There are many different types of water treatment devices currently being used by countries, cities, and even for personal use. Some of the devices that will be analysed are: I m running out of creativity.
In Canada, the most common method of disinfecting drinking water is to use chlorine, chloramine or chlorine dioxide. Chlorination of drinking water is one of the most significant public health advances of the 20th century saving more lives than all of the medicines combined.
It has virtually eliminated all the bacteria that once caused diseases such as cholera, typhoid, dysentery and hepatitis. More than 200 million Canadians receive chlorine-disinfected drinking water every day. Every one of Canada's 3000 drinking water plants uses chlorine disinfection. Chlorine-based disinfectants have the lasting power needed to help prevent re-growth of microorganisms as the water is distributed from the treatment plant to the tap.
But there is a very serious concern about the widespread use of chlorine as the sole disinfectant for water.
The concern is the by-product called "chlorinated hydrocarbon" that is found in surface water supplies treated with chlorine. When chlorine and decaying organic matter such as leaves and animal waste come together, a chlorine compound called Trihalomethane or THM is formed. In studies carried out by the Ontario Cancer and Treatment Foundation, consumption of chlorinated water has been shown to be associated with bladder, colon and rectal cancer. The greatest risk for contracting the cancers was among those who drank water with elevated levels of THM for over 35 years.
Other research has connected high levels of THM's to reproductive disorders such as miscarriages, birth defects and low birth weights.
Authorities warn that the risk of drinking unchlorinated water is much higher.
One of the alternatives to chemical disinfection is ultraviolet energy.
When microorganisms, such as bacteria and viruses are exposed to UV light, their DNA is rearranged and they can no longer reproduce. Microorganisms that cannot reproduce cannot cause illness. Ultraviolet light is produced by lamps that are directly submerged in water. As the water flows past the lamps, microorganisms are exposed to a lethal dose of UV energy. Ultraviolet light is an environmentally friendly way to disinfect water. There is no chemical storage or handling risk through the use of UV and there are no by-products such as Trihalomethane left after disinfection has taken place. This allows a small and safe amount of chlorine to be added to drinking water before it is distributed through the system, providing a dual barrier for disinfection. UV disinfection has had widespread acceptance in the wastewater treatment field throughout North America.
Another disinfection technology used around the world is membrane filtration. Membrane-based water filtration technology has been used historically for desalination of brackish waters. However, it is also effective in trapping microorganisms in drinking water. Membranes act as a physical barrier filtering out contaminants, parasites and bacteria. Slight suction draws pure water through each thin, hollow fibre membrane strand.
Europeans do not rely on chlorine or other chemicals to disinfect their drinking water. Water experts have devised ways to reduce the threat of waterborne diseases by eliminating the organic food sources for bacteria and viruses to grow. It involves the removal of nutrients that feed microorganisms through sand or carbon filtration followed by ultraviolet light as the primary disinfectant. UV has been used as the primary disinfectant in Europe for over 20 years. The very first installation of UV disinfection was in Paris France in 1910. Over 400 larger municipalities in Europe rely on UV disinfection for their drinking water protection including Helsinki Finland, Milan Italy, and Motala Sweden
Ozone has also been used for several decades in Europe for taste and odour control, colour removal as well as disinfection. Ozone acts as an excellent disinfectant; it produces no chlorinated byproducts and is effective against Cryptosporidium and Giardia. Ozone does produce other disinfection by-products including ketones, aldehydes and bromate. These can be removed through a filtration process.