Water pollution means the contamination of water bodies (e.g. lakes, rivers, oceans and groundwater). Water pollution mostly occurs when pollutants are dumped directly or indirectly into water bodies without any proper treatment to remove harmful substances.
Water pollution not only affects the plants and animals living in the water sources but also damages the existence of natural living communities.
Water pollution is a major global concern all over worldwide and the water resource policy keeps the records at all levels. It has been suggested that it is the leading global cause of deaths and disease and it accounts deaths of more than 14,000 people daily. Most countries like India, China and many more are lacking the adequate access of safe drinking water. It has been estimated that not only developing or underdeveloped countries are suffering from inefficient water resources but also developed countries like United States of America are suffering from the improper quality of water resources.
Water is typically referred to as a pollutant when it is affected by anthropogenic contaminants and basically in common sense which does not support the use of human desires such as drinking water. Natural disasters like volcanoes, algae blooms, storms and earthquakes also causes the major changes in water quality and the ecological status of water.
Sources of Water Pollution
The sources in which the water resources are being contaminated continuously:-
Sewage Waste (Waste Water)
Sewage is another name for waste water which are dumped from industries or from domestic household. Despite the strict control by the Environment Agency, it shows that the water and sewage industry accounted for almost a quarter of the serious massacre or incidents that had occurred in England and Wales in 2006.
The most essential reason for agricultural pollution is the continuous use of pesticides and fertilizers which can also lead to water contamination. Some other causes are uncontrolled spreading of slurries and manure, disposal of sheep dip, tillage and ploughing of the land.
Oil spillages affect water quality in a number of ways. Oil can make drinking water unsafe to utilize for human purposes. A substantial amount of oil released into oceans and sea which will ultimately destroys the wildlife and the ecosystem that sustains them. Oil spills also reduce oxygen supplies within the water ecosystem.
The main causes of oil related water pollution are:-
1. Loss from storage facilities
2. Spillage during delivery and;
3. Deliberate disposal of waste oil to drainage systems.
Radioactive waste is another source of water pollution. Radioactive substances are used in nuclear power plants, industrial, medical and other scientific purposes. There are also naturally occurring radioisotopes from organisms and within the environment. These kind of substances can result into a great water pollution incidents.
In household activities, most of the people dumps their garbage wastes and some other inorganic substances into water sources. Water dumping substances not only causes water pollution but also harms the ecosystem and increases the risk of flooding.
The Causes of Water Pollution
Some chemical substances like calcium, sodium, iron, manganese, etc.) which are dumping into the water sources are the main leading cause of water pollution. The high concentration of naturally occurring substances can have negative impacts on marine flora and fauna.
There are some man-made as well as natural substances which can cause water contamination. Some natural and anthropogenic substances may cause turbidity(cloudiness) which blocks the direct ray of sunlight and results then complete disturbance in the growth of small marine plants and also damages in some life of marine species.
Most of the chemical substances are toxic in nature and those of harmful chemical substances can produce waterborne diseases which can ultimately be harmful to
human as well as other organisms living in the environment and are considered as Pathogens. The chemical substances which are dumped from certain industries, factories or household communities can lead to change in temperature and mostly the growth of eutrophication. Eutrophication is an increase in the concentration Of chemical nutrients in an ecosystem to such an extent that increases in the Primary Productivity of the ecosystem. Depending on the degree of eutrophication, any negative environmental effects like anorexia (Oxygen depletion) and major depletion in water quality which may cause disturbance in the ecosystem.
Chemical and other contaminants are mostly of two types:-
Organic (like detergents, chloroform, insecticides, herbicides etc.) and Inorganic (like power plants, ammonia, chemical waste, fertilizers, heavy metals from motor vehicles and silt) water pollutants .
The thermal pollution is the rise or fall in the temperature of the water body which are cause under the influence of human activities. The main point of thermal pollution is the use of water as a coolant by power plants and industries. Increase in water temperature decreases oxygen levels under marine ecosystem as well as other ecosystem composition. Thermal pollution can also be caused by the release of cold water from the base of the water reservoirs into warmer water sources like river etc.
Control of Water Pollution
Domestic sewage mostly contains 99.9 percent of pure water, while the other half 0.1 percent is considered as pollutants. Even though they are small in concentration but can pose risk on a large scale. Mostly in urban areas, domestic sewage is typically treated by the sewage treatment plants. Well-designed and operated systems can remove 90 percent or more of these pollutants. But there are some municipal plants which are not designed to treat toxic pollutants found in industrial wastewater. So, there are some ways in which domestic sewage may be treated properly including -
As we all are aware that most of industries generates waste water with high concentration of conventional pollutants (e.g. oil and grease ), toxic pollutants (e.g.Heavy metals, organic compounds) or other non-conventional pollutants such as ammonia. The facilities which could be needed to remove the toxic pollutants should be installed with a pre-treatment system.
Some industries has been redesigning their manufacturing processes in order to reduce or eliminate pollutants through a process called pollution prevention.
Here, are some ways in which power generated water or industrial sewage water can be treated :-
Agricultural Waste Water
Nonpoint source controls
Farmers may utilize erosion controls to reduce runoff flows and retain soil within their fields. Common techniques include contour plowing, crop mulching, crop rotation, planting perennial crops and installing riparian buffers.
Nutrients (nitrogen and phosphorus) are use by the farmers as commercial fertilizers, animal manure or spraying of municipal or industrial wastewater or sludge. Farmers can develop and implement nutrient management plans to reduce misuse of chemical fertilizers.
Another way to minimize excess pesticides, farmers may use Integrated Pest management (IPM) techniques to maintain the control over pest, reduce the dependence on chemical pesticides and protect the best possible use of water quality.
Point source wastewater treatment
Animal slurries are treated by containment in anaerobic lagoons before disposal by spray or trickle application to grassland. Constructed wetlands are sometimes may used to facilitate the treatment of animal wastes. Some animal slurries are used by mixing with straw and composted at high temperature to produce bacteriologically sterile and manure for soil fertilization.
Construction site storm water
Sediment from construction sites is managed by installation of:
Urban runoff (storm water )
To prevent control of urban runoff involves decreasing the velocity and the flow of stormwater, as well as reducing pollutants. Local government are using a variety of stormwater management techniques to reduce the effects of urban runoff. These techniques may be used to focus on water quantity control, and some others facilities are focus mainly on improving the quality of water resources. Some other techniques could be used includes low-impact development techniques, installation of green roofs and improved chemical handling (e.g. Management of motor fuels and oil, fertilizers and pesticides). Infiltration basins, bioretention systems, constructed wetlands, retention basins are involved in runoff mitigation systems.
Thermal pollution from runoff can be controlled only by one process (i.e. by storm water management facilities as it helps to absorb the runoff or direct it into the groundwater). Retention basins may be less effective like reducing temperature, as it helps the water to heat up by the sun before being discharged to a nearby steam.