SELECTOR TECHNOLOGY SAVES PHILADELPHIA 25,000,000 IN RENEWAL OF SECONDARY TREATMENT PROCESS

A team approach using plant staff expertise, process theory, and consultant's expertise, resulted in the Philadelphia Water Department (Department) saving over 25,000,000 in the renewal of the secondary process at the 210 mgd (795,000 m3/d) Northeast Water Pollution Control Plant (NEWPCP). The facility was expanded in the 1980's to a SURFACT® process due to limited aeration and final clarifier tankage. Because of structural failure of the rotating biological contactor (RBCs), alternative treatment methods were considered in lieu of replacing the RBC units. The use of the latest combination of proven process technologies (sludge reaeration, stepfeed, selectors), and a step-by-step implementation process allowed the plant to perform full plant testing with no capital expenditures versus partitioning a portion of the plant to demonstrate the new process modifications. This approach saved 500,000 and nine months in construction of demonstration facilities.The full plant-testing program was successful due to the cooperative approach of plant staff and consultant in changing operating strategies during the course of testing. Through a pro-active approach of every shift supervisor, the plant continued to achieve permit limits under all conditions (NEWPCP continued to receive AMSA's Gold Awards before, during, and after the study). In fact the plant was recently honored in May 2002 by AMSA with a platinum award for 5 years of perfect compliance. This paper will describe how new wet weather treatment operating strategies are successfully allowing this facility with short aeration time and limited final settling tank area to successfully meet discharge limits even during wet weather events.The collaborative approach of “in-house” and consultant expertise in sequentially implementing new technologies to replace the existing secondary process at the NEWPCP has resulted in large saving for the City of Philadelphia. Key to this success was the support of Department management and pro-active work by plant operating and maintenance staff.