Anaerobic Fluidized\nBed Membrane Bioreactor with Multichanneled\nBiocarrier for Carbon-Neutral, Decentralized Greywater Treatment

This study investigated the effect of hydraulic retention\ntimes\n(HRTs) on the organic removal efficiency, membrane fouling, and methane\nproduction rate from an anaerobic fluidized bed membrane bioreactor\n(AFMBR) to treat synthetic greywater with a soluble chemical oxygen\ndemand (SCOD) of 300 mg/L. Here, a polyvinylidene fluoride (PVDF)-based\nbiocarrier was applied to control membrane fouling and facilitate\nattached biofilm growth. At an HRT of 16 h, which corresponds to 3.75\nL/m<sup>2</sup> h of permeate flux, transmembrane pressure was maintained\nas 0.15 bar. As the HRT decreased 12 h, the SCOD removal efficiency\ndropped 42% quickly while bulk volatile suspended solid (VSS) concentration\nincreased 1300 mg/L. However, when the HRT was further reduced to\n8 h, the SCOD removal stabilized at 81% gradually with reducing the\nbulk VSS to 300 mg/L. During the entire operational period, the biogas\nproduced by AFMBR under the fluidization of multichanneled media consisted\nof 50% methane. The methane yield was 0.13 L of CH<sub>4</sub>/day\nat an HRT of 8 h. A 16S ribosomal ribonucleic acid analysis of the\nmicrobial community demonstrated that the relative abundance of Methanosaeta\ngrown on the PVDF media increased as the HRT decreased. Spectroscopic\nobservation revealed that a significant portion of biomass was grown\ninside media channels having higher surface roughness than their outer\nsurfaces.