Production and Prototyping Equipment for Manufacturing Ceramic Media for Water Biofiltration

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Image: Research Associates Rosy Heywood and Sonny Lightfoot using the extruder

Written by Rosy Heywood, Research Associate, Centre for Print Research

The production and prototyping of ceramic media has been predominantly based at the Centre for Print Research labs. The centre has expansive facilities with an array of technical equipment. Specialist machinery used in this project includes a hydraulic piston extruder and 3D printer. Other workshop equipment was utilised including an industrial dough mixer, ball mill and laser cutter.

During the design phase of creating the ceramic media it was considered a requirement that the production methods are able to produce 160 pieces of each type of media efficiently and consistently in size and also, the production method should be scalable and easily repeatable for future experimentation.

In our research, the importance of the porosity of the ceramic media was being analysed. And three production methods were established for the creation of three sets of media of varying porosities. Low porosity media was produced through extruding standard terracotta clay, medium porosity was produced by extruding a clay and sawdust composite and high porosity media was produced using an organic foam impregnation method. The specialist technical equipment used for low and medium porosity media is detailed below.   

Extrusion

With its origins in the production of bricks, extruders are now used in many different industries. According to Frank Handle in Extrusion in Ceramics, notable applications are in the production of foodstuffs such as pasta, shaping of aluminium profiles, wrought copper alloys and steel and for the extrusion of hard metal, graphite, coal and plastics.

The extruder housed at The Centre for Print Research was built by the technical team for the specific use with clay and clay composites. The clay is pushed through a die by the manually operated hydraulic ram. The die determines the extruded profile shape and size which can be extruded to different lengths.

To create the desired extrusions, we designed dies and 3D printed them to fit the ram cylinder. The benefits of using a piston extruder for this research is; it is easy to clean so small chance of contamination, little material is wasted and bespoke extrusion profiles can be produced with ease and precision using desktop 3D printers.

3D Printing

3D printing technology was utilised in this research to create bespoke manufacturing tools. Additive manufacturing is the production of 3D objects printed from a CAD (Computer Aided Design) model.

Filament is fed through the printer and the model is printed layer by layer. In prototyping we used a recycled Polylactic Acid (PLA) filament for the tools. PLA is a bio-plastic made from fermented plant starch and is commonly used in 3D printing due to versatility and ease of printing.

The advantage of using this technology is that we could create bespoke tools for specific processes during manufacturing the media. For example, a die was printed to extrude cylinders 20mm in diameter and a cutting jig was printed to cut them into exactly 20mm individual lengths.

Figure 2 3D printer in action printing an extrusion die

Getting back into the conference circuit

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Image: Exterior of IWA World Water Congress and Exhibition’s Gala Dinner held at the Øksnehallen.

By Dr Gillian Clayton, Centre for Research in Biosciences, College of Health, Science and Society

It has been several years since we’ve been able to attend any international conferences in person, but Darren Reynolds and I recently attended the International Water Association World Water Congress and Exhibition in Copenhagen, Denmark. This congress included 8,00o attendees, with over 300 exhibitors from all over the world to discuss all aspects of water. The overall theme of the congress was Water for Smart Liveable Cities, encouraging universities, independent research institutions, utilities, and industry to share information and work together. The congress theme aligns with the United Nations Sustainable Development Goal 6: Clean Water and Sanitation for All, and many of the talks and workshops discussed solutions to overcome key issues around water, sanitation and hygiene (WaSH). There were six key themes throughout the congress including, utility management, drinking water and potable reuse, city-scale planning, communities and partnerships and water resource management. This congress was a great way to share knowledge and create collaborations around many aspects of water that we cover within the Healthy Waters research cluster.

The breadth of this conference was introduced nicely with the opening keynote given by Professor Jason Box of The Geologic Survey of Denmark and Greenland. Here Professor Box highlighted the need for actions to prevent or slow increases in global temperatures. This talk provided a great overview of climate change, stating that global temperature increases are disproportionately affecting the arctic region, specifically the Greenland ice sheet, which was highlighted in the first episode of the new Frozen Plant 2 series. Increased glacial melting in the artic regions are not only causing an increase in water levels, but the additional cold freshwater entering in oceans is affecting global weather patterns, through the shifting ocean currents. This has never been more obvious with extreme weather events are becoming more common, such as hurricane Fiona recently affecting Puerto Rico, severe flooding in Pakistan and the typhoon in Japan.

