A Novel Anaerobic Electrochemical Membrane Bioreactor (AnEMBR) with Conductive Hollow-fiber Membrane for Treatment of Low-Organic Strength Solutions
K.P. Katuri, C.M. Werner, R.J. Jimenez-Sandoval, W. Chen, S. Jeon, B.E. Logan, Z. Lai, G.L. Amy, P.E. Saikaly
Environ. Sci. Technol., 48 (21), 12833-12841, (2014)
Anaerobic Electrochemical Membrane Bioreactor
A new anaerobic treatment system that combined a microbial electrolysis
cell (MEC) with membrane filtration using electrically conductive,
porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to
treat low organic strength solution and recover energy in the form of
biogas. This new system is called an anaerobic electrochemical membrane
bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode
for hydrogen evolution reaction (HER) and the membrane for filtration of
the effluent. The AnEMBR system was operated for 70 days with synthetic
acetate solution having a chemical oxygen demand (COD) of 320 mg/L.
Removal of COD was >95% at all applied voltages tested. Up to 71% of
the substrate energy was recovered at an applied voltage of 0.7 V as
methane rich biogas (83% CH4; < 1% H2) due to
biological conversion of the hydrogen evolved at the cathode to methane.
A combination of factors (hydrogen bubble formation, low cathode
potential and localized high pH at the cathode surface) contributed to
reduced membrane fouling in the AnEMBR compared to the control reactor
(open circuit voltage). The net energy required to operate the AnEMBR
system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1–2 kWh/m3).
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