Optimal operation of water reclamation facilities (WRFs) is critical for an indirect potable reuse (IPR) system, especially when the reclaimed water constitutes a major portion of the reservoir's safe yield. It requires timely and informed decision-making in response to the fluctuating operational conditions, e.g., weather patterns, plant performance, water demand, etc. Advanced integrated modeling techniques can be used to develop reliable operational strategies to mitigate future risks associated with water quality without needing high levels of financial investment. The Upper Occoquan Service Authority (UOSA) WRF, located in northern Virginia, discharges nitrified reclaimed water directly into a tributary of the Occoquan Reservoir, one of the major water supply sources for Fairfax County. Among the many operational challenges at UOSA, one is to regulate the nitrate concentration in its reclaimed water based on the denitrifying capacity of the reservoir. This study presents an integrated model that is used to predict future reservoir conditions based on the weather and streamflow forecasts obtained from the Climate Forecast System and the National Water Model. The application captures the dynamic transformations of the pollutant loadings in the streams, withdrawals by the water treatment plant, WRF effluent flows, and plant operations to manage the WRF performance. It provides plant operators with useful feedback for correctly targeting the effluent nitrates using an intelligent process simulator called IViewOps. The platform is powered by URUNME, a new software that fully automates the operation of the reservoir and process models integrating forecasting products, and data sources. URUNME was developed in C#.NET to provide out-of-the-box functionality for model coupling, data storage, analysis, visualization, scenario management, and decision support systems. The software automatically runs the entire integrated model and outputs data on user-friendly dashboards, displaying historical and forecasting trends, on a periodic basis. This decision support system can provide stakeholders with a holistic view for the design, planning, risk assessments, and potential improvements in various components of the water supply chain, not just for the Occoquan but for any reservoir augmentation type IPR system. / Doctor of Philosophy / In an indirect potable reuse (IPR) system, reclaimed water from an advanced wastewater treatment facility is blended with a natural water source, such as a reservoir, to augment drinking water supply. Reliable operation of such a system is critical, especially when the reclaimed water constitutes a major portion of the withdrawals from the reservoir for treatment and distribution. One example of such an IPR system is the Upper Occoquan Service Authority (UOSA) water reclamation facility (WRF) which discharges its reclaimed water into the Occoquan Reservoir, a key water resource for Fairfax County. Integrated environmental modeling (IEM) provides a comprehensive approach towards the design and operation of water resource systems in which water supply, drainage, and sanitation are simulated as a single entity rather than independent units. In IEM, different standalone models, each representing a single subsystem, are linked together to analyze the complex interactions between various components of the system. This approach can be used for developing operational support tools for an IPR system to ensure timely and informed decision-making in response to the fluctuating conditions, e.g., weather patterns, plant performance, water demand, etc. The overarching goal of this research was to integrate different models and the data sources and develop a decision support system (DSS) to manage the UOSA-WRF performance. This resulting integrated model is used to predict future reservoir conditions based on the weather and streamflow forecasts obtained from the National Weather Service. The application runs various future scenarios to capture the possible variations of the pollutant loadings in the streams, withdrawals by the water treatment plant, WRF effluent flows, and plant operations and provide feedback to plant operators. The entire integrated model is operated periodically to output data on user-friendly dashboards, displaying historical and forecasting trends. The DSS provides stakeholders with a holistic view for the design, planning, risk assessments, and potential improvements in various components of the water supply chain, not just for the Occoquan but for any reservoir augmentation type IPR system.

