water pollution

介紹water p0llution
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.



解決方法
There is no easy way to solve water pollution; if there were, it wouldn't be so much of a problem. Broadly speaking, there are three different things that can help to tackle the problem—education, laws, and economics—and they work together as a team.



Education
Making people aware of the problem is the first step to solving it. In the early 1990s, when surfers in Britain grew tired of catching illnesses from water polluted with sewage, they formed a group called Surfers Against Sewage to force governments and water companies to clean up their act. People who've grown tired of walking the world's polluted beaches often band together to organize community beach-cleaning sessions. Anglers who no longer catch so many fish have campaigned for tougher penalties against factories that pour pollution into our rivers. Greater public awareness can make a positive difference.

[編輯] 水污染的治理

更多資料：污水處理與工業廢水處理（Industrial wastewater treatment）
在清理廢水上，根據類型和汙穢的程度，有許多方法可以使用。大多數的廢水可以在工業規模的廢水處理場（Wastewater Treatment Plants，WWTPs）中處理，其中會使用包括物理式、化學式還有生物式的處理程序。然而，化糞池與其他污水就地處理設施（On-Site Sewage Facility，OSSF）普遍在鄉下地區被廣為使用，這其中包括了美國四分之一以上的家庭。最重要的好氧性處理系統是活性污泥法，這個方法必須維持並再循環可以減少廢水中有機物的微生物總量。厭氧性的處理方法廣泛的被應用在工業廢水與生物污泥的處理上。一些廢水可以高度淨化過後而回收成為中水。生態學取向的廢水處理方式，像是使用蘆葦床處理系統（reed bed treatment system，RBTS）的人工溼地（constructed wetland）是可能可以採取的方式。現代的處理系統包括由首先是微孔濾膜法（Membrane filtration或是Micro filtration，MF）或合成透析膜（synthetic membranes）過濾的三重處理過程。經過濾膜過濾後，處理過的水和從自然水源得到的水，在飲用的水質上無法分辨。可以透過微生物的脫硝作用（denitrification）來移除廢水中的硝酸鹽（Nitrate），通常會加入小量的甲醇來防止細菌以廢水當作碳的來源而滋生。臭氧廢水處理（Ozone Waste Water Treatment）也逐漸開始流行，這樣的系統需要臭氧產生機（Ozone Generator）[2]，利用臭氧氣泡過濾通過水槽來淨化廢水。
來自於工業工廠的廢水處理是個困難而且昂貴的問題。大多數的石油煉製廠與石化廠[3] [4]有就地的處理設施去處理它們的廢水，故處理後廢水在排放到民用的廢水處理場或是河流、湖泊或海洋之前，水中污染物濃度必須符合當地或/和國家的合法標準。

回收再用
經過處理過的廢水可利用回收作為飲用水，如新加坡；或是作為工業上的使用，如冷卻塔（Cooling tower）；或是用來作地下水補注（artificial recharge of aquifers）；或是用在農業上，像以色列70%的農業灌溉都是用高度淨化的廢水；或是如佛羅里達的沼澤地（Everglades）那樣，利用處理過的廢水來進行自然生態系的修復重建工作。