MODIFIED VORTEX SEPARATOR AND UV DISINFECTION FOR COMBINED SEWER OVERFLOW TREATMENT

This paper presents the results of a study to evaluate the efficiency of a modified vortex separator (MVS) and an ultraviolet (UV) disinfect ion unit for direct treatment of combined sewer overflows (CSOs). The MVS included dissolved air and coagulant addition. The effluent from t he vortex separator was disinfected continuously using UV light. Bench -scale tests were performed on CSO samples to screen various coagulant s and operating pressures for dissolved air. Field tests were performe d at the CSO pilot facility where simulated as well as actual storm-ge nerated overflow events were studied. Performance comparisons between the MVS and other CSO treatment technologies are presented. Results in dicate that the MVS achieves pollutant removals superior to convention al sedimentation for the same surface loading rates, or can be hydraul ically loaded several times higher than sedimentation to achieve the s ame results. The results also indicate that the MVS significantly impr oved solids concentration capability when compared to the conventional operation of the vortex separator. UV disinfection performance was de pendent on TSS removal and showed promise for full scale implementatio n when combined with MVS treatment. This project was sponsored by the Water Environment Research Foundation and was a collaborative effort b etween ten participating organizations including the US Environmental Protection Agency (EPA), municipalities, consulting firms and equipmen t manufacturers.