Chemical Transients in Water tanks
by
Alex McNabb
University of Auckland and CMIS, CSIRO, Canberra

Large water storage tanks used to monitor the chemical treatment of drinking water, are themselves periodically monitored to assess the residence times of chemical additives such as chlorine and fluoride, under normal flow regimes. One monitoring test involves cutting off the fluoride input while the tank is subject to a steady throughput and after a few hours, turning the fluoride back on again. The concentration of fluoride in the output is measured over a lengthy period of time while its output decays and then recovers. Some simple models can be used to explore the spectrum of responses for various steady throughputs.

Date received: April 30, 1999