Two Year Case Study of Integrated Fixed Film Activated Sludge (IFAS) at Broomfield, CO WWTP

The City & County of Broomfield wastewater treatment plant secondary treatment processes were upgraded to a new biological nutrient removal process described as Integrated Fixed Film Activated Sludge (IFAS) back in 2003 using a moving bed plastic carrier element to help grow the biomass. This allows the existing aerobic reactors to maintain nitrification during year round operation while still operating near conventional activated sludge solids retention times (SRT) one would find in just carbonaceous treatment plants. The upgraded IFAS system includes anaerobic and anoxic reactors to help meet new effluent Total Nitrogen and Total Phosphorus limits. The performance of the entire system since July 2003 averaged effluent concentrations of 2.4 mg/L for BOD, 4.2 mg/L for TSS, 0.3 mg/L for NH3-N, 8.3 mg/L for NOx-N and 1.25 mg/L for TP while operationally during this period of time the aerobic suspended MLSS SRT averaged 4 days, the MLSS concentration averaged 1,718 mg/L and the SVI averaged 120 mL/L. The plant has operated with one set point for both the RAS and WAS rates for months at a time while meeting these very consistent effluent results.