By Saptarshi Das IX-A

Roll no. 37

Water Pollution Due to Sewage

SO WHAT IS POLLUTION?

• Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.

ORIGINS OF SEWAGE• Sewage is generated by residential, institutional, commercial and

industrial establishments.

• It includes household waste water from toilets, baths, showers, kitchens, sinks and so forth that is disposed off via sewers. In many areas, sewage also includes liquid waste from industry and commerce.

• Sullage is applied to waste water which does not contain human excreta e.g. Waste water from bathroom and kitchen.

[Sullage is waste water from household sinks, showers, and baths, but not waste liquid or excreta from toilets.]

Causes of Sewage Pollution Domestic sewage - It is waste water generated from household activities. [sewage also includes liquid waste from - industry & commerce]. Domestic sewage water contains - - Organic materials & inorganic materials such as - phosphates & nitrates. Organic - from food & vegetables & inorganic - from soaps & detergents. Improper handling of waste water is the main reason behind pollution.

EFFECTS:- Spreading of diseases - Pathogenic micro-organisms enter the water

system through sewage and the bacteria & viruses may cause - malaria & typhoid.

BOD [Biological oxygen demand] increases through sewage water pollution.

[BOD is a measure of oxygen utilized by micro-organisms during oxidation of organic matter. Higher the amount of BOD, more polluted is the water.]

EFFECTS (contd.)• Waste water and sewage from various sources may carry pathogenic

organism that can transmit disease to humans and other animals. Sewage also contains organic matter that can cause odour and nuisance problems of receiving water bodies, and can lead to eco toxicity. Also there is an economic loss as sewage discharged in water bodies makes it unfit for agricultural and drinking purposes.

• NOTE : Ecotoxicity is the subject of study of the field of ecotoxicology which refers to the potential for biological, chemical or physical stressors to affect ecosystems.

• Sewage-contaminated water causes eutrophication, which is the increase in concentration of chemical elements required for life.

AN UNSPECIFIED NUMBER OF RESIDENTS LIVING DOWNSTREAM OF THE SPILL WHO DRAW THEIR DRINKING SUPPLIES FROM THEIR PRIVATE WELLS HAVE REPORTED WATER DISCOLORATION.

SEWAGE POLLUTION SPOILS SOUTH COAST

An image of untreated sewage being discharged into a water body.