Impact of Sodium and Potassium on Environmental Systems

Domenic Grasso
Keith Strevett
Harish Pesari

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DOI: 10.2190/RRND-6Y9Q-JN16-06ND

Abstract

Health effects associated with sodium-cycle water softening has led to the consideration of potassium-cycle ion exchange as an attractive alternative. Regulatory agencies, however, have expressed concern regarding the environmental impacts associated with discharge of potassium-laden brine. To assist in providing guidance regarding the relative environmental impacts deriving from discharge of sodium- and potassium-cycle softener regeneration brine, this article summarizes available literature exploring systems potentially impacted by brine discharge. The literature indicates that replacing sodium chloride with potassium chloride as a water softener regenerant appears to result in a more environmentally benign scenario and may, in certain circumstances, be environmentally beneficial. Some areas where potassium chloride may be advantageous are land application of sewage sludge, viral inactivation, mobility in soil, effects on soil properties and impacts on plant life. There are no significant differences between sodium chloride and potassium chloride in effect on engineered physicochemical processes of in aquatic life systems. The impact of sodium may be detrimental to the environment because the uptake of phosphorus by algae was reportedly enhanced by sodium. Potassium, on the other hand, was not reported to enhance phosphorous uptake. Some questions remain about the impact of potassium and sodium on septic tank bacteria, biological waste treatment processes, and effects on natural flora. The literature reviewed on these topics was somewhat conflicting. Further efforts to assess the impact of potassium and sodium should be directed at resolving these literature discrepancies.

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