Este trabalho traz como contribuição o início sistemático de estudos para o projeto e execução de ozonizadores dedicados a estações de tratamento de água e esgotos domésticos com tecnologia totalmente nacional. O objetivo é desenvolver um sistema que apresente custo reduzido de fabricação, implantação, manutenção e também boa eficiência na produção de ozônio. Equipamentos auxiliares para bombeamento e tratamento do ar não são necessários, além de ser possível a ampliação do sistema. Devido ao caráter multidisciplinar, este trabalho aborda a problemática da geração de subprodutos danosos ao homem e ao meio ambiente pelo uso de desinfetantes tradicionais, bem como um processo alternativo de tratamento pelo emprego do ozônio. Após descrever os fenômenos físicos envolvidos no método das descargas corona, um tratamento matemático apresenta elementos para o projeto ótimo deste sistema. Contudo, para viabilizar o uso de materiais disponíveis no mercado, os valores adotados nos arranjos iniciais seguiram aproximadamente estas indicações. Os ensaios foram realizados e a produção de ozônio foi obtida por titulação iodométrica. Os primeiros resultados foram tabulados e comparados com valores informados pelos equipamentos de mercado. Sugestões de implantação em campo para trabalhos futuros são apresentadas. / Studies for the project and execution of ozonizers dedicated to the wastewater and water treatment with total national technology were presented. The aim of this work consists of developing a system which minimize the manufacturing process, implementation and maintenance costs and also improves the ozone production efficiency. Accessory pumping equipments has been eliminated with the use of Venture\'s system to inject the ozone in liquid and air treatment has not been used to reduce costs. While this system loses efficiency with air no treatable, it allows a parallel and serial set-up to improve its performance. To support this work, an extended bibliographical analyzes has been carried out, which due to its multidiscipline characteristic was separated into studies of the traditional disinfectant procedures, alternative ozone treatment and, the physical corona discharges phenomena. The two prototypes were developed and, their obtained with the iodometric titration method, was also compared with those of market equipments. These preliminary comparisons have shown that these prototypes have a good performance inclusive with one of them having an ozone production superior than one of market equipments. Suggestions of implantation in field and other improvements for future work are also presented.

Este trabalho traz como contribuição o início sistemático de estudos para o projeto e execução de ozonizadores dedicados a estações de tratamento de água e esgotos domésticos com tecnologia totalmente nacional. O objetivo é desenvolver um sistema que apresente custo reduzido de fabricação, implantação, manutenção e também boa eficiência na produção de ozônio. Equipamentos auxiliares para bombeamento e tratamento do ar não são necessários, além de ser possível a ampliação do sistema. Devido ao caráter multidisciplinar, este trabalho aborda a problemática da geração de subprodutos danosos ao homem e ao meio ambiente pelo uso de desinfetantes tradicionais, bem como um processo alternativo de tratamento pelo emprego do ozônio. Após descrever os fenômenos físicos envolvidos no método das descargas corona, um tratamento matemático apresenta elementos para o projeto ótimo deste sistema. Contudo, para viabilizar o uso de materiais disponíveis no mercado, os valores adotados nos arranjos iniciais seguiram aproximadamente estas indicações. Os ensaios foram realizados e a produção de ozônio foi obtida por titulação iodométrica. Os primeiros resultados foram tabulados e comparados com valores informados pelos equipamentos de mercado. Sugestões de implantação em campo para trabalhos futuros são apresentadas. / Studies for the project and execution of ozonizers dedicated to the wastewater and water treatment with total national technology were presented. The aim of this work consists of developing a system which minimize the manufacturing process, implementation and maintenance costs and also improves the ozone production efficiency. Accessory pumping equipments has been eliminated with the use of Venture\'s system to inject the ozone in liquid and air treatment has not been used to reduce costs. While this system loses efficiency with air no treatable, it allows a parallel and serial set-up to improve its performance. To support this work, an extended bibliographical analyzes has been carried out, which due to its multidiscipline characteristic was separated into studies of the traditional disinfectant procedures, alternative ozone treatment and, the physical corona discharges phenomena. The two prototypes were developed and, their obtained with the iodometric titration method, was also compared with those of market equipments. These preliminary comparisons have shown that these prototypes have a good performance inclusive with one of them having an ozone production superior than one of market equipments. Suggestions of implantation in field and other improvements for future work are also presented.

