Water insecurity is prevalent in limited-resource communities without reliable access to safe drinking water. Many people in these communities rely on water sources contaminated with bacteria, viruses, chemicals, and other contaminants. Ceramic water filters (CWFs) have emerged as a low-cost point-of-use water purification system for these communities due to their ease of production and relatively high efficiency at removing bacterial contaminants. However, concurrent filtration of bacteria, viruses, and chemical contaminants is needed to improve water quality and reduce the risk of waterborne diseases in these communities. In this work, we designed CWFs from kaolin clay doped with hydroxyapatite and alumina, and sieved sawdust (< 500 µm particle size) as the porogen, for concurrent removal of bacteria and chemical contaminants. Five different CWFs were fabricated by varying the proportions of kaolin clay (C), sawdust (S), hydroxyapatite (HA), and alumina (A): C:S 35:65 (vol.%), C:S 32:68 (vol.%), C:HA:S 80:20:67 (total ceramic: sawdust 33:67, vol.%), C:A:S 80:20:57 (total ceramic: sawdust 43:57, vol.%), and C:HA:A:S 80:10:10:57 (total ceramic: sawdust 43:57, vol.%). The proportions of the filter materials were selected to achieve similar flow rates (approximately 2 L/h). Each CWF mixture containing water was pressed into a frustrum shape, dried, and fired at 950°C, resulting in the combustion of the sawdust particles to form pores and the sintering of the ceramic particles into porous CWFs. The efficiency of the CWFs in removing bacterial and chemical contaminants was investigated using E. coli (as model bacteria), arsenic (As), mercury (Hg), and lead (Pb) as model contaminants. Water was spiked with each model contaminant individually at concentrations of 100E+6 CFU/ml for E. coli and 10 ppm for the heavy metals (As, Hg, and Pb). The contaminated water was then filtered through each CWF formulation, and 3M E. coli/coliform count plates were used to determine the E. coli concentration before and after filtration. Similarly, ICP-MS was used to measure the concentrations of As, Hg, and Pb before and after filtration to determine their removal efficiencies. The C:HA:S 80:20:67 formulation was found to be the most efficient in the removal of bacterial contaminants, with an efficiency of 99.9981% corresponding to a log reduction value (LRV) of 4.72. The amount of heavy metals in filtered water by the CWF formulations was below the W.H.O. benchmark values of 10.0, 6.0, and 15.0 ppb for As, Hg, and Pb, respectively. Overall, the C:A:S 80:20:57 formulation was the most efficient in removing As, Hg, and Pb, with efficiencies of 99.9936% (LRV = 4.19), 99.9981% (LRV = 4.72), and 99.9997% (LRV = 5.47), respectively. Taken together, the results indicate that all the CWF formulations effectively removed E. coli and heavy metals (As, Hg, and Pb) from contaminated water. However, selecting the most suitable CWF formulation depends on the contamination level of the water source. The C:HA:S 80:20:67 formulation is preferable in areas with higher bacterial contamination, while the C:A:S 80:20:57 is more appropriate for communities with heavy metal contamination.
