Searching for Optimum Composition of Phosphogypsum: Fly ash: Cement Composites for Oyster Culch Materials

EPA Grant Number: R828598C759
Subproject: this is subproject number 759 , established and managed by the Center Director under grant R828598
(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: Searching for Optimum Composition of Phosphogypsum: Fly ash: Cement Composites for Oyster Culch Materials
Investigators: Rusch, Kelly Ann , Malone, Ronald F.
Institution: Louisiana State University
EPA Project Officer: Lasat, Mitch
Project Period: September 1, 2000 through August 31, 2004
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

Phosphogypsum (PG) is a waste by-product of phosphoric acid production and is classified as a "Technologically Enhanced Natural Radioactive" (TENR) material by EPA (Taha and Seals, 199 The current allowable disposal method for PG is stackpiling. With the US currently producing about 33 million tons a year it is estimated that by the year 2000 the total US inventory of PG stacks will reach 2 billion metric tons (Taha and Seals, 1991). Researchers at Louisiana State University have been investigating methods for stabilizing phosphogypsum (CaSO4.2H20) for use as an oyster culch material. The overall goal is to provide a composite that maintains its physical integrity in saltwater conditions and minimizes the release of radium226, which produces radon gas as a daughter product. Research over the past 2 years has focused on determining the mechanisms leading to composite degradation and determining a composite structure that would survive saltwater submergence for at least 1.5 years. Previous research found that a mixture consisting of 62%:35%:3% PG: fly ash: cement can survive in seawater for more than 1.5 years. Preliminary economic analysis of the aforementioned composite yields a cost of $13.5/ton (including 25% contingency) vs. $13/ton for limestone oyster culch currently, and there is a room for further reducing the percentage of cement and fly ash thus reducing the cost of the composite. In Louisiana, about 1.7 million cubic yards of oyster culch are needed yearly, supporting a market for oyster culch in the state of Louisiana and the Gulf coast. Therefore it is necessary to continue this research to refine the ingredients of PG: fly ash: cement to further reduce the cement and fly ash proportions, thereby decreasing the composite's cost.

The purpose of this research is to search optimal ingredient combinations within the range of 20-35% fly ash and 1-3% cement, such as 72%:25%:3% PG: fly ash: cement and 67%:30%:3% PG: fly ash: cement, for use as oyster culch. A series of dynamic leaching tests on the searched ingredients will be performed, which will provide baseline data for a more comprehensive proposal to be submitted to the Florida Institute of Phosphate Research (FIPR). The objective of the proposed project to FIPR will be to develop a risk assessment model of bioaccumulation of radium up the food chain.

Approach:

Composites will be fabricated with Type II Portland cement, fly ash, and dried/crushed PG in optimum ingredient combinations determined from previous research. Composites will be subjected to a field test to see whether these combinations can withstand seawater attack for at least 1.5 years. A variation of the dynamic leach test (ANS, 1986) will be performed to determine radium release rates from the PG composites. The radium concentration from the composites will be measured based on EPA Standard Methods 908 by adding barium nitrate to sample water to co-precipitate radium with the barium sulfate precipitates. The precipitate will then be washed and sealed till enough radon has accumulated to be measured by beta emissions. A diffusion model, developed by Duedall et al. (1983) using Fick's second law of diffusion alphaC/alphat = D(alpha2C/alphax2) and some related boundary conditions, will be applied to determine diffusion coefficients for the tested composites. This model is one-dimensional for ions in solidified blocks and in well-stirred aqueous systems. After diffusion coefficients for the PG composites with different ingredient combinations are obtained, a statistical model will be applied to find the equation to predict the diffusion coefficients for PG composites. A quadratic model, based on three ingredients, is used to regress the response surfaces for diffusion coefficients of cement/lime/PG composites. The quadratic canonical polynomial model can be fit using the least-square method. Appropriate tests of the hypothesis, including lack of fit analysis, can be performed using the usual regression methods. In SAS software both GLM and REG procedures can be used for analysis of mixture experiments.

