Short methods for controlling river pollution
Answers
Following are the control measures of water pollution:
1. Stabilisation of ecosystem:
It involves following practices:
(a) Reduction of waste at source
(b) Harvesting and removal of biomass
(c) Trapping of the nutrients.
(d) Fish management.
2. Using water hyacinth to remove water pollutants:Water hyacinth is extremely efficient in absorbing and concentrating dissolved nutrients from water in which it lives.
3. Using chemical methods:Several chemical methods have been devised for the treatment of industrial effluents before discharging them in water bodies, like
(a) Ion Exchange:It is a reversible reaction where in an iron from solution is exchanged for a similar charged ion attached to an immobile solid particle which is either naturally occurring inorganic zeolite or synthetically produced organic resins.
(b) Reverse Osmosis:It involves the purification of water with the semipermeable membrane. When used as pre-treatment steps for deionization systems, reverse osmosis will remove feed water bacteria, organics and silica and reduce the dissolved salt content by greater than 95% only.
(c) Precipitation:This process transform dissolved contaminants into an insoluble solid, facilitating the contaminant’s subsequent removal from the liquid phase by sedimentation or filtration.
(d) Coagulation:Chemical coagulation enhances the removal of colloidal particles by destabilising and chemically precipitating them and accumulating the precipitated material into larger floe particles which can either removed by gravity setting or filtration.
4. Cooling methods:For preventing thermal pollution such methods are used like cooling waste water effluent, evaporation tower, cooling ponds, dry cooling towers, wet cooling towers etc.
5. Recycling, Renovation, Recharge and Reuse (4R concept) of waste water:The waste water consisting of domestic sewage industrial effluents, thermal and radioactive pollutants receive some sort of treatment before mixing into water bodies. Urban sewage and sludge etc may be recycled and reused to generate cheaper fuel, gas and electricity.