Chlorine Decay Constant from a Bottle Test
The inverse of the chlorine-decay tile: the first-order decay constant k from an initial and a measured residual over an elapsed time, k = ln(C0 / C) / t, with the half-life. A residual falling 2.0 -> 0.7358 mg/L in 10 h gives k = 0.100 1/hr (a 6.9 h half-life). The field number that feeds the forward decay and booster-spacing model. Per EPA 815-R-02-020 and AWWA M14.
Formula and source
First-order decay C(t) = C0 x exp(-k x t) solved for the rate constant: k = ln(C0 / C) / t, from an initial residual C0 and a measured residual C over an elapsed time t (a distribution bottle test). Half-life = ln(2) / k.
EPA 815-R-02-020 (Effects of Water Age on Distribution System Water Quality); AWWA M14.
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