Determination of Reaeration Coefficient of Saline Receiving Water for Water Quality Management

Abstract

A practical method of determining reaeration coefficients would greatly aid design engineers in determining the degree of wastewater treatment required for a proposed effluent discharge. Many previous tidal river and estuary studies emphasized mainly the effects of flow conditions (such as velocity, water depth, turbulent intensity, hydraulic gradient, etc.) and temperature on stream aeration, but the effect of salts was not seriously considered. In this research new mathematical models of reaeration coefficient considering the effect of salts have been developed for water quality analysis of tidal rivers and estuaries. The reaeration coefficient in saline water, K2s (day−1, base e) at any chloride concentration, chlorinity, or salinity, and at 20 °C, can be expressed by the authors’ NCKU (National Cheng Kung University) equations:K2s=K2fexp0.0127Chlorinity$$ {\mathrm{K}}_{2\mathrm{s}}={{\mathrm{K}}_2}_{\mathrm{f}} \exp \left(0.0127\ \mathrm{Chlorinity}\right) $$K2s=K2fexp0.0000127Chloride$$ {\mathrm{K}}_{2\mathrm{s}}={\mathrm{K}}_{2\mathrm{f}} \exp \left(0.0000127\ \mathrm{Chloride}\right) $$K2s=K2fexp0.007Salinity$$ {\mathrm{K}}_{2\mathrm{s}}={\mathrm{K}}_{2\mathrm{f}} \exp \left(0.007\ \mathrm{Salinity}\right) $$where