Water Treatment Guide PDF

water Hard water is water that will not easily form a lather with soap Drinking Water Treatment Temporary hardness is hardness that can be removed by boiling. Permanent Distillation: All ions are removed. hardness 1. Flocculation is the coming together of small suspended solids in water. cannot be r...

water Hard water is water that will not easily form a lather with soap Drinking Water Treatment Temporary hardness is hardness that can be removed by boiling. Permanent Distillation: All ions are removed. hardness 1. Flocculation is the coming together of small suspended solids in water. cannot be removed by boiling. 2. Sedimentation: The suspended particles settle to the bottom of the tank from where they are removed. Causes of Hardness 3. Filtration: Water is filtered through Temporary Permanent Ca(HCO₃)₂ CaCl₂ Mg(HCO₂)₃ MgCl₂ sand beds on top of gravel which removes the last of the suspended solids. 4. Chlorination: Enough chlorine must be CaSO₄ added to kill any pathogenic bacteria present, & keep the water MgSO₄ bacteria free until it reaches its destination. Removal of Temporary Hardness; Boiling; causes calcium hydrogencarbonate to 5. Flouridation: Flourine is added to strengthen teeth & prevent decay. decompose Permanent hardness is hardness that 6. pH Adjustment: If water is too acidic ∴ lime (Ca(OH)2) can only be removed by methods other it may corrode pipes. than boiling. is added. If water is too basic sulphuric acid is added. The main methods of removing permanent hardness are: Sewage Treatment Ion exchange: The Ca²⁺or Mg²⁺ ions in hard water swap places with Na+ ions. 1. Primary treatment involves screening & settling, & is a physical process. Deionisation: cation exchange resin 2. Secondary treatment is a biological replaces any positively charged ions in process involving the oxidation by water with H⁺ ions. micro-organisms of the nutrients present in the effluent. anion exchange resin replaces negatively charges ions with OH⁻ ions. 3. Tertiary Treatment: Tertiary treatment involves reducing the levels of phosphates (PO₄³⁻) and nitrates (NO₃⁻ ). water Eutrophication is caused by the overenrichment of water by nutrients such as nitrates & phosphates. It can lead to algal bloom. Heavy metal pollution - Heavy metals include metals such as mercury, cadmium, and lead can seep into waterways. These metals can be removed from water by precipitation.