Long-term performance evaluation of granular activated carbon fluidization and biogas sparging in anaerobic fluidized bed membrane bioreactor: Membrane fouling and micropollutant removal

In this study, fluidization of granular activated carbon (GAC) by the recirculation of a bulk suspension through an anaerobic fluidized bed membrane bioreactor (AFMBR) and biogas sparging from the bottom of an anaerobic membrane bioreactor (G-AnMBR) for treating low-strength wastewater were compared to investigate organic removal and fouling rate. The chemical oxygen demand (COD) removal efficiency obtained by both the AFMBR and G-AnMBR exceeded 90 %, and the proportion of methane in the biogas produced was 60 % at the same hydraulic retention time (HRT). In the AFMBR, the transmembrane pressure (TMP) gradually increased, but a rapid TMP jump was not observed during operational period. In the G-AnMBR, the TMP increased rapidly as the biogas flowrate was 2 and 3 L/min (LPM) at 8 h of HRT while the TMP below 0.1 bar was maintained over 90 d at 4 LPM. Our results also indicated that organic micropollutants, such as Bisphenol A (BPA), Sulfamethoxazole (SMX), and Methylparaben (MeP), were removed by AFMBR almost completely. However, the G-AnMBR showed relatively low SMX and MeP removal efficiencies of 47.6 % and 74.9 %, respectively. The estimated energy required to operate the G-AnMBR was 1.37 kW h/m3, while it was only 0.06 kW h/m3 for AFMBR. (c) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

This study compared the fluidization of granular activated carbon in an AFMBR and the biogas sparging from the bottom of a G-AnMBR for treating low-strength wastewater. The results showed that AFMBR achieved high organic removal efficiency, methane production, and removal of organic micropollutants, while G-AnMBR had lower efficiency but lower energy consumption.