Development and testing of a fully gravitational submerged anaerobic membrane bioreactor for wastewater treatment

Abstract

A gravity-operated submerged anaerobic membrane bioreactor (SAnMBR) was set up in order to test its principle of operation as an alternative to conventional pumped permeation of the membrane. This operating mode allowed the membrane flux rate to be measured accurately whilst maintaining a constant transmembrane pressure (TMP), and allowed small transient variations in flux rate to be observed. The reactor was operated at 36 0 C for a period of 115 days using a nutrient-balanced synthetic substrate with a high suspended solids concentration. Membrane cleaning was in-situ by a gas scouring system using recirculation of headspace biogas. With an initial TMP of 7.0 kPa the membrane flux slowly decreased due to membrane fouling and had not reached a constant value by day 71. The results indicated that the system was still acclimatising up to 50 days after start-up; but from that point onwards performance parameters became much more stable. A constant flux of 2.2 L m by increasing the influent strength. Under these conditions the average COD removal efficiency was 96% and the specific methane potential (SMP) was 0.31 L CH4 g -1 COD removed.

Effect of mean cell residence time on transmembrane flux, mixed-liquor characteristics and overall performance of a submerged anaerobic membrane bioreactor

“…It was made from a mixture of: sterilised yeast to give a biosolids component; milk and dried blood as sources of protein and fat in soluble and colloidal form; sugar as a readily utilisable soluble carbon source; urea as a further source of organic nitrogen; and a mixed mineral supplement. The mix has been previously reported as a synthetic wastewater (SWW) [19], as the C:N:P ratio and ratio of solids components is based on typical values for European municipal wastewaters when used at a lower strength.…”

“…1), each with a working volume of 9.6 L and a headspace of 2.1 L, were operated with the TMP applied by gravitational head, as described by Pacheco-Ruiz et al [19]. The membranes used were type 203 cartridge flat plate chlorinated polyethylene (Kubota Co., Japan) with a nominal pore size of 0.4 µm and an effective surface area of 0.113 m 2 , giving a membrane packing density of 0.012 m 2 L -1 .…”

Design of anaerobic membrane bioreactors for the valorization of dilute organic carbon waste streams

“…53 The release of dissolved methane to the atmosphere via reactor effluent is a persistent problem for AnMBRs that has significant impacts on energy recovery and life cycle GWP. 1,54,55 Existing approaches include the use of sweep gas 18,19 or vacuum extraction with a degassing membrane; 45 the latter was examined in this study as well as in Pretel et al 30 If DMs are ultimately able to recover the same amount of energy (as methane) than that which is required to operate the system (as electricity), these systems would reduce the life cycle GWP of a plant by more than half but at a 5% increase in NPV. These environmental benefits may also be achieved through alternative uses of soluble methane, including the production of chemicals (e.g., methanol) [56][57][58][59][60] or the facilitation of denitrification.…”

Operation of Submerged Anaerobic Membrane Bioreactors at 20 °C: Effect of Solids Retention Time on Flux, Mixed Liquor Characteristics and Performance

“…The substrate used was a synthetic wastewater [36], which was prepared fresh each day as a concentrate and diluted to the required working strength. It was designed to give a C:N:P ratio of around 100:20:4 and solids contents similar to those of typical municipal wastewaters [37,38].…”

“…Membrane performance was evaluated on the basis of the flux achieved at constant TMP, calculated as described in Pacheco-Ruiz et al [36]. SAnMBR performance and operational stability were assessed on the basis of COD percentage conversion, specific methane production (SMP) per g of COD removed, MLSS and mixed liquor volatile sus-…”