Manzano, Josep

Josep is a seasoned Chemical Engineer with a Master’s degree in Environmental Engineering and Product Management. With over thirteen years of...

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Description: Installation and Start-up of First 'Drop In' MABR System for Process Intensification...

Installation and Start-up of First 'Drop In' MABR System for Process Intensification (UK)

Abstract

Spernal Wastewater Treatment Plant (WWTP) processes wastewater from the surrounding catchment area as well as excess biosolids from satellite plants. Consistently seeking to optimise treatment plant process effectiveness and efficiency, and aware that biosolid loadings will increase in the future, Severn Trent considered solutions that could easily increase the nitrification capacity of a typical activated sludge plant. OxyMem was considered as it promised to upgrade without needing to take the existing tanks off-line. Thus, ten OxyMem membrane aerated biofilm reactor (MABR) modules were installed at Severn Trent's Redditch Spernal site, which became the largest MABR system in the UK. The DuPont OxyMem MABR modules were simply lowered into the anoxic zone of lane 3 over a two-day period and quickly boosted the nitrification capacity of the current process. An additional 43 kgN/d was removed in lane 3, equipped with MABR, when compared to lanes 1 and 2, without MABR, - equalling 2.9 gN/m2.d on average. The best performance was observed when the influent NH4-N load to all three lanes increased to 450 kgN/d :- on this day lanes 1 and 2's effluent ammonia increased to 124 kgN/d, where lane 3 increased only to 71 kgN/d. The difference in the effluent was 53 kgN/d, showing the peak nitrification capacity of the hole hybrid MABR process or 3.6 gN/m2.d.

Spernal Wastewater Treatment Plant (WWTP) processes wastewater from the surrounding catchment area as well as excess biosolids from satellite plants. A number of considerations led Severn Trent to look for solutions that could increase the nitrification capacity of the existing activated sludge plants. Thus, ten (10) OxyMem membrane aerated biofilm reactor (MABR) modules were installed at Severn Trent’s Redditch Spernal site in Worcestershire. The DuPont OxyMem MABR modules were simply lowered into the anoxic zone and instantaneously boosted the nitrification capacity of the current process. The paper summarizies the main results obtained to date in Spernal WWTP.

SpeakerManzano, Josep

Presentation time

13:35:00

13:40:00

Session time

13:30:00

14:30:00

SessionProcess Intensification: Full-scale MABR

Session number504

TopicEnergy Production, Conservation, and Management, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Josep Manzano

Author(s)J. Manzano1; B. Heffernan1; J. McConomy1; D. Lynch1; S. Pitt2; J. Silver2;

Author affiliation(s)OxyMem Ltd, Moydrum Business Park, Athlone, Co Westmeath, IR1Severn Trent Water, Coventry, UK 2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158157

Volume / Issue

Content sourceWEFTEC

Word count14

North America's First Full-scale OxyMem-based MABR: Lessons and Performance Results

Abstract

Introduction
Membrane aerated biofilm reactor (MABR) is a process intensification technology offering benefits of increased process capacity, improved nitrification and nutrient removal performance, as well as reduced energy consumption and greenhouse gas footprint. The Regional Municipality of Waterloo (the Region) faced challenges at Elmira WWTP due to high strength industrial wastewater and high peak flows. The Region selected OxyMem's (Dupont) OxyFAS technology following a competitive equipment preselection in 2021. Eight MABR modules were retrofitted into existing unaerated zones at the head end of the two parallel bioreactors and commissioned in June 2023, making it the first full-scale OxyMem-based MABR in North America. This paper discusses performance testing, first year of operation and lessons learned during the design, construction, and commissioning phases. Thus, showcasing the challenges and opportunities that may arise when implementing a full-scale MABR system, as this emerging technology continues to gather interest across North America.

Performance Results
Fall and winter performance tests were conducted to evaluate the system's ability to achieve the designed nitrification rate (NR) of 20.3 kg N/d. The fall performance test had two sampling campaigns over two weeks, while the winter test had four sampling campaigns over the same period. NR was calculated by measuring the ammonia concentration from the mixed liquor upstream and downstream of the MABR zone. Average NR from both performance tests are shown in Figures 1 and 2.

