Filamentous bulking in nutrient (N & P) removal activated sludge systems is a problem of considerable magnitude - three quarters of 45 plants surveyed were found to have bulking sludges to the extent that sludge settleability (DSVI) was adversely affected. If filamentous organism proliferation could be controlled and thereby sludge settleability improved to below DSVI of 100 ml/g, then with provision for factors such as additional aeration capacity, between 50% and 7 5% more wastewater could be treated in existing nutrient removing activated sludge plants. Anoxic-aerobic (AA) or low F/M filaments appear to proliferate in activated sludge plants that incorporate biological nitrogen removal. From earlier research, Casey et al. (1992a) showed that the cause for AA filament proliferation lay in the denitrification behaviour of the N removal systems. They hypothesized that filamentous and floe-forming organisms have different denitrification behaviour - the former reducing nitrate only as far as nitrite whereas the latter reducing nitrate all the way to nitrogen gas via the denitrification intermediates nitrite, nitric oxide (NO) and nitrous oxide (N₂O). If nitrate and nitrite removal to nitrogen gas is not complete in the anoxic reactor, then, when conditions become aerobic, the accumulated denitrification intermediates, in particular NO, inhibit oxygen uptake in the floc-formers. The filaments do not experience this inhibition because by reducing nitrate only to nitrite, no denitrification intermediates accumulate in their cytoplasmic membrane and consequently they can successfully compete against the floe-formers and proliferate in the N removal systems. If denitrification is complete, no residual intracellular denitrification intermediates remain in the floc-formers. Therefore, when conditions become aerobic, the floc-formers are not inhibited in their oxygen uptake and can successfully compete against the filamentous organisms which cause the bulking.

Since 1989 a wide ranging program of research has been under way to identify the factors that effect low F/M filament proliferation. Completed work has established an important factor conducive to low F /M filament proliferation - the presence of anoxic and aerobic zones, or, alternating anoxic-aerobic conditions in a system. It was also established that the presence or absence of readily biodegradable COD (RBCOD) or slowly biodegradable COD (SBCOD) were not deciding factors in their proliferation. The research presented in this thesis focuses on the effects of; • sludge age, • magnitude of the aerobic mass fraction, • magnitude of the nitrate concentration during the anoxic period, on the low F /M filaments. The experimental set-up consisted of two intermittently. aerated anoxic-aerobic (20 minute cycles, peak DO 2 to 2,5 mgO/l), single reactor completely mixed continuously fed systems. The experimental investigation was chronologically divided into 3 phases and examined the effect of the following conditions on the low F/M filaments.

In South Africa, it is a legislative requirement that all water supply points be metered (van Zyl, 2011). Conventional meters are mostly used as the main means of monitoring water consumption by South African municipalities. In the last two decades, the water metering industry has seen substantial developments with new capabilities added to the conventional water meter, known as advanced meters. These advanced water meters have capability of processing, storing and communicating data without the need of human intervention. As such they come with desirable capabilities for both consumers and municipalities. These include prepaid meters which are special type of advanced water metering technology that is mostly applicable in the low income areas of South Africa. However, advanced water meters have significant drawbacks, such as higher failure rates (due to electronics, batteries and more components), higher purchase and maintenance costs and susceptibility to tampering. It is therefore necessary to make a conscious and informed consideration when deciding on which metering technology to implement for different users. This could be achieved through having a technology evaluation framework. The goal of this research was to develop an evaluation framework to help municipalities in the selection of appropriate advanced water metering technologies for application in low income communities. This goal was achieved through: determining the range of functionality of technologies both available and under development for advanced water metering; documenting case studies of both successful and failed implementation of advanced water meters, including social perception and impacts; developing an evaluation framework that can evaluate advanced water metering; and evaluating on technical, social, economic and environmental grounds. The results from literature and case studies indicate that in low income communities, advanced water metering is mainly implemented for cost recovery purposes. However, some municipalities implement advanced metering schemes for water management and debt recovery. The most advanced water metering technology being installed in low income communities is prepaid meters. Prepaid meters have a potential to fulfill all the range of objectives that municipalities install advanced metering technology for. This technology is found to have high maintenance requirements due to high failure rate. For successful implementation, it is important that municipalities have adequate budget for repairs and maintenance or seek technical support from manufacturers.

