Abstract
The biofilms generated in a fire extinguishing water supply system can cause corrosion and a reduction in the water supply capacity; thus, degrading the system performance. To mitigate microbial corrosion, appropriate disinfection measures are necessary. In this study, the secondary addition of chlorine is employed to investigate the kinetics of chlorine decay, and shock disinfection is applied to investigate the removal efficiency of corrosion bacteria, and the microbial composition of a biofilm on the pipe wall was also clarified. The results show that the residual chlorine content in the secondary chlorination process was directly correlated with the decay rate of residual chlorine and the corrosion rate of the pipe wall. Additionally, the chlorine impact disinfection method could reduce the electrochemical corrosion phenomenon of the pipe wall. When the concentration of chlorine was 3 mg/L, the removal rate of corrosion bacteria was higher in 60 min than in 30 min. Specifically, most of the bacteria were inactivated in 60 min and the biofilm was severely damaged. Shock disinfection could significantly inactivate all microflora in the biofilm; the relative abundances of microflora varied significantly, while the change of microflora at the phylum level was insignificant. This study can provide theoretical support for the secondary addition of chlorine and shock disinfection in a fire extinguishing water supply system.
Highlights
Failures in firefighting and delays in fire suppression result in serious consequences, of which 81.5% are due to the lack of a fire extinguishing water source and imperfect fire extinguishing water supply facilities [1,2]
Due to the large number of users and accessories used in the municipal water supply system, the circulation time of the water in this system is short, while the water in the fire extinguishing water system only comes out once a fire breaks out, or when the end water test devices are repaired at ordinary times
The residual chlorine, corrosion potential, corrosion rate, and removal rate of corrosion bacteria were regularly analyzed after the secondary chlorination using a simulated pipeline system
Summary
Failures in firefighting and delays in fire suppression result in serious consequences, of which 81.5% are due to the lack of a fire extinguishing water source and imperfect fire extinguishing water supply facilities [1,2]. Because a water-based fire extinguishing system is only used when there is a fire, the commonly used metal pipelines that are always filled with water are exposed to severe corrosion and scaling. The water for the fire extinguishing system comes from the municipal water supply network, the fire extinguishing system is only opened during firefighting or maintenance. There are still some differences in the state of the pipe network and water demand between two water supply systems. The water in the pipe network of the fire water system is static most of the time
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