Thames Water Research Articles

Washroom behaviour and users' perceptions of “novel” water-efficient appliances

A variety of washroom appliances are available which claim to be water efficient. However there are a number of “human” factors, which may adversely affect the water savings actually achieved when the appliances are installed. These were investigated as part of Thames Water's “Watercycle” project at the Millennium Dome, where a range of water efficient devices, such as infra-red controlled taps, waterless urinals and dual-flush toilets, were installed in the washrooms and compared to standard appliances. As well as monitoring actual metered water usage, to help understand how users interacted with the range of appliances, the work also involved a survey conducted by interview and an observational study of water using behaviour in the washrooms. The results highlighted significant differences between males and females, for example females were more likely to wash their hands following toilet use. With respect to “novel” dual flush toilets and waterless urinals, both fairly unusual in the UK, they were well received by users. In contrast, the infra-red controlled taps were found difficult to use and least likely to be accepted for use in the home. Relevant signage and labelling was found to have a positive effect on conservation and user opinions.

Water hammer in pressurized polyethylene pipes: conceptual model and experimental analysis

This paper analyzes the dynamic effects of pipe wall viscoelasticity on hydraulic transients. These effects have been observed in transient data collected from two polyethylene (PE) pipe systems. The first is a 270 m pipeline, 50 mm diameter, at Imperial College London, and the second is the world's longest experimental PE pipeline, 1.3 km long, 110 mm diameter, buried underground at Thames Water Utilities (London, UK). A mathematical model has been developed to calculate hydraulic transients in polyethylene pipe systems based on the assumption that the viscoelastic behaviour of pipe walls is linear. An additional term has been added to the continuity equation to describe the retarded deformation of the pipe wall and the resulting governing equations are solved by the Method of Characteristics. The numerical results are compared with both the classic elastic solution and with collected transient data. Good agreement between numerical results for the viscoelastic solution and observed data was obtained by fitting the creep function J(t). Unlike classic water hammer analysis, the developed mathematical model is capable of accurately predicting transient pressures in polyethylene pipes and the circumferential strains in the pipe walls.

Trickling filters for upgrading low technology wastewater plants for nitrogen removal

Previous work through the 1990s in the Thames Water region in the UK has demonstrated the ability of the trickling filter process to produce fully nitrified effluents, reliably throughout the year. The original data used for the nitrification model derivations have been reanalysed, to investigate the degree of nitrogen removal across the process. Removals of total nitrogen ranging from 0% to over 50% were observed across the trickling filter process and calculated total nitrogen removals of 26-63% were obtained when primary treatment was included. The degree of nitrogen removal and biological denitrification (excluding cellular assimilation) was found to be strongly influenced by BOD load, irrigation velocity and media size. Regression models were produced which gave good predictive relationships for the data ranges used. The models produced worked for filters used with and without a recirculation of effluent nitrate which suggests that a significant degree of nitrification occurred in areas of high heterotroph activity (BOD removal). The simplicity and energy efficiency of the trickling filter process, combined with its capacity for full nitrification and partial denitrification, make the process attractive as a combined process used with pond systems in developing countries where nitrogen removal may be required. Some of these synergies have already been developed with the PETRO process in South Africa.

DETERMINATION OF SLUDGE COMPOST QUALITY BY BIOASSAY

ABSTRACTThe paper reports the progress on a plant germination and growth trial as part of Thames Water's quality‐control procedure for sludge composting and recycling. The experiment was conducted by cultivating two types of plants in a greenhouse under controlled environmental conditions, using (a) standard peat‐based multipurpose compost, (b) Terra Eco Systems multipurpose compost, and (c) woodchip‐amended sludge compost.Tomatoes and petunias were selected for the trial, and the varieties were first‐generation (F) hybrid. Germinated seed counts were used to calculate germination percentages and germination values, to assess compost performance. Calculated germination values for tomato and petunias were 26.52 and 17.76 respectively for the peat‐based compost: the values of tomato plants for Woodchip‐amended compost and Terra Eco compost were 17.80 and 11.84 respectively; and for petunia, all composts performed similarly, with germination values ranging from 14.00 to 17.76. It was concluded that there were no significant differences between the petunia plants in three composts used in this trial.

Evaluation of a polyclonal antiserum to pentachlorothiophenol-acetic acid-KLH immunogen: binding properties and use with heterologous PCP derivatives in ELISA for pentachlorophenol.

