Identification of fouling mechanisms in MBRs at constant flowrate: model applications and SEM-EDX characterizations

Evaluation of the fouling potential of sludge in a membrane bioreactor integrated with microbial fuel cell

This study focused on the fouling characteristics evaluation of the sludge in a membrane bioreactor integrated with microbial fuel cell (MFC-MBR) to reveal the mechanisms of membrane fouling mitigation. The filtration of soluble microbial products (SMPs) in MFC-MBR showed lower flux decline rate than those in the control system (C-MBR). Based on the extended Derjaguin-Landau-Verwey-Overbeek analysis, decreases in free energies of adhesion between the SMPs and clean membrane or SMP-fouled membrane were observed in MFC-MBR. When approaching the clean membrane or SMP-fouled membrane, the SMPs in MFC-MBR had to overcome a higher energy barrier compared to those in C-MBR, indicating the inhibition of adsorption of SMPs on the membrane surface in MFC-MBR. Additionally, sludge flocs in MFC-MBR exhibited lower hydrophobicity and were less negative surface charged in comparison to those in the C-MBR. In MFC-MBR, the sludge flocs approaching the clean membrane, SMP-fouled membrane and cake layer all experienced higher energy barriers and lower secondary energy minimums compared to those in C-MBR, exhibiting the lower potential of cake layer formation. These results confirmed that decreases of the fouling potentials of SMPs and sludge flocs were essential for the membrane fouling mitigation in the MFC-MBR.

Membrane processes

This literature review provides a review for publications in 2018 and 2019 and includes information membrane processes findings for municipal and industrial applications. This review is a subsection of the annual Water Environment Federation literature review for Treatment Systems section. The following topics are covered in this literature review: industrial wastewater and membrane. Bioreactor (MBR) configuration, membrane fouling, design, reuse, nutrient removal, operation, anaerobic membrane systems, microconstituents removal, membrane technology advances, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include the following: Biological Fixed-Film Systems, Activated Sludge, and Other Aerobic Suspended Culture Processes, Anaerobic Processes, and Water Reclamation and Reuse. This publication might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants.

Model-based evaluation of fouling mechanisms in powdered activated carbon/membrane bioreactor system

Identifying the fouling degree of a membrane bioreactor (MBR) provides guidance on the determination of suitable membrane cleaning methods. There is still a lack of knowledge on the effects of powdered activated carbon (PAC) refresh ratio on the MBR fouling mechanism. Major fouling mechanisms of an MBR with constant flow rate at different PAC replenishment ratios were investigated by individual and combined mechanistic fouling models. The root mean square errors were employed to assess the prediction accuracy of the used fouling models. The combined models showed better prediction. The cake-complete model provided far better fits of the transmembrane pressure data, and provided good fits of other individual model predictions regardless of the PAC refreshment ratio. Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed that the cake layer clogging was the main fouling mechanism followed by complete blockage and standard plugging. The cake-complete model may be used to predict the fouling mechanisms in PAC/MBR systems.