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.
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.
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.
Written by Chad Staddon, Professor of ResourceEconomies and Policy.
A lack of access to safe, piped water services in many parts of the world means that alternative water supplies, such as rainwater harvesting (RWH), are often all that is available. However some studies have shown that RWH may pose a health risk because of its potential to carry microbial pathogens through wet deposition (bonding of chemicals in the air before hitting the roof), transit via the catchment area (usually a rooftop), drainage gutters and pipes, and the residence time in the storage tank itself. Indeed, water quality testing undertaken by a UWE Bristol team in southwestern Uganda in 2019 suggested that up to 50% of water samples from RWH systems could be contaminated in excess of WHO limits.
In 2018 and 2019 UWE Bristol staff and students worked to better understand the extent of the water quality challenge associated with RWH and to options assess possible solutions including granular media, solar disinfection and ceramic pot filters. Now, the UWE Bristol Healthy Waters team, including Chad Staddon, Tavs Jorgenson and Jiseon You, is working to determine if CPFs can be manufactured in accordance with appropriate technology principles stipulating that technologies should be locally reproducible and maintainable with essentially existing skills and resources. The team aims to develop a trial for locally produced CPFs using existing ceramics making processes including open pit firing during 2022. If successful the team hopes to support and encourage the scale up of production by local producer groups, enterprises or cooperatives, thus addressing capacity gaps identified in earlier research.