Difference between revisions of "Chemical Coagulants"

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==Costs==
 
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Revision as of 23:22, 15 May 2012

Alum block. Photo: www.cdc.org

The sedimentation process can be quickened by adding coagulants to the water. Chemical coagulants are commonly used in community drinking water treatment systems though some application in household water treatment occurs. The main chemicals used for coagulation are aluminium sulphate (alum), polyaluminium chloride (also known as PAC or liquid alum), alum potash, and iron salts (ferric sulphate or ferric chloride). Lime (Ca(OH2)), lime soda ash (Na2CO3) and caustic soda (NaOH) are sometimes used to "soften" water, usually ground water, by precipitating calcium, magnesium, iron, manganese and other minerals that contribute to hardness.

Suitable conditions

Construction, operations and maintenance

Users follow the manufacturer’s instructions and add the prepared dose of coagulant to the water. The water is then stirred for a few minutes to help create flocs. The flocs can be settled out or removed by filtration.

Costs

Capital Cost Operating Cost Replacement Cost
US$0 US$9-91/year1 US$0

Field experiences

Acknowledgements