Ceramic Water Filters for the Removal of Bacterial, Chemical, and Viral Contaminants

Abstract

In this study, the combination of capture mechanisms in ceramic water filters (doped with hydroxyapatite and alumina) was considered for the removal of contaminants from drinking water. It was found that hydroxyapatite and alumina were conserved during the firing process of the ceramic water filters up to 950°C. The nanopores resulting from the conservation of the additives increased the specific surface area of the ceramic water filters from 3.7 to 21.0 m 2 · g −1 . On the other hand, the microscopic pores associated with the processing of the ceramic water filters (i.e., pressing and drying) and the combustion of the sawdust reduced the filtration time from 24 to 4 h. The efficiency of the resulting filters in removing bacterial, chemical, and viral contaminants from water was investigated using E. coli, fluoride, and MS2 as model contaminants. The contaminants were found to be captured from water by trapping in the pores, substitution in the hydroxyapatite, and adsorption on the surface of alumina. Hence, the ceramic water filters incorporating hydroxyapatite and alumina combined the different capture mechanisms. They had an efficiency of 99.998%, 99.970%, and 99.450% in the removal of bacterial, chemical, and viral contaminants, corresponding to log reduction values (LRVs) of 4.69, 3.47, and 2.26, respectively.

Assessment of Ceramic Water Filters for the Removal of Bacterial, Chemical, and Viral Contaminants

“…It can be noted that the standard deviation (0.31% by volume) is relatively low. Typically, the values are all included between 62.75% and 63.80% by volume because the pores are homogeneous and well dispersed in the clay matrix (Nigay et al 2019). This can be attributed to the sieving of the sawdust prior to the mixing with the clay and the additives.…”

“…The proportions of the mixture were as follows: clay, 45% by weight; sawdust, 15% by weight; hydroxyapatite, 20% by weight; and alumina, 20% by weight (i.e., 30% by volume of clay, 50% by volume of sawdust, 10% by volume of hydroxyapatite, and 10% by volume of alumina). These proportions were regarded as optimum for filtration and mechanical performance based on the results of the authors' previous research (Nigay et al 2018(Nigay et al , 2019.…”

“…of the filters with hydroxyapatite and alumina, which results in a high percentage of porosity and a high permeability (Nigay et al 2019). On the other hand, the standard deviation is relatively important.…”

“…increase in the flow rate (Nigay et al 2019). Typically, the water flow through the clay matrix becomes too fast to fulfill the kinetics of surface adsorption on alumina.…”

“…Typically, the contaminants are removed by substitution for elements of the hydroxyapatite in the clay matrix (Bhatnagar et al 2011). Recent studies have shown that doping ceramic water filters with metal oxides can also lead to 97.4881% removal of viral contaminants from drinking water (Brown and Sobsey 2009;Michen et al 2012;Nigay et al 2019). The removal is achieved by adsorption of the viral contaminants on iron, aluminum, or magnesium oxides that are kept unchanged in the clay matrix.…”