THE DISINFECTION POTENTIAL OF TWO ENHANCED PRIMARY TREATMENT TECHNOLOGIES TREATING WET WEATHER FLOWS AT EDMONTON, GOLD BAR WWTP

This paper presents the results from a pilot study that evaluated two chemically enhanced primary treatment (EPT) technologies for the treatment of wet weather flows at the Gold Bar WWTP. The EPT technologies evaluated were ballasted flocculation and inclined plate settling. EPT in the existing clarifiers was also given limited testing, however that test work is not part of this paper.The pilot study is a continuation of the City's Combined Sewer Overflow (CSO) Control Strategy. That strategy includes the use of EPT followed by the disinfection of CSO received as wet weather flow (WWF) at the Gold Bar Wastewater Treatment Plant (WWTP). Full secondary treatment is provided for the first 420 MLD received at the plant. Enhanced primary treatment is being considered for the next 600 MLD. Based on the results of the pilot study, the City was able to make a rational judgement concerning the most appropriate EPT and disinfection technologies to implement for the treatment of wet weather flows.This pilot test program is unique in that the EPT performance criterion being tested and evaluated is ultraviolet transmissivity (%UVT), in addition to the removal of total suspended solids (TSS).