Important Chemical Characteristics of Drinking Water
Chemical Characteristics of Drinking Water
Chemical Characteristics
- H2O is the chemical formula for water.
- Water's capacity to "stick" to itself and other surfaces is due to its unusual form, which has both hydrogen atoms on the same side of the oxygen atom.
- The hydrogen atoms provide a positive electrical charge, whereas the oxygen atom produces a negative electrical charge.
Total Dissolved Solids (<500)
- Total solids can be found by evaporating a sample of water and weighing the dry residue left.
- Suspended solids can be found by filtering a water sample through Whatman filter paper No.44
- The maximum number of solids that can be present in water is usually regulated at 500 parts per million (ppm).
pH (6.5 to 8.5)
- It is measure by hydrogen ion concentration in water.
- It is measure by Potentiometer and Colorimetric method
Alkalinity & Acidity
- Alkalinity is caused by bicarbonates of Ca & Mg and carbonates, hydroxides of Ca, Mg, Na, K.
- Alkalinity effect - Incrustation and sediment deposit in pipelines and difficult in chlorination.
- Acidity is caused by Mineral Acids, Free Co2, Sulphates of Fe & Aluminum.
- Acidity effect - Tuberculation & Corrosion of pipelines.
- Alkalinity and Acidity are estimated by Titrimetric.
- Total Alkalinity < 200 mg/l as CaCo3
Hardness (<200 ppm)
- It is measured by the EDTA test( Versante method)
- Temporary hardness caused by Bicarbonates and carbonates of Ca & Mg
- Permanent hardness caused by sulfate, chloride, and nitrate of ca & Mg.
- 1 French degree hardness = 10 ppm
- 1 British degree hardness = 14.25 ppm
- 1 American degree hardness = 17.15 ppm
Content of Chloride
- The chloride concentration of treated water intended for public consumption shall not exceed 250 parts per million.
- By titrating the water with a standard silver nitrate solution and using potassium chromate as an indicator, the chloride level of the water may be determined.
Nitrogen
- The presence of nitrogen in water can be caused by any of the following factors.
- Free ammonia
- Organic or Albuminous Matter
- Nitrites
- Nitrates
Toxic Chemical Substance (Drinking water Standards)
- Barium: - < 1 mg/l
- Lead: - < 0.1 mg/l
- Boron: - < 0.01 mg/l
- Cadmium: - < 0.01 mg/l
- Arsenic: - < 0.05 mg/l
- Chromium: - < 0.05 mg/l
- Cyanide: - < 0.05 mg/l
- Phenols: - < 0.001 mg/l
- Mercury: - < 0.001 mg/l
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