AWWA JAW49826

A Langmuir model provides the best available prediction of full-scale removal of total organic carbon (TOC) during enhanced coagulation. Because jar tests allow more transfer of carbon dioxide gas than treatment plants, the model can even correct certain errors arising during such tests. When the model was adapted to predicting TOC removal in two raw water sources mixed together in different proportions, standard error was only 0.15 mg/L for two years of jar-test data at one utility. Case studies of 27 full-scale utilities showed accurate prediction of TOC removal by coagulation: at a range of utilities using alum, ferric, or polyaluminum chloride coagulants; over long time periods without a need for frequent recalibration; with use of a predicted rather than measured coagulation pH; and, for two raw water sources mixed in various proportions. Includes 18 references, tables, figures.