These changes in weather events are going to further exacerbate uneven distribution of freshwater around the planet, with the poorest nations suffering the most. Therefore, utilising alternative water sources for drinking and daily use, and developing technologies and solutions to effectively treat water with minimal resources and environmental impact is necessary. The research I presented investigates treating stored waters, such as rainwater or ground water, with an in-situ electrochemical cell that reduces bacterial load (such as E. coli), making it safe to drink. The work is ongoing with project partners Bala Vikasa/Frank Water based in Telangana, India and the University of Antananarivo and Sadabe in Madagascar.

One aspect the congress organisers were keen to highlight was the transformation of the Copenhagen Harbour over the past ten years. Throughout the summer people are swimming, kayaking and paddle boarding throughout the canals which cut through the centre of the city. Ten years ago, there were constant instances of wastewater entering the Copenhagen harbour, yet with investment in wastewater treatment facilities the harbour is an example of sustainable city living. The transformation of Copenhagen harbour provides hope Conham River Park and Eastwood Farm Nature Reserve where there is an ongoing petition to designate the areas with bathing water status.

Investigating The Unique Properties of Ugandan Barkcloth as a Potential Filtration Material for Cleaning Contaminated Waters

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Main image: Final barkcloth. Source National Geograpic.

Written by Rosy Heywood, Research Associate, Centre for Print Research

On the Healthy Waters project one of our key focusses has been creating highly porous ceramic pots for direct filtration in third world countries and low resource settings. I have recently been investigating a new material as either an alternative to ceramics or used in conjunction with it. The Ugandan barkcloth is made from bark of the native Mutuba tree (Ficus Natalensis). The bark regenerates itself for up to 100 years and the process of making it into useable cloth requires little resources and a moderate amount of labour compared to conventional cloth. No spinning of fibre, weaving of threads or dyeing of cloth is necessary. Although, sometimes the cloth is naturally dyed for aesthetic purposes. So, it is a very sustainable and renewable material.

Barkcloth making in Uganda is on the UNESCO Representative List of the Intangible Cultural Heritage of Humanity. The inner bark of the Mutuba tree (Ficus natalensis) is harvested in the wet season and beaten with wooden mallets until soft. The final cloth will be roughly 10 times its original size. Any tears are hand stitched and often fragments of cloth are stitched together to make larger pieces. The introduction of cotton has rendered barkcloth an endangered craft in Uganda. If using the cloth as a water filter proves successful, then it could give skilled jobs to local village people. The cloth is historically made by men but there is potential here to empower women by teaching them a new skill.

Simple cloth filters are used as a quick way to rid larger particles from contaminated waters. Studies have shown old worn sari cloth can reduce cholera incidence from water collected from ponds and rivers by half. (Huq et al, Colwell RR et al.)

The use of barkcloth from the Mutuba tree as a water filter has not yet been researched however there is some research of the properties of barkcloth for medical purposes and as a fashion textile. New research from science and textile researchers published in the Journal of Applied Microbiology examined the feasibility of using bark cloth as an antimicrobial fabric within wound care management. It found that Ugandan bark cloth could stop the growth of MRSA by more than 99 per cent. Researchers from Istituto Marangoni London and Manchester Metropolitan University have collaborated with artists, environmentalists, farmers and fashion design practitioners across the world to discover the potential applications of barkcloth including how it could be used as a responsible material in luxury fashion.

I have carried out an initial porosity test by folding the cloth twice and wrapping it over a bucket. Water was then poured through a perforated cup on top of the cloth. The cloth showed resistance to water initially and then slowly water was able to flow through. The filtered water had a slightly orange tinge and contained a small amount of bark fibres. I tried pre-soaking the barkcloth however the soaked water changed colour to an orange/red hue.