A polyclonal antiserum to pentachlorothiophenol-acetic acid-KLH was generated in sheep and assessed by solid phase ELISA. The assessment procedure included use of double checkerboard analysis in the absence and in the presence of analyte loads, estimation of cross reactivities of chlorophenol pesticides, assessment of the effect of pH, Tween 20, and Thames water matrix. The antiserum was highly specific for pentachlorophenol and enabled minimum detection limits of less than 0.2 ng mL(-1) in river water matrix. Particularly important was the significant improvement of assay performance in the absence of Tween 20 and at pH 4 and the very low cross reactivity (less than 0.01%) for other commonly used chlorophenols-2,4,5-trichlorophenol and 2,4,6-trichlorophenol, 2-methyl-4-chlorophenoxyacetic acid, and 2,4-dichlorophenoxy acetic acid. The study re-affirms the importance of the judicious choice of hapten derivatives in the synthesis of immunogens and assay reagents for pentachlorophenol analysis by competitive immunoassays.

TREATISES AS PRECEDENTS OF ENGLISH LAW: UNJUST ENRICHMENT MARCHES ON

In Rowe v. Vale of White Horse District Council [2003] EWHC 388 (Admin), [2003] 1 Lloyd's Rep. 418 Lightman J. held that the defendant Council could not succeed in a claim for restitution in respect of unpaid sewage services provided to Mr. Rowe, a successor in title to a former tenant of the Council. The former tenant had bought the house from the Council in 1982 and Mr. Rowe had bought the house in 1988. When the Council claimed payment for the services, Mr. Rowe brought proceedings for judicial review of the Council's decision. The Council's defence was based on a claim to restitution for services rendered. From 1982 to March 2001, the Council gave no intimation that it was entitled to charge for the sewage services and Mr. Rowe had no reason to believe that his payments to the Council and to the Thames Water Authority were anything other than all that was demanded of him.

SOUTH‐EAST HOUSING DEVELOPMENT — THE QUEST FOR SUSTAINABILITY: WATER AND SEWERAGE NEEDS

ABSTRACTIn March 2000, a document entitled Draft Regional Planning Guidance for the South East was published with the primary aim of providing a regional framework for the preparation of development plans to the year 2016.This paper discusses the potential effects for the water industry of SERPLAN’s predicted levels of housing growth on water resources, sewage treatment and the environment. The need for sustainable development with the competing pressures of water‐resource limitation, changing regulation, increasing demand and the environment, are discussed. Thames Water’s scale of operations is described together with the range of measures aimed at managing the reasonable demands of customers, consistent with achieving sustainable growth. Basingstoke is described as a wastewater case study, highlighting the problem in fulfilling the sewerage undertaker’s statutory duties in (a) meeting already stringent effluent‐treatment standards which are necessary to maintain and improve river quality, and (b) providing the necessary infrastructure for an area which is earmarked for continuing development.

The Role of Ozone in Improving Drinking Water Quality in London and Oxford

In recent years, drinking water quality has become a major subject for public and political debate, with the issue of pesticides in drinking water receiving much attention. The EC Drinking Water Directive included a limit of 0.1 µg/1 for individual pesticides, a standard far more stringent than health-based minimum levels set by such bodies as the World Health Organizations and the US EPA.With traditional treatment processes such as chemical coagulation, flocculation, filtration and slow sand filtration unable to meet the stricter pesticide standard, an additional method of treatment was required. Consequently, ozone and granular activated carbon (GAC) have been installed at all the major water treatment works (WTWs) in London and Oxford treating river Thames water. Groundwater WTWs, deemed to be at risk from pesticides, have GAC filters only.Computational Fluid Dynamics (CFD) was investigated as a tool for optimizing the design of ozone contractors. The aim was to distribute ozone flow uniformly so that maximum contact would be made between the water and gas. However, the application of ozone in water treatment processes remains expensive when compared to conventional treatment. Consequently, a cost benefit analysis of continuous versus intermittent ozone operation was carried out. Operational data was obtained and compared for two Thames Water UK and Ireland (TWUKI) surface water treatment works (one conventional (chemical) works and the second based on biological processes).

