Methane bioreactor

Methane has also been used in aerobic bioreactors that are part of a pump-and-treat operation, and toluene and phenol have also been used as co-substrates at the pilot scale (29). Anaerobic reactors have also been developed for treating trichloroethylene. Eor example, Wu and co-workers (30) have developed a successful upflow anaerobic methanogenic bioreactor that converts trichloroethylene and several other halogenated compounds to ethylene. 

Bugante, E.C. et al, Methane production from hydrogen and carbon dioxide and monoxide in a column bioreactor of thermophilic methanogens by gas recirculation, /. Perm. Bioeng., 67(6), 419,1989. 

The Biotrol methanotrophic bioreactor system is an ex situ remedial technology that uses methanotrophic bacteria to degrade contaminants in groundwater. Methanotrophs use methane... 

According to information from the vendor, Biotrol is not opened for bnsiness and the methan-otrophic bioreactor system is no longer available. 

Nemati investigated the inhibiting effect of ferrous iron on the rate of oxidation in a bioreactor packed with a polyurethane foam. Fynn and Whitmore investigated the ability of methanogen species to colonize reticulated polyurethane foam in a continuous culture system. Electron micrographs confirmed that two methanogen species colonized the matrix. The methane output was superior to a liquid culture control. 

Anaerobic bioreactors have been used since the 1880s to treat wastewaters with large amounts of suspended solids. However, anaerobic reactors are sensitive to toxic pollutants and vulnerable to process upsets, and have been used mainly for municipal sludge digestion. For methane production the sequential metabolism of the anaerobic consortia must be balanced, and the methanogens in particular are vulnerable to process upsets. Recently, anaerobic-aerobic processes (Figure 1.1) have been developed for the mineralization of xenobiotics. These processes take advantage of an anaerobic reactor for the initial reductive dechlorination of polychlorinated compounds or the reduction of nitro substituents to amino substituents. If the reduced compounds are more readily mineralized in an aerobic reactor, an anaerobic-aerobic process is feasible. 

Girnis P.R. Orphan V.J. Hallam S.J. and DeLong E.F. (2003). Growth and methane oxidation rates of anaerobic methanotrophic archaea in a continuous-flow bioreactor. Applied and Environmental Microbiology, 69, 5472- 5482. 

Strandberg G.W., Donaldson, T.L., Farr, L.L. (1989) Degradation of trichloroethylene and trans-1,2-dichloroethylene by a methan-otrophic consortium in a fixed-film, packed-bed bioreactor. Environ. Sci. Technol. 23, 1422-1425. 

LNG comes primarily from natural underground reservoirs. Significant quantities are now being recovered from both landfill sources and bioreactor sources around the world. LNG is composed predominantly of methane, which may contain minor quantities of ethane, propane, nitrogen, helium, and other components normally found in natural gas. 

For example, fixed-film bioreactors (using sand as the biofilm matrix, and methane or natural gas as the primary substrate) can remove up to 60% of trichloroethylene (TCE) from polluted water. They can also remove more than 90% of TCE and trichloroacetic acid (TCA) from vapor streams generated by the air stripping of polluted ground-water. 

Akkerman, 1. et al., Photobiological hydrogen production photochemical efficiency and bioreactor design, in Bio-methane and Bio-hydrogen, Reith, J.H., Wijfels, R.H., and Barten, H., Eds., Dutch Biological Hydrogen Eoundation, Petten, The Netherlands, 2003, chap. 6. 

An example of this configuration is filtration of the methane fermentation broth from a sewage sludge liquor [Kayawake et al., 1991]. The liquor is u eated anaerobically in a fermentor. The broth is pumped to a ceramic membrane module which is contained in the fermentor. The retentate is returned to the fermentor while the permeate is discharged to the environment This is schematically shown in Figure 8.2. Although the membrane module is enclosed in the bioreactor for compactness and process simplification, the membrane step in essence follows the fermentation step. 

Liquid-fluidized beds predate gas-fluidized beds, but they have considerably fewer applications because of a smaller number of advantages. Most applications are physical, with bioreactors being the sole significant reactor application. Much of the recent attention has focused on aerobic wastewater treatment and fermentation processes, e.g., with methane as the organic substrate (see Refs. " for more details). In these processes, microbial cells are attached to the surface of inert particles (e.g., sand or activated carbon) as a biofilm, or trapped within the pores or interior of particles, causing the particle size and/or density to vary with time. Loaded particles therefore have... 

Table 2 Integration of immobilized hydrogen production and immobilized methane production (20 g COD glucose culture medium, two sequential bioreactors, 35 °C).

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