Protozoa and Virus Disinfection by Silver- and Copper-Embedded Ceramic Tablets for Water Purification

Abstract

Point-of-use water treatment (PoUWT) technologies have been shown to reduce incidences of waterborne diseases. However, their effectiveness is limited against the most harmful pathogens, such as protozoa and viruses, due to the inability to deliver effective and safe levels of disinfectant. This paper studies disinfection mechanisms and efficiency of silver and copper against Cryptosporidium parvum, Giardia lamblia, and MS2 bacteriophage through a novel PoUWT method, a ceramic tablet embedded with metallic ions. Results demonstrate that the PoUWT method can deliver safe and effective levels of silver and copper to inhibit sporozoite metabolic ability, and thus disinfect protozoa. Excystation reduced from 74% to 14% for Cryptosporidium parvum oocysts treated with silver-embedded ceramic tablets. Similar results were observed among Giardia lamblia oocysts and copper-treated oocysts. Fluorescence microscopy demonstrated two mechanisms for protozoa disinfection by metallic ions: (1) structural damage of oocyst walls, and (2) alteration of sporozoite structure. Also, MS2 bacteriophage viability reduced by 89% when treated with ceramic tablet treatment. Using the PoUWT method in this study, silver and copper show promise as disinfecting agents for protozoa.