Supplemental Keywords:

phosphogypsum, environmental chemistry, hazardous waste, fly ash, risk assessment, bioaccumulation, radium., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, TREATMENT/CONTROL, INDUSTRY, Sustainable Industry/Business, POLLUTION PREVENTION, Waste Treatment, cleaner production/pollution prevention, waste reduction, Environmental Chemistry, Hazardous Waste, Economics and Business, Hazardous, Environmental Engineering, Industries, hazardous substance disposal, hazardous waste disposal, risk assessment, waste minimization, Production/Pollution Prevention, environmentally conscious manufacturing, construction industry, phosphogypsum, radium, fly ash, chemically activated fly ash, alternative materials, oyster culch materials, engineering, production processes, waste recovery, economic analysis, construction material, bioaccumulation

Progress and Final Reports:

  • 2001 Progress Report
  • 2002
  • 2003
  • Final Report

  • Main Center Abstract and Reports:

    R828598    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).
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    R826694C627 The Interaction of Microbial Activity and Zero Valent Iron Permeable Barrier Technology
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    R826694C630 Microbial Cometabolism of Recalcitrant Chemicals in Contaminated Air Streams
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    R826694C635 Electrokinetic/Surfactant-Enhanced Remediation of Hydrophobic Pollutants in Low Permeability Subsurface Environments
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    R826694C640 Environmentally Friendly Organic Synthesis in Supercritical Fluids
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    R826694C651 Adjustable Biopolymer Chelators for Cadmium, Lead, and Mercury Remeidation
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    R826694C705 A Pilot Plant for Producing Mixed Ketones from Waste Biomass
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    R826694C724 Mercury Removal from Stack Gas by Aqueous Scrubbing
    R826694C725 Transport, Fate and Risk Implications of Environmentally Acceptable Endpoint Decisions
    R826694C731 Development and Application of a Real-Time Optical Sensor for Atmospheric Formaldehyde
    R826694C734 An Advanced System for Pollution Prevention in Chemical Complexes
    R828598C001 Field Study Abstract: A Model of Ambient Air Pollution in Southeast Texas Using Artificial Neural Network Technology
    R828598C002 Hollow Fiber Membrane Bioreactors for Treating Water and Air Streams Contaminated with Chlorinated Solvents
    R828598C003 Fugitive Emissions of Hazardous Air Pollutants from On-Site Industrial Sewers
    R828598C004 Biofiltration Technology Development
    R828598C005 A Risk-Based Decision Analysis Approach for Aquifers Contaminated with DNAPLs
    R828598C006 In-Situ Remediation for Contaminated Soils Using Prefabricated Vertical Drains
    R828598C007 Membrane Technology Selection System for the Metal Finishing Industry
    R828598C008 Sequential Environments for Enhanced Bioremediation of Chlorinated Aliphatic Hydrocarbons
    R828598C009 Waste Minimization in the Magnetic Tape Industry: Waterborne Coating Formulations for Magnetic Tape Manufacture
    R828598C010 Soil Remediation by Agglomeration with Petroleum Coke
    R828598C011 Recovery of Dilute Phosphoric Acid in Waste Streams Using Waste Gas Ammonia: The Regenerative MAP/DAP Process
    R828598C012 Stochastic Risk Assessment for Bioremediation
    R828598C013 Selective Removal of Heavy Metals from Wastewater by Chelation in Supercritical Fluids
    R828598C014 Optimization of Treatment Technologies for Detoxification of PCB Contaminated Soils
    R828598C015 Wastewater Remediation by Catalytic Wet Oxidation
    R828598C016 Permanence of Metals Containment in Solidified and Stabilized Wastes
    R828598C017 Combustion Enhancement by Radial Jet Reattachment - Low Generation of Hazardous Gases and High Thermal Efficiency
    R828598C018 A Process To Convert Industrial Biosludge and Paper Fines to Mixed Alcohol Fuels
    R828598C019 Homogeneous Catalysis in Supercritical Carbon Dioxide
    R828598C020 Ultrasonic Enhancement of the Removal of Heavy Metals
    R828598C021 The Binding Chemistry and Leaching Mechanisms of Advanced Solidification/Stabilization Systems for Hazardous Waste Management
    R828598C022 Development of an Air-Stripping and UV/H2O2 Oxidation Integrated Process To Treat a Chloro-Hydrocarbon-Contaminated Ground Water
    R828598C023 A Comparative Study of Siting Opposition in Two Counties
    R828598C024 Sonochemical Treatment of Hazardous Organic Compounds II: Process Optimization and Pathway Studies
    R828598C025 Laser Diagnostics of the Combustion Process within a Rotary Kiln Incinerator