This proved more testing is required for better quality outputs. This line of experimental research is at a very early stage and further inquiry is required to find out if barkcloth is a suitable material for filtering water. Including a toxicity report of the barkcloth soaked water, flow rate analysis and testing it in conjunction with ceramic filter discs.

Biofiltration – a new future for fresh water

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Around the world, the pressure to secure future supplies of fresh water is mounting. Only 2.5% of the world’s water is fresh, and only 0.77% of that water is deemed accessible. As if that’s not enough, only 10% of that is reported to be suitable for human consumption. Water demand globally is projected to increase by 55% between 2000 and 2050, driven by growing population sizes and their demand for agricultural products, energy supply and drinking water.

UNICEF’s 2019 report estimates that 1 in 10 people still lack basic water services (a protected and accessibly drinking water source, use of an improved toilet or latrine, and handwashing facilities in the home). This includes the 144 million people who drink untreated surface water; the consumption of biologically contaminated water is estimated to cause almost half a million annual deaths.

Researchers at UWE Bristol’s Centre for Research in Biosciences have been developing methods of treating biologically contaminated water using biofiltration. In their recently published study ‘The control of waterborne pathogenic bacteria in freshwater using a biologically active filter’, researchers Joshua Steven, Robin Thorn, Gareth Robinson, Dann Turner, and Darren Reynolds, alongside Jack Lee of Origin Aqua Technologies, set out to investigate the control of three species of bacteria commonly associated with biologically contaminated water.

UWE academics identified an unmet need for low-energy, sustainable solutions for the provision of potable water in communities with limited infrastructure. This study aimed to see if biofiltration was a viable option for treating water, as it is cheaper and less energy-intensive than techniques like chlorination and ozonation. Biofiltration is a technique which involves using bacteria to break down and consume unwanted contaminants, utilising microbial biofilms in filter columns. Biofilms are self-supporting communities of microorganisms, established on granular filter media such as sand or ceramic – so, biofiltration essentially uses bacteria to control bacteria.

This study’s outcomes were promising: biofilter water systems showed a significant reduction in the presence of harmful pathogens. If scaled up, this pathogen-management technique has the potential to be used to treat stores of harvested rainwater, ground, and surface waters, preventing the regrowth of bacteria such as E. coli after water treatment. Other practical applications include using biofilters to reduce the biological burden of final sewage discharges, and potentially improving the water quality of inland bathing waters or drinking water supplies.

The full study can be found online in the journal npj Clean Water.

Meet the team: Rosy Heywood

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Rosy Heywood is a Research Associate at The Centre for Print Research (CFPR) at UWE. In this interview, she discusses her work as a sustainable textiles designer & researcher, and her role in the Healthy Waters research cluster.

Could you tell us a bit about your background and how you came to work in your current area?

I studied a MA in Design at UWE, during the pandemic. I started in 2019 and graduated last year, and my tutor, Dr Laura Morgan, was working at CFPR – the Centre For Print Research – which is the department that I’m working in now. She hired me as a Research Associate on a natural dyeing and laser engraved biomaterials project because my MA project was very relevant, I had focused on textiles and sustainable materials and specifically natural dyeing. So, when this project came along with Healthy Waters, it overlapped with the natural dyeing work that I did; you can’t get away from the amount of water and the toxicity of water that synthetic dyes use, so sustainable water management was an area that I was already very interested in.

So, about a month after the project with natural dyes finished, Tavs [Dr Tavs Jorgensen, Associate Professor and AHRC/RCUK Innovation Fellow] got in contact with me about the Healthy Waters project. And I thought, ‘Wow, this sounds exciting’. Ceramics is a slightly new area for me – I did do some on my Master’s, because when you first start you have to do a lot of different workshops in different areas of design – but it’s been really great to be picking up a new skill and starting to become a bit more of an expert in it. Sonny [Sonny Lee Lightfoot, Research Assistant and Product Design Technician] and Tavs have been brilliant, I’ve been able to pick up lots of skills in ceramics. For me, I’ve come into this with my design training and my design thinking, and it’s been amazing to apply that in a new, fresh area.

It’s been really interesting to hear how the arts and science departments have been collaborating on this project. What’s the experience been like for you, leaning further towards the technical scientific elements of the project?

