COMBINING UV AND FREE CHLORINE FOR DISINFECTION: EFFECTS OF OPERATING CONDITIONS

摘要

Proper disinfection is vital to ensuring that wastewater effluents are safe for reuse. Most wastewater treatment plants currently disinfect with chlorine or ultraviolet (UV) radiation. Combining the two disinfectants may provide advantages such as improved reliability and operational flexibility. This work focused on the effects of operating conditions on the performance of the combined UV/chlorine process. Relative chlorine/UV dose and disinfectant order both affected the combined UV/free chlorine process. Dosing chlorine first or simultaneously with UV provided synergies in some cases, and increasing the relative chlorine dose improved disinfection and resulted in greater transformation of trace organic constituents (TrOCs), but also higher levels of disinfection byproducts (DBPs). "Optimum" operating conditions are likely to be site-specific to each facility, due to variations in disinfection requirements, concentration limits on DBPs, plant configurations, and costs for energy and chemicals.