Human Adenovirus 40 Removal in Sidestream Membrane Bioreactor

Abstract

This preliminary study investigates how the removal of human adenovirus in a membrane bioreactor (MBR) depends on the MBR configuration. Results from a sidestream MBR (ssMBR) are compared with data from an immersed MBR (iMBR) and literature data for another iMBR with 0.45-μm pore size hollow-fiber membranes used in all three reactors. The central premise of the study is that different fouling mitigation approaches in the ssMBR and iMBR lead to differences in membrane fouling and human adenovirus 40 (HAdV 40) removals. The hypothesis tested is that the fouling layer acts as an additional separation barrier and is largely responsible for virus removal in MBRs. Higher HAdV 40 rejection observed in the ssMBR is attributed to a higher density fouling layer formed in the ssMBR under conditions of cross-flow shear. The interpretation is supported by the measured differences in the dissolved organic carbon (DOC) removal and in the specific UV254 absorbance (SUVA254) reduction as well as in the transmembrane pressure response to periodic cleaning in the two MBRs (average decreases in HAdV 40 log removal value of 0.30 and 0.85 in ssMBR and iMBR, respectively). Although the additional energy required to create cross-flow in the ssMBR does not result in permeate flux enhancement over the iMBR baseline, the denser fouling layer in the ssMBR is a more effective barrier for viruses. This trade-off should be considered when weighing the priorities of energy savings and effluent quality.