Exam Question

### (a) Treatment Scheme to Improve Potability of Water from a Low-Pressure Evaporator (6 Marks)
A comprehensive treatment scheme is essential to convert the distilled water (distillate) produced by a low-pressure evaporator into safe, palatable, and stable potable water. The distillate is pure but corrosive, unpalatable, and lacks essential minerals. The treatment process involves several stages in a specific sequence:
1. **Re-hardening / Mineralisation:**
* **Purpose:** To add essential minerals (calcium and magnesium salts) to the distilled water. This corrects the taste, increases alkalinity (raises pH), and reduces the water's natural corrosivity, which would otherwise damage piping and tanks.