The water molecule, rotationally state selected in the third and fourth streching overtone (|04>- and |05>-) and stretch-bend combination (|04>|2>-) levels, has been photodissociated at γ ≈ 282 nm via the à state. The OH photofragment rotational distributions, determined by OH(A-X) laser-induced fluoresence (LIF), are found to differ from those reported previously by Andresen and coworkers (H₂O|01>- + 193 nm), Grim and coworkers (H₂O|04>- + 239.5 nm) and Rosenwaks and coworkers (H₂O|01>⁺ + 193 nm). These variations become more apparent with increasing angular momentum in the parent water molecule and with an increasing number of OH stretching quanta in the intermediate vibrational overtone. The Franck-Condon model of Balint-Kurti is able to qualitatively reproduce the observed trends, provided that dissociation at lower photolysis photon energies and via higher intermediate overtone states is assumed to occur preferentially from extended R_H-OH configurations. The calculations suggest that the variation in the photofragment rotational distributions lies in a gradual change in the inertial properties of the bound state water molecule as the H-OH bond is stretched. In a second study, the partially deuterated water molecule, rotationally state selected in the third and fourth OH stretching vibrational overtone levels have been photodissociated via the à state at γ ≈ 288 nm. A branching ratio betweem the H + OD and D + OH dissociation channels is estimated from OD and OH (A-X) LIF measurements to be φ(OD)/φ(OH) > 20; this compares well with the previous measurements of Grim and coworkers, and the theoretical work of Imre and coworkers. The small shift in the centre of mass in the water molecule arising from the substitution of of a deuterium atom for one of the hydrogen atoms is shown to have a marked effect on the rotational distributions of the OD photofragment. Calculations using a modified Franck-Condon model, which includes an approximate exit-torque, are able to reproduce qualitatively the experimental OD rotational distributions at sensible values of R_R-OD(~ 1.4 Å). In addition to being sensitive to the dynamics of the parent molecule on the ground state potential, the product OD state distributions are shown to be very sensitive to even the smallest exit channel torque on the excited potential surface.

Biological nutrient removal (BNR) activated sludge systems (designed and operated with an additional function of biologically removing nitrogen and phosphorus) produce a waste activated sludge (WAS) that is rich in nitrogen (N) and phosphorus (P). When digested, this nitrogen and phosphorus are released, producing a dewatering liquor high in ammonia or nitrate and phosphate. Not only does this dewatering liquor need to be treated, but the phosphate also precipitates in the digester and surrounding pipework, resulting in loss of digester capacity and pipe blockages. This investigation studies anoxic-aerobic digestion (aerobic digestion with intermittent aeration), as an alternative digestion of BNR WAS. Aerobic digestion is simple to operate – being an extension of the activated sludge process, requiring aeration and limited recycling. This compared with anaerobic digestion which is complex to operate requiring airtight containers with fire risk, heating and much recycling. In anoxic-aerobic digestion, the nitrogen is removed by nitrification-denitrification, which has the added advantages of reducing the digester's oxygen demand and recovering some of the alkalinity lost in nitrification. Phosphate is precipitated in the digester - a convenient location. This results in a digester dewatering liquor low in nitrogen and phosphorus (<5 mgNH₄-N/l, <15 mgNO₃- N/l and 20 to 30 mgPO₄-P/l) that can be returned to the activated sludge plant without overloading it.

