Over the past 20 years there have been extensive developments in the activated sludge method of treating wastewater. The functions of the single sludge system have expanded from carbonaceous energy removal to include progressively nitrification, denitrification and phosphorus removal, all mediated biologically. Not only has the system configuration and its operation increased in complexity, but concomitantly the number of biological processes influencing the system performance and the number of compounds involved in these processes have increased. With such complexity, designs based on experience or semi-empirical methods no longer will give optimal performance; design procedures based on more fundamental behavioural patterns are required. Also, it is no longer possible to make a reliable quantitative, or sometimes even qualitative prediction as to the effluent quality to be expected from a design, or to assess the effect of a system or operational modification, without some model that simulates the system behaviour accurately. To address these problems, over a number of years design procedures and kinetic models of increasing complexity have been developed, to progressively include aerobic COD removal and nitrification (Marais and Ekama, 1976; Dold et al., 1980), anoxic denitrification ( van Haandel et al., 1981; WRC, 1984; Henze et al., 1987; Dold et al., 1991) and anaerobic, anoxic, aerobic biological excess phosphorus removal (Wentzel et al., 1990; Wentzel et al., 1992; Henze et al., 1995). In terms of the framework of these design procedures and kinetic models, the influent carbonaceous (C) material (measured in terms of the COD parameter) is subdivided into a number of fractions - this subdivision is specific to the structure of this group of models. The influent COD is subdivided into three main fractions, biodegradable, unbiodegradable and heterotrophic active biomass. The unbiodegradable COD is subdivided into particulate and soluble fractions based on whether the material will settle out in the settling tank (unbiodegradable particulate) or not (unbiodegradable soluble). The biodegradable material also has two subdivisions, slowly biodegradable (SB COD) and readily biodegradable (RBCOD); this subdivision is based wholly on the dynamic response observed in aerobic (Dold et al., 1980) and anoxic/aerobic (van Haandel et al., 1981) activated sludge systems, that is, the division is biokinetically based. Thus, as input to the design procedures and kinetic models, it is necessary to quantify five influent COD fractions, that is, to characterize the wastewater COD. From a review of the literature on existing tests to quantify the COD fractions, it was evident that the existing procedures are either too elaborate or approximate or sometimes not even available. This research project addresses these deficiencies. In this research project, the principal objective was to develop simple accurate procedures to quantify the influent wastewater COD fractions. A batch test method has been developed to quantify the five influent COD fractions; namely heterotrophic active biomass, readily biodegradable COD, slowly biodegradable COD, unbiodegradable particulate COD and unbiodegradable soluble COD. Also, the physical flocculation-filtration method of Mamais et al. (1993) to quantify RBCOD has been evaluated and refined.

