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

Hydraulic conditioning to manage potable water discolouration

Results are reported from studies conducted using a unique laboratory-based, full-scale, temperature-controlled pipe facility to examine the impact of conditioning shear stress on discolouration risk, as characterised by bulk water samples (turbidity, iron and manganese) and biofilm pipe wall measurements. The facility uniquely allowed for replication of the dynamics of an operational network but with rigorous control, thus yielding fully representative results overcoming the limitations of bench-scale or operational studies. The effect of the daily variation in flow (and boundary shear stress) was observed to be greater than the effect of the average daily flow rate at reducing discolouration risk. This is useful for informing operation and maintenance strategies, specifically that regularly imposing cycles of flow variation are more effective than increasing total average flow rates at limiting discolouration risk. The application of such knowledge aids the development of cost-effective, proactive, operational interventions to manage discolouration

Between resistance and resilience: a study of flood risk management in the Don catchment area (UK)

The river Don catchment area in Sheffield and Rotherham offers a good place for a case study of flood risk management, given the impact of a flooding event in 2007 and the way in which local events have become entwined with national and international policy shifts. To interpret local policy, a combination of systems-based and socio-cultural theory is used. Both the theories and the case study serve to disentangle the multiple meanings of resilience. Understood in opposition to flood resistance, resilience has only limited applicability in an area such as the case study where engineering works protect employment and infrastructure. Resilience as a policy discourse also lacks political transparency and a recognition of socio-cultural influences. Underlying the shift towards resilient styles of management is an appreciation of the importance of capacity, to learn and to act. The case study identifies blockages to the realisation of that capacity

A methodological proposal to investigate the long term storage of pollutants in freshwater sediment biofilms and their response to environmental disturbances.

This research will review novel methodologies for understanding the behaviour of microbial communities and their role in pollution storage. Freshwater sediments are inhabited by attached microbial communities (biofilms) which are responsible for the majority of a river's metabolic activity. Biofilms thus provide valuable information on the environmental quality of the river and its surrounding areas. Despite remediation of freshwater sediments, biofilms can still store large quantities of pollutants. Biofilms have the exceptional capacity to adjust to new conditions including natural and anthropogenic environmental disturbances. Gaining a more comprehensive understanding of biofilm behaviour is therefore fundamental to developing improved management strategies. The initial focus of this research will be in the River Doe Lea in North East Derbyshire. The River Doe Lea extends 18km from the South at its source near Tibshelf, to the North at its discharge at the River Rother. In the 1990s the River was famed for having the highest level of dioxins in the world, 27 times higher than the second most polluted. The acute cause of this was a single pollutant event, however the river has also been subjected to long term anthropogenic pollution through industry, agriculture, transport (railways, M1) and wastewater pollution. While previous studies by the Environment Agency have focused on the flow, chemical, biological and ecological quality of the river, no research has been conducted into the role and behaviour of biofilms

Inappropriate flushing of menstrual sanitary products

This paper explores the disposal strategies of menstrual sanitary products through in-depth semi-structured interviews of women aged 18-30 years. There have been many educational campaigns to encourage solid stream waste disposal, however inappropriate disposal and blockages are still a major problem for the water industry. Whilst there have been quantitative studies exploring self-reporting of flushing norms, there is evidence to suggest these results may not take into account the complex set of socio-cultural factors associated with menstrual product disposal. Bridging this gap, our interviews found that although all participants had a desire to responsibly dispose, their ability to utilise solid waste streams or to minimise waste by using reusable products was not always possible because they felt, to some degree, restricted by the wider societal requirements for discretion and the design, accessibility and availability of bins and bathroom facilities. Based on these findings Industry recommendations are suggested

Together or apart? An analysis of social workers' decision-making when considering the placement of siblings for adoption or foster care

There is little consensus regarding whether siblings fare better if placed together or apart in foster care or adoptive placements. This case study explored the decision-making of social workers when considering whether to place siblings together or apart. A psychological framework, the Information Processing Approach to decision-making, was used. I aimed to explore the key information that social workers attended to, the constraints they faced, which people influenced their decision-making and what heuristics they relied on. Semi-structured interviews were conducted with six social workers working within one Local Authority. The interviews were transcribed and analysed using thematic analysis. Findings suggested that social workers attended to information regarding the individual needs of the children, the detrimental effects of separating siblings, and the positive and negative aspects of the sibling relationship. They faced constraints such as their previous experiences as a social worker and systemic issues. The social workers appeared to be influenced by a number of people during the decision-making process. As part of the assessment process, the social workers took into account published research relating to siblings. The social workers also appeared to use a number of heuristics to aid their decision-making. Implications for future practice and research are considered

Understanding microbial ecology to improve management of drinking water distribution systems

Microorganisms in Drinking Water Distribution Systems (DWDS) and in particular the microbial communities that form biofilms on infrastructure surfaces, drive critical processes impacting water quality. This paper reviews knowledge, research approaches and monitoring methods to consolidate understanding of the microbial ecology of DWDS. The review highlights how microbial characteristics and subsequent behaviour can be broadly classified as common or complex. Common behaviour relates to the ubiquitous and continual development of biofilms, consistent core communities and mediated material accumulation. In contrast, the complex aspect relates to the shape, structure and composition of the microbiome, defined by site specific properties such as supplied source water, pipe material and hydraulic regimes. It is shown how the latest microbial tools and techniques can be applied to increase our understanding of DWDS ecology and how water utilities are starting to use this knowledge. This is not because of regulatory requirements, but in recognition that they provide valuable information facilitating pro-active management and operation benefits to these critical yet ageing systems, protecting water quality and public health in the process

Social inclusion for children with hearing loss in listening and spoken Language early intervention: an exploratory study

Background: Social inclusion is a common focus of listening and spoken language (LSL) early intervention for children with hearing loss. This exploratory study compared the social inclusion of young children with hearing loss educated using a listening and spoken language approach with population data. Methods: A framework for understanding the scope of social inclusion is presented in the Background. This framework guided the use of a shortened, modified version of the Longitudinal Study of Australian Children (LSAC) to measure two of the five facets of social inclusion ('education' and 'interacting with society and fulfilling social goals'). The survey was completed by parents of children with hearing loss aged 4-5 years who were educated using a LSL approach (n = 78; 37% who responded). These responses were compared to those obtained for typical hearing children in the LSAC dataset (n = 3265). Results: Analyses revealed that most children with hearing loss had comparable outcomes to those with typical hearing on the 'education' and 'interacting with society and fulfilling social roles' facets of social inclusion. Conclusions: These exploratory findings are positive and warrant further investigation across all five facets of the framework to identify which factors influence social inclusion

Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

The erosion of the cohesive layers of particulate matter that causes discolouration in water distribution system mains has previously been modelled using the Prediction of Discolouration in Distribution Systems (PODDS) model. When first proposed, PODDS featured an unvalidated means by which material regeneration on pipe walls could be simulated. Field and laboratory studies of material regeneration have yielded data that suggest that the PODDS formulations incorrectly model these processes. A new model is proposed to overcome this shortcoming. It tracks the relative amount of discolouration material that is bound to the pipe wall over time at each of a number of shear strengths. The model formulations and a mass transport model have been encoded as software, which has been used to verify the model’s constructs and undertake sensitivity analyses. The new formulations for regeneration are conceptually consistent with field and laboratory observed data and has potential value in the proactive management of water distribution systems, such as evaluating change in discolouration risk and planning timely interventions