Arsenic Removal and Stabilization with Synthesized Pyrite

EPA Grant Number: R831276C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant CR831276
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Gulf Coast HSRC (Lamar)
Center Director: Ho, Tho C.
Title: Arsenic Removal and Stabilization with Synthesized Pyrite
Investigators: Batchelor, Bill
Institution: Texas A & M University
EPA Project Officer: Lasat, Mitch
Project Period: December 1, 2003 through November 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

Arsenic is the second most commonly found contaminant of concern both at sites on the National Priority List and at sites under DOE control. Furthermore, the recent lowering of the MCL for arsenic in drinking water will result in additional production of arsenic-contaminated residuals. Lowering of other regulatory standards for arsenic to maintain similar risk levels, would result in higher levels of treatment required for arsenic-contaminated ground water, soils, sediments and other wastes found at contaminated sites. The primary method that is currently used for removing arsenic from water produces residuals that can be unstable when disposed under anoxic conditions, such as typically found in a landfills. An alternative approach would be to remove arsenic with compounds that are have a high affinity for arsenic and are stable under anoxic conditions. Pyrite is such a compound and recent research has demonstrated how to produce micro- and nano-sized pyrite crystals, which have high specific surface areas that lead to high capacities to adsorb arsenic. Although the initial removal mechanism would be adsorption, chemical reactions would be expected to occur on the surface between arsenic and pyrite producing new solid phases such as arsenian pyrite (Fe(S,As)2) and arsenopyrite (FeAsS). These compounds are stable for geologic time periods and are very insoluble under reducing conditions. Pyrite could also be applied to stabilize arsenic-contaminated media such as soils, sediments and sludges.

The objective of this project is to develop a novel treatment method for removal of arsenic from water and stabilization of arsenic contaminated soils, sediments and sludges based on application of micro- and nano-sized synthesized pyrite.

Approach:

The objective will be achieved by pursuing five specific objectives. The first task would characterize and optimize the synthesis procedure for micro- and nano-sized pyrite. Effects on the synthesis of pyrite particles of iron concentration, sulfide or polysulfide concentration, pH, reaction time, and method of reagent addition will be investigated in batch reactor systems. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry will be used to size and characterize the pyrite particles. The second task would be to measure the effects of operational variables on removal of arsenic from solution. The effects of synthesized pyrite size and dose, pH, and competing ions on adsorption of arsenic (III and V) will be measured in a series of batch equilibrium adsorption experiments. The third task would develop a chemical equilibrium model to describe behavior observed in Task 2. The fourth task would measure the stability of residuals from pyrite-treated water. Arsenic-pyrite residuals will be produced with both valence states of arsenic (III, V) using conditions identified by Task 2 as being optimal for arsenic removal. The leachability of arsenic from these residuals will be measured under conditions of the TCLP test and over a range of pH . The fifth task would measure the stability of arsenic-contaminated soils treated with pyrite. The effects on stability of arsenic contaminated soils of pyrite size and dose, arsenic type (III, V), arsenic concentration and soil type will be investigated. Stability of the treated soils will be evaluated by the TCLP and equilibrium extraction test over a range of pH. Costs of pyrite-based treatment of soils/sediments/wastes would be similar to those for solidification/stabilization ($60 - $290/ton). However these costs could be as much as $50/ton lower due to reduced reagent costs.

Expected Results:

Costs for removing arsenic from water with pyrite would be similar to existing technologies, but would have the advantage of producing inherently stable residuals. This project would be completed in three years.

Supplemental Keywords:

RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, Water, POLLUTANTS/TOXICS, Contaminated Sediments, Environmental Chemistry, Arsenic, Hazardous Waste, Soil Contaminants, Water Pollutants, Drinking Water, Hazardous, Engineering, Chemistry, & Physics, Environmental Engineering, hazardous waste treatment, nano sized pyrite crystals, synthesized pyrite, contaminated sediment, nanotechnology, contaminated soil, arsenic removal, groundwater remediation, remediation, contaminated groundwater, pyrite, arsenic exposure, drinking water contaminants, drinking water treatment, other - risk management, pyrite crystals, contaminant candidate list

Progress and Final Reports:

  • Final

  • Main Center Abstract and Reports:

    CR831276    Gulf Coast HSRC (Lamar)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R831276C001 DNAPL Source Control by Reductive Dechlorination with Fe(II)
    R831276C002 Arsenic Removal and Stabilization with Synthesized Pyrite
    R831276C003 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
    R831276C004 Visible-Light-Responsive Titania Modified with Aerogel/Ferroelectric Optical Materials for VOC Oxidation
    R831276C005 Development of a Microwave-Induced On-Site Regeneration Technology for Advancing the Control of Mercury and VOC Emissions Employing Activated Carbon
    R831276C006 Pollution Prevention through Functionality Tracking and Property Integration
    R831276C007 Compact Nephelometer System for On-Line Monitoring of Particulate Matter Emissions
    R831276C008 Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
    R831276C009 Linear Polymer Chain and Bioengineered Chelators for Metals Remediation
    R831276C010 Treatment of Perchlorate Contaminated Water Using a Combined Biotic/Abiotic Process
    R831276C011 Rapid Determination of Microbial Pathways for Pollutant Degradation
    R831276C012 Simulations of the Emission, Transport, Chemistry and Deposition of Atmospheric Mercury in the Upper Gulf Coast Region
    R831276C013 Reduction of Environmental Impact and Improvement of Intrinsic Security in Unsteady-state
    R831276C014 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
    R831276C015 Improved Combustion Catalysts for NOx Emission Reduction
    R831276C016 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
    R831276C017 Minimization of Hazardous Ion-Exchange Brine Waste by Biological Treatment of Perchlorate and Nitrate to Allow Brine Recycle
    R831276C018 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions