Sewage Water Pollution

Pollution caused by sewage water is one of the major problems in cities. Sewage water is drained off into rivers without treatment. Careless disposal of sewage water leads to creation of a chain of problems like spreading of diseases, eutrophication, increase in Biological Oxygen Demand (BOD), etc.

Waste water that flows after its use for domestic, industrial and other purposes is termed as sewage water. In ideal situations, sewage water is channeled or piped out of cities for treatment. Bulk of the sewage contains water as the main component, while other constituents include organic wastes and chemicals. Water pollution occurring from sewage is mainly observed in developing countries. In these countries, disposal of sewage is not carried out in a proper manner. In developed nations, a network of sewage pipes takes the sewage away from cities. Treatment of the waste minimizes the pollution caused by sewage water.

Main Causes of Sewage Water Pollution

Improper handling of waste water is the main reason behind pollution of water. The sewage is drained off in large quantities into rivers. It slows down the process of dilution of water constituents; this in turn stagnates the river. It also causes health problems, for example, diarrhea.

Draining the water without treatment is one of the major causes of sewage water pollution. Effluents contained in sewage water contain innumerable pathogens and harmful chemicals. The detergents that release phosphates in water allow growth of algae and water hyacinths.

Ill-effects of Sewage Pollution
Pathogens present in sewage water spread many different diseases. Stagnant water fosters the growth of mosquitoes, which in turn causes malaria. Another disease that spreads through contaminated water is typhoid. Sewage water may also contain protozoans like Cryptosporium and Giardia. These pathogens pose a great risk to human health. Polluted water is therefore, host to several pathogenic microbes.

The process of excessive deposition of chemical nutrients in water bodies is termed as eutrophication. It is one of the many problems caused by sewage water pollution. Degradation of the quality of water, reduction in the number of fish and increase in biological oxygen demand (BOD) are the major effects of eutrophication. Increase in concentration of phosphates, nitrates and other chemicals including organic wastes in water bodies causes excessive growth of algae and bacteria. Growth of these organisms is responsible for increase in BOD and thereby, reduction in the number of aquatic creatures.

Toxins released in rivers through sewage water are consumed by the fish and other organisms; the possibility of toxins entering the food chain thereby, increases. Coral reefs are affected by sewage pollution the world over. Sewage water that is dumped in oceans affects the coral reefs to a great extent. Toxins present in polluted water inhibit the growth of corals.

Water bodies in their natural form contain many different chemical compounds like bicarbonates, nitrates, chlorides, sulfates, etc. Increase in the amount of these compounds causes many problems. For example, water becomes unsuitable for drinking and irrigation. The Total Dissolved Solids (TDS) present in water should be less than 500 mg/gram for the water to be considered potable. Water that contains salts is not useful for irrigation either. Use of such type of water for agricultural purpose leads to salinization of soil, which in turn causes soil erosion.

Treatment of Sewage Water
If sewage water is treated before its release into rivers, most of the problems pertaining to pollution would be solved. Removal of contaminants is the main objective of the treatment of sewage water. Before the actual treatment of water, effluents need to be pretreated. The process of pretreatment helps in the separation of materials like oils, greases, gravel and sand from the polluted water. It is carried out by the filtration of sewage water. Biological wastes dissolved in water are treated with microbes. It helps in converting the wastes into a solid mass which can be easily separated thereafter. After the biological treatment is over, partially pure effluent is treated with chemical disinfectants. The water that is treated in treatment plants can be used in golf courses, for watering the lawns and also in agriculture for irrigation. Sewage treatment plants generate clear and clean water at the end of the process.

Restoration of wetlands is one of the means of treating sewage water. The wetlands help in processing sewage water naturally, without using any artificial method/technique. The idea underlying the restoration of wetlands is that the bacteria present in them would dilute the nitrates and phosphates. The same process takes place in sewage water treatment plants, except for the fact that, here (in the wetlands) it is carried out naturally.

Sewage water treatment is a must, especially when environmental issues are of concern in today's world. Efforts need to be taken to purify the effluents. It will not only benefit human beings but also the varied flora and fauna of our planet. Let's pledge to keep our environment beautiful and free from any form of pollution.