Municipal recycling is driven by a variety of factors. Yet how these factors change over time is not well understood. I analyze a suite of contextual and program variable in multiple time periods, spanning 16 years, in the Commonwealth of Massachusetts. Based on the models run, I reach the surprising conclusion that most program variables have an insignificant effect on recycling rates. These findings can inform municipal officials and waste managers as they seek new ways to increase municipal recycling participation.

In our fickle economy today, retail can be booming one year and going out of business the next. When things aren't going so well commercial retail buildings are left vacant and then can become eyesores that lead to a communities economic downturn. This thesis proposes a solution by designing commercial buildings for re-use by designing for deconstruction; so that whole buildings can be disassembled and relocated, or that building components can be recycled back into the materials loop.

Copper is a metal that is commonly found in our society's infrastructure, such as cables and wires. In addressing the climate threat, society is facing a major transition towards electrification and digitization, and here copper plays an essential role. Since copper is a main component in the infrastructure, the demand for copper has increased rapidly due to the electrification of, for example, the automotive industry. Even though copper in the earth’s crust is a scarce resource, it can be recycled an infinite number of times without losing its quality. For this reason, meeting future demand partly through secondary copper production is likely to be important. The aim of this study is to investigate what factors influence the secondary refined copper production levels in nine different countries in Europe. Specifically, the study examines how electricity prices, copper scrap prices, primary production of copper, GDP per capita and cost of labor affect the supply of secondary refined copper. The empirical analysis is based on data from nine European countries and over a period of 21 years, 1998 – 2019, thus adopting a panel data approach. The results from the econometric analyses show that all five variables tend to influence the supply of secondary refined copper, some having a more profound effect than the others. For instance, the findings suggest the presence of a low and negative electricity price elasticity of secondary refined supply, while an increase in the copper scrap price appears to have significant deterring impact on secondary refined copper production.

Production and purification of rare-earth elements (REE) is among the most demanding separation practices. In general, extracting REE from natural ores requires a large amount of chemicals and energy. Separating the ores contents is also a complex process which needs a tremendous amount of organic solvent mixtures to produce high purity lanthanides. Partial mitigation to this issue lies in urban mining. Recycling old, discarded electronics is an important step in implementing the circular economy concept, making electronics more sustainable. In this work, specific components of old mobile phones were selected for targeted metal recovery. The main focus was on treating permanent magnets containing Nd, Pr and Dy as REE. These magnets were dissolved with nitric acid and the dissolutions were used to measure multicomponent adsorption in different polymeric commercial cationic resins. The adsorption of lanthanides on Amberlite IR-120 and DOWEX 50WX8 resins is found to reach equilibrium within 60 minutes. Across all the metals and lanthanides, Amberlite IR-120 has shown a greater adsorption. Generally, it is observed that more metals are adsorbed at higher pH values. This behavior seems to be consistent for both metals and lanthanides. The experimental data of the three lanthanides (Pr+3 , Nd+3 , and Dy+3) was fitted with diverse models and Sips rendered the best results. Freundlich and Langmuir models also provide satisfactory correlation coefficients

M.S.

No description available.