    R828598C026 Use of Inorganic Ion Exchangers for Hazardous Waste Remediation
    R828598C027 Kaolinite Sorbent for the Removal of Heavy Metals from Incinerated Lubricating Oils
    R828598C028 Destruction of Chlorinated Hydrocarbons in Process Streams Using Catalytic Steam Reforming
    R828598C029 Integrated Process Treatment Train (Bioremediation {Aerobic/Anaerobic} and Immobilization) for Texas Soils Contaminated with Combined Hazardous Wastes
    R828598C030 Photo-Oxidation by H2O2/VisUV of Off-Gas Atmospheric Emissions from Industrial and Environmental Remediation Sources
    R828598C031 Concentrated Halide Extraction and Recovery of Lead from Soil
    R828598C032 Biodegradable Surfactant for Underground Chlorinated Solvent Remediation
    R828598C033 A Software Guidance System for Choosing Analytical Subsurface Fate and Transport Models Including a Library of Computer Solutions for the Analytical Models
    R828598C034 Hydrodynamic Modeling of Leachate Recirculating Landfill
    R828598C035 Measurement of Oxygen Transfer Rate in Soil Matrices
    R828598C036 Sorbent Technology for Multipollutant Control During Fluidized Bed Incineration
    R828598C037 Pollution Prevention by Process Modification Using On-Line Optimization
    R828598C038 Pollution Prevention by Process Modification
    R828598C039 Water Solubility and Henry's Law Constant
    R828598C040 Transferring Technical Information on Hazardous Substance Research by Publishing on the World Wide Web
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    R828598C042 Life-Cycle Environmental Costing for Managing Pollution Prevention in the Chemical and Petroleum Refining Industries: A Cross-Border Approach
    R828598C687 Improved Halogen Resistance of Catalytic Oxidation Through Efficient Catalyst Testing
    R828598C696 Phytoremediation and Bioremediation of Land Contaminated By PAHs, PCBs, and TNT
    R828598C697 Fundamental and Kinetic Investigation of Sorbent Technology for Optimum Mercury Emission Control
    R828598C700 Effects of Natural Cyclic Variations on Contaminated Fate and Transport
    R828598C703 Enhancement of DNAPL Dissolution Rates by Dechlorinating Anaerobes
    R828598C705 A Pilot Plant for Producing Mixed Ketones from Waste Biomass
    R828598C722 The Effects of an Oily-Phase on VOC Emissions from Industrial Wastewater
    R828598C724 Mercury Removal from Stack Gas by Aqueous Scrubbing
    R828598C725 Transport, Fate and Risk Implications of Environmentally Acceptable Endpoint Decisions
    R828598C731 Development and Application of a Real Time Optical Sensor for Atmospheric Formaldehyde
    R828598C734 An Advanced System for Pollution Prevention in Chemical Complexes
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    R828598C753 Adsolubilization and Photocatalysis in a Semiconducting Monolithic Reactor for Wastewater Treatment
    R828598C754 Remote Detection of Gas Emissions in Industrial Processes
    R828598C759 Searching for Optimum Composition of Phosphogypsum: Fly ash: Cement Composites for Oyster Culch Materials
    R828598C761 Development of a Phytologically-Based Biosorptive Water Treatment Process
    R828598C766 Chlorinated Solvent Impact and Remediation Strategies for the Dry Cleaning Industry
    R828598C769 Soil/Sediment Remediation by Hot Water Extraction Combined with In-Situ Wet Oxidation
    R828598C771 Fluoracrylate Polymer Supported Ligands as Catalysts for Environmentally Benign Synthesis in Supercritical Fluids
    R828598C774 The Feasibility of Electrophoretic Repair of Impoundment Leaks
    R828598C777 Surfactant Enhanced Photo-oxidation of Wastewaters
    R828598C778 Stationary Power Generation Via Solid Oxide Fuel Cells: A Response to Pollution and Global Warming
    R828598C786 Photocatalytic Recovery of Sulfur and Hydrogen From Hydrogen Sulfide
    R828598C787 Biosurfactant Produced from Used Vegetable Oil for removal of Metals From Wastewaters and Soils
    R828598C789 Genetic Engineering of Enzymatic Cyanide Clearance
    R828598C791 Characterizing the Intrinsic Remediation of MTBE at Field Sites
    R828598C799 Simultaneous Water Conservation/Recycling/Reuse and Waste Reduction in Semiconductor Manufacturing
    R828598C801 Building Defined Mixed Cultures To Biodegrade Diverse Mixtures Of Chlorinated Solvents
    R828598C802 Engineering of Nanocrystal Based Catalytic Materials for Hydroprocessing of Halogenated Organics
    R828598C807 Commercial Demonstration of Hydrogen Peroxide Injection to Control NOx Emissions from Combustion Sources
    R828598C809 Evaluating Source Grouting and ORC for Remediating MTBE Sites
    R828598C810 Application of Total Cost Assessment To Process Design In the Chemical Industry
    R828598C846 Quantitative Demonstration of Source-Zone Bioremediation in A Field-Scale Experimental Controlled Release System