The Sulf-IX^TM ion exchange process is a two stage process employing two different resins to remove calcium and sulphate ions (Ca²⁺ and SO₄^2-) from water. The resins are regenerated using the low-cost reagents, sulphuric acid and lime, so that the only products of the process are clean water that can be discharged or re-used, and a solid gypsum product that can be used in building products and fertilizer production. A simple schematic of the process is shown below.

The Sulf-IXT process is particularly suited for the removal of sulphate from lime plant effluent but is applicable for the treatment of any process stream or wastewater high in Total Dissolved Solids (TDS) and Ca/Mg hardness. The complete process cycle includes resin loading, regeneration and rinsing. Feed water is first passed through a series of contactors containing cation exchange resin to remove primarily calcium and magnesium by loading the cations onto the resin, and then through contactors containing anion exchange resin to remove sulphate.

The technology was initially based on the GYP-CIX technology developed in South Africa, which also uses sulphuric acid and lime for resin regeneration. The Sulf-IX^TM process, however, overcomes difficulties of the GYP-CIX process associated with limited process flexibility for varying feed chemistry, mechanical entrainment of gypsum in the regeneration stage, and limitations on sulphate removal when magnesium is present in significant concentration in the feed water.

BioteQ is working with a large mining firm to build a demonstration plant at a mine site in the US. Click here to find out about more BioteQ's developing projects.

Benefits of the Sulf-IXT ion exchange technology

• Uses simple and low-cost reagents to remove sulphate from water to levels that meet or exceed tightening sulphate regulations.
• Produces only clean water and a clean gypsum product than can provide added-value due to its potential use as a construction material.
• High recovery of water
• Ideally suited for sulphate removal from lime plant effluent
• Costs less compared to alternative processes.