abstract: The water and wastewater industry in the United States is in dire need of renovation due to dwindling infrastructure and requires substantial reinvestment. Design-bid-build (DBB) is the traditional method of project delivery most widely applied in this industry. However, alternative project delivery methods (APDM) are on the rise and touting the benefits of reduced project schedule and cost. The main purpose of this study is to conduct a qualitative and quantitative performance evaluation to assess the current impact of APDM in the water and wastewater industry. A national survey was conducted targeting completed water and wastewater treatment plant projects. Responses were obtained from 75 utilities and constructors that either completed their projects using DBB, construction manager at risk (CMAR), or design-build (DB). Data analysis revealed that CMAR and DB statistically outperformed DBB in terms of project speed and intensity. Performance metrics such as cost growth, schedule growth, unit cost, factors influencing project delivery method selection, scope changes, warranty and latent defects, and several others are also evaluated. The main contribution of this study was that it was able to show that for the same project cost, water and wastewater treatment plants could be delivered under a faster schedule and with higher quality through the utilization of APDM. / Dissertation/Thesis / Masters Thesis Construction Management 2018

Water and wastewater treatment is a critical service provided for protecting human health and the environment. Over the past decade, increasing attention has been placed on energy consumption in water and wastewater systems for the following reasons: (1) Water and energy are two interrelated resources. The nexus between water and energy can intensify the crises of fresh water and fossil fuel shortages; (2) The demand of water/wastewater treatment services is expected to continue to increase with increasing population, economic development and land use change in the foreseeable future; and (3) There is a great potential to mitigate energy use in water and wastewater systems by recovering resources in wastewater treatment systems. As a result, the goal of this dissertation study is to assess the life cycle energy use of both water supply systems and wastewater treatment systems, explore the potential of integrated resource recovery to reduce energy consumption in wastewater systems, and understand the major factors impacting the life cycle energy use of water systems. To achieve the goal, an input-output-based hybrid embodied energy model was developed for calculating life cycle energy in water and wastewater systems in the US. This approach is more comprehensive and less labor intensive than the traditional life cycle assessment. Additionally, this model is flexible in terms of data availability. It can give a rough estimation of embodied energy in water systems with limited data input. Given more site specific data, the model can modify the embodied energy of different energy paths involved in water related sectors. Using the input-output-based hybrid embodied energy model, the life cycle energy of a groundwater supply system (Kalamazoo, Michigan) and a surface water supply system (Tampa, Florida) was compared. The two systems evaluated have comparable total energy embodiments based on unit water production. However, the onsite energy use of the groundwater supply system is approximately 27% greater than the surface water supply system. This was primarily due to more extensive pumping requirements. On the other hand, the groundwater system uses approximately 31% less indirect energy than the surface water system, mainly because of fewer chemicals used for treatment. The results from this and other studies were also compiled to provide a relative comparison of embodied energy for major water supply options. The comparison shows that desalination is the most energy intensive option among all the water sources. The embodied energy and benefits of reclaimed water depend on local situations and additional treatment needed to ensure treated wastewater suitable for the desired application. A review was conducted on the current resource recovery technologies in wastewater treatment systems. It reveals that there are very limited life cycle studies on the resource recovery technologies applied in the municipal wastewater treatment systems and their integrations. Hence, a life cycle study was carried out to investigate the carbon neutrality in a state-of-art wastewater treatment plant in Tampa, FL. Three resource recovery methods were specifically investigated: onsite energy generation through combined heat and power systems, nutrient recycling through biosolids land application, and water reuse for residential irrigation. The embodied energy and the associated carbon footprint were estimated using the input-output-based hybrid embodied energy model and carbon emission factors. It was shown that the integrated resource (energy, nutrient and water) recovery has the potential to offset all the direct operational energy; however, it is not able to offset the total embodied energy of the treatment plant to achieve carbon neutrality. Among the three resource recovery methods, water reuse has the highest potential of offsetting carbon footprint, while nutrient recycling has the lowest. A final application of the model was to study on the correlation between embodied energy in regional water supply systems and demographic and environmental characteristics. It shows that energy embodied in water supply systems in a region is related to and can be estimated by population, land use patterns, especially percentage of urban land and water source, and water sources. This model provides an alternative way to quickly estimate embodied energy of water supply in a region. The estimated embodied energy of water supply can further be used as a supporting tool for decision making and planning.

