Treating CSOs Using Chemically Enhanced Primary Treatment With and Without Lamella Plates–How Well Does it Work?

King County's regional wastewater services plan (RWSP) called for development of satellite combined sewer overflow (CSO) treatment facilities. The 5-year CSO program update from 2005 recommended that King County continue to monitor high rate treatment for potential consideration for CSOs at the King/Kingdome, Hanford/Lander, Brandon and Michigan sites. Likewise, the 2006 CSO Control Program Review recommended that pilot tests “be conducted on promising new CSO treatment technologies.” The purpose of this project was to develop and implement a pilot test program to evaluate and compare potential CSO treatment technologies such as the use of lamella plates, assess whether or not the technologies are effective in meeting King County performance goals in full-scale CSO treatment facilities, and make recommendations based on that assessment.This paper reports on the combination of chemically enhanced primary treatment (CEPT) in conjunction with the use of lamella plates (CEPT + Plates) for remote satellite CSO treatment systems. The main goal of using CEPT + Plates was to reduce the process footprint therefore lowering capital costs using a non-proprietary process.