Performance of pilot-scale membrane aerated biofilm reactors integrated with anoxic nano-biotechnological reactor for domestic wastewater treatment

Membrane-aerated biofilm reactors (MABRs) have aroused increasing attention due to their excellent perfor-mance in treating wastewater, where the membranes behave as bio-carriers for microorganisms and bubbleless air diffusers. The MABR technology has not been fully commercialized due to reactor design and low total ni-trogen (TN) removal efficiency at short hydraulic retention times (HRT). In this study, a hybrid system of MABR 1 integrated with an anoxic nano-biotechnological reactor filled with Granulated Nanoscale Oxyhydroxides of Fe (GNOF) media was evaluated to assess the improvement in nitrogen removal performance at 12, 10, and 4 h of HRTs. At the same time, another MABR (MABR 2) was operated individually at 12, 10, 8, 6, 4, and 2 h of HRTs to assess the influence of HRT on nitrogen removal performance. An enhancement in removal performance was reported in the hybrid MABR-GNOF, achieving the highest removal efficiencies of 74.3 +/- 3.1% for ammonium nitrogen (NH4+-N), 69.8 +/- 2.1% for total nitrogen (TN), and 90.9 +/- 1.7% for chemical oxygen demand (COD), at 12 h HRT. The hybrid MABR-GNOF system attained 18% higher nitrogen removal than the MABR-only system at 12 h of HRT. A simultaneous anoxic nitrification-denitrification and COD oxidation might be developed for the removal of COD, NH4+-N, and TN from domestic wastewater by using GNOF as an electron acceptor in the hybrid MABR-GNOF unit. The findings in this study confirmed the possibility of integration of GNOF and MABR on a pilot scale and are promising for the application of this hybrid system on a full scale.

Automated summary

Membrane-aerated biofilm reactors (MABRs) have attracted attention for their wastewater treatment performance, but face challenges with reactor design and low total nitrogen (TN) removal efficiency. This study evaluated a hybrid system of MABR integrated with an anoxic nano-biotechnological reactor filled with Granulated Nanoscale Oxyhydroxides of Fe (GNOF) media to improve nitrogen removal. The hybrid MABR-GNOF system achieved higher removal efficiencies than the MABR-only system, with an 18% increase in nitrogen removal at 12 hours of hydraulic retention time (HRT).