Over the last few decades, water stress has been imminent in most municipalities around the world. The problem of water losses from pipelines is a major concern due to the increasing demands. Leakage is normally responsible for a large percentage of water losses in distribution systems and results in enormous wastage of valuable resources and energy. Leaks may be developed in many forms and locations in the system and active leak detections are required to find and repair damaged pipes. Few studies have been done on the soil-leak interaction in real pipeline systems. Recent research have shown that the high velocity water jets entering the surrounding soil causes a fluidisation zone outside leaks. The fluidised zone of soil and water is responsible for dissipating most of the energy of the water jet from the pipe leak and thus, limiting the leak's ability to reach soil surface. In municipalities where active leak detections are not implemented, it is easier for municipalities to detect leaks if they appear on the surface and thus, it is crucial to understand the routes of water leaks and the factors causing them to appear above the ground. This study investigated the soil-leak interaction focusing mainly on factors affecting leakage flow paths in water distribution systems. An experimental set up was designed and built to study the different factors in a controlled environment. A series of experiments were performed where water jets from manufactured circular leaks were released in different trench set ups. Three main variables were investigated namely flow rate, leak orientation and in-situ soil to start understanding the movement of the leak flow as a preliminary study. The volumetric moisture content were measured using EC-5 moisture sensors at different locations in the tank to analyse the movement of leakage water and iPERLS smart water meters were used to measure the flow of water through the walls of the trench. The results of the experiments showed how much leakage water is actually lost through the side and bottom walls. The volumetric moisture content readings indicated the movement of the leak in the tank. The results of the study indicated that leak orientation has the greatest influence on the paths of the leaks. Also, the flow rate had to be increased to a very high value so that the leak appears above the sand surface. The permeability of the in-situ soil was found to have the least effect on the leakage flow paths.

Over the past 10 years the Water Research Commission (WRC) has recognized the potential benefits of the dual digestion system for South Africa where anaerobic digestion is the preferred method of sludge stabilization. Accordingly, from 1981 to 1984 under WRC sponsorship, the Johannesburg City Council (JCC) undertook a pilot plant study into the performance of the autothermal thermophilic aerobic reactor oxygenated with pure oxygen. As a consequence of the encouraging results obtained in this study (Trim and McGlashan, 1984; Trim, 1984), in 1987 the WRC and Milnerton Municipality supported a frill scale evaluation of dual digestion ( 45 ma pure oxygen oxygenated aerobic reactor and 600 ma anaerobic digestor) at Milnerton's Potsdam Wastewater Treatment Works, with scientific and academic input by the Division of Water Technology of the CSIR and the Department of Civil Engineering, of UCT. In this evaluation a number of important considerations needed to be addressed such as (1) oxygen requirements and oxygen utilization efficiency with pure oxygen and air oxygenation, (2) minimum retention time that can be achieved in the aerobic reactor and in the anaerobic digestor without comprormsmg the attainment of thermophilic temperature in the reactor and VS removal, gas production and sludge stability in the digestor, (3) temperature control of the aerobic reactor and anaerobic digestor, ( 4) efficacy of pathogen inactivation and mode of operation to prevent recontamination, (5) dewaterability of the anaerobically digested sludge, (6) operation and economic evaluation of the system. In this thesis, the results obtained pertaining to operation and performance of the Milnerton aerobic reactor are presented in detail. Also, the observed results are generalized and, based on the observed general principles, a design procedure and a simulation algorithm and computer programme for pure oxygen and air oxygenated reactors are developed, in accordance with objectives (1) to (3) above.

Cape Town is experiencing its worst drought in recorded history. Notwithstanding that the Western Cape has always been a water scarce region, it is this current drought that has brought home the area’s inherent vulnerability and highlighted the governance issues. The world wherein South Africa’s water governance was created is very different to the world we find ourselves in today. It is a world of uncertainty and unpredictability not contemplated in water governance comprised of legislation, policy, guidelines and practice. The current water governance constructs a conventional approach based upon predictability and certainty and is no longer appropriate to meet today’s new challenges. Consistent with this conventional approach, Cape Town’s municipal water supply is almost completely dependent upon surface water which makes it even more vulnerable to drought than if its supply was comprised of a variety of water supply options. With surface water sources fully exploited and storage opportunities within the urban edge limited alternative water supply options must be more seriously considered and the water governance reformed to accommodate its use. Water governance is the focus of reform because it is the framework for infrastructure planning and therefore controls the resultant system, infrastructure and management. This thesis interrogates the current water governance as the starting point before firstly discussing the proposed incremental approach towards a decentralised, hybrid system for water infrastructure and secondly, identifying specific areas where intervention is necessary for implementation.

