Resistance of bacterial pathogens to calcium hypochlorite disinfectant and evaluation of the usability of treated filter paper impregnated with Nano-silver composite for drinking water purification

Research Abstract

Objectives: Innovative techniques are urgently required to remove pathogenic bacterial contamination of drinking water sources. This study aimed to evaluate the biocidal activity of calcium hypochlorite Ca(OCl)2, silver nanoparticles (AgNPs) and its loaded forms (Ca(OCl)2/AgNPs composite) against isolated bacteria from drinking water supplies (tap and hand pump water), then implemented a field trial to evaluate a biocidal filter paper containing Ca(OCl)2/AgNPs composite against existing bacteria and indicator coliforms bacteria. Methods: One hundred water samples were collected from the main source and water troughs used for cattle drinking and examined for the presence of pathogenic bacteria. The sensitivity of sixty strains of isolated bacteria were evaluated against Ca(OCl)2, AgNPs and Ca(OCl)2/AgNPs using broth macro dilution method. Thereafter, a field trial was applied through examination of different water samples collected from both water supplies (pre and post-treatment) using filter paper impregnated in Ca(OCl)2/AgNPs . Results: Ca (OCl)2 loaded on AgNPs at a concentration of 1.5 mg/L showed the lethal effect on E. Coli, S. aureus and K. pneumoniae (100% each) on exposure to 180 minutes. Furthermore, Ca(OCl)2/AgNPs filter paper exhibited a biocidal effect (100%) against the existing bacteria, total viable bacterial count (TVC) CFU/ml, total coliforms (TCC) and fecal coliforms bacteria (FCC) CFU/100 ml. Conclusions: the use of the disinfectant, Ca(OCl)2, against isolated bacteria exhibited the existence of bacterial resistance profile. Therefore, a new trend for enhancement of the biocidal effect of tested disinfectant using Nano-silver particles was reliable proving that Ca(OCl)2/AgNPs had a biocidal effect (100%) against isolated bacteria at 1.5 mg/L as well as inactivation of coliforms and pathogenic bacteria during percolation through the bactericidal filter paper.

Research Keywords

Keywords: Calcium hypochlorite. bacterial pathogens. Water purification. Bactericidal filter paper. Nano-silver