Figure 1 and Figure 2 show that NR is higher in the morning and decreases in the afternoon. NR peaks tend to correlate with the typical ammonia loads observed in municipal wastewater diurnal profiles. The higher the influent ammonia the greater the driving force for nitrification, hence why MABRs are typically installed in the first anoxic zones in combination with suspended growth activated sludge system. This allows the MABR to target ammonia, while the activated sludge provides supplemental treatment of residual ammonia and organics. A tabulated summary of the nitrification performance from both tests are shown in Table 1. Measured Oxygen Transfer Rate (OTR) from the fall performance test was also included in the data set. Due to issues with the oxygen analyzer OTR data was not available during the winter performance test.

The MABR system at Elmira WWTP exceeded the designed NR targets in both fall and winter performance tests. Average wastewater temperatures between the two tests were 18.5 °C and 10.5 &DEG;C, respectively. Higher wastewater temperature, which leads to higher biological activity likely contributed to the higher NR observed in the fall performance test. Of note, based on the stoichiometric oxygen consumption for conventional nitrification (4.57 gO2/gN) and the measured OTR 189.65 kgO2/d, the observed oxygen demand for nitrification during the fall performance test was approximately 89%. This means that 89% of the oxygen transferred across the membrane was utilized for nitrification, the remainder 11% was likely used to oxidize other compounds such as COD and/or hydrogen sulfide.

Lessons Learned
Mixing Importance: adequate mixing ensures the even distribution of substrates and nutrients into the biofilm for optimal performance, while also preventing potential sludge accumulation within the MABR zone. Computational fluid dynamics (CFD) modelling was conducted to validate the mixer selection, identify dead zones, short circuiting and additional tank modifications required to provide even flow distribution into the cassettes.

Understanding Hydraulic Gradeline: a specific range of water surface elevations within the MABR cell must be maintained when operating OxyMem modules. A hydraulic model was developed during design and later adjusted per site conditions to confirm the MABR installation elevations and bioreactor effluent weir height adjustments.

Heat tracing: cold climate MABR applications with off-gas analysis requires heat tracing and insulation of the MABR off-gas manifold. From a design and procurement perspective, including the heat tracing and insulation as part of the vendor's scope would prompt the vendor to provide a better tailored solution to their system.

Back-flow in MABR zone: Bulk liquid density differences between the MABR zone and the downstream aerated zone caused back-flow into the MABR zone, presenting a challenge for MABR performance evaluation based on ammonia concentrations. Bulk liquid differences between zones adjacent to the MABR system should be considered along with a thorough review of plant hydraulics.

Challenges with analytical instruments: ease of operation, maintenance, and overall instrumentation reliability are critical for MABR systems, since the process is fully automated, and these instruments provide a live snapshot of the MABR performance.

Conclusions
MABR technology continues to gather interest from global utilities due to its ability to increase process treatment capacity, and ease to retrofit into existing infrastructure. The presented lessons learned throughout the design, construction, commissioning and operation phases should be taken into consideration for future MABR installations. Despite some of the challenges faced, the MABR system at Elmira WWTP has shown promising results exceeding the design NR targets as shown by the results from both performance tests.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

13:30:00

14:00:00

Session time

13:30:00

15:00:00

SessionFull-Scale MABR Successes in Performance Optimization and N2O Control

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment Technology - Secondary & Tertiary Treatment

Author(s)

Flores, Jesus, Willoughby, Adrienne, Constantine, Timothy, Manzano, Josep, Medd, Jeff

Author(s)J. Flores1, A. Willoughby1, T. Constantine1, J. Manzano2, J. Medd3

Author affiliation(s)Jacobs1, OxyMem2, Regional Municipality of Waterloo3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159907

Volume / Issue

Content sourceWEFTEC

Word count11

Description: Process Intensification with Low Apparent Sludge Age at Monkmoor STW Using Membrane...

Process Intensification with Low Apparent Sludge Age at Monkmoor STW Using Membrane Aerated Biofilm Reactor

Abstract

SUMMARY OF KEY FINDINGS
The installation of 48 OxyMem™ Membrane Aerated Biofilm Reactor (MABR) modules at Monkmoor Sewage Treatment Works (STW) in Shrewsbury demonstrated the ability of the MABR system to seamlessly retrofit an existing treatment plant to provide process intensification and in this case to manage increased flows and loads associated with population increase. The MABR system achieved ammonia removal rates of 243 kgN/d which is a nitrification rate of 3.4 gN/m2.d and increased the nitrifier aerobic sludge age to 9.2 days enabling effluent ammonia-N concentrations below 1 mg/L even in cold weather.

