Novel Membrane Bioreactor with Gas/Liquid Two-Phase Flow for High-Performance Degradation of Phenol

Abstract

The use of a membrane bioreactor with cell retention to achieve high biomass concentrations has been examined for phenol degradation by the bacteria Alcaligenes eutrophus. This process is particularly interesting for toxic substrates as the hydraulic dilution rate and the growth rate are independently controlled. In the case of a transitory excess of phenol, this potentially toxic situation can be overcome by modifying the substrate concentration or the dilution rate without any loss of cells. The injection of a gas phase at the filter inlet increased both the permeate flow rate (by a factor of 1. 75) and the oxygen transfer capacity (by a factor of 1.5). This has enabled the cell concentration to reach a maximal value of 60 g L-1 with a hydraulic dilution rate of 0.5 h-1 and a phenol feed concentration of 8 g L-1. The volumetric productivity of this process corresponds to a phenol degradation rate approaching 100 kg m-3 day-1. The on-line measurement of the characteristic yellow color of 2-hydroxymuconate semialdehyde, a metabolic intermediate of the phenol degradation pathway, in the permeate provides an interesting basis for process control of phenol supply into the reactor since the color intensity correlates directly to the specific rate of phenol degradation.

High efficiency degradation of tetrahydrofuran (THF) using a membrane bioreactor: identification of THF-degrading cultures of Pseudonocardia sp. strain M1 and Rhodococcus ruber isolate M2

“…In comparison to the performance of other MBR systems reported in the literature, the maximum THF loading rate in this study was higher than that for a highly degradable COD waste stream [8,34], but was significantly lower than that reported for phenol degradation using two-phase flow [20]. Loading rates of different MBR systems are affected by the degradability of the waste stream, biomass concentration, temperature and system configuration, and may not be readily comparable to one another.…”

“…Reactor biomass concentrations were within the range reported for other MBR systems [8,9,21,34]; however, concentrations as high as 60 g/l cell dry weight have been reported [20]. The high biomass concentrations in the MBR caused difficulties in maintaining reactor DO, in part because increasing the VSS increases the biomass viscosity [3] while the oxygen transfer coefficient decreases [24].…”

“…Retention of all microorganisms results in high biomass concentrations in the bioreactor, which allow the system to treat high-strength wastewater resulting in a system with a relatively small footprint. MBR technology has been successfully applied to treat a variety of high-strength wastes including high molecular weight compounds [8,34], organic wastes containing surfactants [19], fermentation wastewater [21], phenol [20], contaminated gas streams [11,27,28] and industrial waste [29]. Retention of soluble high molecular weight compounds keeps slowly degradable compounds in the bioreactor while non-degradable compounds are discharged with the sludge [16].…”

Enzyme Transmission during Crossflow Filtration of Yeast Suspensions Using Gas/Liquid Two‐Phase Flows

“…One approach to reducing the deposition of suspended cells or particles on the membrane is to use improved fluid hydrodynamics. In this respect, several studies have pointed out the value of gas/liquid two‐phase flows to enhance the flux in ultrafiltration and microfiltration for various applications (drinking water production,1 biological treatment,2–4 and macromolecule separation5–8). In all these studies, the permeate flux enhancements were always significant, ranging from 20 to 320%, according to the application, the membrane type and the two‐phase flow pattern.…”

A MEMBRANE SEPARATOR/BIOREACTOR COUPLED WITH ABSORBANCE MEASUREMENT FOR DETECTION OF Escherichia coli O157:H7

“…Membrane bioreactors were utilized to synthesize many kinds of compounds such as N-acetylneuraminic acid (Kragl et al 1991), enantiomerically pure a-amino acids (Bommarius et al 1992), 2-keto-3-deoxy-D-glycero-D-galacto-nonopyranulosonic acid from D-mannose and pyruvic acid with a conversion of up to 85% (Salagnad et al 1997), proteins by using the product of polymerase chain reaction as a template (Nakano et al 1999), 1,2-epoxy-7,8-0ctene from 1,7-0ctadiene with Pseudomonas oleovorans (Doig et al 1999) and hydrophobic molecules (Doig et al 1998). Membrane bioreactors were also capable of processing wastewater such as extracting and biodegrading toxic organic pollutants in chemical industry wastewater (Livingston 1994), detoxifying and bio-treating industrially produced 3,6dichloroaniline wastewater Livingston 1993, 1994), phenol in synthetically concocted wastewater (Livingston 1993a;Leonard et al 1998) and 3-chloronitrobenzene in industrially produced wastewater (Livingston 1993b). This paper reported a new application of a membrane separator/bioreactor, detection of bacteria.…”