Minimum Source Dilution as a Method to Regulate Discharge of Toxic Brine from Industries and Mining Processes

摘要

The concept of minimum source dilution applied to submerged dense discharges is proposed to regulate the release of toxic brine from industries and mining processes. Predicting and monitoring dilution at the source are effective means of protecting environmentally sensitive areas that require minimal mixing zones around the discharge point. The proposed concept of minimum source dilution is essentially reducing the mixing zone to the edge of the discharge pipe. Existing environmental regulations in most countries are stipulating mixing zones for the disposal of toxic brine varying in size from 0 m to 500 m, depending upon toxicity of brine, sensitivity of the area, and environmental awareness. It has been recognized in this study that in the presence of variable ambient currents, the vertical dense discharge configuration (θ=90°) is more reliably diluting brine than an inclined discharge (0°≤ θ <90°). And in the case of a vertical discharge, the minimum source dilution was determined to be μ_(min) = 0.82F_0 , where F_0 is the discharge densimetric Froude number, calculated using the diameter of the source. Inclined discharges can produce higher concentrations of brine at the bottom of the receiving water when the ambient current is in a direction opposite to the discharge.