Grantee Research Project Results

Final Report: Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process

EPA Grant Number: R825549C013
Subproject: this is subproject number 013 , 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: HSRC (1989) - Great Plains/Rocky Mountain HSRC
Center Director: Erickson, Larry E.
Title: Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
Investigators: Kross, Burton C.
Institution: University of Iowa
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 1989 through February 1, 1991
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management

Objective:

This project was initiated to study optimal ozone dose and other operating conditions in ozonation of aqueous alachlor and solution at concentration about 10 mg/L, and then continued looking into the reaction mechanisms and the mass transfer phenomenon.

Summary/Accomplishments (Outputs/Outcomes):

This research is designed to contribute needed information for the development of a point-of-use water treatment system to remove pesticides from well water. The need for inexpensive, effective point-of-use water treatment systems from rural water supplies is critical. Rural residents with shallow wells who have herbicide contamination problems are most likely to use this technology.

Because of the need for pesticide disposal at farm sites, a batch-type small volume (2L) stirred reactor was adopted. Important engineering factors were explored which influence rate of alachlor destruction with ozone, such as concentrations of gaseous ozone (16 to 5 mg/L) and alachlor (10 mg/L to 220 mg/L).

This research indicates that alachlor is effectively removed using conventional ozonation processes. The strategy for optimal control of the ozonation process requires higher ozone partial pressures for pH 7 and greater mass transfer rates for pH 10. The optimal operating gas flow rate for pH 10 was at 3.5 scfh, which delivered the maximum amount of ozone into the solution (8.0 mg/L*min). At 1.0 scfh for pH 7, the dissolved ozone concentration of 16.5 mg/L at the interface was the maximum for this system. It is widely accepted that most ozone reactions are fast and limited by mass transfer. It is true for ozonation of alachlor at pH 10, but at pH 7 the direct ozonation of alachlor is considered slow and controlled by both reaction rate and diffusion.

Under our study conditions, monitoring the ozone residual in the bulk water phase, the ratios of saturated ozone concentration at pH 7 versus pH 2.29 were found to increase with gas flow rate. The overall mass transfer coefficients (KLa) increased with gas flow rate and decreased with pH. The decrease of KLa indicated that a change of reaction mechanism or reaction rate would also result in a change in KLa. Hence, KLa was not an appropriate parameter to totally define the mass transfer characteristics for our reactor of ozone and alachlor. As a result, the double-film theory was adopted. The typical values of liquid film (L=0.01 cm) and interfacial area (a= 3, 6, and 9 for 1.0, 2.0, and 3.5 scfh, respectively) predicted the ozone residual in water. The first-order rate constant (kd=0.216) of ozone self-decomposition in the ozone stirred reactor was found to be 10-fold higher than that in the kinetic study.

For direct ozonation of alachlor, the disappearance rate of alachlor was found to be 3/2 order with respect to alachlor and first order with respect to ozone residual. The disappearance rate of ozone was found to be first order with respect to alachlor and ozone. Reaction rate constants for ozone reacting with alachlor were less than rate constants for ozone reacting with the hydroxyl ion. The reaction rate constants for ozone-alachlor reactions were greater than for ozone-atrazine reactions. The rate constants were also found to be enhanced by higher pH under excess alachlor conditions. The stoichiometric factor was found to be about 6 to 7 molecules of ozone per molecule of alachlor reacted at pH 7.0.

The possibility for the ether moiety of alachlor becoming involved in an auto-oxidation reaction is unlikely. At pH 7.0 high concentrations of alachlor probably stabilizes the radical chain reaction. Thus, direct ozonation was predominant. When the amount of alachlor in water was reduced to concentrations comparable to the ozone residual, direct ozonation was believed to occur along with reactions involving the OH radical, corresponding to the initiation, propagation, and termination steps of ozone self-decomposition.

At pH 10, direct ozonation of alachlor is unlikely. Instead, a radical chain reaction arising from ozone self-decomposition is predominant and limited by ozone mass transfer rate. At 3.5 scfh the constant mass transfer rate of ozone can provide a sufficient amount of OH radicals for alachlor up to about a concentration of 50 mg/L. From this series of tests, the rate coefficient (0.370 min~1) was obtained.

According to one of our observations, a weight ratio of alachlor to ozone should be less than about 4, when the optimal pH is 7. On the other hand, at pH 10 or when other catalyzed ozonation predominates, the weight ratio of alachlor to ozone should be larger than about 4.

The results have been presented at a professional meeting and made available to interested parties.

Journal Articles:

No journal articles submitted with this report: View all 2 publications for this subproject

Supplemental Keywords:

ozonation, water treatment, pesticides., RFA, Scientific Discipline, Waste, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Remediation, Environmental Chemistry, Geochemistry, Chemistry, Fate & Transport, Analytical Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, EPA Region, sediment treatment, fate and transport, contaminant transport, soil and groundwater remediation, fate and transport , well water, contaminated sediment, pesticides, enzymatic ozonation, contaminated soil, groundwater remediation, chemical kinetics, Region 7, Region 8, enzymatic reduction, contaminated groundwater, pesticide runoff, hazardous wate, pesticide residue, groundwater contamination, phytoremediation

Relevant Websites:

http://www.engg.ksu.edu/HSRC Exit

Progress and Final Reports:

Original Abstract

1989

Main Center Abstract and Reports:

R825549    HSRC (1989) - Great Plains/Rocky Mountain HSRC

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