Membrane bioreactors (MBRs) are now main stream wastewater treatment technologies. In recent times, novel pressure driven rotating membrane disc modules have been specially developed that induce high shear on the membrane surface, thereby reducing fouling. Previous research has produced dead-end filtration fouling model which combines all three classical mechanisms that was later used by another researcher as a starting point for a greatly refined model of a cross flow side-stream MBR that incorporated both hydrodynamics and soluble microbial products' (SMP) effects. In this study, a comprehensive fouling model was created based on this earlier work that incorporated all three classical fouling mechanisms for a rotating MBR system. It was tested and validated for best fit using appropriate data sets. The initial model fit appeared good for all simulations, although it still needs to be calibrated using further appropriate data sets.

Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti’s RPU-185 Flexidisks membrane bioreactor (MBR) use novel rotating membranes to assist in ameliorating it. In earlier research, this rotating process was studied by creating a simulation model based on first principles and traditional fouling mechanisms. In order to directly compare the potential benefits of this rotational system, this follow-up study was carried out using Avanti’s newly developed static (non-rotating) Flexidisks MBR system. The results from operating the static pilot unit were simulated and modelled using the rotational fouling model developed earlier however with rotational switching functions turned off and rotational parameters set to a static mode. The study concluded that a rotating MBR system could increase flux throughput when compared against a similar static system. It is thought that although the slowly rotating spindle induces a weak crossflow shear, it is still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded at the micro level and lessening the potential of rapid trans-membrane pressure increases at the macro level.

11Featured Application: Static membrane bioreactor systems do perform well in wastewater 12 treatment, but they might be supplanted in the future by newly developed rotating membrane 13 bioreactor systems that potentially have both reduced bio-fouling and subsequent energy 14 consumption. However, the current rotational simulation models that can be used for improved 15 process control are in their early stages of development and validation when compared to their 16 static counterparts.17 Abstract: Fouling by activated sludge in membrane bioreactor (MBR) processes for wastewater 18 treatment can be reduced using several strategies such as backflushing, relaxation, and chemical 19 cleaning. Some proprietary systems such as Avanti's RPU-185 Flexidisks MBR use novel circular 20 rotating, flat sheet membranes to assist in limiting this fouling. An attempt has already been made 21 to model this novel rotating fouling process by developing a simulation model based on first 22 principles and traditional fouling mechanisms. In order to directly compare the potential benefits 23 of rotational MBR system, a follow-up study was carried out using Avanti's newly developed static 24 (non-rotating) Flexidisks MBR system. This new process uses the same proprietary and patented 25 membrane modular arrangement as used in the circular rotational unit, but is configured instead as 26 a static square-shaped unit which is in-line with the more traditional and popular format used for 27 submerged flat sheet MBR systems. During this study, the results from operating the static pilot 28 unit were simulated and modelled using a standard fouling model coupled with a viscosity to 29 mixed liquor relationship model. These results were then compared with those obtained from 30 running the rotating MBR model however with rotational switching functions turned off and 31 rotational parameters set to a static mode. This comparison was done to ascertain whether the basic 32 premise of the developed rotational model was sound in empirical terms when compared to a 33 standard MBR flux model. The study concluded that relatively good agreement was reached 34 between the two types of models, thus vindicating the usage of a complex rotational MBR model. 35Follow on studies will now compare results from the rotating MBR system using rotational models 36 developed by other researchers to ascertain the effectiveness rotating MBR modelling approach. 37