Novel start-up of simultaneous partial nitrification, anammox, and denitrification (SNAD) in HMBR and SBBR for post-combustion carbon capture (PCC) wastewater treatment

Considering global warming and continued reliance on fossil fuels, PCC is a key transitional technology toward net-zero emissions. However, amine-based PCC systems generate wastewater containing amines, ammonia, nitrosamines, and degradation byproducts, requiring effective treatment. This study, for the first time, demonstrates the successful start-up of the SNAD system in parallel hybrid membrane bioreactors (HMBRs) and a sequencing batch bioreactor (SBBR) treating synthetic monoethanolamine (MEA)-containing wastewater. The HMBRs operated continuously, and the SBBR operated in batch mode at 30-35 °C. Intermittent aeration (20/60 min) was applied in all bioreactors to suppress nitrite-oxidizing bacteria (NOB) and achieve partial nitrification. System robustness was improved by inoculating mature anammox granules and gradually adding MEA to enhance microbial adaptation. Stable SNAD performance was achieved within 150 days in HMBRs, which outperformed the SBBR due to better biomass retention, reduced anammox washout, and enhanced biofilm formation on membrane surfaces. During startup, the HMBRs achieved total nitrogen, ammonium, and chemical oxygen demand (COD) removal efficiencies of 60-78%, 70-80%, and 85-90%, respectively. Following the stable startup, the system applicability was preliminarily evaluated using diluted real reclaimer wastewater. Over two months, the HMBRs maintained effective nitrogen and COD removal, demonstrating the SNAD system’s potential for PCC wastewater treatment.