As the world is getting more crowded, at the same time as people increase their consumption, there is a need for us taking control of our resource consumption and changing our behaviors into more sustainable ones. First of all, our consumption needs to decrease in order to prevent use of resources and prevent the production of waste. Secondly, there is a need for reusing and recycling materials already in the system, where the latter is a subject this study is going to focus on. In order to increase knowledge of recycling, exploration of new methods of spreading information and awareness is of interest. This study explores the spreading of information with a game-based learning approach, targeting young adults. A quantitative pre-study was conducted to investigate their recycling behavior, to get an understanding of what prevents and promotes recycling. Based on the findings from the pre-study, along with findings from previous research, a game was developed with the aim of meeting these preventing and promoting factors. The game explores how a digital game can be used to spread information of recycling along with a motivation to recycle. It was followed by a qualitative user study, to evaluate the game and explore users’ experience of learning through a game. According to the results, a game-based learning approach showed to be appreciated amongst the participants in general. They showed appreciation towards this type of learning and thought it was an entertaining alternative of learning. Crucial game elements for learning were detected along with further improvements. The game-play contributed to a knowledge increase, and after playing the game, participants saw potential in it being a motivational tool, but mostly, they saw it as a tool for motivating learning. / I takt med att vi blir fler människor på jorden, samtidigt som vår konsumtion ökar, är det nödvändigt att vi tar kontroll över vår förbrukning av resurser och förändrar våra beteenden till mer hållbara. För det första måste vår konsumtion minska, för att minska användningen av resurser och minska det avfall som uppstår. Det finns också ett behov av att återanvända och återvinna resurser och material som redan finns i systemet. Det senast nämnda, återvinning, är det ämne som denna studie fokuserar på. För att öka kunskap om återvinning är det intressant att utforska olika metoder att sprida information och medvetenhet på. Denna studie undersöker spridningen av information genom ”game-based learning”, en spelbaserad inlärningsmetod, och fokuserar på unga vuxna. En kvantitativ förundersökning har utförts för att undersöka målgruppens återvinningsbeteende, för att få en förståelse för dem faktorer som förhindrar och främjar deras återvinning. Baserat på resultaten från förundersökningen, tillsammans med resultat från tidigare forskning, utvecklades ett spel för att möta dessa förebyggande och främjande faktorer. Spelet skulle undersöka hur ett digitalt spel kan användas för att sprida information om återvinning och motivera användare till att återvinna. En kvalitativ användarstudie utfördes för att utvärdera spelet och användarnas erfarenhet av att lära genom spel. Resultaten visade att ett spelbaserat inlärningssätt i allmänhet var uppskattat bland deltagarna, då de uppskattade denna typ av lärande och tyckte att det var ett roligt alternativ av lärande. Avgörande spelelement för lärande upptäcktes, tillsammans med ytterligare förbättringar. Spelandet bidrog till en kunskapsökning och efter spelets gång såg deltagarna potential i spelet som motivationsverktyg, men framförallt som ett verktyg för att motivera lärande.

Growth media recycling during algae cultivation is necessary to increase the efficiency and reduce the cost of biofuel production from algae feedstocks. Without recycling media, the cost of algae based biofuel production would be prohibitively high and large scale algae based biofuel production would not be economically viable. The ratio of media recycled to media wasted assumed for algae farms is generally calculated to maintain salt concentrations below growth inhibitory levels, ignoring the influence of secondary metabolites which might decrease productivity. Secondary metabolites, which include allelopathic or auto-inhibitory biological contaminants, might lead to the accumulation of growth-inhibiting compounds in recycled media used in algae production. Chlorella sorokiniana (strain DOE1412) was a leading algae biofuel feedstock candidate and has not previously been evaluated for inhibitor production. To test the effects of water recycling on the growth of DOE1412, media was recycled through multiple rounds of algae cultivation. DOE1412 was grown in modified BG11 culture media until reaching the end of linear growth phase, at which point the biomass was removed, nutrients replenished to their initial concentrations, and the recycled culture media used for a subsequent round of growth. The culture media was recycled through five rounds of growth with cultures grown on recycled media compared to controls grown on freshly prepared growth media. Biomass density was monitored via optical density and the specific and productivity growth rates were used to quantify the extent of inhibition. Exploratory work was performed with the goal of identifying potential inhibitory substances produced by DOE1412 during cultivation. Samples of recycled media were analyzed for polyunsaturated fatty acids which have been demonstrated to be inhibitory. The carbohydrates content of used media was analyzed to assess the amount of organic materials shed by DOE1412 into recycled media during growth. The log phase growth rate (day-1) of DOE1412 was inhibited by 3±2%, 8±1%, 10±2%, and 18.6±0.9% when grown in media recycled 1-4 times, respectively, with a 99% level of confidence that inhibition was observed in each round of regrowth. The productivity growth rate (OD750/day) of DOE1412 was not inhibited in media recycled 1-3 times. The productivity growth rate of DOE1412 was inhibited by 13±3% when grown in media recycled 4 times with a 99% level of confidence that inhibition was observed. Zinc was found to accumulate in the recycled media to potentially toxic levels (>0.09 mg/L), therefore it is uncertain if the observed inhibition was due to an accumulation of inhibitory secondary metabolites or the accumulation of zinc. Two inhibitory polyunsaturated acids, linoleic and linolenic acid, were identified in media recycled 4 times. The carbohydrate content of recycled media fluctuated between 8-10% of total fixed carbon in media recycled 1-3 times and increased to 18% in media recycled 4 times. However, changes observed in media recycled 4 times may have been due to improper storage of used media.

