Ryan Thacher
Ryan Thacher, Ph.D.
Manager
Environmental & Earth Sciences
  • Orange County


Dr. Thacher specializes in groundwater remediation systems for toxic metal contamination, and the effects of natural groundwater constituents on these systems. He has studied the removal of hexavalent chromium and hexavalent uranium from water using zero-valent iron nanoparticles (nZVI), and the economic advantages of pre-concentrating contaminants in the subsurface prior to nanoparticle addition using electrokinetic transport technology. Dr. Thacher has experience in dual-chamber microbial fuel cells (MFCs) for groundwater remediation applications, as well as benthic microbial fuel cells (BMFCs) for powering small electronics packages. He has experience in numerical modeling of contaminant fate using MATLAB, flow through porous media using MODFLOW, and has performed chemical equilibria studies using PHREEQC.

Dr. Thacher’s graduate research was in the electrokinetic transport of metal contaminants through soil media, and integration with treatment technologies. As part of this work he explored the efficiency of zero-valent iron nanoparticle injection for remediation applications, with an emphasis on optimizing injection by integration with electrokinetic transport phenomena. This research included a comprehensive analysis of the effects of natural organic matter (NOM) on nZVI as a remediation tool. He also designed, fabricated, and operated MFCs as an ex situ groundwater remediation option, and evaluated the feasibility of integrating MFCs with electrokinetic transport systems. Additionally, this work researched the benefits of NOM serving a multi-functional role as an electron shuttle and a terminal electron acceptor in MFCs. During a research position with the Space and Naval Warfare System Command (SPAWAR) System Center Pacific he worked in a small team designing, fabricating, and testing a field-scale BMFC for powering submersible electronics.

CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Engineering, University of Southern California, 2013
  • M.S., Environmental Engineering, University of Southern California, 2009
  • B.S., Chemical Engineering, University of California, Santa Barbara, 2007
  • USC Viterbi Undergraduate Mentoring Research Award, 2013

    USC Sonny Astani School of Civil and Environmental Engineering Best Teaching-Assistant Award, 2011

Publications

Thacher R, Hsu S, Ravindran V, Nealson K, Pirbazari M. Modeling the transport and bioreduction of hexavalent chromium in aquifers: Influence of natural organic matter. Chemical Engineering Science 2015; in press.

Hsu L, Chadwick B, Kagan J, Thacher R, Wotawa-Bergen A, Richter K. Scale up considerations for sediment microbial fuel cells. RSC Advances 2013, in press. Epub ahead of print: http://pubs.rsc.org/en/content/articlelanding/2013/RA/C3RA43180K.

Posters and Presentations


Hsu L, Thacher R, Wotawa-Bergen A, Kagan J, Bell R, Arias-Thode M. Analysis of solid and fiber brush graphite and carbon cloth as cathode materials for benthic microbial fuel cells. Association for Environmental Health and Sciences Foundation, 24th Annual International Conference on Soil, Water, Energy, and Air, Abstract reference No. 0192-000167, San Diego, CA, March, 2013.

Thacher R, Pirbazari M. Hexavalent chromium remediation by electrokinetic transport and zero-valent iron nanoparticle injection: Effects of organic and inorganic groundwater constituents. Presented at the AIChE Annual Meeting, Pittsburg, PA, October 28–November 2, 2012.

Thacher R, Hsu L, Pirbazari M. Integrated electrokinetic and microbial fuel cell technologies for enhanced transport and bioremediation of hexavalent chromium in groundwater. Presented at the AIChE Annual Meeting, Pittsburg, PA, October 28–November 2, 2012.

Gray H, Thacher R, Ravindran V, Pirbazari M. Removal of radioactive uranium from groundwater using nanoparticle technology and bioremediation strategies. AIChE Annual Meeting, Pittsburg, PA, October 28–November 2, 2012.

Thacher R, Pirbazari M. Evaluating the dynamics of an integrated electrokinetic and zero-valent iron nanoparticle system for treatment of hexavalent chromium in groundwater. Presented at the AIChE Annual Meeting, Minneapolis, MN, October 16–21, 2011.

Thacher R, Chan C, Hsu L, Pirbazari M. Transport and remediation of chromium (VI) in groundwater using an integrated electrokinetic and nanoscale particle technology. Presented at the AIChE Annual Meeting, Minneapolis, MN, October 16–21, 2011.