abstract: Water utilities across the United States are facing numerous challenges, such as limited funding and increasing project complexity, in constructing and upgrading their aging infrastructure. One innovative method to overcome these challenges is through the use of alternative project delivery methods (APDM), such as construction management at-risk (CMAR) and design-build (DB). Previous research has shown that APDM have the potential to deliver higher performing water infrastructure projects when compared to the traditional design-bid-build (DBB) method. However, there is a need to further examine APDM practices and develop tools that may support utilities in the delivery of their APDM water infrastructure projects. This study fills the knowledge gap by conducting several studies that may support public and private utilities in improving the delivery of their APDM water infrastructure projects. First, APDM implementation practices for water infrastructure projects are identified by assessing the state of practice, particularly during project procurement and execution. Second, DB project administration best practices are determined to support utilities seeking to add DB to their organization’s project delivery toolbox. Third, a pioneering web-based project delivery method decision-support tool was developed to aid utilities in selecting the appropriate delivery method for their water project. Finally, project-specific factors and attributes that impact project delivery performance are investigated through exploratory modeling and analysis. The study collected data on 75 completed treatment plant projects, conducted interviews with ten utilities that successfully deliver their water projects using DB, and worked closely with several industry experts through industry workshops and panels. Key findings related to water infrastructure project delivery revealed in this study included: (1) guaranteed maximum price (GMP) is the preferred compensation type for APDM projects; (2) utilities statistically having the lowest comfort level with delivering CMAR projects; (3) qualifications-based procurement is an effective DB project delivery practice; (4) the identification of 13 key project delivery method selection factors; and (5) the three highest predictors that impact unit cost performance are project complexity, project team chemistry and communication, and project size. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

Syfte: Hållbarhetsindex (HBI) är ett verktyg som har skapats av Svenskt vatten medsyftet att hjälpa VA-organisationer att analysera, utveckla och förbättra verksamheten.Den första HBI-undersökningen med 97 deltagande kommuner genomfördes 2014. År2019 deltog 171 kommuner. I studien som ligger till grund för den här rapportenundersöktes hur kommuners VA-organisationer använder HBI i praktiken samt vaddessa organisationer anser om HBI. Metod: En webenkät skickades till alla VA-organisationer i Sveriges kommuner.Svarstiden var mellan 31 mars och 9 april 2020. Totalt inkom 45 enkätsvar. Ettefterföljande mejlbrev till 14 av respondenterna genererade 7 fördjupade svar kringstudiens frågeställningar. Det genomfördes även en litteraturstudie av aktuell forskningi området och en dokumentanalys av HBI:s resultatrapport 2019. Resultat: 80 % av enkätrespondenterna anser att HBI identifierar viktiga frågor förverksamheten och även ger en överblick av VA-verksamhetens status. Endast 24%menar att HBI har hjälpt dem att ta fram dokument såsom VA-planer. Enkätsvaren visaratt 80 % tycker att HBI möjliggör jämförelser med andra kommuners HBI-resultat menendast 27 % anser att HBI faktiskt har hjälpt dem identifiera områden där samverkanmed andra kommuner kan ske. Resultatet i den här studien visar på stora variationermellan olika kommuners användning av HBI. Cirka en tredjedel av respondenterna -personer inom verksamheten som förväntas ha bäst inblick i HBI - vet inte huruvidaHBI använts som hjälp för att ta fram långsiktiga planer eller för att underlättakommunikationen med politiker. Konsekvenser: Slutsatser som dras utifrån den här studien är att landets VAorganisationerser positivt på HBI och att det finns ett behov av verktyget. Användandetav HBI varierar dock stort mellan olika kommuner. För att kunna tillämpa HBI ochstyra verksamheten mot en hållbar utveckling krävs resurser och rätt kompetens.Rekommendationer baserat på studiens resultat är att införa vägledande guider kringHBI i Svenskt vattens statistikdatabas VASS samt att ta fram riktlinjer och praktiskatips för hur HBI kan implementeras i VA-verksamheten. Begränsningar: Det går inte att dra några slutsatser av den här studiens resultat iförhållande till kommunernas olika förutsättningar gällande resurser,organisationsform, storlek etcetera. Undersökningen har inte berört HBI påparameternivå eller gjort dokumentanalys av respondenternas HBI-resultat. Trotsavgränsningar och begränsade möjligheter till generaliserering anses resultatet ändåvara användbart och ge en inblick i hur HBI har tagits emot och används av VAorganisationerna. / Purpose: Sustainability Index (SI) is a tool that has been created by Swedish Waterwith the aim of helping water and sewerage organizations to analyze, develop andimprove operations. The first SI survey with 97 participating municipalities wasconducted in 2014. In 2019, 171 municipalities participated. The study that forms thebasis of this report examined how municipalities' VA organizations use SI in practiceand what these organizations think about SI. Method: A web survey was sent to all VA organizations in Sweden's municipalities.The response time was between 31 March and 9 April 2020. A total of 45 questionnaireresponses were received. A subsequent email to 14 of the respondents generated 7 indepthanswers to the study's questions. A literature study of current research in the areaand a document analysis of SI's results report 2019 were also used as methods. Findings: 80% of the survey respondents believe that SI identifies important issues forthe business and also provides an overview of the VA operations' status. Only 24%believe that SI has helped them produce documents such as VA plans. The surveyresults show that 80% think that SI enables comparisons with other municipalities' SIresults, but only 27% believe that SI has actually helped them identify areas wherecollaboration with other municipalities can take place. The results of this study showlarge variations between different municipalities' use of SI. About a third of therespondents - people in the business who are expected to have the best insight into SI -do not know whether SI has been used to help develop long-term plans or to facilitatecommunication with politicians. Implications: Conclusions drawn from this study are that the country's VAorganizations view SI positively and that there is a need for the tool. However, the useof SI varies greatly between different municipalities. In order to be able to apply SI andsteer the business towards sustainable development, resources and the right skills arerequired. Recommendations based on the results of the study are to introduce guidingguides about SI in the Swedish Water's statistics database VASS and to developguidelines and practical tips for how SI can be implemented in the VA operations. Limitations: It is not possible to draw conclusions from the results of this study inrelation to the municipalities' different conditions regarding resources, organizationalform, size, etcetera. The survey did not refer to SI at the parameter level or did documentanalysis of respondents' SI results. Despite the limitations and limited possibilities forgeneralization, the results are still considered useful and provide an insight into how SIhas been received and used by the VA organizations.

