ABSTRACT

578Various conventional and innovative physiochemical, biological, and disinfection technologies for treating combined sewer overflow (CSO) and wastewater are reviewed and discussed. Special emphasis is placed on Introduction and investigation of innovative dissolved air flotation (DAF) technology and DAF-filtration (DAFF) technology. The cost-effectiveness of stormwater quality control equipment (offline storage-release systems, swirl concentrators, screen, sedimentation basins, disinfection equipment, etc.), best management practices (BMP), and control costs are presented. A case history involving the removal of soluble arsenic (+5) from an oil company’s storm run-off water by DAF, DAFF, granular activated carbon adsorption (GAC), and ion exchange (IX) processes was introduced in detail for the purpose of illustration. The best pretreatment unit was DAFF clarifier consisting of both flotation and filtration. DAFF consistently removed over 90% of arsenic, turbidity, and color, and over 50% of chemical oxygen demand (COD) and oil and grease. Using either DAFF or DAF for pretreatment, and then using either GAC or IX for second-stage treatment, the soluble arsenic in the storm water can be totally removed. The waste sludge generated from the DAF or DAFF cell did not possess any characteristic of extraction procedure toxicity (EPT) and thus was not hazardous. The dewatered sludge met the New Jersey Department of Environmental Protection’s limits on cadmium, chromium, copper, nickel, lead, and zinc for ultimate land application.