A review of the impact of testing conditions on the performance and quality control of locally manufactured, point-of-use ceramic water filters

Abstract

The microbial removal performance of point-of-use ceramic water filters (CWFs) varies widely depending on the manufacturing practices and testing conditions. A critical review of the most recent studies on CWFs, published between 2009 and 2020, was performed. The goals of this review were to (1) identify inconsistencies in testing procedures used to assess CWF microbial removal performance and (2) discuss methods of standardization that could improve our understanding of the effects of manufacturing parameters on CWFs used worldwide. First, the impacts of manufacturing materials on CWF performance were reviewed and analyzed. Our review of manufacturing variables shows that CWFs made with smaller grained clays, sawdust, and silver nanoparticles have slightly higher log removal values (LRVs) compared to CWFs made with larger grained clays, rice husks, or silver nitrate. Next, we reviewed the potential impacts of testing conditions (focusing on influent water chemistry) on CWF performance. The variability in CWF testing conditions makes it difficult to aggregate the data on CWFs to show the impacts of manufacturing conditions on microbial removal. Standardized methodologies for CWF testing are one potential solution for providing more useful information highlighting the effect of manufacturing conditions on CWF performance. We discuss the application of two available CWF testing protocols from the United States Environmental Protection Agency (USEPA) and World Health Organization (WHO) for their applicability as standardized quality control techniques. The application of either of these protocols will bring greater consistency and easier comparisons between studies on CWFs. Our assessment of the impacts of manufacturing and testing conditions on CWF performance provides insights on the benefits of the USEPA and WHO standardized testing schemes. The application of a standardized quality control technique could improve CWFs in the field by identifying how differences in manufacturing affect performance.