Grantee Research Project Results
Final Report: Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
EPA Grant Number: R825549C056Subproject: this is subproject number 056 , established and managed by the Center Director under grant R825549
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Center for the Study of Metals in the Environment
Center Director: Allen, Herbert E.
Title: Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
Investigators: Bajpai, Rakesh K. , Zappi, Mark E. , Banerji, Shankha K. , Puri, Ravi
Institution: University of Missouri - Columbia , Missouri University of Science and Technology
EPA Project Officer: Hahn, Intaek
Project Period: May 18, 1995 through May 17, 1996
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The goal of this project will be to develop a slurry biotreatment process for soils contaminated with PCP and creosote. Its specific objectives will be
a. screen nonionic and anionic surfactants, and explore cosolvents for enhancement of the solubility of high molecular weight (HMW)PAHs in aqueous phase.
b. investigate means to create efficient mixing in the soil slurry and determine their power consumption.
c. explore the use of pure oxygen to meet oxygen demand and to minimize the problems of foaming in slurry bioreactor, and determine the efficiency of oxygen utilization.
d. study the kinetics of biodegradation of PCP and creosote-PAHs in slurry bioreactors, specifically the effect of temperature and pH, and strategies of addition of surfactant and primary carbon source for cometabolism (dosage and timing) in order to enhance the rates of biodegradation, and analyze for any intermediate metabolites produced during biodegradation.
e. develop reliable performance data and preliminary estimates of costs of operation slurry bioreactors for bioremediation.
Summary/Accomplishments (Outputs/Outcomes):
PCP and creosote PAHs are found in most of the contaminated soils at wood-treatment sites. The treatment methods currently being used for such soils include soil washing, incineration, and biotreatment. Soil washing involves removal of the hazardous chemicals from soils using solvents; the solvent stream must still be treated for destruction of the contaminants. Incineration is an effective tool for destruction of the contaminants. But the cost of incineration is very high; it is also very difficult to install new incineration facilities due to strong public opposition. Bioremediation has been considered and used for treatment of soils contaminated with wood-treatment chemicals. But the present state of bioremediation technology results in rapid mineralization of low molecular weight PAHs only, leaving PCP and high molecular weight PAHs in the spent soil. Unfortunately, these are the chemicals that are the most toxic, carcinogenic, and regulated. Slurry-phase biotreatment of contaminated soils and sediments is an innovative treatment technology. It's advantages include easy manipulation of physicochemical variables and operating conditions to enhance the rates of biodegradation, and ease of containment of exhaust gases and effluent. Use of slurry bioreactors is particularly attractive for fine soils (high silt/clay content) having complex contaminant-matrix, and for systems in which problems of low mass transfer rates and of limited solubility of strongly sorbed contaminants preclude the use of other simpler solid-phase treatment technologies such as land farming and biocells. Bioslurry technology is currently hampered by a lack of information concerning the operating conditions and the strategies for reactor operation that result in mineralization of PCP and high molecular weight PAHs within reasonably short residence times of solids in the reactors, efficient means of keeping the solids in slurry and delivery of oxygen, and reliable cost numbers for operation and maintenance. Relieving these bottlenecks will result in rapid adaptation of this technology and its successful implementation.
Engineering and process development aspects of bioslurry treatment of PCP and creosote contaminated soils from a Superfund site will be studied in this project in shake flasks and in 14 liter well instrumented fermentors. Use of surfactants and cosolvents will be explored in order to enhance the aqueous solubility of hydrophobic and sparingly soluble contaminants. The effect of cosolvent on microbial activity will be studied. Kinetic studies for the biodegradation of PCP and PAHs will be carried out in sealed bioreactors so that accurate material balances can be taken. Experiments are planned to investigate the role of surfactant/cosolvent, temperature, carbon source, and oxygen delivery by sparging of pure oxygen in reduction of concentrations of PAHs and PCP in the contaminated soil slurry.
Reactors with power measurement devices (dynamometer) will be used to investigate several different types of mechanical agitators in order to keep the solids in suspension. The power requirement under aerated and unaerated conditions will be correlated with geometrical and system parameters such as particle size, nature of soil (as determined by plasticity and flow indices), solid density and physical dimensions in the reactor. Oxygen transfer rate and oxygen transfer efficiency in the slurries with sufficient power input for minimal and complete suspension will also be studied in this reactor. Correlations will be developed for these two very important operating parameters for which no information is available from literature.
All of the information will be used to develop a flow diagram of the bioslurry treatment process for cleanup of contaminated sites and to generate cost data that may be used to determine the cost effectiveness of this process for field-scale treatment. This, of course, will require SITE demonstration that will be undertaken in a follow-up stage on the basis of information gathered in this project.
