Lanthanum (III)-Coated Ceramic Filters in Point-of-Use Water Treatment for Bacterial Removal

Low-cost and efficient ceramic water filters for point-of-use (POU) water treatment are a sustainable solution for low-income areas suffering from microbial contamination in drinking water sources. In this work, a novel coating of lanthanum (La) on a ceramic filter prepared using paper and leaf fibers as combustible materials was developed for enhanced bacterial removal. Results from filtration experiments showed that the La coating thermally treated at 400 degrees C led to the highest bacterial removal of >6 log reduction value, which was >2 and similar to 4 orders of magnitude better than those of the filters treated with higher La-coating temperatures and the uncoated filters, respectively. Additionally, the La-coated (400 degrees C) filters made using recycled paper can efficiently treat similar to 60,000 pore volumes of bacterial contaminated water to meet the drinking water standard (<0 CFU/100 mL) in long-term filtration tests, extending the service life span of ceramic filters. The characterization of La-coated filters, calculation of extended Derjaguin-Landau-Verwey-Overbeek energy profiles, as well as biospectroscopic analysis showed that the enhanced bacterial removal by La-coated filters may be attributed to (1) the formation of microscopic pores with sizes favorable for bacterial removal through straining, (2) the favorable attachment and immobilization condition due to the presence of a significant attractive secondary energy minimum, and (3) the interaction of the La coating and bacterial cells likely through bonding of La and the phosphate group in the cell structure. Our findings suggested that La-coated ceramic filters made of readily available and sustainable materials could provide a low-cost and effective POU treatment solution for bacterial removal, which can be particularly well suited for the developing countries.