Drinking water treatment residuals (DWTRs) contain sand, clays, organic matter, and oxy-hydroxides of Fe and/or Al formed after the addition of chemicals like ferric chloride, aluminum chloride, polyaluminum chloride, and ferric sulfate during the coagulation-flocculation step in drinking water treatment. The surface chemical reactivity of freshly precipitated Fe and Al phases in DWTRs may represent an untapped resource if applied within reuse strategies (e.g., metal & nutrient immobilization). They may also become an environmental concern when discharged to surface waters, especially for watersheds where drinking water sources are enriched with metals and metalloids. This work uses hydrochemical parameters of raw waters used for drinking water production to assess whether DWTRs are an opportunity or a liability. A model that estimates production and physicochemical characteristics of DWTRs was proposed considering water geochemistry, drinking water standards, and the production of drinking water facilities across different geochemical environments in Chile, an Andean country with diverse water qualities. The information was integrated by indexes that discriminated when DWTRs may become an attractive alternative for reuse and when their interaction with receptor environments should be further scrutinized. Overall, the application of this simple approach allows identifying challenges, opportunities, and scenarios for DWTRs management considering local geochemistry.

A simple geochemical approach to identify scenarios for managing drinking water treatment residuals (DWTRs)

ACS Spring Meeting 2021

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