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CWEA Members: $25.00
Non-Members: $35.00 

1.2 Contact Hours Towards CWEA Certifications: TBD

The membrane aerated biofilm reactor (MABR) process is an emerging activated sludge intensification technology that has received much interest in the wastewater industry. MABRs include a biofilm with high concentrations of nitrifiers. The biofilm removes a portion of the influent ammonia, and sloughed biomass seeds the activated sludge process with nitrifiers. This allows the activated sludge process to be operated at a lower sludge retention time (SRT) which translates to more capacity. Capacity benefits are more significant in cold weather applications where long SRTs are typically needed for reliable nutrient removal. Given the limited full-scale operating experience, technology evaluation and design must rely on pilot and modeling results.

The Sanitation Districts recently conducted a successful MABR pilot (Mansell et al 2022); however, due to mechanical issues, the pilot could not be operated at low SRTs to confirm performance and capacity benefits. Due to the warm climate, steady-state modeling indicates that CAS can achieve similar nitrogen removal as MABRs at aerobic SRTs as low as 3 days. It also shows reliable MABR performance at aerobic SRTs as low as 2 days. Steady-state modeling typically predicts better performance than what is experienced with the day-to-day variability of real treatment plants. To better quantify the performance and capacity benefits of warm weather operation at low SRTs, year-long dynamic modeling simulations are performed over a range of operating conditions for CAS and MABR. Frequency distributions for effluent performance and nitrifying biomass are developed to establish target SRTs that achieve comparable performance, reliability, and risk for CAS and MABR processes. This evaluation will help support the Sanitation District’s decision-making for upgrades at LCWRP.

•         Learning Objectives/Attendee Takeaways: 
No. 1: MABR Technology for Capacity Enhancement: MABR technology intensifies activated sludge processes by efficiently removing ammonia and seeding activated sludge with nitrifiers, increasing capacity, especially in cold weather.
No. 2:  Evaluation at LCWRP: LCWRP is considering MABR for future capacity and treatment enhancement. Modeling suggests that MABRs can achieve similar nitrogen removal as conventional methods at lower SRTs in warm climates, with reliable performance.
No. 3: Dynamic Modeling for Decision Support: Dynamic modeling over a year-long period helps quantify performance and capacity benefits, aiding in establishing target SRTs for comparable performance and reliability between CAS and MABR processes. This supports decision-making for plant upgrades at LCWRP.