Biodegradation of mixed-organic wastes by microbial consortia in continuous-recycle expanded-bed bioreactors

Abstract

Microbial consortia enriched from subsurface sediments contaminated with chlorinated hydrocarbons proved capable of degrading mixed-organic wastes. Methane and/or propane as foodstock enabled aerobic mineralization of greater than 20 mg L"1 trichloroethylene (TCE) plus 1 mg L"1 vinyl chloride, benzene, and toluene in cell suspension or bioreactor experiments. The microbial consortia degraded 80-95% of TCE at 20 mg L"1 within 5 days in continuous-recycle expanded-bed bioreactors requiring 50-100 mol of foodstock/mol of TCE degraded. When the bioreactors were challenged with groundwaters contaminated with mixed-organic wastes, the microbial consortia degraded greater than 99% of the benzene, toluene, xylene, vinyl chloride, and nine chlorinated hydrocarbons, 85% of the TCE, and 60% of the tetrachloroethylene within 21 days, while requiring 80 µ of methane plus propane per micromole of mixed-organic waste degraded. The potential for bioremediation of groundwater contaminated with mixed-organic wastes was demonstrated in laboratory reactors.

Biodegradation of chlorinated aliphatics and aromatic compounds in total-recycle expanded-bed biofilm reactors

“…The trichloroethylene degradation rates (in the presence of mixed waste) observed in this study are almost an order of a magnitude higher than those reported earlier from this laboratory (14). Decreased rates of trichloroethylene observed in reactor 2 after 8 d agreed well with other studies (12,13).…”

“…These studies have reported a decrease in trichloroethylene degradation rates as concentrations of trichloroethylene decreased to approx 500 #g/L. The degradation of aromatic compounds, like benzene, toluene, and xylene, was also found to be faster than found earlier in this (14). The presence of methane and propane did not seem to affect degradation of aromatics, like benzene, toluene, and xylene.…”

“…Biodegradation of trichloroethylene has been shown to be stimulated by methane and propane (7,(10)(11)(12)(13)(14). Bacterial cultures capable of degrading aromatics have been well documented (14)(15)(16)(17)(18)(19)(20)(21)(22). Biodegradation of mixed organic waste that contained trichloroethylene, benzene, toluene, and xylene in a total-recycle expanded-bed biofilm reactor is reported in this study.…”

Use of gene probes to assess the impact and effectiveness of aerobic in situ bioremediation of TCE

“…PCE while not degraded by methanotrophs, is easily degraded to TCE by anaerobic reductive dechlorination. This was demonstrated to occur in the large number of anaerobic microniches created in the subsurface by the biostimulation of methanotrophs (Phelps et al, 1990;Enzien et al, 1994;Pfiffner et al, 1997;Hazen, 1999) in bulk aerobic environments. Thus stimulation of methanotrophs will result in significant biodegradation of PCE.…”

Immobilized lysozyme protein on fibrous medium: Preliminary results for microfiltration applications

“…Numerous compounds such as chemical residues, organic matter, and fouling of tiny sizes are hardly retained by a filter medium, being, in most of cases, responsible for levels of toxicity commonly detected in drinking water (Mallevialle, 1996). A possible way to enhance removal effectiveness is to combine the separation process with the presence of living organisms, biopolymers or natural biofilms coatings in the filter cake, promoting *Corresponding author interactions at molecular level (Bryers et al 1990;Phelps et al 1990;Weber-Shirk and Dick, 1997). The biopurification process is a very desirable clean-up technology employing active elements for in-situ removal, not only of bacteria and viruses but also for the degradation of chemical residues such as fertilizer and herbicide contaminants in water and soil (Bollag, 1996).…”