The aim of this thesis was to contribute to the development of urban water management in large cities in a development context. This study presents a case study of Indonesian cities and Jakarta in particular and provides a monitoring framework to examine the impact of urban water management services on the environment and public health, as well as some alternative solutions for mitigation. Assessments were made by analysing the water demand of the urban population based on existing regional and international standards. To monitor major freshwater resource quality in Jakarta, remote sensing techniques based on Sentinel-2 MSI were used, while Sentinel-1 SAR was used to monitor land subsidence. The study also analysed urban wastewater management in Jakarta in comparison with other major cities in Indonesia and across the wider region. Water quality monitoring of the Ciliwung River, the longest river in Jakarta, was done to understand the impact of urban sanitation on surface water. The impact of water and wastewater management on public health on the incidence of diarrhoeal diseases among children was assessed using available statistical data. Some data were obtained from the Indonesian Demographic and Health Surveys (DHS) 2017 and the ESA Copernicus Science Hub for Sentinel-1 and Sentinel-2 satellites. Other data were obtained from field monitoring and laboratory analysis of water quality in river and reservoir, and from official reports on current coverage of and recent progress in urban wastewater management. These data and information were used to estimate and validate the field data, for instance those on Chlorophyll-a, provided by the Indonesian Fisheries Centre. Water quality monitoring data were compared with those of Sentinel-2 MSI, upon which correlation/regression analysis was performed. Data from on-site monitoring of land subsidence MONAS were compared with Sentinel-1 SAR data. Multivariate statistical analysis was used to assess the association between diarrhoea disease in children under 5 years of age (U5) and associated factors, for instance access to water sources and basic sanitation facilities, education attainment, breastfeeding practices, and other social factors. Thus, strategic intervention can be derived to reduce the incidence of diarrhoeal disease among children. A framework has been developed to monitor rapid urban development, water services and finally consequences for the environment and public outcomes. To monitor water management in urban settings, on-site water and wastewater quality monitoring, the latest remote sensing technology and statistical analysis should be integrated to measure and observe the outcome of urban water services on the environment and public health.:Declarations Foreword Acknowledgement Abstract Table of contents List of figures List of tables Abbreviations Currency equivalents Units Chapter 1 Introduction 1.1 Background 1.2 Objectives and scope 1.3 Research questions 1.4 Hypothesis of the study 1.5 Factors affecting the study 1.6 Outline of dissertation Chapter 2 Literature review 2.1 Economic development and rapid urbanization in Jakarta 2.2 Consequences of rapid urbanization 2.3 Sustainable urban water management 2.4 Withdrawal, treatment, and distribution of fresh water 2.5 Water quality monitoring 2.5.1 Freshwater quality standard 2.5.2 Drinking water quality standards 2.6 Wastewater treatment systems 2.7 Remote sensing with satellite technology 2.7.1 Interferometry synthetic aperture radar (SAR) 2.7.2 Sentinel-2 MSI 2.8 Multivariate analysis of diarrhoea and other factors Chapter 3 Methodology 3.1 Research framework 3.1.1 Remote sensing and water resources management 3.1.2 River water quality monitoring 3.1.3 Gap analysis of drinking water supply and wastewater treatment services 3.1.4 Association of diarrhoea with water and wastewater management 3.2 Global climate change 3.2.1 Urban development 3.2.2 Geography 3.2.3 Local climate characteristic 3.2.4 Precipitation rate 3.2.5 Population 3.3. Data collection and analysis Chapter 4 Results and discussion 4.1 Water quality monitoring at Jatiluhur reservoir 4.1.1 In-situ water quality monitoring 4.1.2 Pre-processing of Sentinel-2 optical images 4.1.3 Post-processing of Sentinel-2 images 4.1.4 Results of post-processing Sentinel-2 images 4.1.5 NDWI of Sentinel-2 images 4.1.6 Discussion of key findings 4.1.7 Major findings regarding water resource management 4.2 Land-subsidence monitoring with synthetic aperture radar (SAR) 4.2.1 Remote sensing for land