Demonstration of innovative MABR low-energy nutrient removal technology at Chicago MWRD

Abstract

An innovative MABR (membrane-aerated biofilm reactor) membrane technology was demonstrated at the O'Brien Water Reclamation Plant (OWRP) of the Metropolitan Water Reclamation District of Greater Chicago (Chicago MWRD). The demonstration unit was equipped with one full-scale membrane cassette. The technology was evaluated for its potential to improve performance for total suspended solids (TSS) and ammonia removal during stressed conditions (specifically cold temperature peak flow periods) and to meet future effluent phosphorous limits. Over a period of 9 months, the MABR oxygen transfer rate was stable and ranged between 8 and 12 g-O2/d/m2 of membrane surface area. The nitrification rate varied between 0.5 and 2.5 g-N/d/m2 and was affected primarily by the ammonia loading rate and the feed carbon to nitrogen ratio. Most of the oxygen transferred was accounted for by nitrification. The MABR hybrid process enables important process improvements while reducing plant energy consumption.

Recent progress using membrane aerated biofilm reactors for wastewater treatment

“…Higher average OTRs, which translate into higher average contaminant removal fluxes and treatment capacity, are usually achieved in the flow-through rather than dead-end operation (Syron & Casey 2008b). Therefore, the flow-through operation is preferred in commercial applications (Kunetz et al 2016;Peeters et al 2017aPeeters et al , 2017bUnderwood et al 2018;Guglielmi et al 2020). The higher average OTRs in flow-through MABRs can be explained by the higher oxygen partial pressure, which allows uniform intra-membrane oxygen velocities in the membrane lumens and relatively constant biofilm thickness.…”

“…Houweling & Daigger (2019) described two methods: (1) the pressure-based model and (2) the exhaust oxygen-based model. (Peeters et al 2017a(Peeters et al , 2017b) used a version of the pressure-based model to account for variations in the oxygen partial pressure along the length of the MABR fiber. Guglielmi et al (2020) developed an exhaust oxygen-based model to monitor the key performance indicator OTR, which correlated with the ammonia removal rate in the biofilm.…”

“…MABRs enable high NRs in the biofilm, which is beneficial for plants to achieve effective ammonia removal. A pilot plant in Ontario, Canada using the Zeelung Hybrid MABR/AS process reported an NR of 2.6 g N/m 2 -d in the biofilm (Peeters et al 2017a(Peeters et al , 2017b. Similarly, the fullscale spirally-wound hybrid MABR achieved an average NR of 3.1 g N/m 2 -d in the biofilm (Nathan et al 2020).…”

“…Incorporating MABRs in the unaerated zones creates an aerobic condition in the biofilm for nitrification, and the produced nitrate is released into the anoxic bulk liquid where the suspended biomass performs denitrification for complete nitrogen removal (Houweling et al 2017). The SND pathway has been well-demonstrated in pilot-scale testing (Kunetz et al 2016;Peeters et al 2017aPeeters et al , 2017b and full-scale applications (Houweling et al 2017;Underwood et al 2018;Nathan et al 2020). Nathan et al (2020) reported that 97% of the ammonia removed in the MABR zone was denitrified in the same tank.…”

“…The advantages of MABR technology include high effluent quality (Sunner et al 2018;Sathyamoorthy et al 2019), high carbon processing efficiency (Houweling & Daigger 2019;Mehrabi et al 2020), up to 100% oxygen transfer efficiency (OTE) (Heffernan et al 2017;Bicudo et al 2019), and compact reactor footprints (Sunner et al 2018). Compared to other biofilm reactors, like Moving Bed Biofilm Reactor (MBBR) with a typical designed nitrification rate (NR) of 0.5 g N/m 2 -d, MABRs achieve greatly improved NRs of 1.0-3.0 g N/m 2 -d (Côté et al 2015;Kunetz et al 2016;Peeters et al 2017aPeeters et al , 2017bUnderwood et al 2018;Nathan et al 2020). The greatly improved NRs result from high oxygen transfer rates (OTRs) in MABRs.…”