Methanogenic and perchloroethylene-dechlorinating activity of anaerobic granular sludge

Abstract

The biodegradation and toxicity of tetrachlorethylene (C2Cl4) and trichloroethylene (C2HCl3) were studied with different anaerobic enrichment cultures using the following electron donors: acetate, propionate, butyrate, methanol, formate and hydrogen. All of them sustained dechlorination except propionate, for which C2Cl4 biodegradation rates were not significant. The best results were obtained with butyrate. Hydrogen appeared to be a relevant electron donor for dechlorination with the present cultures. In the presence of specific inhibitors such as bromoethanesulphonate or molybdate, a slight inhibition of dechlorination was observed. According to dechlorination kinetics, Monod-type behaviour was observed up to 120 microM C2Cl4 or 200 microM C2HCl3 with Ks values around 7 microM for both compounds. Dechlorination was partially inhibited at higher concentrations. In contrast, methanogens, or at least methane production, were more sensitive to the presence of chlorinated ethylenes and inhibitions of methanogenesis was observed to different extents over all the C2Cl4/C2HCl3 concentration range tested, even at the lowest concentrations.

Demonstration of Enhanced Bioremediation in a TCE Source Area at Launch Complex 34, Cape Canaveral Air Force Station

“…During most of the period of electron donor addition, methane concentrations did not increase; however, during the bioaugmentation phase of the study, an increase in methanogenesis occurred subsequent to the onset of ethene production (average methane concentration, 14 mg/L). The inhibition of methanogenesis prior to the onset of ethene production is consistent with the results of prior studies indicating that methanogenesis is inhibited by high chloroethene concentrations (e.g., Nielsen and Keasling 1999;DiStefano et al 1991;Yang and McCarty 2002;Lee et al 1997;Kennes et al 1998).…”

Bioreactors for Waste Gas Treatment

“…Maximal styrene elimination capacities around 62-90 g/m .h were reached (Cox et al , 1997). Similar results were obtained in the presence of an alkylbenzene degrading culture composed of mixed populations of bacteria, yeasts and filamentous fungi (Figure 3.7) (Veiga et al, 1998;Veiga and Kennes, 2001a). Some examples of yeasts and fungi inoculated in vapour phase bioreactors appear in Table 3.9.…”

Dechlorination of TetrachloroetheneInfluence of Tetrachloroethene and Methane in Batch Cultivation under Methanotrophic Conditions in the Presence of Oxygen

“…Others report on dechlorination PCE concentrations of between 3 µmol/l and 170 µmol/l PCE [19,20]. KENNES et al found the optimum concentration of PCE for degradation to be between 50 µmol/l and 120 µmol/l PCE [3]. KENGEN et al used PCE concentrations similar to those being dechlorinated in this study.…”

“…Tetrachloroethene (PCE), a common organic pollutant found in aquifers [1][2][3][4], is only degradable under anaerobic conditions [5]. Cometabolic [6,7] and respiratory [8][9][10] transformations are known.…”