subsidence monitoring 4.2.2 Results of remote sensing analysis 4.2.3 Discussion of remote sensing using SAR 4.2.4 Major findings of monitoring land subsidence 4.3 River water quality monitoring 4.3.1 Wastewater management and river water quality 4.3.2 Effluent water quality standards and GoI regulations 4.3.3 Key findings from river water quality monitoring 4.3.4 Pollutant index 4.3.5 Biological water quality parameters 4.3.6 Physical water quality parameters 4.3.7 Chemical water quality parameters 4.3.8 Discussion of river water quality monitoring 4.3.9 Key findings from river water quality monitoring 4.4 Drinking water, wastewater demand analysis, and public health 4.4.1 Coverage of drinking water supply and wastewater treatment capacity 4.4.2 Production, distribution and use of drinking water 4.4.3 Collection and treatment of wastewater 4.4.4 Diarrhoeal diseases 4.4.5 Discussion of water demand analysis and public health 4.4.6 Major findings from the analysis of water demand, wastewater and public health 4.5 Analysis of diarrhoea and associated factors 4.5.1 Introduction to multivariate analysis 4.5.2 Focus of study area 4.5.3 Fixed variable 4.5.4 Dependent variables 4.5.5 Results of multivariate analysis Chapter 5 Conclusion 5.1 New insight on urban water management 5.2 Socio-economic factors 5.3 Implication on further study and development List of References Annexes Disclaimer

Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study. Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas-liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa. The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used. ii These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17β-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17β-estradiol (E2) converted to estrone (E1) at the beginning of the reaction. A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.

Sewage misconnections currently pose severe threats to water quality especially in urban areas in the UK. These misconnections lead to the discharge of untreated wastewater into receiving watercourses via surface water outfalls. Regular discharges from this source could lead to these watercourses failing to meet standards set by the Water Framework Directives. Despite the impacts resulting from this urban diffuse pollutant source, research into this area is limited. The study area is the River Lee, which is known to experience issues with water quality especially within the heavily urbanized lower Lee section. Misconnections are one of the major contributors to the poor water quality status of the River. In this study, the Lee was investigated using several parameters. The approach involved the monitoring of coliform bacteria to detect outfalls where misconnections were likely, then biofilm samples below selected outfalls were used for both clean and polluted sites to look for community types. Results showed severe pollution within some sections of the River particularly within the lower Lee. Pymmes Brook was used as a case study, both coliform bacteria and biofilm communities below outfalls were further investigated for clean and polluted sites. Results from the Pymmes Brook study also showed that this watercourse was experiencing severe issues with water quality, with elevated levels of coliform bacteria identified below polluted outfalls. Biofilm community data obtained during the pilot and experimental phases of study were analyzed using a range of multivariate techniques. Results of the analysis showed consistent x patterns in community structure within sites with similar water quality, with indicator species identified. Communities below polluted outfalls were composed mainly of species tolerant of organic pollution thus indicating a response of communities to misconnection discharges. Currently, the identification of misconnections are carried out through trackbacks, a process which is expensive and time consuming. During this study an inexpensive and rapid approach is proposed for assessing misconnections within a catchment. Using this method, misconnection hotspots are mapped out using coliform bacteria and biofilm communities. Using catchment data and predicted coliform bacteria from enumerated counts, misconnections within these hotspots are assessed. Having tested this approach on Pymmes Brook, a tributary of the River Lee, the results obtained were promising. Pending further verification, this system provides an economical and rapid tool for the assessment of misconnections within a catchment.