Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system

Abstract

a b s t r a c tTo quantify the effect of dynamic particle size changes and degradation and accumulation of suspended solids (SS) in influents to reactors on membrane fouling frequency in hybrid powder-activated carbon (PAC)-microfiltration (MF) reactors, we operated a PAC-MF system (hollow-fiber module) for more than five months to purify river water before and after pretreatment by a biofilter. The transmembrane pressure, backwashing pressure, resistance to filtration, and SS accumulation and degradation during these dynamic changes were evaluated. The initial dose of PAC was 40 g/L of the reactor and no additional PAC was added during this continuous operational period. The presence of PAC reduced the membrane resistance to filtration even at the end of filtration period when the number of particles in the smallest range (>1.0-3.6 m) was the highest measured by the flow cytometer and microscopy image analysis. This resistance was reduced further when the river water was biofiltered prior to membrane filtration. This real-time study demonstrates that over time PAC and other particles coming into the reactors through the influents degrade and/or become smaller because of the turbulence caused by continuous aeration below the MF membrane fibers. The number of particles in the reactors with diameters less than 10 m increased with time, increasing the fouling frequency; however, the presence of PAC further reduced the particle enhanced fouling. The presence of PAC also increased SS degradation by up to 10%. The increased number of bacteria inside the PAC-MF systems did not contribute to the number of membrane fouling. Even though the particle sizes inside the reactors became smaller with time, the gradual increase in net accumulation of SS was also an important factor controlling the performance of the PAC-MF system.Published by Elsevier B.V.

Treatment of coal gasification wastewater by membrane bioreactor hybrid powdered activated carbon (MBR–PAC) system

“…Meanwhile, the microbial cells attached to PAC secrete enzymes into the micropores which leads to extracellular biodegradation of adsorbed organics. The mechanisms mentioned above are probably responsible for higher biodegradation efficiency with PAC (Satyawali and Balakrishnan, 2009a;Khan et al, 2011). Results show long PAC sludge ages suggested more resistance to high OLR and the stability of effluent quality has been enhanced with PAC which are in good agreement with previous literatures (Sher et al, 2000;Munz et al, 2007;Taimur Khan et al, 2013).…”

Combined effects of EPS and HRT enhanced biofouling on a submerged and hybrid PAC-MF membrane bioreactor

“…In the past decades, microfiltration (MF) has emerged as one of the most reliable, cost-effective and sustainable unit processes for surface water treatment separating macromolecules, bacteria and discrete particles (Lebeau et al, 1998;Khan et al, 2001Khan et al, , 2011Fabris et al, 2007). In this process, biofouling has been identified as the key factor affecting long-term MF membrane separation processes and worsening overall plant performance.…”

Novel Water Treatment Processes Based on Hybrid Membrane-Ozonation Systems: A Novel Ceramic Membrane Contactor for Bubbleless Ozonation of Emerging Micropollutants

“…Khan et el. [21] studied the influence of particle size on membrane fouling at a PAC-UF system. In addition, absorption-membrane filtration processes have been tested for the removal of micropollutants such as geosmin [22] and diclofenac [23].…”