AWWA WQTC71601

This paper addresses changes of lead release and colloidal mobilization from lead dioxide (PbO₂) associated with the introduction of chloramine, presence of natural organic matter (NOM) and addition of phosphate corrosion inhibitors in drinking water distribution systems. Experimental work showed that when NOM was present, the surface potential of PbO₂ exhibited a prominent negative shift and colloidal mobilization of Pb(IV) particles became prominent. The presence of chloramine did not significantly change these effects of NOM on the colloidal behavior of PbO₂. Effects of phosphate corrosion inhibitors on colloidal lead release were examined. It was determined that the formation of nano particles of hydroxypyromorphite Pb₅(PO₄)₃OH greatly decreased lead release. Includes 9 references, figures.