There is growing concern that South Africa's urban centres are becoming increasingly vulnerable to water scarcity due to stressed surface water resources, rapid urbanisation, climate change and increasing demand for water. Furthermore, South Africa is a water-stressed country with much of its surface water resources already allocated to meet current demands. Therefore, in order to meet the future urban water supply requirements, countries like South Africa will need to consider alternative forms of water management that focus on moving towards sustainability in urban water management. WSUD is one such approach that aims to prioritise the value of all urban water resources through reuse and conservation strategies, and the diversification of supply sources. This study investigates the capacity of the Cape Flats Aquifer (CFA), assessing the feasibility of implementing Managed Aquifer Recharge (MAR) as a strategy for flood prevention and supplementing urban water supply. The implementation of MAR on the CFA aims to facilitate the transition towards sustainable urban water management through the application Water Sensitive Urban Design (WSUD) principles. The fully-integrated MIKE SHE model was used to simulated the hydrological and hydrogeological processes of the CFA in Cape Town at a regional-scale. Using the results of the regional-scale model, four sites were selected for more detailed scenario modelling at a local-scale. Several MAR scenarios were simulated to evaluate the aquifer's response to artificial recharge and abstraction under MAR conditions. The first objective was to evaluate the feasibility of summer abstractions as a flood mitigation strategy at two sites on the Cape Flats prone to winter groundwater flooding, viz. Sweet Home and Graveyard Pond informal settlements. The second objective of the study was to assess the storage potential and feasibility of MAR at two sites in the south of the Cape Flats, at Philippi and Mitchells Plain. In addition, the migration of solute pollutants from the injected or infiltrated stormwater was simulated and climate change simulations were also undertaken to account for potential fluctuations in rainfall and temperature under climate change conditions. The results indicated that flood mitigation on the Cape Flats was possible and was likely to be most feasible at the Graveyard Pond site. The flood mitigation scenarios did indicate a potential risk to local groundwater dependent ecosystems, particularly at the Sweet Home site. Yet, it was shown that a reduction in local groundwater levels may have ecological benefits as many of the naturally occurring wetlands on the Cape Flats are seasonal, where distinct saturated and unsaturated conditions are required. Furthermore, MAR was shown to improve the yield of wellfields at Philippi and Mitchells Plain through the artificial recharge of stormwater while also reducing the risk of seawater intrusion. MAR was shown to provide a valuable means of increasing groundwater storage, improving the supply potential of the CFA for water supply while aiding the prevention or mitigation of the seasonal flooding that occurs on the Cape Flats. Furthermore, the case was made that MAR is an important strategy to assist the City of Cape Town in achieving its WSUD objectives. MAR and groundwater considerations, in general, are essential for the successful implementation of WSUD, without which, there is an increased risk of overlooking or degrading urban groundwater resources. The findings of this study resulted in a number of recommendation to urban water resources managers, planners and policy makers. First, MAR is an important means for Cape Town to move towards becoming a truly water sensitive city. This study indicated that the CFA should be incorporated as an additional source of water supply for Cape Town especially considering the recent drought conditions and due to its ability for the seasonal storage of water, this would improve the city's resilience to climate change. Furthermore, it was recommended that the application of MAR on the CFA could also be used to reduce groundwater related flooding on the Cape Flats. Second, it was emphasised that urban planning, using WSUD principles is essential for the protection of the resource potential of the CFA. Finally, for the implementation of WSUD and MAR to be successful, there needs to be appropriate policy development alongside the implementation of these strategies to ensure they are achieving their initial objectives and are not causing detriment to the aquifer.

This thesis compares the Roman water systems in Pompeii and Nîmes in order to understand the relationship of the water systems to the urban layout of the city. Analyzing the nature and location of an urban water system enables a better understanding of the urban functions within a city, as well as prediction of the nature and location of particular structures within an urban plan. I examine the primary sources of Vitruvius and Frontinus, the topography of each city, the urban orientations, the hydro-technologies employed, and the public and private buildings to which water would have been supplied. My survey of water systems begins with the source of water and the aqueduct that supplies each city and also assesses the relationship of the aqueduct to the rural landscape. In both Pompeii and Nîmes, water from the aqueduct is deposited in a central settling tank within the city and dispersed from the settling tank to various destinations. I have analyzed the buildings, public and private, that had or would have required direct access to this water source and created water supply routes for each colony.

