Effect of Flow Velocity on Chlorine Decay in Water Distribution Network:A Pilot Loop Study

Abstract

Experiments were run in the pipe loop setup to estimate bulk and wall chlorine decay rates under varying flow and chlorine levels for groundwater. A recirculating loop of 50 mm inner diameter polyvinyl chloride pipe and a variable flow pump with feed and recirculation tank were used to design a pipe loop. Sodium hypochlorite was introduced as free chlorine into the test water. The study came up with three important findings: (a) bulk chlorine decay rate in test water decreased with increase in chlorine levels, which is attributed to the type and level of organic matter present in test water. (b) Chlorine decay rate in pilot loop setup increased with increase in flow velocity. The result showed that under turbulent conditions, in addition to chlorine, mass flux transfer from bulk to wall and biofilm removal from pipe surface contributed to chlorine decay. We also noted that with increase in flow velocity the contribution of bulk reaction to total chlorine decay in pipe loop decreased. (c) ANOVA test on experimental dataset showed that as compared to initial chlorine levels, flow velocity has statistically significant effect on chlorine dissipation in a pipe loop. We also found that after turbulent flow is achieved, the effect of flow velocity on the wall decay is negligible.

Influence of physical and water quality parameters on residual chlorine decay in water distribution network

“…This could have been due to the low velocities that ranged from 0.001 to 0.10 m/s as in Table 1 (descriptive statistics). This is similar to the velocities in the study of [ 27 ] that ranged from 0.0 to 0.12 m/s with Reynold's number <2000. The laminar flow could have resulted in steady flow because of little or no valve modulation and changes in pumping action in this gravity flow.…”

“…This laminar flow ensured bulk chlorine decay reaction characterized by little or no chlorine mass transfer to pipe wall. Therefore, wash-off of wall organic biofilm and exposure of wall bacteria that are active chlorine reactants was most probably minimal [ 27 ]. Consequently, there was insignificant and negligible correlation between velocity and residual chlorine decay.…”

Modelación y calibración del cloro residual en el software Epanet. Caso de estudio: Municipio de Villa de Leyva (Boyacá, Colombia)

“…Posteriormente, en la calibración hidráulica dinámica se asignó a los nudos de consumo la curva de comportamiento de la demanda de agua construida mediante una lectura continua cada hora durante un día. Adicionalmente, se registró el consolidado de la mediana de las presiones tomadas en campo en el lapso de lunes a viernes [10,11].…”

Estimation of chloramine decay in drinking water distribution systems

“…Pilot-scale methods typically incorporate pipe loops, pipe segments harvested from the field, as well as the collection of water, and thereby serve as a common alternative to field testing (Mutoti et al, 2007;Jamwal and Kumar, 2016;Douterelo et al, 2016;Clark and Haught, 2005). Benchscale evaluations are often a practical alternative or supplement to pilot-scale trials.…”