AWWA ACE70744

This powerpoint presentation begins by providing a brief overview of West Basin Municipal Water District (WBMWD). The executive summary states that previous work at WBMWD showed that chloraminating seawater made a "free" residual that oxidized the reverse osmosis (RO) membranes. This work confirmed that both the amperometric and DPD methods for chlorine report a "free" residual when conventional chloramination methods are applied in seawater, and this work confirmed that the residual present is monobromamine. This work also showed that when pre-formed chloramines are added to seawater, no bromamine is formed and neither the amperometric or DPD methods report a "free" residual. With the support of the WateReuse Foundation, WBMWD is now doing pilot studies to further examine the idea. Study hypothesis states that preformed chloramines can be used, and the absence of "free" chlorine can be tentative evidence that monobromamine is absent. Project tasks included: manufacturing chloramines; selecting residual measurement method and characterizing its response; and, confirming that "free chlorine" is not formed. Includes figures.