Simultaneous Removal of Hardness and Silica

Question

I want know what is the best solution for removing simultaneously 1500 ppm total hardness as CaCo3 and 100 ppm silica?

MOHAMMED NAZEER · Answer

Several softening  methods Lime soda process is better.Bicarbonate hardness removed by lime and chloride,MG removed by soda ash.Other methods ION XCHANGE and Zeolilite process followed with Ultrafiltation is better for silica as well as hardness removal.

Stanton Smith · Answer

My first instinct is chemical precipitation. I agree with other answers that the final quality and maybe use of the treated water should be defined. Also need TDS, alkalinity, pH, TSS of feed to answer the question well. With no feed quality, the most flexible choice is chemical precipitation using MgO and/or aluminate for silica, and depending on pH, add caustic or lime or acid to get pH to about 10. Then clarify and/or filter as finely as needed, adjust pH as needed. Good luck.

Martin Tashi · Answer

Definitely softener for hardness removal, of course depending on quantity of consumption. If quantities are big maybe antiskalant can be a solution. For silica it still depends on type of silica. Sand filtration can be the first one. If sand filtration doesn't work than Reverse osmosis is required.

Rafael Gay-de-Montella MSc PEng · Answer

In the Heavy Oil industry (Alberta) this is commonly done with (Hot or Warm) Lime softening, with and Magox to reduce content of Silica.
At effluent: Hardness is 30 and Silica about 40-50; to prepare BFW the softened Produced water then passes to WAC beds.

Randall E Witte · Answer

I forgot to mention that this process also provides pre-heated make-up water for the boiler system- reducing overall "raw" thermal input and related environmental impact.

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