Effects of electrochemical processes application on the modification of mixed liquor characteristics of an electro-membrane bioreactor (e-MBR)

Abstract

Abstract This study evaluated the effects of electrochemical processes on the mixed liquor characteristics of an electro-membrane bioreactor (e-MBR) applied to municipal wastewater treatment. A laboratory-scale e-MBR was assessed under two experimental runs: without the electric field (run I) and with electric field, controlled by the application of an electric current set in 10.0 A m−2 under intermittent exposure mode of 6 minutes ON/18 minutes OFF (run II). The electric field caused approximately 55% removal of both soluble microbial products (SMP) and extracellular polymeric substances (EPS), whereas the proteins/carbohydrates ratio in EPS was increased from 1.9 in the run I to 2.9 in run II, leading to an increment of flocs' hydrophobicity. Additionally, the sludge floc size average value was reduced from 42.2 μm in run I to 24.6 μm in run II, which led to a significant enhancement in the sludge settleability. As a result, the membrane fouling rate was always less than 3.80 mbar d−1 in run II, whereas in run I these values reached up to 34.7 mbar d−1. These results demonstrated that the electrochemical processes enhanced the mixed liquor filterability. Therefore, their implementation represents a great alternative to improve the operational stability of membrane bioreactors.