TEA to present at Battelle Miami
TEA to present at Battelle Miami
Fourth International Symposium on Bioremediation and Sustainable Environmental Technologies
May 22-25, 2017 | Miami, Florida
Below are the three abstracts that were selected to be presented at the Fourth International Symposium on Bioremediation and Sustainable Environmental Technologies.
Comparison of Biological, Biogeochemical and In Situ Chemical Reduction for Treatment of Mixed Chlorinated Ethenes and Methanes
Grace Su, Michael Tischuk (TEA, Inc., Moraga, CA, USA)
Audrey Sidebottom (The Dow Chemical Company, Fort Saskatchewan, AB, Canada)
Sandra Owen, Brianna Desjardins (PeroxyChem, Tonowanda, New York, USA)
Dan Leigh (PeroxyChem, Walnut Creek, CA, USA)
Background/Objectives Soil and groundwater at a chemical manufacturing facility in Northern California have been impacted by high concentrations (>100 mg/L) of mixed organics consisting of chlorinated ethenes (CEs) and chlorinated methanes (CMs). Ongoing treatment of the site groundwater has primarily consisted of biologically mediated reductive dechlorination using propylene glycol (PG) as an electron donor. While PG has been an effective electron donor, alternate remedial approaches are being tested to optimize the remedial process.
Approach/Activities. A bench test was conducted to evaluate three remedial approaches including biological only (BIO), biogeochemical (BGC) and in situ chemical reduction (ISCR) to treat the observed contaminants. Site groundwater, with up to 44 mg/L of CEs and 70 mg/L of CMs, was added to each test and a control. In each active process (BIO, BGC and ISCR) test, a combination of 10% PG and 90% emulsified lecithin substrate (ELS™), and a dechlorination microbial culture (SDC-9™) was added to site groundwater to enhance biological processes. In addition, the BGC test also included a soluble organic iron and sulfate source to generate reactive iron sulfides. The ISCR test included zero valent iron to enhance direct abiotic degradation processes.
Results/Lessons Learned. Upon mixing the substrates, highly reducing conditions (-500 mV) were established in each of the tests. The BGC and ISCR bottles turned black by Day 14 and Day 42, respectively, indicating the precipitation of iron sulfides.
Carbon tetrachloride (CT) was reduced from 38,000 μg/L to 180 μg/L (99.5%) in less than 42 days in the BGC test without production of chloroform (CF) nor methylene chloride (MC). CT was reduced by 99.8% to 42 μg/L in less than 42 days in the ISCR test. Less than stoichiometric production of CF production was observed which was subsequently degraded in the ISCR tests.
Tetrachloroethene (PCE) was reduced in both the BGC (94%) and ISCR (88%) tests by Day 42. However, trichloroethylene (TCE) was only generated in the ISCR test suggesting an initial biological reduction process in that test with primarily abiotic degradation in the BGC. Significant CM and CE reduction was not observed by Day 42 in the BIO test. Carbon disulfide was observed in the BGC test suggesting reduction of CT by contact with reactive iron sulfides.
Although biological processes have been demonstrated to effectively treat the contaminants at the site, the addition of an iron source substantially increased the degradation of both the CEs and CMs in the bench test. The BGC degradation of CT occurred without the production of daughter products. The presence of CT was considered to be responsible for the early inhibition of biological degradation of CEs. It is anticipated that as CT is reduced, CEs reduction will increase. The bench test indicate that both BGC and ISCR can substantially enhance treatment. The test is ongoing and the presentation will compare bench test and field observations.
Novel Monitoring Data Presentation Method Provides a Simplified View of the Approach to Compliance Levels
Amy H. Bass, Les Porterfield, P.E. (email@example.com),
John D. Schell, Ph.D., and Bradley F. Droy, Ph.D. (TEA Inc., Santa Rosa Beach, FL, USA)
Background/Objectives. The presentation of monitoring data for groundwater remediation sites generally involves numerous data plots that can be tedious to present and interpret. This can be particularly problematic where there are multiple constituents and, as with the example site to be presented, multiple target goals for each contaminant. A simplified, straightforward method of data presentation has been developed to clearly show the decrease of the various contaminant concentrations to compliance levels, each to the appropriate and relevant compliance level, simultaneously on a single plot. Where the contaminants represent a parent compound and the degradation products (as at the example site), presentation on a single plot in this manner can also clearly illustrate the ongoing dynamics of the degradation process. This results in more succinct discussion in the monitoring report and easier interpretation by reviewers – a win-win outcome!
