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Download fileRemoval of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes
journal contribution
posted on 2017-09-28, 00:00 authored by Hong Cheng, Pei-Ying HongAn
anaerobic membrane bioreactor was retrofitted with polyvinylidene
fluoride (PVDF) microfiltration membrane units, each of which was
fouled to a different extent. The membranes with different degrees
of fouling were evaluated for their efficiencies in removing three
antibiotic-resistant bacteria (ARB), namely, blaNDM‑1-positive Escherichia coli PI-7, blaCTX‑M‑15-positive Klebsiella pneumoniae L7, and blaOXA‑48-positive E. coli UPEC-RIY-4, as well as their associated
plasmid-borne antibiotic resistance genes (ARGs). The results showed
that the log removal values (LRVs) of ARGs correlated positively with
the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes
with a minimal foulant layer could remove more than 5 log units of
ARB. However, as the membranes progressed to subcritical fouling,
the LRVs of ARB decreased at increasing operating transmembrane pressures
(TMPs). The LRV recovered back to 5 when the membrane was critically
fouled, and the achieved LRV remained stable at different operating
TMPs. Furthermore, characterization of the surface attributed the
removal of both the ARB and ARGs to adsorption, which was facilitated
by an increasing hydrophobicity and a decreasing surface ζ potential
as the membranes fouled. Our results indicate that both the TMP and
the foulant layer synergistically affected ARB removal, but the foulant
layer was the main factor that contributed to ARG removal.