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Water treatment options

609 bytes added, 01:46, 30 March 2009
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Turbidity - the cloudiness of the water
NTU - a measure of turbidity ==Intake Design==
One of the most often neglected elements in the water treatment system is the intake. The intake must be diesigned to limit the amount of dirt and debris taken into the system to reduce problems downstream.
====Sedimentation====
The easiest way to remove suspended solids is through sedimentation.If it is possible to let the water sit for a period of time, or pass slowly through a tank, heavier particles can settle out. (See {{WP|Sedimentation (water treatment)}}.) Also, if the sedimentation period lasts days to weeks, sedimentation can also have the effect of killing off bacteria. If the water is relatively clear, this step may not be important. Or if the water is turbid (cloudy) but the solids do not settle out easily, this step may be of little use. A simple test of the efficacy of sedimentation involves, taking a jar of the water and allowing it to sit after being mixed. If the {{WP|supernatent} water is less than 5NTU after 6-8 hours, then either filtration or coagulation must be employed.  INSERT SOME METHOD FOR DETERMINGING SEDIMENTATION TANK SIZE AND CONTACT TIME When designing sedimentation tanks, special care should be taken to ensure that inlets and outlets produce minimal disturbance.
====Coagulation and Flocculation====
*Chlorine or iodine.
 ==Removing arsenic==
In cases of arsenic contamination the {{WP|Sono arsenic filter}} should be considered. As it contains sand and charcoal, the filter should also be effective against other impurities. Arsenic containing water is typically groundwater and thus should not usually contain significant pathogens. Iron and manganese oxides can offer a cheap method of removing low levels of arsenic from water. The oxides are able to adsorb arsenic ions and remove them from solution.
== References ==
http://www.oxfam.org.uk/resources/downloads/emerg_manuals/water_treatment.pdf
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