Experimental Investigation of Purging Saline Solution from a Dead-End Water Pipe

Abstract

Salty groundwater might find its way into dead end legs of a water distribution network and thus efforts are required to clean such parts of the network. This paper reports, for the first time, the results of a visual study for laboratory experimental investigation on the purging process of saline water from a dead-end water pipe using fresh water. Three purging locations and a number of purging flow rates were considered to identify the effect of purging location and purging flow rate on the time required to completely remove saline water from the dead-end pipe. Image processing analysis techniques were used to capture data from the experimental lab setup. A universal gray-intensity to salinity curve was experimentally found to formulate a color intensity to salinity mapping. A script code based on Octave numerical package was written for this regard to determine the temporal variation of the total dissolved salt (TDS) value within the dead leg pipe. It is generally noted that, as Reynolds number gets higher, the time removal ratio (t/ts) gets bigger. It is also noted that, as a purging location gets farther from the dead end, the time required for the complete removal of TDS increases exponentially.

The limitations of hydrodynamic removal of biofilms from the dead-ends in a model drinking water distribution system

“…Dead-ends are associated with high organic material sedimentation, favourable corrosion conditions, absence of residual disinfectants and pose a high risk to health (Barbeau et al, 2005;Carter et al, 1997). Studies of water distribution systems have shown that bacteriological hot spots are three to four times more likely to occur at dead-ends (Elgamal and Farouk, 2019). In purging saline solution from a dead-end pipe it was shown that as the distance of purging location from the dead-end increased, the removal time increases exponentially.…”