Eight Years of Successful Cold Weather Nitrification with Integrated Fixed-Film/Activated Sludge

Abstract

In 1997 the North Buffalo Water Reclamation Facility in the City of Greensboro could not consistently meet their winter permit limit for ammonia-nitrogen. They decided to try a full scale demonstration of Integrated Fixed-Film/Activated Sludge (IFAS) using a new fabric media called BioWeb. IFAS technology adds a high surface area synthetic media directly into the aeration basins of a conventional activated sludge plant. The additional media yields an attached growth bacterial population that increases the total biomass in the system without overloading the clarifiers. This can be extremely useful and cost-effective for increasing capacity or for increasing treatment levels at existing plants. North Buffalo added the media to one of their four parallel aeration flow trains and have complied with their ammonia-nitrogen permit ever since.

Side-by-Side Comparison of IFAS and CAS Processes at Demonstration Scale at the Lakeview WWTP

“…Interconnections between trains are a frequent limitation to conducting valid process comparison studies at full scale (e.g. Yerrell et al (2001), Hubbell et al (2006)). Retrofit of the IFFAS train.…”

“…• It allows the total biomass to increase in the biological tank without increasing the solids loading rate (SLR) on the final clarifier, 2003)) while others were not able to establish a difference (Hubbell et al (2006)). …”

“…(ii) Only one other full scale IFFAS case study with floating plastic carriers is reported at a large WWTP in North America (Johnson and Haegh (2005), Rutt et al (2006)). Other published case studies were either at a much smaller scale (Jones et al (1999)), or located on a different continent (Yerrell et al (2001)), or using different IFFAS media such as floating sponges (Federico et al (2002); Masterson et al (2004)) or fixed media (Psaltakis et al (2003); Hubbell et al (2006)). …”

Comparison of Performance and Operation of Side‐By‐Side Integrated Fixed‐Film and Conventional Activated Sludge Processes at Demonstration Scale

“…Before modifications necessary for the IFFAS trial, the two trains were identical and interconnected through their return activated sludge lines. The connections were eliminated, because they are a limitation to conducting a valid process comparison (Hubbell et al, 2006;Yerrell et al, 2001). During the study, the operators strived to operate both trains identically, in terms of loading and suspended biomass concentration, so the performance of the two processes could be compared directly.…”

“…Other full-scale studies with similar IFFAS carriers examined plants that were either much smaller (Jones et al, 1999) or located outside North America (Yerrell et al, 2001). The remaining North American IFFAS case studies deal with different media, such as floating sponges (Federico et al, 2002;Masterson et al, 2004) or fixed media (Hubbell et al, 2006;Psaltakis et al, 2003).…”