ENVE 436
UV/OZONE/PEROXIDE TREATMENT
Group Members:
Jeffrey Clarin
Martin Fletcher
Donna Reichardt
The first use of ozone was in 1906 in France. It was used as an oxidizing agent to disinfect
water. After 70 years of advancement in wastewater treatment technology, the synergistic
effects of UV light, ozone, and hydrogen peroxide were finally discovered in 1976. During the
years before this finding, technology was created combining ultraviolet light (UV) with ozone
and UV with hydrogen peroxide. Following the discovery of treatment technology combining
these three components, Ultrox International of Santa Ana, California built a system to treat
wastewater using UV, ozone, and peroxide in 1984 (1).
UV/Ozone/Peroxide treatment is an ultraviolet radiation and oxidation technology. As the name
implies UV/Ozone/Peroxide treatment is comprised of three individual components: ultraviolet
radiation, ozone gas, and hydrogen peroxide solution. The components together use radiation
and chemical oxidation to disinfect and destroy a wide range of contaminants. To understand
how the UV/Ozone/Peroxide treatment works it is necessary to understand the individual
components. Together ozone and hydrogen peroxide comprise the chemical oxidation aspect of
UV/Ozone/Peroxide treatment while ultraviolet light makes up the radiation aspect.
CHEMICAL OXIDATION
Chemical oxidation is a process by which compounds, such as waste products are oxidized to a
more environmentally benign state. Waste products that can be destroyed by oxidation include
organic molecules, chlorinated VOCs, mercaptans, phenols, and some inorganics. Cyanide
(NaCN) is one such product, which can be oxidized in the presence of ozone to a safer state (2):
O3 + NaCN --> NaCNO + O2
Oxidation and reduction equations occur in pairs to make up an overall redox equation. The
governing factor behind oxidation is the standard electrode potentials of the chemicals involved.
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Chemicals, which have high positive values for electrode potential, such as hydrogen peroxide
and ozone, spontaneously react with other chemicals. Ozone is commonly used in water and
wastewater applications as a disinfectant because it is a powerful oxidant, and reacts with most
toxic organics. Ozone reacts with organic molecules in many ways: inserting an oxygen into a
benzene ring, breaking double bonds to form aldehydes and ketones, reacting with alcohol to
form organic acids (2).
Hydrogen peroxide is used to treat liquid and solid hazardous wastes because it readily reacts
with organic chemicals to form carbon dioxide and water. Chemicals that are reactive with
hydrogen peroxide are as follows: nitriles, aldehydes, alcohols, amines, metals, alkylboranes,
azo-compounds, cyanides, phenols, sulfides, and chromium (1). But, it is not necessarily
hydrogen peroxide or ozone which reacts with a reducing agent. Ozone decomposes in a
solution of water and hydrogen peroxide decomposes in the presence of an iron catalyst to create
a large number of hydroxyl radicals (OH-). It is the hydroxyl radicals that react with compounds
at a much higher rate than the parent compound. Another way to enhance the oxidation reactions
for both ozone and hydrogen peroxide is through the use of ultraviolet radiation.
RADIATION
Radiation is a process by which energy is transferred from one location to another. One such
form of radiation is ultraviolet light. Ultraviolet light is often used as a disinfectant in water and
wastewater treatment. Radiation in high doses can permanently damage the building blocks of
life. It is with this method that ultraviolet light is used to kill microorganisms and disinfect
water. Ultraviolet radiation is powerful enough to break many covalent bonds. Alone it can
degrade PCBs, dioxins, polyaromatic compounds, and BTEX (1). UV light has another affect; it
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enhances chemical oxidation. The way ultraviolet light enhances chemical oxidation is
somewhat of mystery. One theory is that organic compounds absorb light energy at visible or
ultraviolet wavelengths and as a result are easier to destroy. In short, UV/Ozone/Peroxide
treatment is combination of the above technologies. In combining several oxidation methods
with a source of radiation energy, the limitations of the individual components are reduced.
A full scale UV/Ozone/Peroxide treatment system treats contaminated groundwater, industrial
wastewater, and leachates containing chemicals such as: halogenated solvents, phenol,
pentachlorophenol, pesticides, PCB's, explosives, BTEX, MTBE, and many other organic
compounds. The UV radiation and oxidation system consists of a UV/Oxidation reactor, an air
compressor with an ozone generator module, and a hydrogen peroxide feed system. A common
UV/Ozone/Peroxide process is shown below in Figure 1(3):
Figure 1: UV/Ozone/Peroxide Process Schematic
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ADVANTAGES
The advantages of a treatment process using ultraviolet light, ozone, and hydrogen peroxide are
numerous. The first one involves the actual treatment technology. A UV/Ozone/Peroxide
system is a destruction process, and the final products are only carbon dioxide, water, and inert
salts (4,5). Therefore, the process residuals do not require any additional treatment, as they
might in conventional systems.
