Quantifying the effects of fumarate on in situ reductive dechlorination rates

https://doi.org/10.1016/j.jconhyd.2004.07.002Get rights and content

Abstract

In situ methods are needed to evaluate the effectiveness of chemical amendments at enhancing reductive dechlorination rates in groundwater that is contaminated with the priority pollutant, trichloroethene (TCE). In this communication, a method that utilizes single-well, “push–pull” tests to quantify the effects of chemical amendments on in situ reductive dechlorination rates is presented and demonstrated. Five push–pull tests were conducted in each of five monitoring wells located in a TCE-contaminated aquifer at the site of a former chemical manufacturing facility. Rates for the reductive dechlorination of the fluorinated TCE-surrogate, trichlorofluoroethene (TCFE), were measured before (test 1) and after (test 5) three successive additions (tests 2–4) of fumarate. Fumarate was selected to stimulate the growth and activity of indigenous microorganisms with the metabolic capability to reduce TCFE and TCE. In three wells, first-order rate constants for the reductive dechlorination of TCFE increased by 8.2–92 times following fumarate additions. In two wells, reductive dechlorination of TCFE was observed after fumarate additions but not before. The transformation behavior of fumarate was also monitored following each fumarate addition. Correlations between the reductive dechlorination of TCFE and the reduction of fumarate to succinate were observed, indicating that these reactions were supported by similar biogeochemical conditions at this site.

Introduction

Significant research efforts have been devoted to the development of in situ bioremediation as an approach for remediating groundwater contaminated with the priority pollutant, trichloroethene (TCE). In anaerobic environments, this approach depends on the metabolic capability of indigenous subsurface microorganisms to catalyze the reductive dechlorination of TCE to the dichloroethene (DCE) isomers, chloroethene (CE) and ethene (Fig. 1a) (Vogel et al., 1987, McCarty, 1997, Bradley, 2000). Engineered approaches are needed where natural attenuation does not result in the complete conversion of TCE to ethene or where rates are too slow to meet risk management goals.

A common approach for enhancing in situ reductive dechlorination is to stimulate the growth of indigenous dechlorinating microorganisms with the addition of chemical amendments. A wide variety of chemicals and chemical mixtures have been evaluated for their suitability as amendments for enhancing reductive dechlorination. Lee et al. (1997) reviewed results from laboratory tests that were designed to assess the effectiveness of potential amendments such as complex organic mixtures (molasses, wastewater, cheese whey permeate, corn steep liquor and manure tea), metabolic intermediates (benzoate, lactate, propionate, acetate and butyrate), alcohols (methanol and ethanol), molecular hydrogen, sulfate, nitrate, vitamins and micronutrients. While many of these amendments were effective, disadvantages were associated with each and none were universally effective at stimulating reductive dechlorination in groundwater at all sites. To the best of our knowledge, fumarate (trans-1,2-ethenedicarboxylate) has not previously been tested as a chemical amendment for enhancing reductive dechlorination rates. There is evidence that a number of dechlorinating microorganisms use fumarate as an alternative electron acceptor (Neumann et al., 1994, Neumann et al., 1995, Scholz-Muramatsu et al., 1995, Gerritse et al., 1996, Krumholz et al., 1996, Krumholz, 1997, Miller et al., 1997, Gerritse et al., 1999) and that certain dechlorinating organisms grow faster on fumarate than on chlorinated ethenes (Gerritse et al., 1999). Some dechlorinating microorganisms are also known to use fumarate (Kengen et al., 1999) or its reduction product, succinate (1,2-ethanedicarboxylate) (Gerritse et al., 1996), as electron donors during reductive dechlorination. Hence, an objective of this work was to evaluate the effectiveness of fumarate at enhancing in situ reductive dechlorination rates.

The effectiveness of a chemical amendment is generally evaluated by comparing reductive dechlorination rates measured with and without the chemical amendment in laboratory experiments with pure or mixed cultures of microorganisms. Experiments conducted in actual aquifers are not as common because field experiments, especially those involving well-to-well tests, are perceived as complicated, expensive and/or time-consuming in comparison to laboratory experiments. In addition, in situ transformation rates are difficult to obtain because solute concentrations in groundwater are affected by both transformation and transport (advection, dispersion and sorption) processes. Nevertheless, the need for field methods that can be used to evaluate the effectiveness of chemical amendments is becoming increasingly apparent as concerns about discrepancies between laboratory and field results mount (Chapelle and Lovely, 1990, U.S. EPA, 1998, Suarez and Rifai, 1999, Washington and Cameron, 2001). Field pilot tests designed to determine in situ reductive dechlorination rates in the presence of chemical amendments (e.g. acetate, nitrate and sulfate) were reviewed by Lee et al. (1998). In all but 1 of the 13 reported pilot tests, in situ reductive dechlorination rates were determined using well-to-well tests that involved recirculating amended groundwater between injection and extraction wells.