The main aim of this thesis was to explore the impact of urbanisation on the provision of water to the people of the Durban Metropolitan Area. The literature study revealed that urbanisation is proceeding rapidly and that the urban population in Durban will continue to grow and expand. Employment opportunities and enhanced service delivery in urban areas were two of the primary factors that attracted people to the city centres. The provision of water was identified as a growing priority in the new South Africa. It was found that whilst the privileged minority enjoyed first world lifestyles, the majority of people were poverty stricken and had little or no access to basic services. The literature as it exists reflects that local government is entrusted with a mammoth and crucial task in enhancing sustainable service delivery at affordable prices to impoverished communities. In light thereof, local government required a concerted strategy to address urban needs if it is to respond more effectively to its clientele and to the effects of urbanisation in the new millennium. The empirical study included the use of questionnaires to: - managers at the Urban strategy Unit; - managers at Durban Metro Water Services; and - two hundred subjects randomly selected from the Inanda/ Phoenix, Cato Crest / Cato Manor, Clare Estate / Reservoir Hills and Umlazi informal settlements. The data was analysed using both descriptive and inferential statistics. The findings illustrates that an increase in urbanisation patterns has caused a decline in job opportunities and has added pressure to the local government infrastructure. The data revealed that the major obstacles to water delivery was accelerated urbanisation, lack of finance, high construction costs, high population growth rates, shortage of skilled labour, violence and crime and inadequate community participation. The empirical study revealed that people of all ages resided in the informal settlements. The majority of people were unemployed, generally had access to primary or secondary education and occupied menial jobs which were poorly remunerated. There is a need to create a National Commission on Urbanisation Development which can serve as an advisory body to government. This provision is universally recommended by urban geographers and government officials. This study calls for central government to play a more meaningful role in service delivery by strengthening the authority of local governments to raise adequate revenues to meet rising urban service needs. Central government must also provide technical assistance and training to local officials in improving tax administration, collection procedures and increasing revenues from existing and new sources. Local authorities need to improve their own performance in service delivery. This can be achieved if it has the capacity to act effectively and efficiently. Administrative structures and practices should be designed according to the services to be provided and the policies to be implemented. Furthermore, private sector involvement is crucial to ensure the provision of water to people, especially in impoverished areas. / Thesis (DPA)-University of Durban-Westville, 2000.

Water is an important natural resource and a building block to all life on earth. However, substantial increase in water demand and consumption has led to numerous nations, including South Africa, to face water scarcity. Improved water demand management strategies and water monitoring approaches are imperative. In South Africa, it's a legal requirement for all water supply points to be metered. Currently, water flow is primarily measured by conventional meters. However, substantial developments have been noted in the last two decades where conventional meters with added capabilities (such as communication capabilities) added have been introduced. These meters are known as advanced water meters. These capabilities offer functions such as leakage detection and more immediate consumption feedback. However, advanced meters also have significant disadvantages such as require high start-up capital and are susceptible to higher failure rates than conventional meters. It remains to be seen if advanced metering technology is an appropriate technology to be adopted in South Africa. Due to the different dynamics of South Africa's income level groups, the metering application and effects will differ for each income level group. Therefore, the purpose of this study is to investigate the feasibility of implementing advanced metering systems in high income areas in South Africa. An evaluation framework was developed to gauge the viability of implementing advanced metering systems on four performance criteria; technical, economic, environmental and social. The composite indicator framework template was selected as it was not tailor made for a specific reason and could be adapted for this research. The necessary framework input parameter data were acquired from practitioners in the field through questionnaires and from literature. Due to lack of advanced metering case studies in South Africa (except for prepaid meter), literature from developed countries were used as proxies. The input data entailed details of the current metering system, advanced metering system and new conventional metering system with the later used as a control for comparative purposes. The typical high-income scenario was derived from typical input data. For each input parameter, there were value ranges from the low parameter value to high parameter value. These ranges were used to conduct the sensitivity analysis on the framework to access critical input parameters to the success or failure of implementation Implementing advanced metering systems in high income areas in South Africa was found to be less economically viable than conventional meters. This is due to the lack of needed infrastructure for advanced metering as well as high initial capital costs and high operating costs. Advanced meters however proved to be more environmentally viable than conventional meters as they offered higher reduction in consumption. However, the manner in which faulty batteries are disposed could lead to environmental damage. Social factors were considered negligible for high income areas as revolts to introduction to new meters arises from financial constraints that those meters might induce. Further research with more South Africa based case studies and smaller scale advanced metering systems has been recommended.