[Evaluation of powdered activated carbon efficiency in removal of dissolved organic carbon in water treatment]

ABSTRACT

Powdered Activated-carbon is known as a suitable absorbent for organic materials. The aim of this research is evaluation of Powdered Activated-Carbon [PAC] efficiency in removal of Dissolved Organic Carbon [DOC] in water treatment in Isfahan. The increase of PAC for DOC reduction has done in three paths in the Isfahan water treatment plant [WTP]. These paths including 1] Intake up to entrance of WTP 2] Intake to exit of WTP 3] Between entrance and exit of waterworks. The paths were simulated by the Jar test system. Then DOC and UV[254] absorption were analyzed and SUVA parameter for samples and activated-carbon adsorption isotherm was calculated. The injected PAC doses of 20,40,60,80 and 100 mg/l caused decreasing in DOC and UV [254] absorption in every sample in all paths. The average of this decrease, from intake to WTP.s exit [second path] was the greatest 69.8 +/- 3.9% and the common WTP process had capability of removing 35% of DOC. The first path also showed that PAC can reduce 33 +/- 2% DOC of raw water by itself. Activated-carbon absorption results were adhered from Freundlich adsorption isotherm. In the third path there was less DOC removal efficiency than excepted when Activated-Carbon injected in rapid mixed basin with coagulant. Powdered activated carbon porosity reduction due to effect of coagulant can be the reason for this issue. Also according to different paths, the point of intake is more suitable for powdered activated carbon addition