P.1.092 Olanzapine versus lithium in relapse prevention in bipolar disorder: A randomized double-blind controlled 12-month clinical trial

The seismic response of a 2200-mm-diameter welded steel pipe at strike slip Kullar fault crossing in Izmit, Kocaeli during 1999 Kocaeli earthquake is investigated. The pipe was crossing the fault-line with an angle of 55° and suffered leaks due to 3.0 m of right lateral movement of fault, which imposed compressive axial strain in the pipe. The backfill material of the trench was native soil which was non-homogenous (soft and stiff clay) with respect to fault line-soft material on the North side, stiff material on the South side. Field observations revealed two major wrinkles with finger width cracks and a minor wrinkle on the soft soil side of the fault. Large plastic strains and local folding were observed at wrinkles due to compressive strains. The case is known as one of the best documented fault crossing examples.The failure behavior of the Thames water pipe during 1999 Kocaeli earthquake is simulated by utilizing a 3D nonlinear continuum FE model. The numerical model considers contact surface at soil pipe interface and performs large deformation analyses of the pipe. The locations of wrinkles as well as axial displacements/rotations demands due to fault rupture are predicted. It is observed that once wrinkle initiates, strain in the pipe away from the wrinkle reduces after initial local buckling and additional shortening of the pipeline tends to accumulate at the wrinkle causing large plastic strains and rotation demands associated with fault rupture, an observation consistent with field observations and 2005 ALA guidelines.

COMPARISON OF THE LONG‐TERM SECURITY OF SEWAGE‐SLUDGE TREATMENT AND DISPOSAL OPTIONS

ABSTRACTA comparative ‘best practicable environmental option’ assessment of fourteen potential sewage‐sludge treatment processes and disposal options was undertaken to support the development of Thames Water's sewage‐sludge strategy. The assessment was generic in nature and designed to provide comparative performance data on a range of potential process options forming the basis for subsequent site‐specific assessments. The study assessed: the relative technical practicability of each process option; the discounted costs of each option (including necessary environmental‐mitigation measures); environmental sustainability; and environmental nuisance. The assessment was quantitative wherever possible.The paper (a) describes the evaluation process. (b) highlights some weaknesses and strengths of the technique, and (c) demonstrates that the technique should form an essential first step in the development of any sludge treatment and disposal strategy.

Flood Defence Law after Marcic

The Court of Appeal decision in Peter Marcic v Thames Water Utilities (2002) raises some profound issues concerning common law liability for private nuisance and liability for infringement of human rights. Previously there had been recognised to be good reasons for excluding the liability of sewerage undertakers for sewer flooding, but these have been overturned by the decision. The finding of liability for environmental human rights infringements also defeats the purposeful avoidance of general statutory liability upon undertakers for sewer flooding and raises fundamental concerns about the respective roles of the courts and Parliament in contexts of this kind. The broad-based reasoning of the Court raises the implication that the same approach should be applied in contexts beyond that of sewer flooding. However, application of the same principles to the broader context of protection from flooding generally raises significant doubts as to the realistic scope of a right to such protection. Critical discussion, therefore, follows as to the need for careful qualification of any proposed right to flood defence and the failings of the Court in not taking account of the complexity of what is involved in dealing with liability for phenomena that arise from natural causes.

Thames Water acquires Spanish water businesses

Thames Water acquires Spanish water businesses

A Biosolids Composting Challenge: Meeting Demand for a Peat‐Free Horticultural‐Grade Product

AbstractIn 1996, Thames Water launched a range of peat‐free compost products based on biosolids. In order to keep up with demand and to maintain the high standards of product quality, the company has investigated higher‐rate composting processes and optimisation of the maturation stage. Agitated‐bay composting systems are the preferred in‐vessel technology for large sludge treatment centres using woodchip as a bulking agent. These automated systems (i) accelerate the composting process, (ii) maximise throughput on a smaller footprint, and (iii) achieve better control of odour emissions.A maturation trial with composted material from the US Filter agitated‐bay system confirmed that a horticultural‐grade product could be attained. Small‐scale maturation trials showed that seeding with mature green waste compost can accelerate nitrification to such a rate that near zero levels of ammonia can be achieved after one month of maturation.

Revealed: London's network of power tunnels

The vast Thames Water Ring Main and Jubilee Line Extension projects impressed us with further proof that tunnelling can deliver major urban infrastructure with minimum impact. Less dramatic, but arguably more important, is London's little-known but fast-expanding network of deep power tunnels. Creation of the UK's national grid in the 1960s made London's old power stations redundant but the 66 kV central distribution network was still good for a few more years. However, by the 1980s, this needed upgrading to 132 kV to keep up with the city's voracious appetite for electricity—and trenching was an increasingly less viable option. This paper reports on the key design and construction aspects of London Electricity's 30 km network of high-voltage cable tunnels, their many advantages, the lessons that have been learned and plans for the future.

