A Brief Review on the Resistance-in-Series Model in Membrane Bioreactors (MBRs)

Abstract

The cake layer deposited on the membrane modules of membrane bioreactors (MBRs), especially under a submerged configuration, represents a relevant and fundamental mechanism deeply influencing the development of membrane fouling. It negatively affects the total resistance to filtration, while exerting a positive effect as a “pre-filter” promoting the “dynamic membrane” that protects the physical membrane from internal fouling. These two opposite phenomena should be properly managed, where the submerged membranes are usually subjected to a periodical cake layer removal through ordinary (permeate backwashing and air scouring) and/or irregular cleaning actions (manual physical cleaning). In this context, the physical removal of the cake layer is needed to maintain the design filtration characteristics. Nevertheless, the proper evaluation of the effect of physical cleaning operations is still contradictory and under discussion, referring in particular to the correct evaluation of fouling mechanisms. The aim of the present work was to summarize the different aspects that influence the fouling investigations, based on simple models for the evaluation of the resistance to filtration due to the cake layer, through physical cleaning operations.

Influence of Ozone Treatment on Ultrafiltration Performance and Nutrient Flow in a Membrane Based Nutrient Recovery Process from Anaerobic Digestate

“…Pilot plant operation and data capture was fully automated. Calculation of permeate flux and recovery was according to Equations (1) and (2). Operation of the UF pilot plant was quasi-continuous-a centrate batch was continuously processed during working hours and operation was stopped during nights and weekends.…”

“…Ultrafiltration (UF) is a state-of-the-art technology for municipal and industrial wastewater treatment, e.g., as membrane bioreactor in combination with activated sludge processes [1]. The interaction mechanisms between biological suspension and membrane surface are well understood and commonly classified into deposition, reversible and irreversible (bio-)fouling, and pore-blocking [1,2]. Solid concentration, particle size and structure as well as sludge rheology have an impact on membrane fouling [3,4].…”

Effect of Pretreatment on Hydraulic Performance of the Integrated Membrane Process for Concentrating Nutrient in Biogas Digestate from Swine Manure

“…The average flux decline rate (FD, %) for CUFM and HFUFM was 37.08% ± 4.54% and 37.56% ± 5.28%, respectively, showing that there were no significant differences ( p > 0.05), which indicated that the fouling characteristics of CUFM and HFUFM were similar in the batch process. The decline of the membrane flux was due to the forming of the cake layer on the membrane surface, which caused membrane fouling and resulted in a decrease of the membrane permeability [ 37 ]. The results were similar to the data from other studies presented in Table 3 .…”

Simultaneous sludge minimization, biological phosphorous removal and membrane fouling mitigation in a novel plant layout for MBR

“…Concerning the membrane service-life preservation, it is of paramount importance to minimize the pore-blocking mechanism or, alternatively, maximize the recovery of the membrane permeability with chemical cleaning operations. The highest value of the "irremovable fouling", defined as the residual portion of fouling after chemical cleanings (Di Bella and Di Trapani, 2019), was observed in Period 4, whereas the lowest in Period 1. This result indicated that the integration of the AMSR might cause a potential decrease in the membrane service-life.…”