The microbial colonization of activated carbon block point-of-use (PoU) filters with and without chlorinated phenol disinfection by-products

Abstract

Activated carbon based point-of-use drinking water filters change the bacterial community structure and increase the absolute abundance of genera, including those associated with opportunistic pathogens.

Environmental Management of Legionella in Domestic Water Systems: Consolidated and Innovative Approaches for Disinfection Methods and Risk Assessment

“…It has been seen, for example, that the application of carbon filters may result in a greater presence of Legionella in water because the bacterium can colonize the filters while passing through [ 99 , 100 ]. On the contrary, membrane filters have shown to control the colonization of hospital water systems up to 2–8 weeks of continuous use [ 101 , 102 ], especially when they are covered with a silver layer [ 103 ].…”

Bacterial transmission and colonization in activated carbon block (ACB) point-of-use (PoU) filters

“…For example, multiple studies that rely on culture-based methods have shown that heterotrophic bacterial counts increase with time in the effluent of ACB PoU filters to levels that exceed those in the tap water influent, even when used within the manufacturers' recommended usage period. [7][8][9][10] Other culture-based studies found that the composition of bacteria in the filter effluent was different from the tap water. [10][11][12] Chaidez et al (2004) found that indigenous Aeromonas hydrophila, Pseudomonas aeruginosa and total coliforms were more abundant in the effluent than in the influent using culture-based techniques.…”

“…[7][8][9][10] Other culture-based studies found that the composition of bacteria in the filter effluent was different from the tap water. [10][11][12] Chaidez et al (2004) found that indigenous Aeromonas hydrophila, Pseudomonas aeruginosa and total coliforms were more abundant in the effluent than in the influent using culture-based techniques. 11 Using culture-independent techniques, studies have similarly found that ACB PoU filters significantly alter the bacterial abundance and composition in filter effluents.…”

“…11 Using culture-independent techniques, studies have similarly found that ACB PoU filters significantly alter the bacterial abundance and composition in filter effluents. 10,13 Despite evidence that some bacteria can pass through or grow in ACB PoU filters, it is unclear how efficiently pathogens or opportunistic pathogens of interest can move through them. ACB filters employ a solid block of compressed and polymer-fused powdered activated carbon as the filter media.…”

“…The ACB contains extensive surface area for physical adsorption of chemical contaminants and has low porosity for mechanical filtration of some particulate contaminants. 10 The porosity of the ACB is expected to be very small; for example, line pressures of at least 210 kPa (30 psi) are required for water to pass through the ACB cylinder radially and exit to the annular effluent channel. 10 In addition, in an earlier study we estimated that the average micropore size of the activated carbon in one brand of ACB PoU filters is 22 Å.…”