A New Method for Nanosilver Application in Ceramic Water Filters

A new method of silver application to porous ceramic water filters is being investigated in the laboratory and field. Fieldwork was performed at an existing ceramic water filter factory:the PureMadi Mukondeni Pottery Cooperative, in Limpopo, South Africa. Results show there is no statistical difference in E. coli and total coliform removal between filters made using the conventional method of paintingan aqueous suspension of silver nanoparticles onto the ceramic filter and a new method that applies a silver nitrate solution to the clay-sawdust-water mixture prior to pressing and firing the filter. Laboratory tests studied E. coli removal with the two silver application methods using ceramic disks in a flexible-wall permeameter. Silver amounts applied using the silver nitrate method were varied. Results show that the two methods of silver application and amounts performed similarly in regards to E. coli removal. The new method is less expensive because of the lower cost of silver nitrate relative to silver nanoparticles. The new method alsosimplifies the filter manufacturing process, as the labor-intensive painting step is omitted.Potentially, even more silver in the form of silver nitrate can be added to improve the performance of the filters without increasing filter cost compared to conventional methods of silver application.