Sadie, a MSc student who has been using our ceramic beads to test for biological filtration, produced a chart of how well our ceramic media did during filtration and it was great to see the results from our combined work; it’s made me really interested in how I can ‘science-ify’ my research and improve that aspect of it. I’m looking into doing a PhD and I’d like to move towards a material science or textile science direction – that’s something which is happening in the CFPR anyway, we have the graphene lab and the researchers based there have great expertise in material sciences.

Sometimes when you’re creative, you get so embedded in the design or art of something, it’s easy to forget other aspects. So when you’re able to merge it with science, it opens up a new way of thinking around design – going forward, this project is definitely going to change the way I think about designing.

You mentioned earlier that you did your masters throughout COVID lockdowns – what was that experience like for you?

It was difficult because it’s a very practical course. A lot of it was things we’d have to be on campus for, to use the workshops. Initially I was doing a lot of digital embroidery, for example, and that had to be done on campus – I can’t just buy a digital embroidery machine at home! So that definitely changed my path into a different area for my Master’s; I came into it thinking I was going to be doing digital embroidery and art installations, which became increasingly more difficult. So, I chose to do something I could do from home: natural dyeing. My work organically grew into more of a research project. Dyeing was something I could do at home and I was really interested in learning more and experimenting with it. I think in a way COVID kind of made me realise a different path that I wasn’t expecting to go on and brought me to where I am now – even though it was a very difficult time to be stuck at home, it forced me to think a lot more about what exactly I enjoyed doing and what I am good at.

It sounds like the new route you’ve been taken down is pretty great – the Healthy Waters project seems to have a lot of potential to make a big difference in the world!

Definitely. At the beginning of my Master’s, I hadn’t thought much about the importance of the work I was creating. I was only thinking, ‘What do I want to create’ rather than considering the bigger picture. But in research, you have to think about an important question that you want to solve and the solutions often involve other people and everything going on around you; I found my focus in sustainability because it’s so important today. What we’re doing now on the Healthy Waters project is creating a very sustainable method of cleaning water and my work with the CFPR is creating ceramic vessels and media for biological filtration.

Your MA focused on sustainable design as well, do you think you’ve always had that drive to protect the environment or has that grown as you’ve encountered a more scientific angle to work?

It’s hard to avoid it – you see so many statistics, and real-life instances, like this heatwave we’re having, and you see the need for sustainable solutions and change all around you. I think before my MA I hadn’t really thought that I could merge that into my design practice but in the project that I did, about natural dyeing, I started trying to create a more circular method of production. I worked on techniques to use plants to dye biodegradable materials. In essence, they could be buried back into the soil to break down, and the dyes could be naturally disposed of since they’re plant-based and non-toxic to the environment – it’s essentially diluted plant waste returning its nutrients to the ground. That research flowed really nicely into what I’m doing now, creating clean water. It’s been fascinating to hear how they test the water, what they find in the water, and how to deal with it – especially biological filtration, which I didn’t know much about as a method of cleaning water before I joined this project.

One of the Healthy Waters project’s aims is to support low-middle income countries with the technology you’re developing – does that add an extra source of motivation for you?

Definitely. It’s those things that are the most motivating in your work; that’s something that I’ve discovered recently in my professional experience as a researcher, but also in my MA: having motivation is so important in your work and working in such a crucial and important area only motivates me more. It’s inspiring, really.

[You can read more about the goals of the Healthy Waters project on their blog post here!]

You’ve mentioned you’d like to go on to do a PhD. What do you hope the future has in store for you in that regard?

That’s something that I’ve been trying to work out for myself because often to get further in academia, you need to do a PhD. I’m working with a few people at CFPR to figure out what I want to do, what I’d want my research question to be – what I’d want to discover, because a PhD is really all about learning and finding something that needs a solution created. It’ll definitely be in the sustainable materials or sustainable textiles range related to that circular economy I mentioned earlier. But the experience I’ve had now on Healthy Waters has been really great, getting to hear from scientists and work alongside them, to have that new experience for my PhD where I can relate scientific backing to my work. I haven’t got a solid answer but my goal is really to stay at the CFPR, to work on more research projects – there’s always more stuff coming up! I’d love to work with more people at UWE, there are so many people with so many different skills and areas of expertise, and I’d love to branch out and work with people from different departments.

