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

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.

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.

Biological filtration using different porosities of ceramic media

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By Sadie Hadrill (MRes Student)

Freshwater is essential for life on Earth, and the role of freshwater is fundamental to society and for maintaining healthy ecosystems. Biological filtration is a sustainable biotechnology used to remediate biological and chemical contaminants within water. This is performed by establishing polymicrobial biofilms (diverse microbial communities) on a granular substrate, that can be housed within a column, here referred to as a biofilter. Biofilters develop efficient sorptive (attachment) capacity within diverse microbial communities of biofilms.

Filtration media has come in many forms prior to recent experimentation including sand, charcoal and granular activated carbon. Different filter media properties, including permeability, surface area and porosity, can determine the performance of the biofilter. As such, practical knowledge is needed regarding the impact of the type of filter media used. In this example we used ceramic media, more specifically terracotta clay, varying in porosity as described in the previous blog post. The team at UWE’s Centre for Print Research (CFPR) created ceramic media of low, medium and high porosities to determine the impact of porosity on the biofilter systems.

Biofilter maturation

The three variations of ceramic media were equally distributed into three individual filter columns (9 filters in total) and connected to 25 L tanks containing tap water. To aid the beginning stages of biofilm maturation, the water tanks were inoculated with pond water to introduce environmental organisms.

Figure 1. Laboratory scale biofilters containing three different types of clay media, varying in porosity: A) Low porosity, B) Medium porosity and C) High porosity.

Over four weeks of biofilm maturation, the biofilters were monitored weekly for nutrient concentrations (such as phosphates and nitrates) and bacteria. Samples were extracted from both the filter media and the circulation water for analysis.

Figure 2. Laboratory scale biofilter columns containing ceramic media (A), connected to a four-channel peristaltic pump (B) and circulation tanks (25 L) containing mains tap water (C).

An investigation of porosity of media and pathogen removal

Once the biofilters had undergone maturation, the experiment investigated the removal of Escherichia coli (E. coli)and Enterococci, both are bacterial indicators of faecal contamination. Over a 24-hour period pond water was circulated through the biofilters containing the different porosity ceramic media. Samples of the circulated pond water were collected every three hours and analysed for the presence of the E. coli and Enterococci.

Preliminary results indicated a decline in both E. coli and Enterococci recovered from samples taken over a 24-hour period. However, initial findings suggest that the ceramic media porosity has little impact on E. coli and Enterococci removal as there was little difference between the bacteria counts for the three different porosities of ceramic media.

Further experimental work is ongoing to explore pathogen removal in more detail and to determine if the size of the ceramic media (e.g. smaller ceramic beads) impacts the performance of the biofilter.

Running, safe water

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

Access to safe water should be a basic right for all. Turning on a tap to drink from seems so natural to many of us, but with 1 in 3 people around the world not having access to safe drinking water, there is still much to be done. The COVID-19 pandemic has only further highlighted the importance of clean water, sanitation and good hygiene, with those without access to water being disproportionately vulnerable.

Frank Water is a Bristol-based water charity that began life in 2005 as a social enterprise which donated all profits to an NGO in India for water projects. It is now a registered charity providing safe water, sanitation and good hygiene to communities in India and Nepal, helping almost 500,000 people to date. Frank also works within the UK providing education regarding sustainable approaches to water.

UWE Bristol has an ongoing relationship with Frank Water and have been actively working together on a NERC-DST India-UK Water Quality project for the past 4 years. This project focused on the development and implementation of technologies for improved water quality.

One of the key aims within this project was to provide a low-cost small-scale sustainable technology to treat biologically contaminated stored water, such as that from a borehole or harvested rainwater. Working with Frank Water, Indian NGO Bala Vikasa and technology partner Centrego, we have begun the deployment of two prototype systems: one in a government school in Hyderabad, Telangana, to ensure a safe supply of drinking water for the school children and staff; and, a second system in Massampally, a remote tribal village in the Warangal district of Telangana, where the systems are treating water from a contaminated open well to provide a source of safe drinking water to the village’s 33 households which rely on this well for all their water, sanitation and hygiene needs.

Having seen first-hand the amazing work undertaken by Frank Water Projects and their collaborators in India, UWE researcher Dr Bethany Fox has chosen to fundraise for Frank Water by running the Bristol Half Marathon in September 2022. This will be Bethany’s first half marathon but she hopes to raise awareness and money to support Frank Water and the amazing work they do.

Initial Ceramic Research

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Written by Sonny Lightfoot, Research Associate and Technician at Centre For Print Research (CFPR)

In the latest issue of Craft Magazine they look at the work of Potters for Peace (PFP)  ‘a non-profit, social justice organization focused on using clay based solutions to address the problems of poverty.’ The amazing work PFP have implemented and published around locally made ceramic water filters has been a big inspiration for us here at UWE working on Heathy Waters. The literature produced by PFP has been a useful resource to start our own research especially around the use of burn-out material to be added to clay to increase precocity. Where PFP have developed a process where the ceramic filters are produced with a mould and a hydraulic press, we are looking at the already existing skills and process of local potter’s to hand building and pit fire water filter, like that of the craft potters in Kisoro Uganda, who currently produce ceramic cooking stoves.

Foam Impregnated Ceramic

Our initial ceramic tests have been focused on producing ceramic beads of different porosity to work as a medium for a biofilm to grow within a water filter. We have looked at two processes for these beads, extrusion, a well-established industrial process, and a organic foam impregnating method in which we laser cut compressed cellulose sponge that is then expanded in water then dipped in a ceramic slurry.

Extruded clay with added burn out material

Our next tests will be looking at producing a hand build ceramic water filter using a basic hand building technique known as coiling, which is more in line with the hand building process of the Ugandan potters. The pots will be made from terracotta clay with sawdust added in different percentages they will then be tested to establish the balance between increasing precocity to reduce time taken for the water to pass through the filter but still maintain a high efficacy of removing bacteria and pathogens.

Mixing clay and saw dust in preparation to coil build ceramic water filter

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