Biofilm development, dynamics, and control in a pilot drinking water network with different pipe materials

Abstract

Biofilms in premise plumbing systems can decrease the quality of drinking water in several ways. Biofilm removal is possible utilizing disinfectants combined with mechanical cleaning, which can be expensive and challenging to implement in plumbing systems. Thus, alternative methods to control biofilms are needed. This study investigated the effects of hydrodynamic cavitation (HC) and magnetic water treatment (MWT), both of which produce nanobubbles, on biofilms in a pilot-scale drinking water network over a 16-month study period. Additionally, the influence of various materials, including copper, stainless steel, and PEX, on biofilms was investigated. A new biofilm-removal tool was developed to detach biofilms from pipes quantitatively. Biofilms were analyzed quantitatively and qualitatively. PEX promoted significantly higher biofilm growth than metallic materials throughout the sampling period. HC and MWT showed slight effects on biofilm growth in PEX pipes, enhancing growth in young biofilms and inhibiting growth in older biofilms. Biofilm quantities varied across time points due to seasonal fluctuations in water temperature, highlighting the dynamic nature of biofilms. According to the sequencing analysis, pipe material was the most significant factor affecting microbial communities. This study provides insight into the effects of various materials and nanobubble-generating treatments on biofilm growth in premise plumbing drinking water pipes. Due to the many variables and multiple effects caused by HC and MWT, further research is still required to understand the impact of nanobubbles on biofilm control.