Field Studies and Modeling Exploring Mean and Maximum Water Age Association to Water Quality in a Drinking Water Distribution Network

This paper presents the findings of an investigation into predicted/modeled water age and the associated quality characteristics within a UK drinking water distribution network to determine if there is a discernable link. The hydraulic and water quality software Aquis was used to identify water volumes of different ages, generated by localized demand patterns in pipes that are in close proximity to one another. The pipe network studied was small spatially, of a single material, and had a consistent demand attributable to serving predominately light industry, but with interesting hydraulic patterns involving loops and mixing of water volumes, and some long retention times. Field work was undertaken to obtain water quality samples from five network locations identified as containing a broad range of calculated water age. The samples were analyzed for standard regulated parameters by a UK Accreditation Service (UKAS) [formerly known as the National Measurement Accreditation Service (NAMAS)] accredited water laboratory in line with UK water industry standard quality assurance practice. The water sample analytical results were examined to test how a number of physical, chemical, and bacteriological parameters related to the calculated water age at each sample point. Heterotrophic plate counts were used as the indicator of general bacteriological water quality. A limited association between the calculated water mean age and quality parameters was observed. Further investigations, taking into account mixing of different aged water volumes and the maximum age contributions to the mean age at each sample location, produced some association. The work demonstrated that mean age is not a sufficient guide to general water quality in this small network area. Mixing effects, and maximum age volume contributions, need to be taken into account if a more comprehensive understanding of water quality is to be obtained

Witness intimidation in the industrial court

It is in the nature of adversarial proceedings that parties are set against each other, challenging versions of fact and arguing points of law in competition with each other. They do so before a person or persons appointed to listen, to weigh and to decide which versions and arguments should prevail. Witnesses called to give evidence by one or other party are inevitably involved in the muscular give and take of the competition. The process is a robust one and its value to a measure depends on the commitment of the various parties to their positions and their willingness to express these freely and without compromise in the presence of those who challenge them. It requires courage. For many people the experience of giving evidence in court comes as an unpleasant shock, meeting, as they do, not the accommodation and trust that they are used to in their daily dealings but doubt, mistrust and opposition. Insofar as their evidence is to the detriment of another, they speak in the knowledge of cultivating enmity and possibly of inviting reprisal. It says a great deal for the respect accorded to the law and its processes and for people's desire for justice that adversarial proceedings do not generally find that courage lacking

New Card Technologies in Retail Banking: Competition and Collaboration in the 1990s

This thesis examines the alternative bank card technologies being considered for retail banking in the UK in the 1990s. Influential organisations suggest that this technology needs updating, and various new technologies are being developed. The thesis identifies the most influential organisations within four groups considered key for retail banking technology: the technology supply industry, the adopting industry, the market and other key players. The observations and analysis in this thesis are based on information provided by each of these four key groups, through written Surveys, face-to-face and telephone interviews, and from a range of written sources. A selection of past and present bank card trials are also described, with particular focus on the introduction of smart card technology. Results confirm that the innovation process in the retail banking industry accords with a highly interactive model, with feedback loops throughout the innovation process. The adopting industry is seen to follow the innovation process in the opposite direction to that experienced in manufacturing industry. Thus, smaller incremental innovations eventually lead to more radical changes which effect complete systems change on a national basis - a ‘reverse cycle’ model of innovation. The thesis analyses the evolution of competitive and cooperative strategies, particularly between banks and their collective organisations, building societies and retailers. The thesis concludes that the dominant institutions driving card technology innovation and standards globally are the international debit and credit card corporations Mastercard, VISA and Europay, operating through their organisation EMV. In the UK, the major clearing banks, and their ABACS organisation, and the large retailers are also key actors. The thesis suggests that smart card is the most likely to be adopted

The Influence of Ground Conditions on Intrusion Flows through Apertures in Distribution Pipes

This paper presents a new, tractable analytical expression to describe the intrusion of fluids into buried pipes under steady-state conditions. The expression is validated with results from novel experiments. The derivation is based on the combination of the relevant existing models of flows through porous media and the losses through an orifice, with the resulting expression relating the intrusion flow rate to an applied driving pressure. The expression is shown to yield results directly equivalent to those generated from a full three-dimensional (3D) computational fluid dynamics (CFD) model of the intrusion process. Results from the experiments, quantifying volumetric intrusion from a realistic 3D porous media, presented here, compare favorably with calculated values, validating the expression. Although the experimental and analytical results show a high level of agreement, it was found that the analytical expression tends to slightly underestimate the intrusion rate seen experimentally. The absolute difference in the values is low and is thought to be attributed to preferential flow path at the porous media and pipe interface that the analytical expression and CFD model do not include. It is shown mathematically and verified experimentally that the viscous and inertial resistance to flow in the porous media reduces the intrusion (or leakage) flow over that predicted by the standard orifice equation and places additional dependencies of the flow on the size of the intrusion orifice. The values obtained from the expression should be considered as a lower bound to intrusion (and leakage) rates, with upper bounds being provided by the standard orifice equation. Although developed to aid in the quantification of intrusion risk, such as that associated with water distribution systems, the expression is also validated for leakage for the limited case that the external porous media is considered to be fully compacted, consolidated, and immobile

