Final Report: Development of a Cavitating Jet System for Removal of Pesticides and Other Pollutants From Wastewater DischargeEPA Contract Number: 68D02017
Title: Development of a Cavitating Jet System for Removal of Pesticides and Other Pollutants From Wastewater Discharge
Investigators: Kalumuck, Kenneth M.
Small Business: Dynaflow Inc.
EPA Contact: Manager, SBIR Program
Project Period: April 1, 2002 through September 1, 2002
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2002) RFA Text | Recipients Lists
Research Category: Water and Watersheds , SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)
Description:Ultrasonically induced cavitation is capable of oxidizing aqueous organic compounds. In this Phase I research project, Dynaflow, Inc., investigated the ability of their DYNAJET® cavitating water jet technology to efficiently oxidize a number of different pesticides in aqueous solution. The set of compounds selected represents a broad range of pesticide types with varying chemical compositions. These include 2,4-D, alachlor, malathion, carbaryl, chlorhexidine, insecticidal soap, and algae-contaminated pool water, as well as mixtures of some of these compounds. Initial concentrations varied from a few hundred ppb to a few hundred ppm.
Controlled laboratory experiments were conducted with solutions of the selected pesticides at various initial concentrations. These liquids were subjected to cavitation in flow loops outfitted with DYNAJET® cavitating water jet nozzles. Periodic sampling was employed to enable determination of the concentration reduction versus time due to oxidation. Efficiencies also were assessed based on the mass of contaminant removed for given energy input. Initial and periodic contaminant concentrations were measured with compound-specific immunoassays, total organic carbon levels, and gas chromatography/ mass spectrometry. Jet configuration and operating conditions were varied to assess the influence of different parameters. Flow visualization with high-speed videos of the generated cavities were employed to assess the influence of parameters on hydrodynamic and cavity behavior. This parametric study will be expanded in Phase II to optimize the technology and determine a set of scaling laws to enable design of a practical scale system.
The potential applications of this technology are enormous. The technology will provide a reliable, cost-effective means for the removal of pesticides and other contaminants from wastewater discharge, for remediation of contaminated water, or as part of a process for purifying water for various applications. The technology should be easy to implement at different scales, such that it could be effectively utilized for both small and large systems.
All of the compounds listed above were effectively oxidized with high oxidation efficiencies achieved at low pressures. Oxidation performance was found to depend on jet flow conditions with optimal values that likely were concentration dependent. Comparable rates of oxidation were found for a number of different compounds of comparable initial concentrations. The rates of oxidation of individual compounds within mixtures of pesticides were found to be comparable to those of the individual compounds alone. Visualization of the jet flows shows that a large range of cavity characteristics is possible, and that these characteristics depend on the DYNAJET®geometry. Scale-up estimates show much promise for effective and efficient implementation of the technology.
The Phase I research project clearly demonstrated the feasibility and the great promise of the novel DYNAJET® cavitating jet technology for effective and efficient removal of pesticides and other organic contaminants from water. In Phase II, a more detailed investigation resulting in optimization and practical scaling laws will be conducted to lay the groundwork for commercialization in Phase III.
Specific conclusions include:
- Rapid and efficient removal was found for the following substances: (1) 2,4-D, (2) malathion, (3) alachlor, (4) insecticidal soap (potassium salts of fatty acids), (5) chlorhexidine, (6) pool water, and (7) mixtures of pesticide compounds.
- High oxidation efficiencies were achieved at low pressures.
- Oxidation efficiency depended on the flow characteristics. Further investigation is needed to optimize these characteristics to obtain the best oxidation performance and enable efficient scale-up to large systems.
- Visualization of the jet flows shows that a large range of cavity characteristics is possible, and that the cavity characteristics can depend strongly on the DYNAJET® geometry. Further investigation is needed to determine the cavity/hydrodynamic characteristics that result in the best oxidation performance.
- Comparable rates of contaminant mass removal per unit energy input were found for a number of different compounds for comparable initial concentrations. This strongly suggests that this oxidation process will perform similarly well for a wide range of pesticides and other compounds.
- Oxidation of mixtures of pesticides was found to proceed at rates comparable to oxidation of individual compounds.
- A set of scaling relations was postulated. Scale-up estimates using these
relations indicate that the technology is very promising for providing a cost-effective
and efficient technique for the removal of pesticides from contaminated water
over a range of capacities.