Design of arsenic removal plant by coagulation, sedimentation
Design of arsenic removal plant by coagulation, sedimentation
Design of arsenic removal plant by coagulation, sedimentation
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ARSENIC REMOVAL PROCESSES<br />
• Arsenic oxidation states in natural<br />
waters: inorganic form as<br />
oxyanions <strong>of</strong> trivalent arsenite (As<br />
(III)) or pentavalent arsenate (As<br />
(V))<br />
• Redox potential (Eh) and pH are<br />
the most important chemical<br />
factors controlling the <strong>arsenic</strong><br />
speciation<br />
• Removal efficiency for As (V) is<br />
usually better than <strong>removal</strong> for As<br />
(III)<br />
• So, reduced inorganic As (III)<br />
should be oxidized to As (V) to<br />
improve its <strong>removal</strong> Eh-pH diagram for aqueous As species in<br />
the system As–O 2–H 2O at 25 C and 1 bar<br />
Oxidation step<br />
As(III)<br />
uncharged<br />
total pressure (Smedley and Kinniburg,<br />
2002)
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