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The suitability of a new plastic supporting medium for biofiltration was tested over a three year period. Tests were carried out on the stability, surface properties, mechanical strength, and dimensions of the medium. There was no evidence to suggest that the medium was deficient in any of these respects. The specific surface (320m2m-3) and the voidage (94%) of the new medium are unlike any other used in bio-filtration and a pilot plant containing two filters was built to observe its effects on ecology and performance. Performance was estimated by chemical analysis and ecology studied by film examination and fauna counts. A system of removable sampling baskets was designed to enable samples to be obtained from two intermediate depths of filter. One of the major operating problems of percolating filters is excessive accumulation of film. The amount of film is influenced by hydraulic and organic load and each filter was run at a different loading. One was operated at 1.2m3m-3day-1 (DOD load 0.24kgm-3day-1) judged at the time to be the lowest filtration rate to offer advantages over conventional media. The other filter was operated at more than twice this loading (2.4m3m-3day-lBOD load 0.55kgm-3day-1) giving a roughly 2.5x and 6x the conventional loadings recommended for a Royal Commission effluent. The amount of film in each filter was normally low (0.05-3kgm(3 as volatile solids) and did not affect efficiency. The evidence collected during the study indicated that the ecology of the filters was normal when compared with the data obtained from the literature relating to filters with mineral media. There were indications that full ecological stability was yet to be reached and this was affecting the efficiency of the filters. The lower rate filter produced an average 87% BOD removal giving a consistent Royal Commission effluent during the summer months. The higher rate filter produced a mean 83% BOD removal but at no stage a consistent Royal Commission effluent. From the data on ecology and performance the filters resembled conventional filters rather than high rate filters.

The aesthetic beauty of a landscape is a very subjective issue: every person has their own opinions and their own idea of what beauty is. However, all people have a common evolutionary history, and, according to the Biophilia hypothesis, a genetic predisposition to liking certain types of landscapes. It is possible that this common inheritance allows us to attempt to model scenic preference for natural landscapes. The ideal type of model for such predictions is the psychophysical preference model, integrating psychological responses to landscapes with objective measurements of quantitative and qualitative landscape variables. Such models commonly predict two thirds of the variance in the predications of the general public for natural landscapes. In order to create such a model three sets of data were required: landscape photographs (surrogates of the actual landscape), landscape preference data and landscape component variable measurements. The Internet was used to run a questionnaire survey; a novel, yet flexible, environmentally friendly and simple method of data gathering, resulting in one hundred and eighty responses. A geographic information system was used to digitise ninety landscape photographs and measure their landforms (based on elevation) in terms of areas and perimeters, their colours and proxies for their complexity and coherence. Landscape preference models were created by running multiple linear regressions using normalised preference data and the landscape component variables, including mathematical transformations of these variables. The eight models created predicted over sixty percent of variance in the responses and had moderate to high correlations with a second set of landscape preference data. A common base to the models were the variables of complexity, water and mountain landform, in particular the presence or absence of water and mountains was noted as being significant in determining landscape scenic preference. In order to fully establish the utility of these models, they were further tested against: changes in weather and season; the addition of cultural structures; different photographers; alternate film types; different focal lengths; and composition. Results showed that weather and season were not significant in determining landscape preference; cultural structures increased preferences for landscapes; and photographs taken by different people did not produce consistent results from the predictive models. It was also found that film type was not significant and that changes in focal length altered preferences for landscapes.

The scope of the study was to investigate the impact of water conservation on several aspects of solids transfer during low flows in sewerage systems which service small catchments. A newly constructed test-rig allowed for several test regimes in a small catchment, using simulated faeces. The test-rig encompassed WCs/bathrooms, lateral sewers, junctions, three branch sewer types, including a wide egg-shaped pipe and a main sewer which were all adjustable for height and gradient. Testing addressed gaps in the research including simulated human faeces, impact of wipes, cistern height adjustment, effects of non-invert level junctions, single occupancy dwellings, white goods discharge, bath and shower discharge patterns, degradation of human faeces and variable gradients. Original contributions are: 1. Simulated human faeces has been developed; this organic material is known as "The Buncrana". 2. Degradation of human faeces can take place in at least eight stages; this was also verified for the Buncrana. 3. Physical conditions can exist to provide unlimited solid transfer distance of given organic material, in contrast to work of previous researchers. 4. For a given solid and a 6.0 litre flush, limiting solid transfer distances (LSTD) can be established in a 30.0 m long 160 mm OD PVC pipe but not in the equivalent wide egg shaped sewer/pipe. The LSTD values are based on a single solid that is not combined with toilet paper or toilet wipes. 5. The wide egg-shaped pipe/sewer has advantages over circular pipes and at a 1/50 gradient can transfer the Buncrana a minimum of 30.0m with a maximum of 3 No. 6.0 litre flushes. For the same gradient and flush conditions the equivalent 160 mm OD PVC results in transferring the Buncrana circa 10.30511" However solid degradation was inhibited in the wide egg-shaped pipe. 6. Sewer pipeline configuration is key; a "minimum distance to convergence point" must be established to maximise use of water other than WC flush and prevent it bypass solids. 7. A methodology for the scoping of a code of practice for low flow testing has been drafted. 8. Risk of sewer blockages from single occupancy dwellings arises from adhesion of human faeces to the sewer. This thesis has recommended significant further research to provide innovation in the design of sewers to cater for water conservation.