You can connect with Rosy on her website and via her LinkedIn profile.

Rivers are Drying Up All Over the World: what can we do about it?

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Image caption: Map 1:  Water level situation of rivers and streams in part of southwestern England (riverlevels.uk)

By Chad Staddon, Sun Shun and Stevie Miller

As of mid-2022, water levels across the world are lowering due to a long-term drying/heating trend.  Rivers in parts of the UK are rapidly approaching low levels not seen since the historic 1976 drought, when the country saw temperatures exceeding 32°C for fifteen days with the nation’s highest ever recorded temperature reaching 35.9°C in Cheltenham. But now, the Met Office has issued its first Red Warning for heat, indicating a danger to life – but it’s not just the intensity of this heatwave that’s raising alarms. The frequency of heatwaves like this across the world speaks to the influence of human activity on global climates; record after record is being broken as years go by and climate change’s results become more apparent.

The impact of new peak temperatures is not just a family trip to the beach or day without rail travel. The worldwide repercussions of rising temperatures can be seen in examples such as Lake Mead, the almost-dry reservoir behind the iconic Hoover Dam in the US southwest, which is perhaps 100 days from being too low to produce hydroelectricity. Historic low flows in many parts of Australia are contributing to ever worsening fire seasons, a troubling pattern also seen as wildfires rage in parts of France, Spain and Portugal.

Here in the southwest of England we are experiencing an intensifying drought trend. The recent heat – as lovely as some summer warmth has been – has been problematic beyond just an uncomfortable lack of air-conditioning. Map 1 seems to show that whilst many stream flows are significantly below baseline averages (red or yellow dots), many seem to be doing okay (green symbols). But a closer look reveals a more complex picture.

Covering only the area around Bristol and Bath, Map 2 shows that even “green” stream flows tend to be only at or near normal levels for this time of year.  Few streams are experiencing rising flows over any time horizon.  Rather than being truly “healthy waters”, our rivers and streams are under a variety of threats that are combining to reduce average flows, impacting flora and fauna and human communities.  

That’s not all: surface stream flows are only part of the story of our drying environment. During June groundwater levels receded in all aquifers – generally either just reaching normal levels or sinking below (with some notably low levels) – reflecting the prolonged period of below average rainfall and increasing soil moisture deficits.  Similarly, reservoir levels fell, and although some increased relative to average (e.g., in western Scotland and Northern Ireland), others in the midlands (Derwent Valley), southwest (Colliford and Wimbleball), and Wales (Brianne and Elan Valley) were significantly lower than average.  Our reservoirs are not yet as dangerously low as Lake Mead, but they are low enough that we may soon have mandatory water restrictions in some areas.

So, what can we do about the parlous state of our water resources? Certainly we must not give in to the temptation to believe that somehow the winter rains will save us, or that if recent years have been drier than average then surely coming years will be wetter and it will all come good. This is “magical thinking” and divorced from what the science of climate change is telling us. The longer-term climate trends suggest that our rains will be ever more unpredictable across the year and because surface and groundwater storage is limited, even periods of heavier than average rain may not help improve our water balance. We must also not sell ourselves the notion that new technologies, such as desalination or wastewater recycling, will save the day.  Both are wonderful technologies, but they require considerable energy and capital inputs as well as producing waste outputs (e.g., brine) that are difficult to sustainably manage.

Really, it is to ourselves that we need to look for solutions to a deteriorating water supply-demand balance. It is said that the “average” water user in the UK uses 140-160 litres per person per day, though our research suggests that the actual range of water use is from approximately 100 to 250 litres per day. By better understanding who is using what volumes of water, for what reasons and under what conditions, it is possible to design demand-reduction policies that are effective and fit for purpose. This is where the future of water management needs to be. This is how we will save our dwindling water sources.

Source: Centre for Ecology and Hydrology (2022) Hydrological Summary for the United Kingdom, June 2022

How to measure water security?

