Using sound to predict flow rate of leaks in pipes

It's not surprising that leakages in water distribution systems is a worldwide issue with many consequences. These include the money required to fix leaks, the potential for contaminants to enter the water distribution systems, and the environmental impact of wastewater pipe leaks. Leaks can be found through a method called leak noise correlation, where sensors are placed to record and analyse the sound emissions from the leak. This method is widely used to find locations of leaks already, but the sensors record data that could potentially be used to find out the leak’s flow rate. Being able to predict flow rate could help those managing these systems to prioritise repairs based on flow rate. However, no reliable method has been found to predict the flow rate of a leak in distribution pipes using sound emissions. 

Joseph Butterfield, a STREAM researcher, set out to find a way to predict leak flow rate using leak noise correlation. The study aimed to predict the leak flow rate in medium-density polyethylene pipes using sound emission signals. The novel method involved four circular holes of different sizes being tested at several leak flow rates. 

The study was able to accurately predict the leak flow rate, regardless of the area and with no prior knowledge of the area. This shows the potential of this technique being used to assess and prioritise leak repair. As this was the first study, there would need to be much more testing, but now there is a first base case in leak flow rate prediction through sound emissions.

There were also attempts to predict leak area using this model. When contaminants enter water distribution systems through leaks, the leak area influences the level of contamination, and therefore development of this method could prove useful in judging the risk of contamination and therefore the threat to public health. Even further development of the use of leak noise correlation could include using it for detecting locations, flow rate, and leak area simultaneously.

Full article: Prediction of leak flow rate in plastic water distribution pipes using vibro-acoustic measurements, JD Butterfield, V Meruane, RP Collins, G Meyers, SBM Beck, Structural Health Monitoring 17 (4), 959-970

Full-scale Metaldehyde removal via biodegradation

It is a well-established fact in the water treatment industry that polar, low molecular weight pesticides are very difficult to remove from water using conventional methods. One of the main examples of this is metaldehyde, used frequently in slug pellets. It often seeps into water supplies after rain, so contamination is hard to avoid. As a result, metaldehyde is responsible for most of the pesticide-related drinking water failures in the UK. Whilst biological treatment is often effective against micropollutants, only some operational biofilters have be able to remove metaldehyde. Due to the minor role of the other methods used, biodegradation is likely to be the main removal pathway for metaldehyde. 

STREAM researcher Catherine Rolph monitored and assessed the biodegradation in an operational slow sand filter. The long-term data showed that the degradation of metaldehyde did improve when the inlet concentrations increased. Active and inactive sand batch reactors were compared, and that showed that metaldehyde removal happened mainly through biodegradation. 

The removal rates were greater if the biofilm was acclimated through high metaldehyde concentrations – there was a 40% increase in metaldehyde removal in acclimated columns compared to non-acclimated. This suggested that metaldehyde removal was reliant on enrichment, which means the process could be engineered to decrease the treatment times from days to hours. It is also important to note that this increase was sustained for more than 40 days, with an average of 80% removal, reducing metaldehyde concentration to be compliant with the approved levels. The study also looked into the microbial makeup of the acclimated and non-acclimated biofilms, and the microbial communities were found to be slightly different. This implies that as biofilms become acclimated, the bacteria present changes to be more appropriate for breaking down metaldehyde. 

This study provides a new basis for faster, chemical free, low cost, biological treatment of metaldehyde, as well as other polar pollutants, in drinking water.  Whilst this is a first study into this method, the results imply that this is a promising option after further investigation, especially since it was done at full scale and for more than 40 days.

Full article: From full-scale biofilters to bioreactors: Engineering biological metaldehyde removal, C Rolph, R Villa, B Jefferson, A Brookes, A Choya, G Iceton, F Hassard, Science of the Total Environment

Case Study: Reuse at the Olympic Park

There are certain issues, such as ageing water infrastructure and population growth, that are found in all megacities. These issues are likely to make water supply deficits in London worse over time. Addressing this threat could be done using wastewater reclamation and non-potable reuse (NPR), which has the potential to close the supply-demand gap without an impact on environmental water bodies. An important factor in this is understanding the challenges the diverse stakeholders face with regards to the governance of NPR schemes, and how these challenges can be addressed in the context of a megacity such as London. 

A case study was carried out by STREAM researcher Daniel Goodwin to explore these challenges. The study was centred on a sewer mining scheme in London, where reclaimed non-potable water was used for irrigation and toilet flushing around the London 2012 Olympic Park. Qualitative analysis was done on interview and document data.

This case study shows that NPR is viable and can be used to help prevent water supply deficits in megacities such as London. Collaboration and learning opportunities were seen as necessary to improve the governance of such schemes. It also indicated that engagement activities – both formal and informal – that centred on risk management can help develop common understandings, build inter-stakeholder relationships, and help maintain trust. All these factors influence the fact that NPR can contribute to the resilience of megacities, due to the increased diversity of the infrastructure. However, its feasibility will depend on how willing stakeholders are to participate and continually negotiate new risk management practices. As more and more NPR schemes are introduced, the willingness to participate will likely rise, leading to similar schemes becoming more commonplace in megacities over time, which in turn will help reduce the water stress of these areas. 

Full article: Collaboration on risk management: The governance of a non-potable water reuse scheme in London, D Goodwin, M Raffin, P Jeffrey, HM Smith, Journal of Hydrology

The importance of SuDS implementation and the challenges involved: expert opinions

Drainage systems are an essential part of any city’s water management. In particular, sustainable drainage systems (SuDS) have become increasingly important in water sensitive cities, as they have the ability to store and attenuate surface water, and the capability to treat runoff. The implementation of SuDS requires multiple areas, including planning frameworks, engineering designs, construction practices, maintenance processes, community buy-in and ownership agreement, working cohesively and aligning. 

