Sludge characteristics and effect of crossflow membrane filtration on membrane fouling in a jet loop membrane bioreactor (JLMBR)

Abstract

An aerobic jet loop membrane bioreactor (JLMBR) activated sludge process of 35 L working volume was used to investigate its applicability in industrial wastewaters, specifically cheese whey wastewater. A loading rate of 22.2 kg COD/(m(3) day) and 1.6 days of sludge age was achieved with 97% COD removal efficiency. During the study, the activated sludge was found non-settable and slimy characteristic and non-flocculating motile bacteria structure. Therefore, it was been conducted that the membrane separation was indispensable to obtain high performance from jet loop bioreactor (JLB). From the investigation of crossflow microfiltration characteristic of the system, it was found that the fluxes decreased and MFI increased with increasing MLSS concentration. The increasing crossflow velocity greatly reduced the cake formation on the membrane surface and increased the steady state permeate fluxes, decreasing specific cake resistance (alpha) values. The cake layer was in a highly compressible form. The compressibility coefficient was calculated as 0.98. In addition to this, the pseudo gel concentration (C-G) on the membrane surface was calculated to be 73,130 mg/L. For the investigation of the membrane filtration mechanism, it was found that the fouling mechanism showed high compatibility with complete pore blocking model and particularly cake filtration model (R-2 = 0.99). (c) 2006 Elsevier B.V. All rights reserved.