Water pollution is a large set of adverse effects upon water bodies such as lakes, rivers, oceans, and groundwater caused by human activities. Although natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water, water is only called polluted when it is not able to be used for what one wants it to be used for. Water pollution has many causes and characteristics. Increases in nutrient loading may lead to eutrophication. Organic wastes such as sewage impose high oxygen demands on the receiving water leading to oxygen depletion with potentially severe impacts on the whole eco-system. Industries discharge a variety of pollutants in their wastewater including heavy metals, resin pellets, organic toxins, oils, nutrients, and solids. Discharges can also have thermal effects, especially those from power stations, and these too reduce the available oxygen. Silt-bearing runoff from many activities including construction sites, deforestation and agriculture can inhibit the penetration of sunlight through the water column, restricting photosynthesis and causing blanketing of the lake or river bed, in turn damaging ecological systems. Pollutants in water include a wide spectrum of chemicals, pathogens, and physical chemistry or sensory changes. Many of the chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Alteration of water's physical chemistry include acidity, electrical conductivity, temperature, and eutrophication. Eutrophication is the fertilisation of surface water by nutrients that were previously scarce. Even many of the municipal water supplies in developed countries can present health risks. Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily.
Sewage and Wastewater
Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.
• Sewage is the term used for wastewater that often contains faeces, urine and laundry waste. • There are billions of people on Earth, so treating sewage is a big priority. • Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water. • Untreated sewage water in such areas can contaminate the environment and cause diseases such as diarrhoea. • Sewage in developed countries is carried away from the home quickly and hygienically through sewage pipes. • Sewage is treated in water treatment plants and the waste is often disposed into the sea. • Sewage is mainly biodegradable and most of it is broken down in the environment. • In developed countries, sewage often causes problems when people flush chemical and pharmaceutical substances down the toilet. When people are ill, sewage often carries harmful viruses and bacteria into the environment causing health problems. Industrial Waste
Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.
• Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans. • Pollutants from industrial sources include:
o Asbestos – This pollutant is a serious health hazard and carcinogenic. Asbestos fibres can be inhaled and cause illnesses such as asbestosis, mesothelioma, lung cancer, intestinal cancer and liver cancer. o Lead – This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the environment is contaminated. Lead is harmful to the health of many animals, including humans, as it can inhibit...
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