The destruction of Escherichia coli adhered to pipe surfaces in a model drinking water distribution system via various antibiofilm agents

Abstract

The aim of the study is to estimate the effectiveness of three antibiofilm agents against Escherichia coli biofilm that formed in six different types of pipelines. A laboratoryscale water system was built for this work to allow for the creation of biofilm in the pipelines studied. The level of the growth rate of E. coli biofilm cells was monitored over 90 days on those tested pipe materials. The results of bacterial cell densities displayed that the highest biofilm growth was observed in the biofilm formed on the iron (Fe) pipe. In contrast, the biofilm formation rate was significantly lower on copper (Cu) pipe compared to other materials. Three antibiofilm agents, including chlorine, silver ions (Ag +), and silver nanoparticles (AgNPs), were employed to eradicate the biofilm cells. E. coli counts indicated that AgNPs are more efficient in destructing any formed biofilm cells on all tested materials. At the same time, the chlorine was only useful in the case of biofilm developed on plastic and Cu. However, the antibiofilm efficiency of Ag + performs similarly to chlorine against E. coli biofilm cells. Ultimately, AgNPs are considred the most powerful antibiofilm agent among the other agents toward the biofilm cells in their maturation stage, which offers an encouraging way for the long-term functioning of water systems. © 2020 Water Environment Federation • Practitioner points • The growth rate of E. coli biofilm cells was investigated on different materials. • The count of biofilm cells developed on iron pipes was higher than other materials. • The E. coli biofilm on iron pipe could resist chlorine and AgNPs to a large extent. • The developed biofilm on copper pipe was more sensitive to chlorine, Ag +. and AgNPs. • The biofilm cells could be easily eradicated from plastic-based materials with all tested disinfectants.

Novel electro-oxidation unit for electro-disinfection of E. coli and some waterborne pathogens during wastewater treatment: batch and continuous experiments

“…They achieved 4–6 logs of bacterial removal after 180 min using the electrooxidation reactor with two boron-doped diamond and stainless-steel electrodes at the current density of 50 A/m 2 . Correspondingly, the results proved that electro-oxidation is significantly more effective than chemical disinfection using chlorine, where chlorination requires longer exposure (at least 30 min) to achieve a bactericidal performance of 99.94% or higher 19 . Time is essential in designing a disinfection technique related to power and chemical consumption and capital construction 13 .…”

Assessment of the microbiological safety of drinking water in outdoor pipe materials: biofilm formation and chlorine resistance of typical bacteria

“…32,55,56 Biofilm biomass reduction after chlorination Pipe materials could affect the chlorination effect. 14 Fig. 6 presents the biofilm biomass reduction rate after chlorination.…”

“…Among them, Sphingomonas of the α-Proteobacteria and Acinetobacter of the γ-Proteobacteria (ammonia-producing bacteria), 18,19 Acidovorax of the β-Proteobacteria and Microbacterium of Actinobacteria (iron-oxidizing bacteria), 20,21 and Bacillus of the Bacilli (iron-reducing bacterium) 22 may cause iron pipe corrosion. Moreover, it has also been reported that the effect of chlorine may be worse in some pipes 14,23 because some pipe materials may react with disinfectants. 24,25 However, as different typical bacterial strains, pipe materials, and incubation conditions could lead to inconsistent or even contradictory conclusions, it is important to study the effects of biofilm formation in DWDSs by selecting multiple representative bacterial strains and consistently maintaining the incubation conditions for multiple pipe materials.…”

Hybrid Chitosan/CaO-Based Nanocomposites Doped with Plant Extracts from Azadirachta indica and Melia azedarach: Evaluation of Antibacterial and Antibiofilm Activities

“…After that, the plankton was removed, and the wells were washed with PBS to remove non-adherent bacteria. The crystal violet (CV) assay performed as described in detail elsewhere [25].…”