The role of biofilms on the formation and decay of disinfection by-products in chlor(am)inated water distribution systems.

This study investigated the role of biofilms on the formation and decay of disinfection by-products (DBPs) in chlorine (Cl) or monochloramine (NHCl) disinfected reactors under the conditions related to drinking water distribution systems (DWDSs). Biofilm analysis results revealed that at 0.5 mg/L of disinfectant residual, both Cl and NHCl were not effective to remove biofilms.

Effects of Extracellular Polymeric Substance Composition on Bacteria Disinfection by Monochloramine: Application of MALDI-TOF/TOF-MS and Multivariate Analysis.

In our previous study, we reported that the transport of monochloramine is affected by the extracellular polymeric substance (EPS) composition, which in turn affects the cell viability of both biofilm and detached clusters.11 However, although the transport and reaction of monochloramine in biofilm could be observed, the specific biomolecules reacting with the disinfectant and the mechanism of disinfection remains elusive. In this study, the impact of EPS composition on bacteria disinfection by monochloramine was qualitatively determined using both wild-type and isogenic mutant Pseudomonas strains with different EPS-secretion capacity and composition.

Selective reactivity of monochloramine with extracellular matrix components affects the disinfection of biofilm and detached clusters.

The efficiency of monochloramine disinfection was dependent on the quantity and composition of extracellular polymeric substances (EPS) in biofilms, as monochloramine has a selective reactivity with proteins over polysaccharides. Biofilms with protein-based (Pseudomonas putida) and polysaccharide based EPS (Pseudomonas aeruginosa), as well as biofilms with varied amount of polysaccharide EPS (wild-type and mutant P. aeruginosa), were compared.