Assessing Flow Rate and Nominal Pore Diameter as Parameters for Predicting the Removal of Microorganisms by Ceramic Water Filters

Ceramic water filters (CWFs) are manufactured worldwide using local materials and infrastructure. In this study, we assessed flow rate (FR) and nominal pore diameter (NPD) values as parameters to predict the microbial removal of CWFs. Two empirical models (flow rate model, FRM, and nominal pore diameter model, NPDM) were developed based on the log removal values (LRVs) for total coliform obtained from the operation of CWFs manufactured under controlled conditions in the United States. The proposed empirical models were validated using CWFs manufactured in Nepal and India. The models and principal component analysis (PCA) were used to identify materials and processes in CWF manufacturing with the highest impact on LRV. Our results showed that both the FRM and NPDM have a good predictive capability with high coefficients of determination, R², and statistical significance (p) values less than 0.05. PCA showed that the burnout material was the most important variable in the manufacturing process. Even though both models are appropriate to predict LRV from a CWF, the FRM and NPDM could have slightly different applications at CWF factories. The FRM could be used to predict LRVs of CWFs manufactured in an already operational factory as it fits with existing quality control procedures, such as measurement of flow rate. We propose that the NPDM could be applied in the research and performance enhancement of CWFs as additional filter characteristics can be tested for the potential to improve LRV. The use of either model could help factories improve the removal of bacteria by their CWFs.