Thames water

Thames water

Water recycling at the Millennium Dome

Thames Water is working with the New Millennium Experience Company to provide a water recycling system for the Millennium Dome which will supply 500 m3/d of reclaimed water for WC and urinal flushing. The system will treat water from three sources: rainwater--from the Dome roof greywater--from handbasins in the toilet blocks groundwater--from beneath the Dome site The treatment technologies will range from "natural" reedbeds for the rainwater, to more sophisticated options, including biological aerated filters and membranes for the greywater and groundwater. Pilot scale trials were used to design the optimum configuration. In addition to the recycling system, water efficient devices will be installed in three of the core toilet blocks as part of a programme of research into the effectiveness of conservation measures. Data on water usage and customer behaviour will be collected via a comprehensive metering system. Information from the Dome project on the economics and efficiency of on-site recycling at large scale and data on water efficient devices, customer perception and behaviour will be of great value to the water industry. For Thames Water, the project provides vital input to the development of future water resource strategies.

Membrane solution to a “significant risk” Cryptosporidium groundwater source

Collaborative work between Thames Water Utilities and PCI—Leopold outlines how pilot trial work has been taken through to full-scale application of a 9Ml/d, ultrafiltration plant on a “significant risk” Cryptosporidium groundwater source.

Traditional and novel reservoir management techniques to enhance water quality for subsequent potable water treatment

Thames Water treats approximately 2800MI/d of water originating mainly from the lowland rivers Thames and Lee for supply to over 7.3 million customers, principally in the cities of London and Oxford. Most of the river water sources are stored in bank-side, pumped, storage reservoirs prior to treatment for potable use. Storage reservoir sizes vary and typical theoretical retention times lie between a few days to several weeks or months. During storage the riverine biota is largely replaced by lacustrine taxa which can cause problems for subsequent water treatment, particularly filtration. Recent concerns about cyanobacterial toxins has heightened interest in reservoir management. This paper reviews aspects of Thames Water's research, design and operating experiences of managing eutrophic, algal rich, reservoir stored, lowland water. Areas covered include experiences of optimising reservoir water quality to both control algal productivity and to aid subsequent potable water treatment. Traditional reservoir management techniques are reviewed as is research into biomanipulation. Whilst changes in reservoir water quality using these techniques have been marked, actual retention time and quality changes have traditionally been difficult to predict. Computational fluid dynamic (CFD) modelling has been used successfully to substantially increase retention and subsequent changes to water quality. Information from CFD modelling may also be used to reduce risks from protozoan parasites such as Cryptosporidium and Giardia.

Decision-Support System for Domestic Water Demand Forecasting and Management

A decision support system (DFMS) for forecastingdomestic water demand including demand management was developedas part of a highly integrated decision-support system forriver-basin management. The system provides water resourcesplanners with the facilities for estimating future water demandfor domestic use for any demand region and time period, havingregard, to the possibility of introducing demand managementmeasures. The system has the capability of predicting domestic-water demand by various methods according to data availability.It can compute conservation effectiveness due to theimplementation of various demand-management measures,forecasting the number of customers for different consumptionunits (person, household and water connection) and facilitatingthe development of demand-scenarios for evaluating variousoptions. In general, the system comprises of the followingcomponents: (1) geographic information system, (2) databasemanagement system, (3) expert system, (4) multi-decisioncomponent, (5) prediction models, (6) user-interface, (7) hypertext files. The system has been tested and demonstratedusing the data of Swindon demand zone of Thames Water Utility.

The fate of Escherichia coli through water treatment and in distribution.

The removal of E. coli bacteria at each stage of water treatment is presented, showing how the filtration stages contribute most to reduction of bacterial numbers in the water. At treatment works without filtration stages, the emphasis is put on catchment management to limit contamination of the raw water and ensure that the numbers of viable E. coli in the source water remain low. Routine monitoring of the raw water provides data on seasonal trends in numbers of E. coli bacteria and allows effective management of supply. In the UK there is no evidence that E. coli grows in the water distribution system, whether in the planktonic stage or within biofilms (O'Neill et al. 1997). The detection of E. coli in the distribution system is rare and prompts a thorough investigation. Repeat samples are taken from the point which originally failed, along with a number of hydraulically linked samples including samples from hydrants. The response to the detection of E. coli is discussed. A series of experiments carried out on a pilot pipe system is briefly described and the results discussed in relation to the routine samples taken in the Thames Water Supply area.