Biodegradation of chlorinated aliphatic hydrocarbon mixtures in a single-pass packed-bed reactor

Abstract

Aliphatic chlorinated compounds, such as trichloroethylene (TCE) and tetrachloroethylene (PCE), are major contaminants of ground water. A single-pass packed-bed bioreactor was utilized to study the biodegradation of organic waste mixtures consisting of PCE, TCE, and other short-chain chlorinated organics. The bioreactor consisted of two 1960-mL glass columns joined in a series. One column was packed with sand containing a microbial consortia enriched from a contaminated site. The other column provided a reservoir for oxygen and a carbon source of methane/propane that was recirculated through the reactor. Sampling was accomplished by both direct headspace and liquid effluent concentration analyses. The reactor was operated in a single-pass mode. Greater than 99% degradation of trichloroethylene, approaching drinking water standards, was observed when the bioreactor residence time ranged from 1.9 to 3.2 d. Typically, when the reactor was pulse-fed with methane, propane, and air, 1 mol of TCE was degraded/110 mol of substrate utilized. Perturbation studies were performed to characterize reactor behavior. The system's degradation behavior was affected by providing different carbon sources, a pulse feeding regime, supplementing microbial biomass, and by altering flow rates.

Chloroform aerobic cometabolism by butane-growing Rhodococcus aetherovorans BCP1 in continuous-flow biofilm reactors

“…For example, while our " R 000 CAH " c CAH varied between 2.1 and 14 day -1 , in a study of CAH cometabolism by a methane-growing consortium in a packed bed reactor Lackey et al [42] obtained an " R 000 CAH " c CAH ranging between 0.22 day -1 for trichloroethylene (TCE) and 0.50 day -1 for CF; in another study of TCE cometabolism by methanotrophs in a sand-filled column Fayolle et al [43] obtained an " R 000 CAH " c CAH of 0.007 day -1 ; AlvarezCohen and McCarty [41] evaluated a " R 000 CAH " c CAH equal to 1.8 day -1 for TCE cometabolism by suspended cells of a methane-utilizing consortium. Similarly, the mass ratio of CAH degraded to substrate consumed varied between 0.01 and 0.03 in the above-cited studies, versus a 0.03-0.17 range in this work.…”

Long-term aerobic cometabolism of a chlorinated solvent mixture by vinyl chloride-, methane- and propane-utilizing biomasses

“…[3][4][5][6][7]) or the shortterm transformation of binary or ternary CAH mixtures [1,2,8,9], the long-term aerobic biodegradation of complex CAH mixtures was investigated in a limited number of studies (e.g. [10,11]). High-chlorinated CAHs, such as carbon tetrachloride (CT), 1,1,1,2-and 1,1,2,2-tetrachloroethane (1,1,1,2-and 1,1,2,2-TeCA) and perchloroethylene (PCE) are generally considered non-biodegradable in aerobic conditions [12][13][14].…”

Bioremediation of Trichloroethylene and cis-1,2-Dichloroethylene-Contaminated Groundwater by Methane-Utilizing Bacteria.

“…1, no change occurred Chlorinated short-chain aliphatic compounds such as trichloroethylene (TCE) and cis1,2-dichloroethylene (DCE) are major contaminants of groundwater. Because of the carcinogenic effect and the toxicity to the nerve system of these compounds [15,21,22], U.S. Environmental Protection Agency (EPA) revised the maximum permissible concentrations in water to be close to the lowest analytical limit [10]. As for influences of trichloroethylene to livestock, the studies are advanced especially those on chickens.…”