Under the terms of the Water Act 1989, the Office of Water Services (Ofwat) was established and given responsibility for the economic regulation of the English and Welsh water industry. One of the concepts underpinning the new regulatory regime was comparative or 'yardstick' competition. Implementation of the regime required the establishment of a methodology for comparative efficiency measurement. The thesis presents econometric results from estimates of a series of ordinary and stochastic frontier cost functions. These are used to compare the efficiency of operators in both the water supply and sewage treatment branches of the industry. A new water supply database covering the period 1977/86 is constructed for the purpose, and the comparative efficiency rankings for both branches of the industry are shown to be robust. Fieldwork methods are used to analyse the role of yardstick competition in the regulatory regime and the way in which the comparative efficiency results could be applied. The fieldwork covers twelve interviews with officials of water companies, and one with the Director General of Water Services. Based on results on both quantitative and qualitative work, conclusions are drawn as to whether yardstick competition is a more widely applicable regulatory device.

Phase relations of the high Na-low Ca part of CaO-B2O3-Na2O-H2O system, relevant for the chemistry of boron in hydrating cement, were explored on a fine grid basis at 25°C and 55°C. The structure of several observed phases were determined and their diffraction patterns indexed. The experimental phase equilibria of calcium-borate hydrates and calcium-aluminate-borate hydrates were also assessed by calculation with good agreement. Solid solution formation between ettringite (AFt) or monosulphate (AFm) and their boron analgoues, which are candiate boron hosts in cement, was demonstrated by chemical analysis, FTIR and XRD. The size of the unit cells was found to be related to the series of substitutions in the structure. FTIR showed that boron is in [B3O3(OH)5]2- units in B-AFm. In a cement environment, B-AFt or mixed borate/sulphate AFt are stable and have very low solubility, AFm phases are metastable. Incorporation of simulated boron-containing waste water into cementitious matrtix (OPC, ground OPC clinker and BFS/OPC 9:1 blend) were investigated. Boron was used as boric acid, dissolved in the mixing water (4-12%) or sorbed in ion exchange resin (equivalent to 8% boric acid). The strong retardation effect of borates on cement hydration was confirmed. Instant precipitation of calcium-borate hydrates on the cement grains, inhibiting further access to water, is assumed to be responsible for this. Addition of NaOH at a necessarily high Na/B ratio to the mixing water keeps boron initially in solution and results in proper set. Matrix performance was investigated by calorimetry, pore fluid expression and leach testing. The resulting products were characterised by XRD and SEM. Confinement of boron in the major component of hydrated cement, in C-S-H gel, proved to be effective, although it could not be attributed to the formation of any crystalline boron compound. The use of blended cements (e.g BFS/OPC 9:1) instead of pure OPC is recommended due to its relatively low heat evolution, low permeability and low leachability.

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Access to safe water and sanitary means of excreta disposal are essential elements of human development and poverty alleviation. It is estimated that one in four people in the developing world lacks access to water while over half the population has no access to sanitation. From the Alma-Ata declaration in 1978 to the recent Millennium Development Goals, efforts to improve this situation have been hampered by the lack of meaningful indicators to measure hygiene, sanitation and water coverage and establish progress towards the goals and targets set out by the international community. This thesis aims to determine if measuring prevalence of access to water~ sanitation and the practice of hygienic behaviour in hous~hold surveys can be.improved. With no indicators available in current international' laws and targets, various aspects of access and practice were examined to design indicators for field-testing. By using - existing data sets, the research established that there is a high geographic clustering of the measures of interest, which results in large design effects (deff) and rates of homogeneity (roh) in cluster surveys. Based on the calculated roh optimum numbers ofcluster and sample size were calculated for the field trials. This requires introducing survey costs in the sample size calculations. The high clustering of water and sanitation indicator require large sample sizes, resulting in large amounts of data which organisations in the four field trials in Kosovo, South Africa, Kenya and Laos found difficult to handle. Practical problems in the implementation of the survey method resulted in non-sampling errors and could cause reluctance in adoption the methodology. The research improved water and sanitation indicators but found that for individual behaviour such as hygiene the household is not a suitable sampling unit. It also showed that observation among interviewers have to be better standardised to reduce the inter-surveyor.variation. Representative sampling is the current bottleneck in the development of such a survey method. Current method requires a good understanding of sampling theory as well as reliable sample frames, which are rarely available to implementing organisations. Alternative sampling methods are suggested, and recommendations are made for the further development ofthe survey method designed in this research, which to date may be too complex for widespread use.

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