Water, Our Lifeline
* Increase in population, industrialisation and improper disposal of wastes results in water pollution. This, in turn results in the scarcity of clean water.
* The United Nations has declared the period 2005- 2015 as the International Decade for Action “Water for Life”.
* Contaminated water causes many water – related diseases.
* Removal of pollutants from waste water is called Sewage Treatment.
* Wastewater from homes, industries, hospitals and office is called sewage.
* Sewage contains organic and inorganic impurities, disease causing bacteria, saprotrophic bacteria, nutrients and other microbes.
* Organic impurities such as animal waste, human faeces, urine, oil, vegetable and fruit waste, pesticides and herbicides are present in sewage.
* Inorganic impurities such as phosphates, nitrates and metals are also present in sewage.
* Microbes that cause diarrhoea and dysentery are also present in sewage.
* Wastewater from kitchen is called sullage water.
* Wastewater released from toilets is called foul waste.
* Wastewater released from industries and commercial organisation is called trade waste.
* The waste water is carried to the released from or sewage treatment plant and released into nearby water bodies after treatment.
* Sewage water contains lots of toxic contaminants that can kill the aquatic plants and animals.
Water Treatment
* Wastewater that comes from households is treated at the treatment plant to remove the physical, biological and chemical matter in it.
* Physical impurities are removed at the Wastewater plants using bar screens, grit and sand removal tank, and clarifier.
* Bar screens are screens that prevent the floe flow of large objects in Wastewater. These screens help remove large objects like rags, plastic Bags, cans, napkins and sticks from sewage.
* Grit such as sand, gravel, clay, egg shells and coffee grounds settle in the grit and sand removal tank.
* A clarifier is a tank having its central part inclined downwards to allow faeces to settle down on the slope. The water coming out from the clarifier is called clarifier water. The clarifier water does not contain any physical impurities.
* The precipitate formed in the clarifier tank is called sludge.
* Bacteria consume human waste, food waste , soaps and other waste in the clarified water.
* Chlorine or Ozone is added to disinfect the water before letting it out to a water source.
* Oils and fats can harden and block pipes. Fats clog the soil pores in an open drain, reducing the effectiveness of the filtration of water.
* Tea leaves, solid food remains and napkins block the flow of oxygen to the microbes that help in water treatment.
* Chemicals like paints, medicines, motor oil, insecticides and solvents kill the microbes that help in water treatment.
Air Pollution and Its Control
* An undesirable change in the physical, chemical or biological characteristics of air, water, land or soil that may have detrimental effect on living organisms is called pollution.
* Substances that bring about undesirable changes are called pollutants.
Common air pollutants are automobile exhausts, chemicals and toxic gases from industries and natural particulate matter such as dust, pollen and ash.
* The Usage of CNG, unleaded and low – sulphur petrol and diesel, catalytic converters and the implementation of stringent pollution level norms can reduce air pollution.
* Noise is also considered as an air pollutant.