Membrane-Attached Biofilms

Livingston, A.G., Freitas dos Santos, L., Membrane attached biofilms for desctruction of volatile oragnic compounds (VOC), Proc. 3rd Asia Pacific Biochemical Eng. Cong, Singapore, 1994. 

Freitas dos Santos, L.M., Livingston, A.G., Membrane attached biofilms novel technique for measurement of biofilm thickness, density and diffusivity, Proc. lAWQ Conf. Workshop on Biofilm Structure, Growth and Dynamics - Need for New Concept , Noordwijkerjout, The Netherlands, August 1995. 

Freitas dos Santos, L.M., Pavasant, P., Pistikopoulos, E.N., Livingston, A.G., Growth of immobilised cells results and predictions for membrane-attached biofilms using a novel in situ biofilm thickness measurement technique. Immobilised Cells Basics and Applications, Ed. Wijfells, R.H., Buitelaar, R.M., Bucke, C., Tramper, J., Progess in Biotech. 11, pp.290-297, 1996. 

Novel Membrane Bioreactors Membrane Attached Biofilms. 1018... 

NOVEL MEMBRANE BIOREACTORS MEMBRANE ATTACHED BIOFILMS... 

Mathematical modeling can help us understand and design MBfRs. Several researchers have developed mathematical models to further understand processes occurring in membrane-attached biofilms and how operating conditions affect performance. Most modeling efforts have focused on the oxygen-based MBfR. 

Emanuelsson, E. A. C. and Livingston, A. G. 2002. Study of membrane attached biofilm performance with nitrate as electron acceptor. Desalination, 149,211-215. 

Freitas Dos Santos, L. M. and Livingston, A. G. 1995a. Membrane-Attached biofilms for VOC wastewater treatment. II Effect of hiofilm thickness on performance. Biotechnology and Bioengineering, 47,90-95. 

The importance of biopolymer deposition on the membrane has been highlighted by Chu and Li [34] who noted that such material may accelerate bacterial attachment to the membrane in addition to its contribution to fouling resistance. The formation of a slime layer on the membrane, comprising an EPS matrix with embedded bacteria, may be analogous to a biofilm, the significance of which is the difficulty of its removal by nonchemical methods. The question of whether biofilm formation plays a significant role in MBRs is yet to be addressed. Indeed, a comprehensive model of fouling in MBRs is not yet available. 

The dissolved gas phase then has to dilfnse through the biofilm, and the reaction is allowed to occur. The biofilm is usually attached to the membrane rather than being allowed to float (Henstra et al., 2007). Additional problems are created because any by-products, which may be toxic if they are allowed to concentrate, have to leave the reactor through the same manner. In other words, microbial operation may have significant effects on the gas phase concentrations (gas-liquid mass transfer driving force), which could become an additional restriction on total gas-Uquid mass transfer (Kumar et al., 2008). 

Preventive sanitisation is much more effective than corrective disinfection because a single attached bacteria is easier to kill and remove than a biofilm. Membrane life is shortened by extensive sanitisation. 

In medium risk systems, regular preventative cleanings may take the place of or be done in addition to biocide addition. Single attached bacteria are easier to remove than full biofilm. This approach requires a cleaning system and unit downtime. It has a moderate chemical cost but is more labor intensive. Depending on the frequency required and the chemicals used for cleaning, membranes may degrade faster. ... 

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