Hsu L, Thacher R, Yokota-Joshi A, Wong A, Nealson KH, Pirbazari M. Evaluation of a novel bioremediation process coupling an electrokinetic system with microbial fuel cell technology. AIChE Annual Meeting, Salt Lake City, UT, November 7–12, 2010.


Prior Experience

Graduate Research Assistant, University of Southern California, 2010–2013

Naval Research Enterprise Internship Program, Space and Naval Warfare System Command (SPAWAR) System Center Pacific, Summer 2012

Water Resource Engineer Intern, Los Angeles Regional Water Quality Control Board, 2009–2010

Professional Affiliations

American Institute of Chemical Engineers—AIChE (member, 2005–2015)

American Water Resources Association—AWRA (member, 2013–2015)

Project Experience

Compiled relevant information and analyzed data from nearly 900 sources for an ongoing study investigating temporal and spatial changes in hydrocarbon chemistry for a large stretch of shoreline.

Provided an analysis of the timing and occurrence of how hazardous materials came to be located at a property in Waianae, Hawaii. Contamination included used lead-acid batteries; sandblast material; wrecked autos and associated petroleum; and oil, lubricants, painting wastes, and solvents. Additionally, several burn pits were located on the property. The site underwent an emergency remedial action following a raid by the EPA Criminal Investigation Division (CID).

Assisted in an evaluation of the metals distributions in sediments, soil, and dust in the upper Columbia River drainage basin. Numerous mines, mills, and smelters operated in this area. Metals contributions to the Columbia River system from various sources including mines, mills, and smelters, landslides, background, and other anthropogenic sources were considered. Chemical fingerprinting methods were employed for source identification.

Assessed sediment and nutrient loading to Kaelepulu Pond in Kailua, Hawaii, from grading activities at an adjacent construction site. Soil and nutrient loss from the site was estimated using the universal soil loss equation (USLE), as well as by the use of field data collected during storm events. Contributions of sediment and nutrients to Kaelepulu Pond from the construction site were evaluated with regard to sediment and nutrient loading from the greater watershed area. A comprehensive evaluation of site BMPs was conducted, which included comparison of the BMP plan to what was implemented in the field, and an assessment of BMP successes and failures during substantial rainfall events. This case settled at mediation July, 20, 2015.

Supported an analysis of apportionment of surface water contributions to the Kahala drainage system near Honolulu, Hawaii. A review of historic drainage canals, storm water best management practices, and stream hydrology were involved in the evaluation.

Modeled near-field and far-field plume characteristics of effluent from five major industrial facilities in the San Francisco Bay using the EPA Visual Plumes model. Assisted in the development of a method to define a mixing zone for each diffuser that could be applied uniformly regardless of ambient water flow and tidal conditions.

Evaluated storm water runoff quality and quantity from an industrial facility to determine potential harm to receiving waters. Dilution benefits from the mixing of site runoff with storm water from the surrounding watershed was investigated, and EPA Visual Plumes model was used to estimate the size of the mixing zone and dilution at the point of discharge.

Estimated the cost of remediating historically contaminated soils for the purposes of land valuation. RACER was used to determine construction costs for a site investigation, excavation activities, and waste hauling and disposal. Multiple removal scenarios were evaluated based on potential hypothetical future land use for areas in exceeded of risk-based TPH concentrations.

Worked with team members at Space and Naval Warfare System Command (SPAWAR) System Center Pacific on the scale-up approach, design, and fabrication of a benthic microbial fuel cell (BMFC) with a sustained power goal of 1 W to power Navy-relevant submersible electronics. Conducted multiple lab-scale BMFC experiments investigating power density variation relative to anode size, and organized and analyzed data from existing lab-scale and field-scale experiments to guide the scale-up approach. Fabricated a full-scale anode system (20 manode surface area) to meet a Fall 2012 deployment schedule.


CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Engineering, University of Southern California, 2013
  • M.S., Environmental Engineering, University of Southern California, 2009
  • B.S., Chemical Engineering, University of California, Santa Barbara, 2007
  • USC Viterbi Undergraduate Mentoring Research Award, 2013

    USC Sonny Astani School of Civil and Environmental Engineering Best Teaching-Assistant Award, 2011