Biofilm Performance of High Surface Area Density Vertical-Flow Structured Sheet Media for IFAS and Fixed Bed Biofilm Reactor (FBBR) Applications

PVC structured sheet media has recently received increasing attention as a cost-effective alternative for IFAS applications. However, the impact of its type and configuration on the process performance has been less studied. This study was conducted to evaluate the biofilm performance of a high surface area density Vertical-Flow (VF) media in conjunction with a proprietary distribution media for IFAS and Fixed-Bed Biofilm reactor (FBBR) applications.The study demonstrated that the VF media combined with the proprietary distribution media is capable of achieving complete nitrification and high-rate BOD removal for both IFAS and FBBR applications. As an essential element in the VF media system, the distribution media not only maximized the air and wastewater distribution over the entire surface area of the media, but also optimized the airlift pumping through the VF media for sufficient mixing and effective biomass control. Favorable kinetic rates (e.g. tertiary ammonia rates up to 1.4 g NH3−N/m2-day at 15°C, SCOD removal rate of 30 g SCOD/m2-day at a SCOD load of 45 g SCOD/m2-day, and predenitrification rates of 1.0-2.0 g NO3−N/m2-day) have been consistently observed in the VF structured sheet media system, mainly due to the intimate contact between thin biofilm and substrates/oxygen as promoted by the dedicated aeration associated with the media towers.Compared to cross-flow (CF) media, the VF media provides an enhanced air/wastewater distribution and also offers significantly higher treatment capacity per unit media volume due to the increased specific surface area (e.g. 96 ft2/ft3 or 315 m2/m3) and comparable kinetic rates (e.g. concurrent 0.65 and 5.5 g/m2-day ammonia and soluble COD removal, respectively) in the IFAS application. Comparison of the VF media with other media systems (e.g. free-floating media and fabric media) is also discussed in the paper.