An alternative to using well-to-well tests to determine in situ transformation rates is to use single-well, push–pull tests (Istok et al., 1997, Haggerty et al., 1998, Schroth et al., 1998, Hageman et al., 2001, Schroth et al., 2001, Kleikemper et al., 2002, Pombo et al., 2002). Push–pull tests are conducted by injecting (“pushing”) an aqueous test solution containing a nonsorbing, nonreactive tracer and one or more reactants into the saturated zone of an aquifer via a monitoring well. Samples of the test solution/groundwater mixture are then extracted (“pulled”) from the same well over time and analyzed for tracer, reactant and product concentrations. The in situ transformation rate of an injected reactant is then determined by removing the effects of transport processes from measured reactant concentrations using a data processing technique. Push–pull tests are cost-effective relative to well-to-well tests because push–pull tests require only one groundwater well per test. Additional advantages are that push–pull tests take less time to conduct than well-to-well tests since injected solutes do not have to be transported between wells and that push–pull tests can be conducted simultaneously in different wells to assess spatial variability in transformation rates. Hageman et al. (2001) described the development of push–pull tests for determining in situ reductive dechlorination rates and demonstrated the technology by conducting push–pull tests in a TCE-contaminated aquifer. The injected test solution contained trichlorofluoroethene (TCFE), which was used as a surrogate for TCE based on evidence that it undergoes reductive dechlorination by a pathway analogous to that of TCE while retaining the fluorine label (Fig. 1b) (Vancheeswaran et al., 1999). TCE itself was not injected into TCE-contaminated groundwater because mixing of the injected test solution with native groundwater would have rendered it impossible to distinguish injected and background TCE.

The overall objective of the project described herein was to use the approach presented by Hageman et al. (2001) to quantify the effects of fumarate additions on in situ reductive dechlorination rates of TCFE. To this end, TCFE reductive dechlorination rates were measured before and after three consecutive additions of fumarate in five wells located in a TCE-contaminated aquifer. Additionally, the transformation behavior of fumarate was monitored after each fumarate addition so that correlations between reductive dechlorination and fumarate transformation behavior could be assessed.

Section snippets

Chemicals

TCFE (97% pure, containing 0.1% cis-DCFE and 0.3% trans-DCFE), cis/trans-1,2-dichloroethene (DCFE) (98%) and E/Z-1-chloro-2-fluoroethene (97%) were obtained from SynQuest Laboratories (Alachua, FL). Fluoroethene (FE) (98%) was obtained from Lancaster Synthesis (Pelham, NH). Sodium fumarate (98%) and sodium succinate (99%) were obtained from Aldrich (Milwaukee, WI). Potassium bromide (99.7%) and sodium formate (99.6%) were obtained from Fisher Scientific (Fair Lawn, NJ). For use as an internal

Reductive dechlorination rates and product distribution ratios

Reductive dechlorination of TCFE occurred following its first injection into well 10A (test 1) as indicated by decreasing aqueous TCFE concentrations and increasing aqueous cis-DCFE concentrations (Fig. 2a). Trans-DCFE and (E)-CFE were also detected at relatively low concentrations (<0.05 μM). FMB-adjusted concentrations were calculated for each solute (see Section 2.5) (Fig. 2b). The exponential equation that best described the change in FMB-adjusted concentrations of TCFE over time,[TCFE]FMB=

Conclusions

This communication describes the application of a methodology for quantifying changes in in situ reductive dechlorination rates due to the addition of chemical amendments. This methodology has the potential to improve bioremediation technologies because it can be used to measure the effectiveness of bioremediation technologies in the field. To the best of our knowledge, this communication also describes the first use of fumarate in a field method designed to enhance reductive dechlorination

Acknowledgements

We thank Timothy Buscheck, Kirk O'Reilly, Ralph Reed and Mark Dolan for their contributions. Kevin Tam, Robert Alumbaugh, Brian Davis, Jesse Jones and Angelito Tirona assisted in the field. This project was funded in part by grant number 1P42 ES10338 from the National Institute of Environmental Health Sciences (NIEHS), with funds from the U.S. Environmental Protection Agency. Kimberly Hageman was supported by a training core grant from NIEHS 1P42 ES10338. The Western Region Hazardous Substance

References (34)

  • R. Haggerty et al.

