(CAV-OX® Process)
TECHNOLOGY DESCRIPTION:
The CAV-OX® process uses a combination of hydrodynamic cavitation and ultraviolet (UV) radiation to oxidize contaminants in water. The process (see figure below) is designed to remove organic contaminants from wastewater and groundwater without releasing volatile organic compounds into the atmosphere.
The process generates free radicals to degrade organic contaminants. The cavitation process alone has been demonstrated to achieve trichloroethene (TCE) reductions of up to 65 percent. UV excitation and, where necessary, addition of hydrogen peroxide and metal catalysts, provide synergism to achieve overall reductions of over 99 percent. Neither the cavitation chamber nor the UV lamp or hydrogen peroxide reaction generates toxic by-products or air emissions.
Magnum Water Technology (Magnum) estimates the cost of using the CAV-OX® process to be about half the cost of other advanced UV oxidation systems and substantially less than carbon adsorption. Because the process equipment has one moving part, maintenance costs are minimal. According to Magnum, the CAV-OX® process does not exhibit the quartz tube scaling common with other UV equipment.
The process is designed to treat groundwater or wastewater contaminated with organic compounds. Contaminants such as halogenated solvents; phenol; pentachlorophenol (PCP); pesticides; polychlorinated biphenyls; explosives; benzene, toluene, ethylbenzene, and xylenes; methyl tertiary butyl ether; other organic compounds; and cyanide are suitable for this treatment process. Bacteria and virus strains are also eliminated.
This technology was accepted into the SITE Demonstration Program in summer 1992 and was demonstrated for 4 weeks in March 1993 at Edwards Air Force Base (AFB) Site 16 in California. The Applications Analysis Report (EPA/540/AR-93/520), Technology Evaluation Report (EPA/540/R-93/520), and a videotape are available from EPA.
Magnum reports that improvements in UV lamp and reactor technologies have improved the efficiency of the CAV-OX® process three- to five-fold, compared with the pilot-scale unit tested at Edwards AFB under the SITE Program.
CAV-OX® recently (1996) has proven very effective in potentiating ozone concentrations in water reclamation applications. Ozone gas (O3) is relatively insoluble in water. However, hydrodynamic cavitation used in the CAV-OX® process continuously develops micro bubbles which enhances the dispersion of ozone in water. Three O3 techniques are available to Magnum: corona discharge with air feed, electrochemical 'water splitting' method, and electrochemical anodic oxidation.
The CAV-OX® process has been tested at several public and private sites. At a Superfund site, the process treated leachate containing 15 different contaminants. PCP, one of the major contaminants, was reduced by 96 percent in one test series. The process has also been used to remediate former gasoline station sites and successfully reduced contaminants in process streams at chemical and pharmaceutical plants.
The CAV-OX® unit is part of an ongoing evaluation at the U.S. Army Aberdeen Proving Ground. Features of the unit to be tested include remote monitoring and control systems for pH; flow; H2O2 flow rate, storage level, and pump rate; UV lamp, main power, and CAV-OX® pump function; and system shutdown control.
The CAV-OX® process achieved removal efficiencies of greater than 99.9 percent for TCE, benzene, toluene, ethylbenzene, and xylenes. SITE demonstration results for the CAV-OX® process are shown in the table below. Results are presented for both the CAV-OX® I (cavitation chamber by itself) and CAV-OX® II (cavitation chamber combined with ultraviolet radiation) demonstrations.
| CAV-OX® I | CAV-OX® II | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Flow (gpm) | Removal Efficiencies (%) | |||||||||||||
| H2021 Concentrations (mg/L)2 | Flow (gpm)3 | Removal Efficiencies (%) | TCE | Benzene | Toluene | Xylene | ||||||||
| TCE | Benzene | Toluene | Xylene | 5-kW4 | 10-kW | 5-kW | 10-kW | 5-kW | 10-kW | 5-kW | 10-kW | |||
33.1 |
0.5 |
99.9 |
>99.9 |
99.4 |
92.9 |
1.5 |
99.6 |
99.2 |
99.4 |
98.8 |
>99.9 |
98.6 |
>99.9 |
>99.9 |
23.4 |
0.6 |
99.9 |
>99.9 |
>99.9 |
>99.9 |
2.0 |
99.7 |
99.7 |
99.5 |
99.6 |
>99.9 |
>99.9 |
>99.9 |
>99.9 |
4.9 |
1.5 |
71.4 |
88.6 |
87.4 |
65.6 |
4.0 |
87.7 |
98.1 |
89.7 |
98.7 |
88.8 |
97.1 |
78.7 |
87.2 |
48.3 |
0.6 |
99.7 |
>99.9 |
>99.9 |
>99.9 |
1.4 |
99.8 |
99.7 |
99.8 |
99.8 |
>99.9 |
>99.9 |
98.7 |
>99.9 |
6.0 |
0.7 |
87.8 |
96.9 |
94.5 |
92.1 |
1.9 |
98.4 |
99.3 |
98.8 |
99.3 |
96.9 |
98.6 |
93.6 |
97.0 |
4.9 |
1.5 |
61.7 |
81.6 |
83.8 |
80.2 |
3.9 |
85.1 |
97.1 |
89.5 |
97.8 |
91.8 |
97.9 |
90.4 |
96.0 |
5.9 |
0.5 |
96.4 |
99.4 |
99.8 |
98.9 |
1.4 |
99.6 |
99.4 |
99.6 |
99.6 |
99.8 |
99.8 |
99.5 |
99.5 |
5.9 |
0.7 |
87.1 |
96.5 |
97.6 |
98.1 |
1.9 |
97.8 |
99.2 |
99.4 |
99.5 |
99.5 |
99.7 |
99.2 |
99.7 |
6.1 |
1.5 |
60.6 |
86.1 |
87.3 |
>99.9 |
4.0 |
86.3 |
98.9 |
93.5 |
99.5 |
94.5 |
99.6 |
95.4 |
>99.9 |
0 |
- |
- |
- |
- |
- |
1.6 |
94.1 |
99.2 |
49.1 |
68.1 |
20.7 |
54.7 |
43.3 |
46.7 |
0 |
- |
- |
- |
- |
- |
1.8 |
80.6 |
97.6 |
38.5 |
60.5 |
48.6 |
75.2 |
56.9 |
83.8 |
| 1 hydrogen peroxide | 2 milligrams per liter | 3 gallons per minute | 4 kilowatts |
EPA PROJECT MANAGER:
Richard Eilers
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7809
Fax: 513-569-7111
TECHNOLOGY DEVELOPER CONTACTS:
Dale Cox or Jack Simser
Magnum Water Technology
600 Lairport Street
El Segundo, CA 90245
310-322-4143 or 310-640-7000
Fax: 310-640-7005