The objective of this study was to evaluate water conservation and water demand management in an industrialised City of uMhlathuze in Richards Bay. The City of uMhlathuze Local Municipality is the third-largest municipality in KwaZulu Natal (KZN) and is strategically placed to continue attracting investment as an aspirant metropolis due to the newly established Industrial Development Zone (IDZ) and the country's largest deep-water port. As an industrialised city, uMhlathuze's demand for water is already increasing and with the establishment of the IDZ, it is expected that water demand will escalate even further once the IDZ is fully operational. In line with the research question, this study has, therefore, sought to understand whether the industrialised City of uMhlathuze has developed and effectively implemented a water conservation and water demand management strategy and interventions in order to sustain water supply in anticipation of growing demand due to industrialisation and population growth. This objective was achieved by evaluating the city's current interventions and measures using a range of water conservation and water demand management solutions and guidelines. During this study, it was evident that the greatest threat facing South Africa's ambitious future economic growth, poverty alleviation and government's transformation agenda was the inefficient and unbalanced use of available and limited water resources. Thus, in order to avoid this imminent threat, the country as a whole must continuously reduce water consumption and demand from various sectors. This goal can be achieved through sustainable and improved water conservation and water demand management interventions. The study found that, in recent years, the issue of water scarcity had escalated in KZN. The province was in the grip of a drought, which was taking its toll on water supply in various municipalities around the province. The sparse rainfall in most parts of the province had caused the levels of rivers and dams to decrease to a point of crisis. Consequently, the KZN Provincial Government declared the province a disaster area in 2015. During the study, there was very little improvement as the City of uMhlathuze was still subjected to level 4 water restrictions. Evidently, the drought was intensifying the water problem in a municipality already grappling with poor and inadequate water infrastructure. A review of international and local literature was undertaken to theoretically position the objective of the research. An evaluation of the City of uMhlathuze water conservation and water demand management strategy and interventions was conducted using a questionnaire completed by city officials and part of the study included documentation review. This study investigated key elements of water conservation and demand management as well as interventions that were pertinent to achieving the desired outcome of efficient use of water. Respondents were required to answer questions focusing on several water conservation and water demand management related approaches and solutions. During the study, it was identified that there were inconsistencies in the implementation of water conservation and water demand management interventions even though the City of uMhlathuze had already taken the important step of developing a water conservation and water demand management strategy. It was recognised, however, that water conservation and water demand management remained relatively new for most municipalities. Consequently, it would take time for municipalities, together with communities, to implement effective interventions. The focus needs to be on the establishment of a combined team of staff and stakeholders, set up to finding solutions and interventions designed to maximise the most sustainable and efficient use of water. The conclusions drawn from this study and proposed recommendations indicated that wastewater reuse; pipe replacement; water pressure management; rainwater and stormwater harvesting; water sensitive urban design; leak detection and repair; joint planning and research team with the Industrial Development Zone; groundwater and aquifer recharge; stakeholder engagement, education and citizen awareness are feasible options for the City of uMhlathuze to consider in relation to water conservation and water demand management. These solutions should constitute the foundation of a revised and updated water conservation and water demand management strategy to be implemented incrementally with broad-based participation.

A key challenge facing developing countries is the rapid increases in urbanisation and the effect this has on their water systems. Water sensitive urban design (WSUD) is a process that considers the entire water system with the aim of achieving a water sensitive city (WSC). However, little is known about how value can be created through WSUD in terms of the sustainability of urban precincts in South Africa. The researcher therefore considered the well-established literature highlighting the relationship between WSUD and sustainable urban development. To understand the value derived from these concepts, two case studies were assessed, namely the Victoria & Alfred Waterfront (V&A Waterfront) and Century City. However, it should be highlighted that due to the uniqueness of these cases, no generalisations from the findings can be generated. The methodology implemented for the case studies was social constructivist in nature and to satisfy the research objectives, semi-structured interviews were conducted, documentary material was gathered, and photographic evidence was collected. Moreover, a diverse collection of data was assessed, which was extracted through various methods of data collection, thereby resulting in an in-depth understanding of the case studies. This research concludes there is a relationship between WSUD, sustainable urban development and value. It further argues that the underlying principles of facilities management (FM) and more specifically urban FM provide a managerial framework that can connect these concepts to achieve sustainability for urban precincts. Furthermore, the study uncovered the need for value capture mechanisms as a form of infrastructure financing and value creation for urban precincts. However, it was established that neither case study make use of such mechanisms, so future research is required in this regard.

