STACS · Stability of sorbed arsenic by pipe scales and biofilms in drinking water distribution systems

The notion that inorganic contaminants behave conservatively between the point of entry (after conventional or reverse osmosis-desalination water treatment) and the point of use by consumers is currently being re-visited by EU regulatory agencies. One of the main reasons deteriorating the quality of home tap water is related to the accumulation of contaminants, such as arsenic (As) to scale and biofilm growth in drinking water pipe walls. The central hypothesis of the proposed research is that changes in solution chemistry of the finished water adversely influences the stability of sorbed As by pipe scales. Our long-range goal is to provide mechanistic insight to critical unanswered questions related to the stability of sorbed As by pipe scales and biofilm conglomerates (PSBC) in drinking water distribution systems, thereby eliminating health risk associated with human ingestion of As-contaminated water. If we identify the factors influencing the stability of sorbed As, then we could formulate guidelines to minimize the health risk from the release of sorbed As into the finished water. The stability of the pipe scales (amorphous masses of corrosion by-products mixed with biofilms) may be undermined by the presence of disinfection by-products, ii) to the nonconventional corrosivity of desalinated water or iii) by changes in bulk solution chemical properties and SBC surface chemical parameters. Knowledge obtained from this project will, i) minimize the human health risk associated with the presence of toxic As in the finished water; and ii) formulate specific guidelines for the effective decontamination of SBC in drinking water pipes. This IRG project will prove most useful to the recently reintegrated coordinator towards developing his Water and Health research program in the Eastern Mediterranean region.