The effect of SO3-Ph-BTBP on stainless steel corrosion in nitric acid

SO3-Ph-BTBP is a hydrophilic tetra-N-dentate ligand proposed for An(III)/Ln(III) separation by solvent extraction, and a candidate for use in future advanced reprocessing schemes such as GANEX and SANEX. We present the first study of the effect of SO3-Ph-BTBP on the corrosion behavior of stainless steels. Specifically, studies have been performed using steels and conditions equivalent to those found in relevant nuclear reprocessing flow sheets. SO3-Ph-BTBP has been shown to have little effect on either steel passivation or reductive dissolution. However, if driven cathodically into a region of hydrogen evolution at the electrode surface or conversely anodically into a region of transpassive dissolution, observed currents are reduced in the presence of SO3-Ph-BTBP, suggesting corrosion inhibition of the steel potentially through weak absorption of a SO3-Ph-BTBP layer at the metal-solution interface. The lack of any observed corrosion acceleration via complexation of Fe3+ is surprising and has been suggested to be due to the slow extraction kinetics of SO3-Ph-BTBP as a result of a requirement for a trans- to cis-conformational change before binding

Modelling and flow conditioning to manage discolouration in trunk mains

This paper presents predictive discolouration modelling and subsequent field trial results for a cast iron trunk main network. This enabled a UK water company to propose an ‘operational flow conditioning’ maintenance plan that reduces discolouration risk, improves network resilience and asset condition and yet does not require the trunk main to be decommissioned for invasive cleaning. This represents substantial time and cost benefits. Pre-and-post trial turbidity monitoring data is also presented which identified a daily flux of material, a factor in the regeneration of material layers that have been shown to cause discolouration when mobilised. Additional data detecting the occurrence of pressure transients is also presented, a possible cause of contaminant ingress and asset failure

Online modelling of water distribution systems: a UK case study

Hydraulic simulation models of water distribution networks are routinely used for operational investigations and network design purposes. However, their full potential is often never realised because, in the majority of cases, they have been calibrated with data collected manually from the field during a single historic time period and, as such, reflect the network operational conditions that were prevalent at that time, and they are then applied as part of a reactive, desktop investigation. In order to use a hydraulic model to assist proactive distribution network management its element asset information must be up to date and it should be able to access current network information to drive simulations. Historically this advance has been restricted by the high cost of collecting and transferring the necessary field measurements. However, recent innovation and cost reductions associated with data transfer is resulting in collection of data from increasing numbers of sensors in water supply systems, and automatic transfer of the data to point of use. This means engineers potentially have access to a constant stream of current network data that enables a new era of "on-line" modelling that can be used to continually assess standards of service compliance for pressure and reduce the impact of network events, such as mains bursts, on customers. A case study is presented here that shows how an online modelling system can give timely warning of changes from normal network operation, providing capacity to minimise customer impact

Characterising and Understanding the Impact of Microbial Biofilms and the Extracellular Polymeric Substance (EPS) Matrix in Drinking Water Distribution Systems

Drinking water quality deteriorates during transportation through drinking water distribution systems (DWDS). Microbial activity and ecology, particularly within biofilms that occur on the inner-pipe surface of DWDS, are emerging as important drivers in the degradation process. Yet, we have little real-world applicable understanding of the DWDS biofilms. This paper provides a critical discussion of current drinking water biofilm research, highlighting the importance of biofilms, including the extracellular polymeric substances (EPS) and their interactions with the physico-chemical environment. Evidence is presented that the tools for biofilm analysis are becoming more accessible and there is now the opportunity to translate microbial research from idealised bench-top settings to practical real-world applications. It is essential that we understand biofilms and manage them within ageing, deteriorating DWDS infrastructure to protect public health and wellbeing

Bacterial community dynamics during the early stages of biofilm formation in a chlorinated experimental drinking water distribution system: implications for drinking water discolouration

Aims : To characterize bacterial communities during the early stages of biofilm formation and their role in water discolouration in a fully representative, chlorinated, experimental drinking water distribution systems (DWDS). Methods and Results : Biofilm development was monitored in an experimental DWDS over 28 days; subsequently the system was disturbed by raising hydraulic conditions to simulate pipe burst, cleaning or other system conditions. Biofilm cell cover was monitored by fluorescent microscopy and a fingerprinting technique used to assess changes in bacterial community. Selected samples were analysed by cloning and sequencing of the 16S rRNA gene. Fingerprinting analysis revealed significant changes in the bacterial community structure over time (P < 0·05). Cell coverage increased over time accompanied by an increase in bacterial richness and diversity. Conclusions : Shifts in the bacterial community structure were observed along with an increase in cell coverage, bacterial richness and diversity. Species related to Pseudomonas spp. and Janthinobacterium spp. dominated the process of initial attachment. Based on fingerprinting results, the hydraulic regimes did not affect the bacteriological composition of biofilms, but they did influence their mechanical stability. Significance and Importance of the Study : This study gives a better insight into the early stages of biofilm formation in DWDS and will contribute to the improvement of management strategies to control the formation of biofilms and the risk of discolouration