WHAT IS WATER POLLUTION-TYPES, SOURCES & CONTROL

WHAT IS WATER POLLUTION-TYPES, SOURCES & CONTROL

INTRODUCTION

Water pollution occurs when harmful substances damage the physical, chemical or biological characteristics of water bodies and usually by human activities. Water bodies include lakes, rivers, oceans, aquifers and groundwater. Major sources of water pollution are sewage & other wastes, industrial effluents, agricultural discharge and industrial wastes from chemical industries, fossil fuel plants and nuclear power plants.

Surface water pollution- it includes pollution of rivers, lakes and oceans. Marine pollution is subset of water pollution.

Marine pollution- it is defined as the discharge of undesirable and harmful substances in oceans water which contaminate the quality of water, that is harmful to marine ecosystem and use of sea water too. The major sources of marine pollution are sewage, industrial effluents, synthetic detergents, pesticides, fertilizers, heavy metals, plastic, radionuclide wastes, oils and petroleum products. All those are carried out by rivers into oceans or from direct dumping. The most serious pollutant is oil which isolate water from coming in contact with atmospheric oxygen. As a result, the shortage of oxygen inhibits growth of plankton which is the basis of food chain in aquatic ecosystem. Plastic debris can absorb toxic chemicals from ocean pollution, potentially poisoning any creature that eats it. Many of these long-lasting pieces end up in the stomachs of marine birds and animals. This results in obstruction of digestive pathways, which leads to reduced appetite or even starvation.
Mercury pollution- the main source of Hg-containing effluents is chloral alkali plant. Effluents from batteries, thermometers, fluorescent light tubes, high density street lamps and switch making industries also contain Hg. Both organic and inorganic forms of Hg are highly poisonous. It was responsible for the MINAMATA epidemic disease in japan & Sweden.
Lead pollution- effluents of lead and lead processing industries are main sources of lead to water. Cadmium contaminated drinking water and its high level in rice causes the Itai-itai (ouch- ouch) disease).

Sources

Surface water and groundwater have often been studied and managed as separate resources even though they are interrelated. Surface water seeps through the soil and becomes groundwater. Conversely, groundwater can also feed surface water sources. Sources of surface water pollution are generally grouped into two categories based on their origin.

Point sources- it refers to contaminants that enter a waterway from a single, identifiable source, such as a pipe or ditch. Such as discharges from a sewage treatment plant, a factory, or a city storm drain.

Non-point sources– it refers to diffuse contamination that does not originate from a single discrete source. This type of pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. A common example is the leaching out of nitrogen compounds from fertilized agricultural lands. Nutrient runoff in storm water from “sheet flow” over an agricultural field or a forest is also example.

Control of water pollution–

Recycling & Re utilization of waste- recycling of different type of wastes such as industrial effluents, sewage/sludge, thermal pollutants etc. can be used to generate electricity and fuel gas. Recycling and re-utilization offer to reduce pollution and making new techniques and products. Well-designed and operated municipal waste treatment systems can remove 90 percent or more of the pollutant load in sewage.
Removal of pollutants– there are some suitable techniques and methods such as absorption, reverse osmosis, electro dialysis, ionex change etc.by which different water pollutants can be removed. For example reverse osmosis is commonly used to desalinate the saline water and to purify sewage water.
Reduction of waste input– control of source of waste, to reduce harvesting and removal of biomass, trapping of nutrients, fish management and aeration are helpful to stabilize the ecosystem. Biological and physical methods can be used to restore ecological balance and biodiversity in the water bodies.
Control of urban runoff– it can reduce pollutant discharge.
On-site sanitation and safely managed sanitation- Any households or businesses not served by a municipal treatment plant may have an individual septic tank, which pre-treats the wastewater on site and infiltrates it into the soil. This can lead to groundwater pollution if not properly done. The use of safely managed sanitation will help to prevent such type of water pollution.
Control through law & enforcement of standard– the government of India made the water (prevention and control of pollution act) 1974. The central pollution control board (CPCB) established the minimum national standards (MINAS) and the air emission standards to control pollution at source. These standards mean the maximum limit of effluents and emissions discharged into the water body or atmosphere.

WHAT IS WATER POLLUTION-TYPES, SOURCES & CONTROL

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