Based on the work conducted in the previous years, Triton X-100 was selected as surfactant of choice for enhancement of solubility of PAHs from contaminated soil and hence to enhance their biodegradation. The concentration of soil in slurry was 30% (w/w) and surfactant concentration in the slurry was 1% (w/w). Enriched culture was developed from the contaminated soil. The medium used for enrichment contained K2HPO4 (3g/l), KH2PO4 (15. g/l), (NH4)2SO4 (1.25 g/l), Yeast Extract (0.5 g/l), NaCl (0.01 g/l), MgSO4 (0.1 g/l), FeSO4.7H2O (1 mg/l), and acetic acid (0.5 g/l). pH of the culture broth was adjusted to 7 before sterilization for 15 minutes at 121 ?C. Contaminated soil (50 g/l) and phenanthrene (1 g/l) was added to 100-ml sterile broth, which was incubated at 25 ?C and 150 rpm. After 72 hours, the aqueous phase was used to inoculate liquid medium containing phenanthrene and the process was repeated three times; the resulting culture was stored at 4 ?C and used in experiments.
All the biodegradation experiments were conducted in triplicate. The matrix of experiments consisted of:
-Control slurry without surfactant
-Control slurry with surfactant
-Inoculated slurry without surfactant
-Inoculated slurry with surfactant
Samples were collected by sacrificing the flasks. The slurry was centrifuged to separate the liquid medium from solids and both the phases were analyzed separately for a number of PAHs. From these data the total PAHs and B(a)P equivalents in the respective phases were calculated. The concentration of Total PAH and BaP equivalents in the slurry have been reported.
Consistent with the observations of scores of other researchers dealing with hydrophobic organic compounds, the concentrations of PAHs (and BaP equivalents) increased with time before decreasing again. Addition of surfactant resulted in a considerable and rapid increase in the solution-phase concentrations of PAHs as well as in the concentration of extractable PAHs present in the solid phase. Addition of surfactant in absence of enriched culture did not result in any significant differences either in the concentrations of PAHs or in the BaP equivalents. Addition of surfactant in presence of enriched culture increased the maximum extractable PAHs by more than 200% over surfactant-free slurry while still resulting in lower total PAH concentration after 60 days. The experiments were stopped on 60th day. BaP equivalents decreased from a high of 30 mg/Kg to 2 mg/Kg in inoculated slurries with surfactant, compared to a final value of 8-10 mg/Kg in other experiments.
Power requirements and oxygen transfer in agitated and aerated soil slurries: These measurements were conducted in a 310 liter working volume agitated reactor. The reactor diameter was 30 inches and it was equipped with a 10-inch hydrofoil agitator mounted on a central shaft. At the top of the agitator shaft, a torque sensor was fitted to measure the shaft torque. Power consumption by the DC motor was also measured as to control the accuracy of power measurements by the torque sensor. The measurements were first conducted with no fluid in the reactor and these values were deducted from any actual reading from rotating agitator in the slurry in order to account to any friction in the bearings. A PC coupled to the instruments automatically logged shaft torque, current and voltage drawn by the motor and any readings from exit gas oxygen analyzer. Any air sparged through the reactor was introduced through a sintered disk sparger (6" diameter located under the agitator) and its flow rate was measured by rotameters installed in line as well by a mass flow controller whose signal was logged by the PC. The experiments were conducted at several different flow rates of air (corresponding to 0, 0.005, 0.01, 0.05, 0.10 and 0.15 vvm), with and without any soil in the reactor. When soil was present, 30% (w/w) clay slurry was used. In the fluid, Triton X-100 was added to study the effect of surfactant on the power consumption and oxygen transfer rate. Sulfite method was used to measure the oxygen transfer rates in the reactor. At a given flow rate of air, concentration of soil and surfactant in solution, the agitation rate was changed in small increments and shaft torque, exit gas oxygen concentration, and other motor power readings were noted under steady condition. The measurements were conducted while increasing the shaft rpm as well while decreasing the shaft rpm. In general, excellent reproducibility was obtained.
The impeller power numbers (calculated from measured shaft torque values) have been plotted against impeller Reynolds numbers. In general, a classical inverse relationship between power number and impeller Reynolds number was observed at low shaft rpms and at high shaft rpms, the power number was constant. The value of power number under the conditions of high rpms was between 0.2 and 0.4.
This project was the subject of two poster presentations at the annual HSRC conference in 1997. Results from the project have been published in one peer-reviewed journal and more articles are planned. Investigators are planning to make presentations at various scientific conferences and to attend conferences to interact with consultants and companies that are interested in bioslurry reactor technology, as funding allows.