To understand this alignment, as well as building an evidence base on the implementation and management of UK SuDS, STREAMer Peter Melville-Shreeve created a questionnaire to 50,000 industry professionals, which was distributed by the Chartered Institution of Water and Environmental Management. The findings from this suggested that whilst SuDS are beginning to become the norm, the ‘harder’ solutions are still much more commonplace. On top of that, design and construction remain weakly regulated, and the legal framework of SuDS ownership and maintenance is lacking and unclear. The expert practitioners supported the need for a single method of adoption, which would be coordinated by the local authority. They also suggested that there should be policy changes making SuDS mandatory, as their benefits are clear and this would speed up the rate at which the change happens across the UK. 

If the results of this survey are taken into account and supported by policy makers, there is the possibility for SuDS to become the norm, and help water sensitive systems in their water management.

Full article: State of SuDS delivery in the United Kingdom, P Melville‐Shreeve, S Cotterill, L Grant, A Arahuetes, V Stovin, R Farmani, D Butler, Water and Environment Journal 32 (1), 9-16

Quantifying fat, oil and grease build up in drainage systems

Food service establishments (FSEs) are a major source of fat, oil and grease (FOG) getting into sewer systems. Build-up of FOG can cause major blockages in the systems, which cost the management companies a lot of money to clear, as well as problems for those whose drainage systems are backed up as a result. Therefore it is important to know how to manage FOG, and to do that we need to know how much is entering the system.

Unfortunately, current methods for quantifying FOG in FSE wastewater are unsuitable, due to the interference from other substances like surfactants (the chemicals in detergents and the like) and food residue, which interact with FOG and create a compound called an emulsion. 

Caroline Gurd (Cohort V) led research into a novel quantification method, based on the dairy industry Gerber method. This method negates the effect of surfactants, allowing for FOG to be quantified without interference, making it possible to quantify FOG in a realistic manner. On top of that, the method allows free oils and oils that are part of an emulsion to be quantified separately. This separation allows greater insight into FOG management. The method was tested in both synthetic and real FSE wastewater, which indicated that the novel method is more reliable than standard extractions in FOG-rich systems. 

If this method is implemented by sewer management companies, clearing the sewer systems will be easier and more efficient. This would lead to less money being spent clearing sewer systems, less drainage system blockages, and prevent FOG build up from becoming too big to manage effectively. 

Full article: Determination of fats, oils and greases in food service establishment wastewater using a modification of the Gerber method, C Gurd, B Jefferson, R Villa, C De Castro Rodriguez, Water and Environment Journal

Does media bias affect public opinions on water reuse?

Public opinions on water reuse have been and continue to be a barrier to the success of various schemes. The internet allows many to engage with information surrounding water reuse proposals when they may never have encountered the information otherwise. There are benefits to engaging the public online, but there are also challenges associated with media bias and online advocacy. 

A study was undertaken by STREAMer Daniel Goodwin, with Cranfield University and Thames Water to examine the public response to online news outlets reporting on an indirect potable reuse proposal for London. The researchers examined 1323 online comments on six different articles regarding this proposal. The articles were from a variety of news sources, all from the top ten national readership rankings (bar the BBC, which is the most read but is not ranked with the others). The sources were varied in political leanings and included tabloids and broadsheets. This ensured a wide variety of readers and therefore commenters, as well as different message framing. 

Every article did imply a sense of disgust, featuring the idea of “drinking sewage” and a dominant frame of ‘toilet to tap’. Overall, three of the articles were more balanced in using both positive and negative sentiments towards the proposal, whereas the other three were evaluated as somewhat more negatively biased. 

There was no evidence of the way the media framed the event influencing the public reactions, whether positively or negatively. The study shows that whilst countering long-term agendas will be difficult, there may be benefits to experimenting with the way water safety measures and shorter-term gains are framed. This information is vital to anyone wanting to promote and advocate for water reuse proposals online, leading to more effective communications, and hopefully a more informed public when it comes to water reuse. 

Full article: Evaluating media framing and public reactions in the context of a water reuse proposal, D Goodwin, M Raffin, P Jeffrey, HM Smith, International Journal of Water Resources Development 34 (6), 848-868

How different message framing can affect public opinions on water reuse

Water reuse is becoming more relevant, especially in water-stressed regions, yet it is still seen as a controversial option. Providing information on reuse options can have a positive impact of how acceptable people find the concept of reuse. As a result, there is growing interest in understanding the differing impacts from different ways of communicating these messages. 

This study, led by STREAM researcher Daniel Goodwin, aimed to evaluate the way different methods of framing messages about the safety of recycled water impacts attitudes. 689 participants from London, UK, were split into focus groups. Each group was shown an animation about water recycling safety, with a different framing of the message for each group. There were surveys before and after the animation was shown, allowing the researchers to see the impact on the attitudes depending on the framing of the message in each animation.

The results agree with existing knowledge on the impact of difference types of messaging on public attitudes, including important evidence on the positive impact of water safety communications framed in terms of the compliance with water quality requirements. However, there was not an evident positive impact for messages framed in terms of the technology to remove contaminants, nor in terms of the risks relative to other everyday risks. 

These findings help isolate the effects of specific frames and add to the research on how an increased understanding of risk can influence willingness to support water reuse schemes. These results are of great value to water resource planners in creating communication materials that help to improve public perceptions of water reuse, and this could lead to an even further improvement over a larger time frame. As the UK could soon run into problems with water scarcity, it’s important that we begin to change minds so we can avoid wasting such a precious resource.

Full article:
Informing public attitudes to non-potable water reuse–The impact of message framing, D Goodwin, M Raffin, P Jeffrey, HM Smith, Water research 145, 125-135