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Photo: Figure 1. Haitians queue for water in Carrefour-Feuilles Slum. The experiential scale-based metrics attempt to capture other sides of water (in)security, such as the burden associated with queuing for water. Photo by United Nations Photo

This blog is a summary of a published open access article: Octavianti and Staddon (2021). A review of 80 assessment tools measuring water security. WIREs Water. https://doi.org/10.1002/wat2.1516


Adapted by Dr Thanti Octavianti

There are many definitions of water security. It could simply refer to water for domestic use, such as for drinking and cooking, or it could mean water in every aspect of life, including water for the environment, water for economic development and water associated with hazards, such as floods and droughts.

These diverse conceptions also lead to different methods to measure water security. Chad Staddon and I systematically reviewed 107 publications proposing methods and tools to measure water security, and we found:

  1. There are two dominant research clusters in the field:
    • metrics that are based on the physical availability of water with measurement ranging from municipal to global scale and usually expressed in a volumetric unit. We group them as “resource-based metrics”.
    • metrics that are based on people’s experiences with water, usually measured at individual or household level and asking, for example, if one has worried about water or if one has had to change their plans because of their water situations. We group them as “experiential scale-based metrics”.

The former cluster is bigger compared with the latter, which is emerging.

  1. Both clusters are quite distinct in their characteristics. For example, resource-based metrics were mostly formulated by natural scientists and engineers. Domains of measurement vary from metrics solely focusing on freshwater resources to some with a very broad focus (to include water-related disasters, biodiversity, among others).

On the contrary, most experiential scale-based metrics have strong social science elements in them. Water supply and hygiene and their relations to well-being are the main domains being measured.

By understanding the landscape, we argue that the more local the level of measurement and the more specific water domains included, the more meaningful and actionable recommendations would be.

Finally, measuring water security is a resource-intensive process. Selecting which approach to use will be based on the purpose of the investigation and scholarly interests, and we hope this paper would be able to help researchers and practitioners make some informed choices when developing or using a water security metric.

Short bio:

Dr Thanti Octavianti is a Lecturer in Applied Geography, Department of Geography and Environmental Management, UWE Bristol. She is a social scientist with research interest in water security measurement and urban flood resilience.

Safe Water and Antimicrobial Solutions for Resource Constrained Healthcare Facilities

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Written by Dr Gillian Clayton, Centre for Research in Biosciences, Faculty of Health and Applied Science

Humanitarian settings, such as refugee camps, require consistent access to safe, high-quality water, but this can be difficult due to complex supply chains. If supply chains are interrupted or delayed, vital clinical solutions like sterile saline used to wash out wounds, and antimicrobials, such as hypochlorous acid, used to disinfect instruments and wash wounds are essential to ensure patient safety. Typically, clinical fluids (e.g. sterile saline and antimicrobials) are produced, packaged and transported in a ‘centralised’ manner. For example, solutions may be produced in the UK and then held at a storage facility/warehouse, before being transported via land, air and/or sea to the healthcare facility.

However, the Redistributed Manufacturing in Healthcare Network has investigated the potential to allow for clinical fluids to be produced on-site and on-demand, minimising the need for storage and transportation. A proof-of-concept project lead by UWE in collaboration with The Usher Institute (University of Edinburgh), Centrego Ltd, Portsmouth Aqua Ltd, The Royal College of Surgeons of England and Water for People and Peace investigated “The On-Demand Manufacture of Potable & Sterile Water for Emergency Medical, Humanitarian & Healthcare Applications Using Electrochemical Activation Production Technologies”. This project developed, adapted and repurposed Electrochemically Activated technologies for the on-demand production of clinical fluids for healthcare facilities in resources constrained environments. This project demonstrated that simple, low-cost and low-energy technologies can produce sterile solutions from tap or bottled waters, as well as produce a high-quality antimicrobial solution (hypochlorous acid) from a small-scale portable generator. These prototype technologies have shown that remote or resource constrained healthcare facilities can be adaptive and more resilient in a changing world through decentralised production, or redistributed manufacturing.

