The recent supply of large volumes of seawater desalinated water in Israel prompted both the development of new water quality standards and the development of a novel post treatment process, designed to comply with the new standards at a cost effective price. The new process is designed to supply water with alkalinity, Ca2 + and calcium carbonate precipitation potential values as required in the new criteria, along with the addition of a threshold Mg2 + concentration recently recommended by the WHO. The current paper describes the process in general, and focuses in particular on attaining these criteria while maintaining a low total hardness concentration (120 mg/L as CaCO3). The process is based on dissolving calcite using H2SO4 and replacing the excess calcium ions generated in this process by Mg2 + ions (using a specific cation exchange resin—Amberlite) and by Na+ (using a second cation exchange resin—chabazite, from the zeolite group). Once exhausted the resins are re-loaded with Mg2 + and Na+ by the brine generated in the RO process, thus no unwanted brines are generated. A case study is presented for which operational costs were approximated at 0.034 $US/m3 product water.
New desalinated drinking water regulations are met by an innovative post-treatment process for improved public health
R. Penn, L. Birnhack, A. Adin, O. Lahav; New desalinated drinking water regulations are met by an innovative post-treatment process for improved public health. Water Science and Technology: Water Supply 1 August 2009; 9 (3): 225–231. doi: https://doi.org/10.2166/ws.2009.395
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