Journal Articles:
No journal articles submitted with this report: View all 4 publications for this subprojectSupplemental Keywords:
soil, PCP, creosote, slurry bioreactor, wood treatment., Scientific Discipline, Toxics, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Environmental Chemistry, Geochemistry, pesticides, Fate & Transport, Analytical Chemistry, Bioremediation, Ecology and Ecosystems, fate and transport, PCP, migration, contaminant transport, biodegradation, contaminated sediment, adsorption, bioremediation of soils, biotechnology, contaminants in soil, chemical kinetics, slurry biotreatment, agrochemicals, contaminated soils, creosote, PentachlorophenolRelevant Websites:
http://www.engg.ksu.edu/HSRC Exit
Main Center Abstract and Reports:
R825549 Center for the Study of Metals in the Environment Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825549C006 Fate of Trichloroethylene (TCE) in Plant/Soil Systems
R825549C007 Experimental Study of Stabilization/Solidification of Hazardous Wastes
R825549C008 Modeling Dissolved Oxygen, Nitrate and Pesticide Contamination in the Subsurface Environment
R825549C009 Vadose Zone Decontamination by Air Venting
R825549C010 Thermochemical Treatment of Hazardous Wastes
R825549C011 Development, Characterization and Evaluation of Adsorbent Regeneration Processes for Treament of Hazardous Waste
R825549C012 Computer Method to Estimate Safe Level Water Quality Concentrations for Organic Chemicals
R825549C013 Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
R825549C014 The Characterization and Treatment of Hazardous Materials from Metal/Mineral Processing Wastes
R825549C015 Adsorption of Hazardous Substances onto Soil Constituents
R825549C016 Reclamation of Metal and Mining Contaminated Superfund Sites using Sewage Sludge/Fly Ash Amendment
R825549C017 Metal Recovery and Reuse Using an Integrated Vermiculite Ion Exchange - Acid Recovery System
R825549C018 Removal of Heavy Metals from Hazardous Wastes by Protein Complexation for their Ultimate Recovery and Reuse
R825549C019 Development of In-situ Biodegradation Technology
R825549C020 Migration and Biodegradation of Pentachlorophenol in Soil Environment
R825549C021 Deep-Rooted Poplar Trees as an Innovative Treatment Technology for Pesticide and Toxic Organics Removal from Soil and Groundwater
R825549C022 In-situ Soil and Aquifer Decontaminaiton using Hydrogen Peroxide and Fenton's Reagent
R825549C023 Simulation of Three-Dimensional Transport of Hazardous Chemicals in Heterogeneous Soil Cores Using X-ray Computed Tomography
R825549C024 The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
R825549C025 An Electrochemical Method for Acid Mine Drainage Remediation and Metals Recovery
R825549C026 Sulfide Size and Morphology Identificaiton for Remediation of Acid Producing Mine Wastes
R825549C027 Heavy Metals Removal from Dilute Aqueous Solutions using Biopolymers
R825549C028 Neutron Activation Analysis for Heavy Metal Contaminants in the Environment
R825549C029 Reducing Heavy Metal Availability to Perennial Grasses and Row-Crops Grown on Contaminated Soils and Mine Spoils
R825549C030 Alachlor and Atrazine Losses from Runoff and Erosion in the Blue River Basin
R825549C031 Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
R825549C032 Time Dependent Movement of Dioxin and Related Compounds in Soil
R825549C033 Impact of Soil Microflora on Revegetation Efforts in Southeast Kansas
R825549C034 Modeling the use of Plants in Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances
R825549C035 Development of Electrochemical Processes for Improved Treatment of Lead Wastes
R825549C036 Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
R825549C037 Formation and Transformation of Pesticide Degradation Products Under Various Electron Acceptor Conditions
R825549C038 The Effect of Redox Conditions on Transformations of Carbon Tetrachloride
R825549C039 Remediation of Soil Contaminated with an Organic Phase
R825549C040 Intelligent Process Design and Control for the Minimization of Waste Production and Treatment of Hazardous Waste
R825549C041 Heavy Metals Removal from Contaminated Water Solutions
R825549C042 Metals Soil Pollution and Vegetative Remediation
R825549C043 Fate and Transport of Munitions Residues in Contaminated Soil
R825549C044 The Role of Metallic Iron in the Biotransformation of Chlorinated Xenobiotics
R825549C045 Use of Vegetation to Enhance Bioremediation of Surface Soils Contaminated with Pesticide Wastes
R825549C046 Fate and Transport of Heavy Metals and Radionuclides in Soil: The Impacts of Vegetation
R825549C047 Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants
R825549C048 Acid-Producing Metalliferous Waste Reclamation by Material Reprocessing and Vegetative Stabilization
R825549C049 Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil
R825549C050 Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
R825549C051 Field Scale Bioremediation: Relationship of Parent Compound Disappearance to Humification, Mineralization, Leaching, Volatilization of Transformaiton Intermediates
R825549C052 Chelating Extraction of Heavy Metals from Contaminated Soils
R825549C053 Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
R825549C054 Application of PGNAA Remote Sensing Methods to Real-Time, Non-Intrusive Determination of Contaminant Profiles in Soils
R825549C055 Design and Development of an Innovative Industrial Scale Process to Economically Treat Waste Zinc Residues
R825549C056 Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
R825549C057 Effects of Surfactants on the Bioavailability and Biodegradation of Contaminants in Soils
R825549C058 Contaminant Binding to the Humin Fraction of Soil Organic Matter
R825549C059 Identifying Ground-Water Threats from Improperly Abandoned Boreholes
R825549C060 Uptake of BTEX Compounds by Hybrid Poplar Trees in Hazardous Waste Remediation
R825549C061 Biofilm Barriers for Waste Containment
R825549C062 Plant Assisted Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances: Experimental and Modeling Studies
R825549C063 Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
Main Center: R825549
904 publications for this center
182 journal articles for this center