Process for the treatment of saline water

A process for treatment of water containing dissolved solids, said process being usable for each of the following types of water:

• Type 1 water comprising total dissolved solids of 1 to 60 g/L, a Cl−/HCO3− ratio of <2 and a Cl−/2SO42− ratio of >1,
• Type 2 water comprising total dissolved solids of 1 to 15 g/L, a Cl−/HCO3− ratio of ≧2 and a Cl−/2SO42− ratio of >1,
• Type 3 water comprising total dissolved solids of 1 to 15 g/L, a Cl−/HCO3− ratio of >2 and a Cl−/2SO42− ratio of <1,
• Type 4 water comprising total dissolved solids of >15 and ≦60 g/L, a Cl−/HCO3− ratio of >5 and a Cl−/2SO42− ratio of >7,
• Type 5 water comprising total dissolved solids of >15 and ≦60 g/L, a Cl−/HCO3− ratio of >5 and a Cl−/2SO42− ratio of <7,
• Type 6 water comprising total dissolved solids of >60 g/L, a Cl−/HCO3− ratio of >5 and a Cl−/2SO42− ratio of >9, and
• Type 7 water comprising total dissolved solids of >60 g/L, a Cl−/HCO3− ratio of >5 and a Cl−/2SO42− ratio of <9,
• said process comprising the steps of:
• (a) contacting the said water with a first reagent comprising a source of calcium ions selected from the group consisting of calcium oxide, calcium hydroxide, and a combination thereof as a sole agent to cause at least some solids dissolved in the water to react with the first reagent and to form a first solid product and a partially processed water, wherein the water containing dissolved solids is a Type 1 water and the first solid product is precipitated calcium carbonate (PCC) or the water containing dissolved solids is a water of any of Types 2 to 7 and the first solid product is gypsum-magnesium hydroxide mixture (GMH) and wherein the said GMH is further treated by the addition of sulphuric acid to react with 5-50% of the stoichiometric amount of magnesium hydroxide present in the GMH;
• (b) recovering the first solid product from the partially processed water;
• (c) at least partially concentrating the partially processed water or a portion thereof, so as to promote the formation of a precipitate and a mother liquor;
• and
• (d) recovering the precipitate from the mother liquor as a second product, wherein the water is a water of type 1 and the second product is sodium hydroxide, sodium sulphate, sodium chloride or sodium carbonate;
• wherein the water is a water of any one of types 2, 4, 5, 6 and 7, and the second product is sodium chloride;
• or wherein the water is a water of type 3, and the second product is sodium sulphate.