Organic solvent nanofiltration (OSN) is a low-energy alternative for continuous separations in the chemical industry. As the pharmaceutical sector increasingly turns toward continuous manufacturing, OSN could become a sustainable solution for chiral separations. Here we present the first comprehensive theoretical assessment of enantioselective OSN processes. Lumped dynamic models were developed for various system configurations, including structurally diverse nanofiltration cascades and single-stage separations with side-stream recycling and in situ racemization. Enantiomer excess and recovery characteristics of the different processes were assessed in terms of the solute rejection values of the enantiomer pairs. The general feasibility of stereochemical resolution using OSN processes is discussed in detail. Fundamental connections between rejection selectivity, permeance selectivity, and enantiomer excess limitations are revealed. Quantitative process performance examples are presented based on theoretical rejection scenarios and cases from the literature on chiral membranes. A model-based prediction tool can be found on www.osndatabase.com to aid researchers in connecting materials development results with early-stage process performance assessments.

The complexity of networked systems has been continuously growing, and the abundance of online resources has presented practical management challenges. Specifically, system administrators are required to carefully configure their online systems to minimize security vulnerabilities of resource management, including resource creation, maintenance, and disposal. However, numerous networked systems have been exploited or compromised by adversaries, due to misconfiguration and mismanagement of human errors. In this dissertation, we explore different network systems to identify security vulnerabilities that adversaries could exploit for malicious purposes. First, we investigate the identity-account inconsistency threat, a new SSO vulnerability that can cause the compromise of online accounts. We demonstrate that this inconsistency in SSO authentication allows adversaries controlling a reused email address to take over online accounts without using any credentials. To substantiate our findings, we conduct a measurement study on the account management policies of various cloud email providers, highlighting the feasibility of acquiring previously used email accounts. To gain insight into email reuse in the wild, we examine commonly employed naming conventions that contribute to a significant number of potential email address collisions. To mitigate the identity-account inconsistency threat, we propose a range of useful practices for end-users, service providers, and identity providers. Secondly, we present a comprehensive study on the vulnerability of container registries to typosquatting attacks. In typosquatting attacks, adversaries intentionally upload malicious container images with identifiers similar to those of benign images, leading users to inadvertently download and execute malicious images. Our study demonstrates that typosquatting attacks can pose a significant security threat across public and private container registries, as well as across multiple platforms. To mitigate the typosquatting attacks in container registries, we propose CRYSTAL, a lightweight extension to the existing Docker command-line interface. Thirdly, we present an in-depth study on hardware resource management in cloud gaming services. Our research uncovers that adversaries can intentionally inject malicious programs or URLs into these services using game mods. To demonstrate the severity of these vulnerabilities, we conduct four proof-of-concept attacks on cloud gaming services, including crypto-mining, machine-learning model training, Command and Control, and censorship circumvention. In response to these threats, we propose several countermeasures that cloud gaming services can implement to safeguard their valuable assets from malicious exploitation. These countermeasures aim to enhance the security of cloud gaming services and mitigate the security risks associated with hardware mismanagement. Last but not least, we present a comprehensive and systematic study on NXDomain, examining its scale, origin, and security implications. By leveraging a large-scale passive DNS database, we analyze a vast dataset spanning from 2014 to 2022, identifying an astonishing 146 trillion NXDomains queried by DNS users. To gain further insights into the usage patterns and security risks associated with NXDomains, we carefully select and register 19 NXDomains in the DNS database. To analyze the behavior and sources of these queries, we deploy a honeypot for our registered domains and collect 5,925,311 queries over a period of six months. Furthermore, we conduct extensive traffic analysis on the collected data, uncovering various malicious uses of NXDomains, including botnet takeovers, malicious file injections, and exploitation of residual trust. / Doctor of Philosophy / This dissertation investigates the security risks arising from resource management in various network systems. On the one hand, we explore the security risks of software resource mismanagement, examining two specific threats: the identity-account inconsistency threat in Single Sign-On authentication schemes and the typosquatting attack in container registries. On the other hand, we investigate hardware resource misuse in network systems, focusing on two security issues: the exploitation of computing hardware in cloud gaming services and the analysis of NXDomains within the Domain Name System (DNS). By thoroughly analyzing and understanding these security risks, this dissertation contributes to the advancement of networked system security and provides necessary countermeasures to protect Internet users against these threats.