AWWA JAW64705

Gas bubbles forming during conventional water treatment can be problematic for utilities, reducing operating efficiency and interfering with all aspects of treatment. Problems associated with bubble formation include floating floc during coagulation and sedimentation, head loss in media filters and upflow clarifiers, erratic particle counts, and erroneous turbidity measurements. This research found that these phenomena are fairly commonplace yet often unrecognized or overlooked by the drinking water industry. More significantly, engineers may not factor water supersaturation into treatment plant design, leading to consequences ranging from minor nuisances to complete failure of new full-scale facilities. Dissolved gas supersaturation was investigated at several utilities. The case studies highlighted here and the analyses of bubble formation will help water providers in identifying, confirming, and mitigating the adverse effects of bubble formation. In addition, the authors suggest parameters that should be considered in the design of a new treatment plant or modification of an existing facility. Includes 6 references, tables, figures.