Anaerobic Fluidized Bed Membrane Bioreactor with Multichanneled Biocarrier for Carbon-Neutral, Decentralized Greywater Treatment

This study investigated the effect of hydraulic retention times (HRTs) on the organic removal efficiency, membrane fouling, and methane production rate from an anaerobic fluidized bed membrane bioreactor (AFMBR) to treat synthetic greywater with a soluble chemical oxygen demand (SCOD) of 300 mg/L. Here, a polyvinylidene fluoride (PVDF)-based biocarrier was applied to control membrane fouling and facilitate attached biofilm growth. At an HRT of 16 h, which corresponds to 3.75 L/m² h of permeate flux, transmembrane pressure was maintained as 0.15 bar. As the HRT decreased 12 h, the SCOD removal efficiency dropped 42% quickly while bulk volatile suspended solid (VSS) concentration increased 1300 mg/L. However, when the HRT was further reduced to 8 h, the SCOD removal stabilized at 81% gradually with reducing the bulk VSS to 300 mg/L. During the entire operational period, the biogas produced by AFMBR under the fluidization of multichanneled media consisted of 50% methane. The methane yield was 0.13 L of CH₄/day at an HRT of 8 h. A 16S ribosomal ribonucleic acid analysis of the microbial community demonstrated that the relative abundance of Methanosaeta grown on the PVDF media increased as the HRT decreased. Spectroscopic observation revealed that a significant portion of biomass was grown inside media channels having higher surface roughness than their outer surfaces.