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Abstract Submission Form

Desert Remedial Action Technologies

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**Title: Remediation of Mixed Chromium and TCE Releases**

**Name of First Author: Chang, Paula**

**Email of Author:** paula.chang@erm.com **Author Phone Number:**
480-998-2401

**Organization to Which Author(s) belong** ERM-West, Inc., 7272 E.
Indian School Road, Scottsdale, AZ 85207

**Conference Theme Considered Appropriate for Contents of
Presentation:** Presentation

**Other Authors (name and e-mail):** dick.brown@erm.com

### **Author Biography:** Paula Chang has 17 years of experience as a remediation engineer and technical consultant. Ms. Chang's recent project work includes data evaluation, design and subsequent installation of in situ bioremediation systems and chemical reduction via ZVI for treatment of dissolved chlorinated solvents (TCE and TCA) in ground water. She has experience at multiple sites in designing both recirculation and direct injection type bioremediation systems using both insoluble and soluble electron donors. Her past work has included stabilization of soils and ground water contaminated with chlorinated solvents and chromium and evaluation of dual-phase extraction for treatment of constituents of gasoline. 

### 

### Ms. Chang has expertise in the assessment and application of innovative and traditional technologies for remediation of sites containing complex mixtures of contaminants in soil, sediment, and ground water. She has evaluated various innovative remediation technologies including anaerobic reductive dechlorination, chemical reduction and chemical oxidation technologies for the in situ treatment of various metals, benzene, toluene, ethyl benzene, and xylenes (BETX), and chlorinated solvents, pthalates and mining leachate in ground water. She has designed and supervised the implementation of many bench-scale and pilot-scale treatability studies to determine the feasibility of specific treatment technologies under laboratory conditions. Ms. Chang has a Masters of Science and Engineering from the University of Michigan, Ann Arbor and an undergraduate degree in Geology from Wellesley College, Wellesley, Massachusetts.

**Text of the Abstract:** Many plating operations use both chromium VI
and TCE. The chromium VI is used in chrome plating. The TCE is used to
degrease parts prior to plating. As a result of these uses, plating
sites often have mixed plumes of TCE and hexavalent chromium. This
combination of contaminants can complicate remediation as some of the
remediation technologies used for one or the other contaminants are not
compatible while other other combinations can in fact be synergistic.
ERM has experience in selecting the proper technologies and in assuring
their compatibility.

The following table summarizes the technologies that are applicable to
TCE and to Chromium VI. The table also discusses the impact of the
technologies for either TCE or Cr VI on the other, non-target,
contaminant. In general TCE has many treatment options while Cr VI is
essentially treated by reduction and precipitation.

  ------------------------------------ ----------------------------------
  TCE Remediation                      

  Technology                           Impact on Chromium VI

  Pump and Treat -- Captures dissolved Chromium VI would also be
  TCE. Recovered water is treated by   recovered sisnce it is soluble. It
  air stripping, carbon, or            would also require treatment in
  bioreactors                          the recovered water. Air stripping
                                       has no effect on Cr VI. Carbon may
                                       reduce the Cr VI. Bioreactors
                                       would reduce Cr VI.

  SVE/Air Sparging -- Removes TCE by   Has no effect on Cr VI.
  volatilization                       

  Reductive Dechlorination -- A carbon The carbon amendment will also
  amendment is added which stimulates  reduce the Cr VI. High levels of
  the biological reductive             Chromium can be inhibitory to some
  dechlorination of the TCE            biological processes.

  Chemical Reduction -- uses zero      Zero valent iron and ferrous iron
  valent iron or ferrous iron minerals will both reduce Cr VI.
  to dechlorinate TCE.                 

  Chemical Oxidation -- A chemical     The oxidants can potentially
  oxidant - peroxide, permanganate, or oxidize chromium III to hexavalent
  persulfate is added to oxidize the   chromium. Sequencing of oxidation
  TCE to carbon dioxide and chloride   with any chromium reduction needs
  ion.                                 to be considered. Generally
                                       chromium reduyction would follow
                                       TCE oxidation.
  ------------------------------------ ----------------------------------

  ------------------------------------ ----------------------------------
  Chromium VI Remediation              

  Technology                           Impact on TCE

  Pump and Treat -- dissolved chromium Dissolved TCE would also be
  VI is recovered and removed from the recovered and would have to be
  water by reduction and prcipitation  treated by air stripping and/or
                                       carbon. Generally chromate is
                                       romoved separately.

  Chemical Reduction -- a chemical     Some reductants will also reduce
  reductant is added to convert Cr VI  TCE. Others are neutral
  to Cr III.                           

  Biological reduction of Cr VI to Cr  Reductive biological processes are
  III                                  generally compatible with TCE
                                       dechlorination. They may need to
                                       be done sequentially. Chromate
                                       reduction may occur before CE
                                       reduction
  ------------------------------------ ----------------------------------

Not only has ERM successfully remediated TCE and Cr VI sites, but ERM
has also remediated sites that combine both contaminants. ERM is skilled
at balancing technologies for both contaminants.