Task 1
Microorganism/ contaminants in water before treatment Background Information Chemicals added during treatment Background Information
Coliforms They are a broad class of bacteria found in our environment, including the faeces of warm blooded mammals.
If coliforms are found in drinking water they can be an indicator for dangerous disease causing organism.
Coliforms are often used as an indicator as they are often associated with sources of water borne pathogens that contaminate the water. Chlorine Chlorine is an irritating, greenish-yellow gas. It is highly reactive, i.e. it can easily react with nearly all other elements. It is usually produced by the separation of sodium chloride using electrolysis. It is also widely used to disinfect water. However, chlorine can be potentially dangerous. The chlorine added into water can react with other naturally occurring elements in the water and create toxins known as THMs. THMs have been linked to a wide range of illnesses ranging from asthma and eczema to bladder cancer and heart disease.
Cryptosporidium Genus of protozoans which can cause gastrointestinal illnesses such as diarrhoea.
They are also highly resistant to chlorine treatments, but with high enough concentrations and enough time they can be killed off.
People who have a high risk of exposed to the disease include, People who swim regularly in pools with insufficient sanitation (Certain strains of Cryptosporidium are chlorine-resistant)
• Child-care workers
• Parents of infected children
• People who take care of other people with cryptosporidiosis
• Backpackers, hikers, and campers who drink unfiltered, untreated water
• People, including swimmers, who swallow water from contaminated sources
• People who handle infected cattle
• People exposed to human faeces through sexual contact Fluorine Fluorine combines readily with nearly all the other elements, except the noble gases, to form fluorides. In some countries, fluoride is added to the drinking water as a preventive measure against tooth decay.
Fluorine is often used to produce the element uranium. FCHCs (which contain fluorine are used in refrigeration applications. Fluorine is used to produce many chemicals, including several high-temperature plastics.
Sodium fluoride in drinking water at the level of 2 ppm may cause mottled enamel in teeth, skeletal fluorosis, and may be associated with cancer and other diseases. However, topically applied fluoride (toothpaste, dental rinses) has been shown to help reduce dental caries.

Giardia A genus of anaerobic flagellated protozoan parasites. They live in the intestines of infected humans or other infected animals. It causes gastrointestinal diseases. The symptoms of Giardia, which may begin to appear 2 days after infection, include violent diarrhoea, excess gas, stomach or abdominal cramps, upset stomach, and nausea.
Turbidity • It is muddiness created by stirring up sediment or having foreign particles suspended. It can be caused by a variety of factors such as growth of phytoplankton, construction, mining, agriculture, areas prone to high bank erosion and urbanised areas.
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