Water disinfection accelerated rubber seal aging within water distribution system over varied conditions

The degradation of rubber seals (RS) in chlorinated water within the water distribution system has been confirmed, yet there is a lack of research exploring the aging effects of different disinfection conditions on RS surfaces in drinking water distribution systems. This study investigates the impact of various disinfection factors, including disinfectant type, dose, and pH, on RS degradation in chlorinated water. It employs parallel factor analysis of fluorescence excitation-emission matrix (PARAFAC-EEM) and two-dimensional correlation analysis of Fourier transform infrared spectroscopy (2D-FTIR-COS). Results indicate that chlorine caused more significant aging effects on RS compared to monochloramine. High chlorine doses led to the breakdown of RS leachates into aliphatic structures, with acidic conditions further accelerating aging and leaching. PARAFAC-EEM identified two components: tyrosine and protein-like compounds (C1) and hydrophobic acids in fulvic acid-like compounds (C2), both of which varied with disinfection conditions. Additionally, the rise in chlorine concentration promoted the formation of C1 and C2, while an increase in monochloramine suppressed their presence. Under chlorination, C1 was more prevalent and exhibited a fivefold increase under basic conditions, while C2 favored acidic conditions. FTIR analysis showed that the O-H group was most affected by disinfection, and 2D-FTIR-COS indicated that C-H bending and C=C stretching were the initial changes related to disinfection dose and pH, respectively. Monochloramine had a lesser impact on RS degradation than chlorine. Optimizing disinfection protocols is crucial, and further research is needed to identify potential by-products from these disinfection processes.