Sources of Water Supply Rivers (water from rainfall) Ground Waters ( Held in rock structure called aquifers) Drinkable water from sea after desalination (removal of Salts from Sea Water).
Natural substances in water Oxygen (Essential for fish and Life) Dissolved minerals ( Fe, Mg, Ca, K, Zn, nitrate and sulfate ions) Organic Matter ( from decay of dead plants and animals by bacteria) Bacteria (mostly harmless) ( For details refer to p.g 218 Fundamental Chemistry ) Metals Non-metals
Pollutants from Human Activity Rivers passing from farmland, Industrial Area and Seas get polluted with following: Waste from mines (Hg, As, Pb) Factory waste ( Liquid or Effluent) Fertilizers (Nitrates (NO 3 ) -1 and Phosphates (PO 4 ) -3 flourish Algae) Animal Waste and Sewage (containing Nitrates and Phosphates, harmful microbes such as Virus, Bacteria, Parasite) Water from Sewage Works.
Eutrophication Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in marine habitats such as lakes as it can cause algal blooms. Fertilizers are often used in farming, sometimes these fertilizers run-off into nearby water causing an increase in nutrient levels. This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms. This bloom of algae disrupts normal ecosystem functioning and causes many problems. The algae may use up all the oxygen in the water, leaving none for other marine life. This results in the death of many aquatic organisms such as fish, which need the oxygen in the water to live. The bloom of algae may also block sunlight from photosynthetic marine plants under the water surface. Some algae even produce toxins that are harmful to higher forms of life. This can cause problems along the food chain and affect any animal that feeds on them.
Treatment of Water in Plant Step 1: Screening ( Remove Large Particles Such as Twigs) Step 2: Coagulation ( Suspended Particles settle down. Remove Such as Fe Sulfate) Step 3: Floatation ( Coagulated Particles Float and Skimmed Off) Step 4: Filtration ( By using Bed of Fine Sand) Step 5: Charcoal Filtration ( To remove Bad Taste and Smell) Step 6 : Chlorination (To kill Microbes) Step 7: Addition of Fluoride (Fight Tooth Decay, used in some treatment Plants ) Step 8: Storage in Reservoirs.
Also Refer Your Text Books: Fundamental Chemistry Chemistry Matters