Membrane fouling caused by biological foams in a submerged membrane bioreactor: Mechanism insights

An Efficient Method to Determine Membrane Molecular Weight Cut-Off Using Fluorescent Silica Nanoparticles

“…With the increase in the size of NPs, the concentration difference between the permeate and the feed increases. The retention rate [ 17 , 22 , 29 ] was calculated by the Equation (1), according to the French Standard NF X 45-103 [ 4 ] and the variation of the retention rate versus Np size is given in Figure 5 B. where [permeate] t is the solute concentration in the permeate and [Feed] t is the solute concentration in the feed at the same time t. The unit of concentration is in part.mL −1 .…”

“…For the membrane M1, the retention of NPs presented a MWCO at 58.5–79.5 and 110 nm with NPs70-100-200, respectively. In general, small particles penetrate deeper and faster into the membrane [ 28 , 29 ]. Thus, for each NP size tested, the determination of MWCO is affected by the smallest NPs which are blocked in the membrane.…”

“…Furthermore, this old method requires the use of relatively expensive reagents and the precision and robustness of the latter, not yet well proven, in particular by benchmarking against the membranes available on the market. Thus, It is important to choose the mixture of solute to characterize the UF and MF membranes well, since blocking the pores of larger molecules on the surface of the membrane [ 5 , 18 , 27 ], or membrane fouling in forms of retention of large foulants [ 28 , 29 ], droplets deformability [ 30 ], and thermodynamics filtration resistance in gel/cake layer [ 30 , 31 , 32 , 33 ] can potentially selectively impede the transport of different molecular weight solutes, and therefore deflect the MWCO value from the real value [ 34 ]. In most cases, the major factor which does not allow validation of tests, with a single filtration of several components, is the possibility of concentration polarization affecting the membrane filtration [ 34 ].…”

“…This is the reason why continuous single-component filtrations to determine the MWCO are often chosen. [ 14 , 29 ]. Hermia proposed models that explain the main fouling mechanism (s) operating during filtration [ 35 ].…”

Performance evaluation of conventional membrane bioreactor and moving bed membrane bioreactor for synthetic textile wastewater treatment

“…However, one of the most significant disadvantages is membrane fouling in MBR processes, because it reduces both water quality and quantity and increases the operating costs by 60 % [ 16 , 19 , 20 ]. The membrane fouling phenomenon is very complicated and it generally occurs in forms of foulant adhesion/deposition [ [21] , [22] , [23] ] and thermodynamic filtration resistance of gel/cake layer [ 24 , 25 ]. Several factors affecting fouling such as mixed liquor properties, membrane characteristics, hydraulic conditions of the reactor, operational style, temperature and biochemical kinetic parameters [ 16 , 26 , 27 ].…”