soft computational methods, particularly fuzzy logic, were incorporated in the logic controllers of SMART so as to accommodate the uncertainty, complexity, and nonlinearity of the bioreactor landfill processes. Fuzzy logic was used to solve complex operational issues in the control program of SMART including: (1) identify the current operational phase of the bioreactor landfill based on quantifiable parameters of the leachate generated and biogas produced, (2) evaluate the toxicological status of the leachate based on certain parameters that directly contribute to or indirectly indicates bacterial inhibition, and (3) predict biogas generation rates based on the operational phase, leachate recirculation, and sludge addition. The later fuzzy logic model was upgraded to a hybrid model that employed the learning algorithm of artificial neural networks to optimize the model parameters. SMART was applied to a pilot-scale bioreactor landfill prototype that incorporated the hardware components (sensors, communication devices, and control elements) and the software components (user interface and control program) of the system. During a one-year monitoring period, the feasibility and effectiveness of the SMART system were evaluated in terms of multiple leachate, biogas, and waste parameters. In addition, leachate heating was evaluated as a potential temperature control tool in bioreactor landfills. The pilot-scale implementation of SMART demonstrated the applicability of the system. SMART led to a significant improvement in the overall performance of the BL in terms of methane production and leachate stabilization. Temperature control via recirculation of heated leachate achieved high degradation rates of organic matter and improved the methanogenic activity.

The current thesis presents an exploratory study on municipal solid waste generation and minimization in Sweden, with a focus on their connection to basic socio-economic parameters. The fundamental goal of the study is to investigate into correlations and interdependencies between waste generation, waste minimization and basic socio-economic characteristics on municipal level, and to search for models for explanation of waste management parameters through socio-economic factors. Theoretical background involves reasoning on the role of municipal waste management in sustainable development, and extensive analysis of framework, legislation and organization of municipal solid waste management in Sweden. Practical part presents correlation analysis of data, which proved that socio-economic parameters do not explain differences in waste management performance of Swedish municipalities; however they are closely connected to differences between municipalities in aspect of presence of waste-related data.