    Simplified method of “push–pull” test data analysis for determining in situ reaction rate coefficients

    Ground Water

    (1998)
  • Z.C. Haston et al.

    Chlorinated ethene half-velocity coefficients (Ks) for reductive dechlorination

    Environ. Sci. Technol.

    (1999)
  • J.D. Istok et al.

    Single-well, “push–pull” test method for in situ determination of microbial metabolic activities

    Ground Water

    (1997)
  • S.W.M. Kengen et al.

    Reductive dechlorination of tetrachloroethene to cis-1,2-dichloroethene by a thermophilic anaerobic enrichment culture

    Appl. Environ. Microbiol.

    (1999)
  • J. Kleikemper et al.

    Activity and diversity of sulfate-reducing bacteria in a petroleum hydrocarbon-contaminated aquifer

    Appl. Environ. Microbiol.

    (2002)
  • L.R. Krumholz

    Desulfuromonas chloroethenica sp. nov. uses tetrachloroethylene and trichloroethylene as electron acceptors

    Int. J. Syst. Bacteriol.

    (1997)
  • L.R. Krumholz et al.

    A freshwater anaerobe coupling acetate oxidation to tetrachloroethylene dehalogenation

    Appl. Environ. Microbiol.

    (1996)
  • Cited by (16)

    • Laboratory-scale in situ bioremediation in heterogeneous porous media: Biokinetics-limited scenario

      2014, Journal of Contaminant Hydrology
      Citation Excerpt :

      Key situations in which the in situ biokinetics are likely to be the overall rate-limiting process include when the key microbial populations are inhibited and/or substrate limited, as in this work, or present in insufficient numbers. For example, electron acceptors (e.g., oxygen, nitrate, and sulfate) are often introduced into groundwater to enhance degradation of electron-donor contaminants, such as petroleum hydrocarbons (Anderson and Lovley, 2000; Hunkeler et al., 1999; Knapp and Faison, 1997; Salanitro et al., 2000), and electron donors are commonly added to create reduced conditions and stimulate reductive dechlorination of chlorinated solvents, either via direct injection of hydrogen into an aquifer (Aziz et al., 2003), or through indirect addition of hydrogen in the form of a fermentable carbon source such as lactate, fumarate, propionate, methanol, molasses, vegetable oils and cheese whey (e.g., Aulenta et al., 2005; Dyer et al., 2003; Ellis et al., 2000; Hageman et al., 2004; Hoelen et al., 2006; Romer et al., 2003). Similarly, biostimulation via nutrient addition has also been illustrated at the field-scale (Gallego et al., 2001; Menendez-Vega et al., 2007).

    • In Situ Bioremediation

      2011, Comprehensive Biotechnology, Second Edition
    • Estimating first-order reaction rate coefficient for transport with nonequilibrium linear mass transfer in heterogeneous media

      2008, Journal of Contaminant Hydrology
      Citation Excerpt :

      Quantification of contaminant degradation rates is one of the primary tasks for in situ remediation of contaminated groundwater. Simple reaction kinetics, such as zeroth- and first-order reaction kinetics, are often employed to characterize in situ reaction rates (Bekins et al., 1998; Istok et al., 2001; Hageman et al., 2004; Morrill et al., 2005). Although the estimated reaction rate coefficients are lumped parameters, which partly represent the actual reaction rates and partly account for the effects of incomplete aquifer characterization, they still provide useful information for describing the fate and transport of subsurface contaminants during the remediation operations, and thus help practitioners make optimal designs of experiments.

    • In Situ Bioremediation

      2007, Advances in Applied Microbiology
      Citation Excerpt :

      Perhaps the most successful manipulation of environmental conditions for the enhanced anaerobic natural attenuation is the addition of electron donor to create reduced conditions in order to stimulate reductive dechlorination of chlorinated solvents. Hydrogen may be directly injected into an aquifer (Aziz et al., 2003), or through the addition of electron donor in the form of a fermentable carbon source such as lactate (Ellis et al., 2000; Romer et al., 2003), fumarate (Hageman et al., 2004), or methanol (Dyer et al., 2003), which on fermentation is converted into hydrogen, which is used in the dechlorination process. Many of these applications have been successful and are today used in large scale often together with addition of inocula for the dechlorination.

    View all citing articles on Scopus
    View full text