Biofilm reactors

Use of biofilm reactors for ethanol production has been investigated to improve the economics and performance of fermentation processes.8 Immobilisation of microbial cells for fermentation has been developed to eliminate inhibition caused by high concentrations of substrate and product, also to enhance productivity and yield of ethanol. Recent work on ethanol production in an immobilised cell reactor (ICR) showed that production of ethanol using Zymomonas mobilis was doubled.9 The immobilised recombinant Z. mobilis was also successfully used with high concentrations of sugar (12%-15%).10... 

Simultaneous degradation of 2,4- and 2,6-DNT has been achieved in a fluidized-bed biofilm reactor (Lendemann et al. 1998) that was successfully operated with contaminated groundwater containing 2- and 4-nitrotoluenes and 2,4- and 2,6-DNTs. The nitrite that was produced during degradation was recovered as nitrate. 

Reactors which generate vortex flows (VFs) are common in both planktonic cellular and biofilm reactor applications due to the mixing provided by the VF. The generation of Taylor vortices in Couette cells has been studied by MRM to characterize the dynamics of hydrodynamic instabilities [56], The presence of the coherent flow structures renders the mass transfer coefficient approaches of limited utility, as in the biofilm capillary reactor, due to the inability to incorporate microscale details of the advection field into the mass transfer coefficient model. 

Case 3 Leachate Treatment Using an Aerobic Biofilm Reactor. 583... 

The use of an attached growth aerobic biofilm reactor to treat leachate is relatively new. Past studies on anaerobic biofilters showed excellent organic removal up to 90%, and the retention time needed to treat high-strength effluent was between 3 and 5 d. The use of aerobic biofilters using... 

FIGURE 15.2 Schematic diagram of leachate treatment using an attached growth biofilm reactor. 

Idris, A. and Abdullah, A.G.L., Leachate Treatment Using Aerobic Biofilm Reactor, Proc. JSPS-VCC Seminar on Water Resource Management, Kota Kinabalu, Malaysia, 2001. 

Kryst K, Karamanev DG (2001) Aerobic phenol biodegradation in an inverse fluidized-bed biofilm reactor. Ind Eng Chem Res 40 5436—5439... 

Delnavaz M, Ayati B, Ganjidoust H (2008) Biodegradation of aromatic amine compounds using moving bed biofilm reactors. Iran J Environ Health Sci Eng 5(4) 243-250... 

Coelhoso, I., Boaventura, R., and Rodrigues, A., Biofilm Reactors An Experimental and Modeling Study of Wastewater Denitrification in Fluidized-Bed Reactors of Activated Carbon Particles, Biotechnol. Bioeng., 40 625 (1992)... 

Denac, M., and Dunn, I. J., Packed- and Fluidized-Bed Biofilm Reactor Performance for Anaerobic Wastewater Treatment, Biotechnol. Bioeng., 32 159 (1988)... 

Nikolov, L., and Karamanev, D. G., The Inverse Fluidized Bed Biofilm Reactor A New Laboratory Scale Apparatus for Biofilm Research, J. Ferm. Bioeng. 69 265 (1990)... 

A Selected Case Study Pseudomonas Biofilm Reactor... 

Mixed liquor from a municipal WW treatment plant Acid orange 8 Acid orange 10 Acid red 14 Rotating drum biofilm reactor Continuous Aerobic B Drum 22 7... 

Among the wide choice of reactor designs, the biofilm reactor is one of the best suited for azo-dye conversion as it meets two important process requisites. The first is related to the hindered growth feature of bacterial metabolism under anaerobic conditions. The second is related to the necessity to increase cell densities (see previous section) with respect to those commonly harvested in liquid broths [55, 56]. Except for bacteria that forms aggregates spontaneously, immobilization of cells on granular carriers and membrane reactor technology are the two common pathways to achieve high-density confined cell cultures in either discontinuous or flow reactors. 

Table 1 reports a wide spectrum of typologies of biofilm reactor upflow anaerobic sludge bed (UASB), fluidized bed, airlift, fixed bed with and without recycle, mechanically agitated vessel, rotating drum and rotating biological contactor. Each reactor is characterized by positive features and drawbacks. 

A Selected Case Study Pseudomonas Biofilm Reactor for the Conversion of Acid Orange 7... 

A dynamic model has been developed to simulate the behavior of a Pseudomonas sp. 0X1 biofilm reactor for phenol and azo-dye conversion during the aerobic-anaerobic cyclic operation. Phenol and oxygen were considered as the limiting substrates for growth kinetics. 

External mass transfer resistance was neglected, as reported by [63] in biofilm reactors with granular particles (fluidized bed, airlift) the Biot number was generally larger than 100. 

Nicolella C, van Loosdrecht MCM, Heijnen JJ (2000) Wastewater treatment with particulate biofilm reactors. J Biotechnol 80 1-33... 

Qureshi N, Annous BA, Ezeji TC et al (2005) Biofilm reactors for industrial bioconversion processes employing potential of enhanced reaction rates. Microb Cell Fact 4(24) 1-21... 

Viggiani A, Olivieri G, Siani L et al (2006) An airlift biofilm reactor for the biodegradation of phenol by Pseudomonas stutzeri OX1. J Biotechnol 123 464 -77... 

The example of a biofilm reactor setup shown in Figure 7.1 demonstrates how an experiment can be performed under controlled conditions (Raunkjaer et al., 1997). The objective of the study is to determine substrate (acetate) and DO surface removal rates of biofilms that were grown on wastewater. Careful control is needed to do so during conditions where both the substrate and the DO should be studied as limiting factors for the removal rates. A great number of specific details that will not be dealt with here were considered for this experiment. 

Biofilm (cellulose-based temporary skin substitute), 5 364 Biofilm reactor, defined, 3 758t Biofilms, 26 128... 

New process designs, such as the biofilm reactors, encourage different species to live in proximity to one another and the result is a much higher rate of conversion per nnit volume of reactor, although not yet optimal. Biofilms also permit a diversity of environments to develop in proximity to one another so that snitable conditions for the degradation of each substrate and intermediate can exist somewhere within the biofilm. 

Kurt, M., Dunn, I. J. and Bourne, J. R. (1987) Biological denitrification of drinking water using autotrophic organisms with H2 in a fluidized- bed biofilm reactor. Biotechnol. Bioeng. 29, 493-501. 

Industrial hazardous wastewater can be treated aerobically in suspended biomass stirred-tank bioreactors, plug-flow bioreactors, rotating-disc contactors, packed-bed fixed-biofilm reactors (or biofilters), fluidized bed reactors, diffused aeration tanks, airlift bioreactors, jet bioreactors, membrane bioreactors, and upflow bed reactors [28,30]. 

Nogueira, R. Melo, L.F. Purkhold, U. Wuertz, S. Wagner, M. Nitrifying and heterotrophic population dynamics in biofilm reactors effects of hydraulic retention time and the presence of organic carbon. Water Res. 2002, 36, 469-481. 

Helbe, A. Schlayer, W. Liechti, P.-A. Jenny, R. Mobius, C.H. Advanced effluent treatment in the pulp and paper industries with a combined process of ozonation and fixed bed biofilm reactors. Water Sci. Technol. 1999, 40 (11-12), 345-350. 

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