Fixed film reactors

In the fixed-film reactor, the organisms grow on an inert surface that is maintained in the reactor. The inert surface can be gramJar material, proprietary plastic packing, rotating discs, wood slats, mass-transfer packing, or even a sponge-type material. The reacior can be flooded or have a mixed gas-hquid space (Fig. 25-52). The biomass level on the... 

An illustration of a fixed-film reactor system is presented in Figure 24. 

Residuals Produced The residuals produced in a fixed-film reactor are normally small when compared to the residuals produced in a suspended growth system. There can be some sloughing of biomass during system ojjerations, and this may need to be separated from the effluent. The residuals, depending on site-specific requirements, may require additional treatment prior to ultimate disposal. 

Technology Description Hybrid reactors, as the name implies, are a combination of suspended growth and fixed-film reactor principles. In these systems, the fixed film is submerged and the reactor contents are continuously stirred. A large amount of biomass is maintained in the system. 

Henriksen HV, S Larsen, BK Ahring (1991) Anaerobic degradation of PCP and phenol in fixed-film reactors the influence of an additional substrate. Water Sci Technol 24 431 36. 

Massol-Deya A, R Weller, L Rfos-Hernandez, J-Z Zhou, RE Hickey, JM Tiedje (1997) Succession and convergence of biofilm communities in fixed-film reactors treating aromatic hydrocarbons in groundwater. Appl Environ Microbiol 63 270-276. 

Austermann-Haun, U., Seyfried, C. F., Zellner, G., and Diekmann, H., Start-Up of Anaerobic Fixed Film Reactors Technical Aspects, Wat. Sci. Tech., 29(10-11) 297 (1994)... 

ACPCI Alexandra Company for Pharmaceutical and Chemical Industry AMFFR anaerobic mesophilic fixed film reactor... 

ATFFR anaerobic thermophilic fixed film reactor... 

Seif, H.A.A. Joshi, S.G. Gupta, S.K. Effect of organic load and reactor height on the performance of anaerobic mesophilic and thermophilic fixed film reactors in the treatment of pharmaceutical wastewater. Environ. Technol. 1992, 13, 1161-1168. 

Seif, H.A.A. Comparative Study on Treatment of Pharmaceutical Wastewater by Anaerobic Mesophilic and Thermophilic Fixed Film Reactors. Ph.D. thesis, CESE, III, Bombay, India, 1990. 

The BIOX biotreater is a commercially available, ex situ technology for the treatment of wastewater, groundwater, and surface water containing organic contaminants. The BIOX biotreater is a biological submerged, fixed-film reactor capable of aerobic, anoxic, or anaerobic operation. 

The treatment of PAH-contaminated soil in a reactor environment is basically limited to the use of soil slurry reactors. Conversely, many different bioreactor designs exist for the treatment of water contaminated with PAHs. As reviewed by Grady (1989) and Grady Lim (1980), these include fixed film reactors, plug flow reactors, and a variety of gas-phase systems, to name a few. Given the depth and magnitude of such a topic, for the purposes of this review discussions will be limited to a generic overview of reactor applications for PAH bioremediation. 

Tremaine et al. (1994) conducted pilot-scale studies to compare the effect of a suspended-growth reactor and a fixed-film bioreactor with a constructed wetland environment in removing creosote-PAHs from contaminated water recovered from a wood-preserving facility. Mass balanced chemical analysis of 5 PAHs used as model constituents of creosote showed that the wetland yielded between 20 and 84% removal, whereas the fixed-film reactor yielded 90 to 99% PAH removal. Biodegradation accounted for >99% of the losses observed in the fixed-film reactor, but only 1-55% of the compounds removed in the artificial wetland was attributable to biodegradation. Again, physical sorption of PAHs, especially HMW PAHs, was found to be significant. 

Anaerobic treatment of CP-containing liquids has been reported in fixed-film reactors (Hend riksen et al., 1991) and upflow anaerobic sludge bed reactors (UASB) with anaerobic granular sludge, resulting in less-chlorinated phenols (Hendriksen etal., 1992 Mohn Kennedy, 1992 Woods etal., 1989) or mineralization (Wu et al., 1993). WithMCPs, the UASB treatment resulted in mineralization (Krumme Boyd, 1988). UASB had better PCP removal efficiency and stability than anaerobic fixed-film reactors (Hendriksen Ahring, 1993). Anaerobic remediation always requires the addition of an external electron donor. 

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