AWWA WQTC55133

Jar tests were conducted to evaluate enhanced coagulation in California State project water (SPW), Colorado River water (CRW), and varying blends. During the six months of testing, SPW showed consistent amenability to enhanced coagulation treatment (maximum total organic carbon [TOC] removed> or equal to 0.3 mg per 10 mg alum added) while CRW was generally not amenable. A previously developed coagulation model was used to predict the treatability of intermediate blends and to establish a critical blend threshold that divides amenable and non amenable waters. The model was calibrated for each source water using TOC removal data measured in monthly jar tests. Predictions of TOC removed as a function of alum added were then made for intermediate blends. In general, model-predicted TOC removal agreed with measured data; however, at low coagulant doses and when poor flocculation and settling occurred, the model over-predicted TOC removal. The alum-adsorbable TOC varied by 50 percent in SPW and remained relatively constant in CRW. Includes 8 references, table, figures.