Date
Tuesday, September 10, 2024
Time
9:15 AM - 9:45 AM
Location Name
M103
Name
Pushing the Boundaries of Convention: Process Intensification for Achieving Nutrient Removal Limits
Track
Water Resource Recovery
Description

Nearly 15 years ago the Tennessee Department of Environment and Conservation (TDEC) issued a workplan to develop nutrient criteria in response to a US EPA mandate. Since then water quality and effluent discharge standards have been developed. Today many facilities are watching and waiting to see what nutrient limits are going to be issued by TDEC in their next NPDES discharge permit cycle. Generally, the major cities, nearly all of which are on located on major rivers, are not looking at strict limits, whereas the smaller communities located on smaller tributaries are likely to receive the most stringent limits. Conventional strategies to meet future BNR limits in existing plants likely require the installation of additional tankage for unaerated zones to create anoxic conditions (for denitrification) and/or anaerobic conditions (for biological phosphorus removal). Recently, process intensification technologies have entered the market which have been shown to better utilize existing tankage and potentially reduce costly construction activities. This presentation will review established processes such as Integrated Fixed Film Activated Sludge (IFAS) and Membrane Bioreactor (MBR) as well as the most recent process intensification options on the market such as Membrane Aerated Biofilm Reactors (MABR), Aerobic Granular Sludge (AGS) and Mobile Organic Biofilm (MOB). MBR systems are well known that replace conventional solids sedimentation with membranes which allow for much higher concentrations (8,000-10,000 mg/L MBR vs 3,000-4,000 mg/L) as separation limitations are eliminated via the membrane barrier and lower tankage needs thereby resulting in intensification. Technologies like IFAS, MABR, AGS, and MOB all use an attached biofilm that augment a typical activated sludge flocculant MLSS to increase the total amount of biomass for treatment thereby intensifying the system. That extra biomass generally allows for a higher overall treatment capacity and/or more advanced treatment (e.g. BNR) in existing tankage. Finally, an often-overlooked option exists in Natural Treatment Systems (NTS) that avoids upgrades in the existing system and instead uses a tertiary wetland for polishing treatment. While this option requires a large amount of land to be available, the technology has been shown to reduce nutrients to near background levels allowing facilities to meet even the most stringent compliance limits of technology limits. An overview of when each of these technologies may be favorable will be presented as well as the driving design criteria and rule-of-thumb cost metrics. High level case studies will also be presented to illustrate full-scale adaptation.