Abstract
Spatial and short-term temporal changes in water quality as a result of water age and fluctuating hydraulic conditions were investigated in a drinking water distribution system. Online measurements of total and intracellular adenosine tri-phosphate (ATP), total and intact cell concentrations measured with flow cytometry (FCM), turbidity, and particle counts were performed over five weeks at five subsequent locations of the distribution system. The high number of parallel FCM and ATP measurements revealed the combined effect of water age and final disinfection on spatial changes in microbiology in the system. The results underlined that regular daily dynamics in flow velocities are normal and inevitable in drinking water distribution systems, and significantly impact particle counts and turbidity. However, hydraulic conditions had no detectable impact on the concentration of suspended microbial cells. A weak correlation between flow velocity and ATP concentrations suggests incidental resuspension of particle-bound bacteria, presumably caused by either biofilm detachment or resuspension from sediment when flow velocities increase. The highly dynamic hydraulic conditions highlight the value of online monitoring tools for the meaningful description of short-term dynamics (day-scale) in drinking water distribution systems.
Highlights
Drinking water quality can change during water distribution as a result of both increased residence time and hydraulic changes
Resuspension of particle-bound bacteria by either biofilm detachment or release from sediment is a random process, which can be incidentally enhanced by increased flow velocities in distribution areas with highly varying hydraulic conditions
The results showed that highly dynamic variations in flow velocity are inherent to a Drinking water distribution systems (DWDSs) (Figure 4) as a result of daily consumption profiles that are repeatable over days
Summary
Drinking water quality can change during water distribution as a result of both increased residence time and hydraulic changes. Drinking water distribution systems (DWDSs) are complex networks of interconnected pipes of various diameters. Drinking water flows from the treatment plant through large transport mains (400 to 1000 mm in diameter) towards distribution areas with smaller distribution pipes (40 to 300 mm in diameter). Transport mains, and distribution pipes are dependent on the network configuration, pipe diameters, water demand, and water consumption profile of consumers [1,3,4]. Water consumption profiles lead to varying flow rates and velocities, with the highest velocities typically in the morning and in the evening, when the water consumption in residential areas is highest [1,5]. At a given flow rate, a small diameter pipe is subject to a higher flow velocity and higher shear stress than larger pipes; as a consequence of the network layout, small distribution pipes, typically at the end of the network, receive lower flow rates and are
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