INTRODUCTION & OBJECTIVE
Monkmoor STW in Shrewsbury serves a population PE of 116,000, which is projected to increase to 146,000 by 2033. Prior to the MABR upgrade, the facility operated as a conventional activated sludge plant (ASP), treating a mix of domestic and trade waste, including landfill leachate, meat processing wastewater, sludge imports and wastewater from other traders. The site comprises an inlet works, four storm tanks, four primary settlement tanks, four ASP lanes, four final settlement tanks, and a sludge treatment facility for digesting both indigenous and imported sludge from nearby locations.

A target removal of 162 kg of ammonia-nitrogen (N-NH3) per day was set for the MABR system, when installed in the anoxic zones. To achieve this, 48 OxyMem™ MABR units were installed in April 2024. At the time of install, the Monkmoor MABR IFAS system was the largest MABR system in the UK and can be considered the first large-scale commercial installation within the UK.

Performance testing was carried out in December 2024, to coincide with the start of the cold weather operation.

RESULTS AND DISCUSSION
Installation challenge
A key advantage of the MABR system is the potential to drop MABR modules into existing tanks without draining the tanks or stopping the flow, meaning the MABR upgrade can be non-disruptive. The main challenge was the presence of walkways on top of some of the walls required to support the MABR modules. It was not practical to remove these walkways for the installation of the MABR support beams and instead a cantilevered steel structure was fabricated that slotted in underneath the existing walkways (see Figure 2 and Figure 3).

Nitrification rates
The average target ammonia removal load was 161.6 kgN/d. The mass of ammonia removed was calculated by measuring the concentration change before and after the modules and multiplying it by the total flow through the ASP. The measured load and removal is shown in Figure 4. During the sampling campaign, the ammonia load was 1239 kgN/d, 1.28 times the design load and removal was 243 kgN/d, which was 1.5 times the design target.

#The nitrification rate during this period varied between 1.2 and 6.6 gN/m2.d (Figure 5). The MABR performance is a diffusion-driven process; thus, when the ammonia load to the system is higher, there is a higher driving force for the diffusion of ammonia and thus the nitrification rate is higher Figure 6.

The required SRT to achieve the measured Monkmoor STW residual ammonia concentration (Nad) was calculated following Haandel and Lubbe 2012. In theory a sludge age of at least 10.2 days is required to achieve the final effluent ammonia-N concentration of 0.41 mg/L but Figure 7 shows that the MABR IFAS system achieved it with a sludge age of 8.8 days. The better than expected ammonia removal can be attributed to the contribution of nitrifiers attached to the MABR fibers.

The impact of the MABR biomass was quantified through plant simulations using SIMBA# 6.0 software. The simulations suggest that 18.5% of the aerobic ammonia-oxidizing bacteria (AOB), which facilitate the conversion of ammonia to nitrite, were located within the biofilm. Monkmoor STW performance test results show that the MABR contributed to the oxidation of 243 kgN/d, representing 19.6% of the inlet ammonia-N load, which aligns closely with the proportion of AOB mass in the MABR system estimated in the simulation. Consequently, the MABR biofilm increased the effective aerobic sludge age to 10.7 days, supporting the observed low final effluent ammonia-N concentrations at Monkmoor STW. Achieving a minimum aerobic sludge age of 10.7 days at Monkmoor STW without MABR, would have required an additional 2,639 m3 of reactor aerobic volume, equivalent almost to 1 additional ASP lane.

CONCLUSIONS AND LESSONS LEARNED
The successful installation commissioning and start-up of the OxyMem™ MABR IFAS system at the Monkmoor STW reveal several critical insights:

Rapid and non-disruptive retrofit solution
The MABR modules were dropped into the existing tank without ever stopping the flow — demonstrating that IFAS MABR systems can be used to intensify existing plants quickly and non-disruptively.

Process intensification
243 kgN/d of ammonia was removed by the MABR system, equating to a nitrification rate of 3.4 gN/m2.d. As a result, the effluent ammonia concentration was less than 0.5 mg/L despite an apparent sludge age of just 8.8 days.

This installation demonstrates that municipalities can quickly increase their nitrification capacity in a matter of weeks with modular drop-in MABR units and can serve as an example for other facilities with capacity challenges.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionLow SRT Performance of Membrane Aerated Biofilm Reactors (MABR)

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment Technology - Secondary & Tertiary Treatment

Author(s)

Manzano, Josep, Heffernan, Barry

Author(s)J. Manzano1, B. Heffernan1

Author affiliation(s)OxyMem1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2025

DOI10.2175/193864718825159987

Volume / Issue

Content sourceWEFTEC

Word count16