The dramatic global trend of population growth has led to a rapid urbanisation, resulting in unprecedented land cover change. The incarnation of accompanying developed has typified impermeable surfaces. These surfaces have disconnected the stormwater component of the natural hydrological cycle, disregarding it as a nuisance and designing it to be rapidly removed from urban areas. Utilising Sustainable Urban Drainage Systems (SUDS) offers opportunities in urban areas to recycle the water and challenge the perception that stormwater is a nuisance and of no value. The current context of drought experienced by Cape Town has highlighted the need for less reliance on surface water resources; implementing SUDS could be a way of reconnecting the hydrological urban water cycle. It could also help to repair the human disconnect from nature that is prevalent in urban areas. The research question explored the role of spatial planning in enabling the implementation of SUDS in the City Bowl, Cape Town. While conceptual and technical frameworks have been developed for SUDS in South Africa, at present there is no spatial guide as to how these interventions could be realised in a specific context and area. This research utilise s the tools of spatial planning to re-imagine the City Bowl in relation to water. The case study methods used, enabling a detailed understanding of the site. This was complemented by interviews with various planning professionals in order to understand the current role spatial planning plays in terms of implementing SUDS. The research suggest is that whilst SUDS has many constraints, the opportunities that they provide for improving water quality and quantity, and surrounding amenities, suggests that this is one which has to be embraced if the City Bowl is going to respond innovatively and sustainably to the drought. It also highlights the need to improve coordination across different spheres and departments of governance, and emphasises the need to value local community knowledge. A prevalent silo approach to complex problems is no longer acceptable. The implications of the research are that implementing SUDS in the City Bowl requires planners to embrace a water literacy approach to spatial plans, and in doing so, return the focus to water

No / It is now well accepted that there are significant challenges to realizing the wide-spread and self-sustaining implementation of sustainable urban water management. It is argued that these challenges are entrenched within the broader socio-political framework, yet often unsuccessfully addressed within the more narrow scope of improving technical knowledge and design capacity. This hypothesis is investigated through a comparative analysis of three independent research projects investigating different dimensions of the water cycle including stormwater management in Australia, and sanitary waste management and implementation of innovative technologies in the UK. The analysis reveals significant and common socio-political impediments to improved practice. It was evident that the administrative regime, including implementing professionals and institutions, appears to be largely driven by an implicit expectation that there is a technical solution to solve water management issues. This is in contrast to addressing the issues through broader strategies such as political leadership, institutional reform and social change. It is recognised that this technocratic culture is inadvertently underpinned by the need to demonstrate implementation success within short-term political cycles that conflict with both urban renewal and ecological cycles. Addressing this dilemma demands dedicated socio-technical research programs to enable the much needed shift towards a more sustainable regime.

No

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Urban drinking-water supplies are still implicated as pathways for the transmission of waterborne disease. A move toward risk informed, proactive water system management has occurred over the past decade and is advocated in current international drinking water guidelines. Quantitative Microbial Risk Assessment (QMRA) is a tool with potential for aiding health risk management; however the refinement of scientific based practical methods to support that philosophy still requires development. This thesis focused on the water utility, its responsibility to manage microbial water safety, and how probabilistic QMRA may aid in developing management strategies. A framework for waterborne disease risk assessment from urban supply systems was derived and tested on an Australian case study. The main premise was that, in order for risk assessment outcomes to inform the management process, the steps should incorporate the concepts of risk variability, the explicit event conditions that can drive it, and that examination of QMRA sensitivity to various risk scenarios/model uncertainties is undertaken. The identified management uses were: (i) prioritising for attention issues hampering the system's ability to meet or the assessor's ability to interpret against (e.g. knowledge gaps about the system), a water quality health target; and (ii) identifying potential strategies or control points for addressing those issues. Additionally, rarely occurring, high impact, adverse fluctuations in treated water quality (and consumer infection risks), especially from source water contaminant "peaks", are highly, nearly totally, influential over the extent of risks averaged over longer, say annual, periods. As such, a case is made calling for widespread adoption of health targets that refer to tolerable consumer risks per exposure, rather than or as well as the current common practice of expressing targets in terms of risks from exposure over a year or lifetime. Doing so may provide incentive and opportunities for improved management, and the future derivation of specific microbial treatment or treated water quality targets, with a view toward protecting the community from extreme high risk periods associated with disease outbreaks.