Development of IFAS Design Parameters from the Full-Scaledemonstration at the TZ Osborne WRF in Greensboro, NC

The City of Greensboro, NC contracted with CDM and Hazen and Sawyer to evaluate options for upgrade of their two water reclamation facilities (WRFs), TZ Osborne (TZO-40 MGD capacity) and North Buffalo Creek (NBC - 16 MGD capacity) to meet future capacity and nutrient removal needs. Because both plants discharge to the Jordan Lake Reservoir, a state designated impaired water due to algae, the City will need to meet stringent nitrogen and phosphorus limits by 2016.During the screening of alternatives, integrated fixed film activated sludge (IFAS) was identified as a technology that could offer significant cost savings to the City relative to a conventional 5-stage BNR system. In order to gain a more complete understanding of IFAS technology and to verify the volume and cost savings possible from the technology, the City made the financial commitment to construct a full-scale IFAS demonstration facility at TZO and to operate the facility for a period of one year. In addition, a substantial sampling effort was undertaken by the City which included sampling at a significant number of locations multiple times each week, weekly profile sampling, and periodic batch testing.The demonstration was operated from April 1, 2008 through April 1, 2009. In addition to gaining a considerable amount of operational experience with IFAS systems, a significant amount of data was collected and compiled. This information was used to establish design parameters to be applied to the potential full-scale design of an IFAS system. These full-scale design parameters are being used to establish preliminary costs for final comparison with a conventional 5-stage BNR system. This paper includes discussion of the conclusions and observations drawn from the pilot data, including process design parameters and practical operation and maintenance considerations learned from the demonstration.