Towards an Improved Ceramic Water Filter Paradigm: From Design Optimization to Participatory Implementation

Abstract

Rural and low-income populations in sub-Saharan Africa (SSA) are disproportionately impacted by challenges with safe drinking water access. Significant attention has resultingly been directed towards home-based drinking water treatment as an immediate-term solution.Ceramic water filters (CWFs) are one such technology that is widely promoted due to its simplicity in terms of use, maintenance, and manufacture. However, cost, flowrate, breakage, and general misuse/disuse in the field are significant barriers to proliferation, adoption, and associated impact. This research addresses each of these limitations by evaluating technological innovations and participatory implementation in rural Tanzania. CWFs are typically produced by mixing clay, sawdust, water, and silver nanoparticles (AgNPs), pressing the mixture into a pot shape, and firing it in a kiln. AgNPs are added to enhance disinfection but are among the most expensive of filter elements. Cost reduction is thus explored through investigation of AgNP replacement and/or supplementation with zinc oxide (ZnO), an inexpensive alternative. Metals are challenged in isolation and combination against E. coli within batch and filter phases and disinfection and elution are assessed across time and varying water qualities. Combined AgNP-ZnO treatment proved synergistic under all conditions, consistently outperforming either metal alone. Maximal effects are further observed when zinc concentrations above 200 ppb are combined with silver concentrations above 10 ppb within the filtrate. Supplementing silver with zinc in CWFs can therefore simultaneously reduce cost while improving bactericidal efficacy.Input sawdust size and proportion within a CWF mixture is also related to flowrate, flexural strength, and bacteria removal, yet the nature of these relationships is unclear. Modelling these performance measures is consequently challenging, especially in such a way that is xxii