Grantee Research Project Results
Final Report: Development of a DynaJet Cavitation System for High-Rate Disinfection of Combined Sewer Overflows
EPA Contract Number: 68D03066Title: Development of a DynaJet Cavitation System for High-Rate Disinfection of Combined Sewer Overflows
Investigators: Chahine, Georges L.
Small Business: Dynaflow Inc.
EPA Contact: Richards, April
Phase: II
Project Period: October 1, 2003 through December 31, 2004
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2003) Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , Watersheds , SBIR - Water and Wastewater
Description:
DYNAFLOW, INC., investigated a novel technique for high-rate disinfection of combined sewer overflows (CSOs) based on harnessing the phenomenon of cavitation and on using the energy produced by the collapse of a multitude of cavitation bubbles in the cavitation reactor to oxidize and disinfect liquids. The process uses DYNAFLOW’s cavitating water jet technology, which is based on the patented DYNAJETS® nozzles. These were shown to be much more effective than ultrasonic devices in disinfecting and oxidizing liquids using cavitation. The DYNAJETS® cavitating jet systems operate without moving parts, except for a pump operated at modest pressures, and require no expendables. During this project, DYNAFLOW demonstrated that the DYNAJETS® are capable of oxidizing the polluted water and disinfecting it from microorganisms, even when operated in the presence of particulates.
The influence of various parameters defining the hydrodynamics of the jets and the parameters of the polluted liquid were investigated and tested under controlled laboratory settings for two families of DYNAJETS® nozzles: (1) the multi-orifice STRATOJET® nozzles, and (2) the DYNASWIRL® swirling jet nozzles. Various operation procedures and process configurations were considered. Numerical modeling of the DYNAJETS® cavitation process also was conducted to evaluate the interaction between bubbles and microorganism cells as a mechanism for disinfection.
Summary/Accomplishments (Outputs/Outcomes):
Both STRATOJET® and DYNASWIRL® nozzles have shown good capability to accomplish the disinfection objectives. The cavitation inception of both nozzles is high compared to conventional nozzles (i.e., they cavitate at lower pump pressures than conventional nozzles), and that of the DYNASWIRL® can be made even higher to attain high efficiency oxidation and disinfection at relatively very low pressures in the 20-30 psi range.
Disinfection of microorganisms, including Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, and Pseudomonas, were investigated, and the DYNAJETS® achieved multi-log reduction for all of these microorganisms. Typical laboratory experiments showed that the system running at 30 psi could disinfect 99.999 percent of the microorganisms (from 107 CFU/mL down to 102 CFU/mL) in contaminated water within 45 to 60 minutes. The DYNAJETS® also showed their capability to reduce microorganisms in the presence of solid particles in the liquid, which are known to significantly deteriorate the disinfection effectiveness of other advanced oxidation processes such as ultraviolet irradiation. Microorganism reduction tests in natural water, such as sewage wastewater and pond water, also were conducted and they produced good results.
Modeling, using DYNAFLOW’s advanced bubble dynamics codes and a cell model, demonstrated that rupture of the microorganism cell could be induced through the interaction of the cell and nearby cavitating bubbles. A scaling model, based on the various laboratory test results, was developed. It enabled design of a large-scale prototype loop, which was fabricated and a preliminary test was conducted. The large-scale model enables excellent visualization and already has produced further insight in the design and scaling of nozzles that are more efficient. Preliminary measurements of H2O2 indicated that the production level of the large-scale nozzle is in the same range as for the smaller nozzles used previously.
Conclusions:
DYNAJETS® cavitating water jet technology was shown to achieve high rate disinfection suitable for the treatment of CSOs. The system requires very low maintenance and no expendables. In designing such a system, operating conditions could be selected flexibly depending on the fundamental requirements, such as achieving the purification in the shortest time or with the minimal energy. The investigation conducted in this project provided the basis for making such a selection and introduced normalization parameters that can be used to design systems of various scales. Based on the scaling deduced from microorganism disinfection experiments, two different types of large-scale prototype loops—a continuous flow-through system and a batch system—were designed. A large-scale prototype loop was built for further investigation in the laboratory and for use in a field demonstration.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 6 publications | 3 publications in selected types | All 2 journal articles |
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| Type | Citation | ||
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Choi JK, Chahine GL. Non-spherical bubble behavior in vortex flow fields. Computational Mechanics 2003;32(4-6):281-290. |
68D03066 (Final) |
not available |
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Choi JK, Chahine GL. Noise due to extreme bubble deformation near inception of tip vortex cavitation. Physics of Fluids 2004;16(7):2411-2418. |
68D03066 (Final) |
not available |
Supplemental Keywords:
RFA, Scientific Discipline, Water, TREATMENT/CONTROL, Wastewater, Environmental Chemistry, Civil/Environmental Engineering, Wet Weather Flows, Engineering, Chemistry, & Physics, Drinking Water, Environmental Engineering, Water Pollution Control, combined sewage outflows, wastewater treatment, contaminant transport, disinfection of waters, cryotosporidium, cryptosporidium , cavitating jet system, combined sewer overflows, groundwater contamination, contaminant removal, drinking water contaminants, drinking water treatment, Giardia, caviatation, disinfectionRelevant Websites:
DYNAJETS®, cavitation system, disinfection, combined sewer overflows,
CSOs, sewage disinfection, Escherichia coli, Klebsiella pneumoniae, Bacillus
subtilis, Pseudomonas, microorganisms, cavitating jet, oxidation, scaling,
EPA, small business, SBIR,
SBIR Phase I:
Development of a DYNAJET Cavitation System for High-Rate Disinfection of Combined Sewer Overflow | Final ReportThe 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.