Most of the water resources should be purified before consumption.In some cases,the resource does not satisfy to the desirable levels regarding their chemical properties,such as hardness,nitrate contamination,heavy metals,etc.Among them,water hardness can emerge problematic in some cases.Water hardness refers to existing divalent ions,such as iron,manganese,calcium and magnesium.Calcium and magnesium ions are generally known as the major components of water hardness.In water purification and treatment plant,chemical precipitation method is one of the most widely used methods for the removal of Ca(Ⅱ) and Mg(Ⅱ).However,one of the main drawbacks of this process is the resulting waste,namely the large amount of liquid sludge produced,as well as the need for re-carbonation of the softened water [1].In addition,the use of additional chemicals to prevent sludge production is restricted and hence water hardness species cannot be fully removed.Other methods for water softening include nanofiltration,electrodialysis,capacitive deionization,and reverse osmosis,but these methods consume high amounts of energy and high operating and maintaining costs [2].Therefore,there is a significant need to develop an eco-friendly,cost-effective and low energy consuming process,which would be an ideal addition to the water softening market.The present study reports a capsule type of effective adsorbent for the removal of water hardness.Poly(styrenesulfonic aicd) (PSSA) was used as a model polymer with sulfonic aicd functional groups.We developed PSSA-impregnated chitosan capsules (PSSA-CC) by encapsulating PSSA with chitosan (Fig.1).For making them,the mixture with 5% PSSA and 4% alginate solutions was prepared and dropwised into the chitosan solution for forming capsules.The capsules were then cross-linked in epichlorohydrin solution for 1 h at 50 °C and washed with distilled water three times.The sorption kinetic and isotherm experiments by PSSA-CC were studied.The PSSA-CC showed high sorption performances for Ca(Ⅱ) and Mg(Ⅱ).