Approach/Activities. The data analysis is based on a parameter we have termed the Relative Exceedance (REx). For each Result that exceeds the relevant Goal, the Relative Exceedance is calculated as shown: Relative Exceedance (REx) = (Result – Goal) / Goal
The Goal might be the same for all the Results, or it might vary based on well depth, location, exposure potential, or other consideration, for each Result. The REx values for each constituent are then averaged to derive the Mean Relative Exceedance (MREx) for that constituent, which is the parameter presented in the data plots (as a function of time). The time-related behavior of the MREx values for each constituent, along with the time-related Number of Exceedances (NEx) (the total number of Results that exceeded the relevant Goal), provides useful information regarding the approach toward compliance and presents it in a clearly understood manner. As the constituent concentrations approach the Goals, the MREx and NEx plots will approach zero – simple! When all the constituent MREx and NEx plots go to zero, compliance has been obtained, and it’s time to begin site closure.
Results/Lessons Learned. The MREx method was developed to facilitate interpretation of the groundwater monitoring data for a site in central Florida, which had been impacted by trichloroethene (TCE) in the surficial aquifer. The site had undergone in-situ remedial action (to destroy TCE and accelerate the subsurface degradation process) and was entering the monitoring-only phase for TCE and its degradation products, cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC). Site-wide and off-site monitoring was ongoing, with wells clusters that characterized groundwater at 3 depths (shallow, intermediate, and deep) within the surficial aquifer. This site presented particularly challenging data presentation needs for the following reasons: (a) 3 constituents of concern, related through the degradation process; (b) 2 sets of Risk-Based Goals – one set applicable to just the shallowest groundwater and the other set applicable to all groundwater depths; (c) consideration of State Criteria for “poor-quality” groundwater, which were conditionally applicable (with institutional controls); and (d) presentation of State Criteria for drinking-water quality groundwater, the ultimate remedial goal for all groundwater of the State. This site will be used as a case study to explain the application of the MREx method and to illustrate the value it can provide in simplifying and clarifying the data presentation and interpretation.
The Effect of Emulsified Zero Valent Iron on Trichloroethene in the Presence of Chlorofluorocarbon 113
Les Porterfield, P.E. (firstname.lastname@example.org) and Bradley F. Droy, Ph.D. (TEA Inc., Santa Rosa Beach, FL);
Cherie Yestrebsky, Ph. D. (University of Central Florida, Orlando, FL);
Jeff Roberts, M.Sc. (SiREM, Guelph, ON)
Background/Objectives. It has been widely reported that 1,1,2-trichloro-1,2,2-trifluoroethene (CFC-113) in groundwater can be inhibitory to the anaerobic biodegradation of chlorinated ethenes. Emulsified Zero Valent Iron (EZVI) has been shown to be effective at degrading trichloroethene (TCE) as Dense Nonaqueous Phase Liquids (DNAPL). A field evaluation was conducted on the effects of EZVI and other amendments on TCE degradation in the presence of CFC-113 in shallow groundwater.
Approach/Activities. The approach involved assessing post-remediation monitoring results from the implementation of a remediation injection scheme with multiple reagents which included EZVI (for DNAPL treatment), vegetable oil, and KB-1® bacteria culture (SiREM) as remediation amendments to enhance the biogeochemistry of the subsurface and accelerate the reductive dechlorination reactions. EZVI was injected to treat the residual DNAPL source in the subsurface; KB-1® bacteria culture was injected to bioaugment the existing dechlorinating bacteria, and vegetable oil was injected to provide additional carbon for the microbial populations. A detailed review of the groundwater monitoring system results was used to assess the effectiveness of the TCE treatment and to evaluate the potential inhibitory effects of CFC- 113.
Results/Lessons Learned. The results indicate that the inhibition of TCE dechlorination by CFC-113 when treated with EZVI in an anaerobic reductive environment did not occur. The EZVI treatment for the TCE DNAPL and the addition of the KB-1® bacteria culture was successful in treating the TCE with no perceived inhibition, and also resulted in the simultaneous reduction in CFC-113. These results are being used in an ongoing laboratory treatability study with subsequent supporting field data using EZVI to remediate a DNAPL source, also containing free product levels of CFC-113, with KB-1® Plus culture capable of degrading CFC-113 and TCE. Results from the field application and laboratory evaluation will be presented and lessons learned discussed.
Contact us for a copy of any of the posters or for more information.