Control of membrane-attached biofilms in extractive membrane bioreactors

Abstract

Control of Membrane Attached Biofilm (MAB) formation and accumulation is a key aspect in the operation of Extractive Membrane Bioreactors (EMBs). In this work, MAB control was attempted in a novel EMB configuration which presents two innovative aspects: the presence of a biphasic biomedium and a contained liquid membrane module. This reactor, where the benefits of high shear forces and the use of a biphasic biomedium are effectively combined, was operated without any biofilm formation or reduction in organic substrate flux over time.

Towards a continuous two-phase partitioning bioreactor for xenobiotic removal

“…The use of rationally-selected polymer tubing in C-TPPBs could extend the application to the treatment of broad classes of pollutants, arising from the "tailoring" of the polymer for specific contaminants as has recently been demonstrated using first principles' thermodynamic methods [11]. Previous studies of EMBs have mainly been focused on the removal of VOCs [12,13], and the bioreactors were operated with a silicone rubber membrane, which was effective for these hydrophobic compounds, but could be limited by the solvation capabilities of the membrane used [14], and the limited capacity of this single type of material (silicone rubber) to sorb other types of important organic molecules such as phenols [15].…”

Biocatalytic membrane reactors (BMR)

“…Consequently, an inverse relationship between the organic flux and biofilm thickness was observed. Several modifications have been attempted to suppress the metabolism of the biofilmforming bacteria, such as addition of sodium chloride [76], increasing the shear stress on the membrane surface [77], using a biphasic system [78] and the addition of nitrate as an electron acceptor instead of oxygen [79]. Nitrate is highly soluble in water and therefore, the nitrate concentration in the biomedium can be sufficiently high to fully penetrate the biofilm, ensuring that nitrate is present at the biofilm/membrane interface.…”

Novel membrane bioreactor: Able to cope with fluctuating loads, poorly water soluble VOCs, and biomass accumulation

“…The concept of applying shear stress to the biofilm surface by providing a flow of nutrient medium, and thereby removing excessive biomass, proved to be a suitable method to hinder biofilm accumulation (Nicolella et al, 2000;Vinage, 2002). We concluded that the calculated shear stress of approximately 0.1 Pa was sufficient to remove excess biomass.…”