The low-cost and low-energy small-scale portable prototype generators, designed to produce sterile solutions from tap or bottled waters (top), as well as a high-quality antimicrobial solution (bottom)

New journal article published in Science of the Total Environment

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Written by Bethany Fox, Research Associate in Centre for Research in Biosciences (CRIB)

A new paper has been published in Science of the Total Environment (STOTEN), “A case study: The deployment of a novel in situ fluorimeter for monitoring biological contamination within the urban surface waters of Kolkata, India”.

This paper details the deployment of a novel in situ fluorescence sensor in the urban surface waters of Kolkata. The case study demonstrates the benefit of this technology with recent advances in understanding and technological capability. Using the new sensor, developed by our technology partner Chelsea Technologies Ltd., the team were able to identify a blackwater contamination event in the Hooghly River (Ganga) in Kolkata, India. The team also conclude that the use of this technology would provide information regarding biological water quality in situ and in real-time, important information which is often missing from our current monitoring practices due limited to time consuming and expensive sampling surveys.

This paper is an output from the NERC-DST India-UK Water Quality project which focused on the development and implementation of technologies for improved water quality. Within this project, UWE has been in partnership with Professor Tapan K Dutta and his team at the Bose Institute in Kolkata alongside multiple UK technology partners.

Sensor boat survey and water quality monitoring of the Hooghly River (Ganga) in Kolkata, West Bengal, India.

Testing Ceramic Methods for Producing Beads for Biofilm Water Treatment

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By Rosy Heywood, Research Associate at Centre for Print Research.

Main image: Fig 1: Boxes of organic foam impregnated ceramic beads and plain ceramic beads adjacent to a pot of traditional beads

In a previous blog post, by my colleague Sonny Lightfoot, we introduced the research being conducted into creating ceramic beads as a medium to grow biofilm within a water filter. We have now created 3 types of ceramic beads which have been tested for water filtration; organic foam impregnating method, clay and sawdust burn off method and plain ceramic. For each method we used the same terracotta clay, made the beads into 20mm pieces, and fired the beads at the same max kiln temperature of 1100˚.

Organic foam impregnating method

For this set of beads we laser cut compressed cellulose sponge into 20mm circles, expanded them in water and dipped them into clay slip. The beads were then left to dry and fired. During the firing process the sponge burns off leaving the porous structure behind. This method has been used to test beads with high porosity and high surface area creating lots of sites for the biofilm to grow onto.

Figure 2: Dipping laser cut sponges into terracotta clay slip

Sawdust and clay method

For this set of beads we mixed fine sawdust with clay at a 5:3 ratio. We are currently experimenting with the best ratio and method of mixing but to produce these beads we mixed by hand initially then used an electric mixer to fully combine the two components. We then extruded the clay using a hydraulic extruder into lengths and cut using a 3D printed jig into 20mm pieces. The beads were then left to dry and fired. During the firing process the sawdust burns off leaving a porous structure behind. This method has been used to test beads with high porosity.

Figure 3: Freshly extruded and cut sawdust and clay beads before firing

To produce the plain ceramic pieces we used the same method as above but without adding the sawdust. This method will test the effectiveness of the natural porosity of ceramic.

After firing we then tumbled the beads in a ball mill to smooth the edges. The beads were then dried in an oven and tested for effectiveness by MSc student Sadie Hadrill and PhD candidate Josh Steven in the science labs on Frenchay campus. Stayed tuned for another blog post coming soon where Sadie and Josh detail their process and results from the testing.  

Developing the methods and experimental work

Since creating these beads, the team and I in the CFPR labs have been experimenting with ways of combining sawdust with clay in large batches and the ratio of sawdust to clay. We have also been furthering our design research by modelling a coil pot from sawdust clay to test it’s suitability for pot making and experimenting with high surface area to low volume shapes using the organic foam impregnating method. These shapes could be tessellated or interlocked to create a unique structure for a vessel to naturally purify water using the biofilm method. The idea is to create a uniquely beautiful and practical container to filtrate water with the design inspired by natural biomorphic structures that can tesselate into user determined patterns and shapes. This experimental research is at its early stages and will slowly develop over the course of the project alongside our bead and porosity testing.

Figure 8: Organic foam impregnated ceramic tessellating shapes experiment

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