In the UV/Ozone/Peroxide process, ozone is used as an oxidant, instead of the more conventional
use of chlorine. Ozone is a better disinfectant than chlorine and is not known to produce toxic or
mutagenic substances (1). Also, because ozone must be generated on site and used immediately,
no storage area is required for the oxidant (6).
The costs involved with the UV/Ozone/Peroxide process are lower than the costs for a system
utilizing only ultraviolet light and ozone, because the addition of hydrogen peroxide allows the
use of a smaller ozone generator and less oxidants (1). Also, the residence times needed to
decrease the concentration of a contaminant to a certain level are lower for the
UV/Ozone/Peroxide system than for ozone alone, UV/Ozone, or UV/Peroxide processes (2).
The final advantage of this treatment technology is the wide variety of contaminants and
concentrations that can be treated. The limitations of ultraviolet light, ozone, and hydrogen
peroxide alone are overcome by combining the three constituents. Finally, the oxidants and the
Ultrox International system are becoming readily available (1,4).
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DISADVANTAGES
There are still a few limitations and dangers involved with the UV/Ozone/Peroxide treatment
technology. High turbidity, solid particles, and heavy metal ions in the aqueous stream are all
interferences that reduce the effectiveness of the treatment (4). Because these substances must
be removed to ensure good treatment, the aqueous stream may need pretreatment.
Unfortunately, the equipment needed for this new treatment process can be expensive and
require a large amount of space. The energy required for the process is high resulting in large
costs (1,4). Also, capital costs are higher for the UV/Ozone/Peroxide system than for
conventional systems, but operating costs are lower (1). Ozone can also be costly, because it
must be generated and immediately applied at the treatment location (2). Finally, large areas are
needed for the many ultraviolet lamps required in this process (5).
Each of the constituents in the UV/Ozone/Peroxide process has dangers. Ozone is explosive,
toxic, and an irritant to the skin, eyes, respiratory tract, and mucous membrane (7). Hydrogen
peroxide is an irritant, can cause chemical burns, and is an explosive hazard (1). Ultraviolet light
can burn unprotected skin and the mercury in UV lamps can damage the central nervous system,
along with inflaming the nose and throat area (4).
Ozone is also a significant air pollutant and monitoring must be completed to ensure that ozone
levels are not exceeding regulatory concentrations (2). Lastly, the UV/Ozone/Peroxide process
mechanisms are still not totally understood.
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CASE STUDY(8)
In developing any new treatment technology, case studies are a must in determining their
capability of treating a contaminant. One of the first case studies for UV/Ozone/Peroxide
treatment was done for the US Department of Energy Kansas City Plant (KCP) in Kansas City,
Missouri. The main source of contamination was volatile organic compounds (VOCs) and the
identified surrogate chemicals were PCE, TCE, 1,2-DCEs and Vinyl Chloride. The field
application used was a pump and treat system that extracted contaminated groundwater for
remediation. The remediation treatment was through advanced oxidation processes (AOP), using
a UV/Ozone/Peroxide treatment system, which ran from May 1988 to May 1993. When the
UV/Ozone/Peroxide system was initiated in 1988, it was one of the first full-scale operating
AOP of its kind. For the first 4 years, close monitoring of the treatment system to develop pilot
studies to verify this new treatment was performed for regulators to see. At the end of the 4
years, an improved UV/Peroxide system was implemented (currently on going) from the
previous 4-year pilot study and is shown below in Figure 2:
Figure 2: Modified UV/Peroxide Treatment Schematic
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The results below illustrate the effectiveness of the treatment at the KCP site:
Table 1: Final Concentrations of the KCP UV/Ozone/Peroxide Treatment Process
Treatment
Process
Contaminant
Influent
Contaminant
Concentration,
g/l
Effluent
Contaminant
Concentration,
g/l
Percent
Removal
Percent
Detected in
Ambient Air
Percent
Detected in
Sewer
Discharge
Initial
UV/O3/H2O2
Modified
UV/ H2O2
Modified
UV/ /H2O2
VOCs
-
-
 94.6%
 3.7%
 1.7%
VOCs
-
-
>99.95%
0.00 %
<0.05%
PCB
0.3
0.0
100 %
0.00%
0.00%
Based on these results the use of the UV/Ozone/Peroxide, especially the modified UV/Peroxide
system, proved an effective process for removing and containing VOC contamination in the
groundwater. The system was designed to treat 30,000 g/l and the average influent was 25,00
g/l. Along with the high contaminant removal, the system design conditions were met. The
modified UV/Peroxide process replaced the UV/Ozone/Peroxide system, because the initial
system, containing ozone, required lots of maintenance on the ozone generator and the delivery
system. Ozone leaks were discovered (causing downtime) and the residual ozone proved to be
corrosive in the reaction chamber. Several other improvements were made to the initial
UV/Ozone/Peroxide process because serious downtime was encountered for acid cleaning of the
filters, UV lamp sheathes, and ozone sparger tubes. The modified system took this into account
and added a pH adjustment before the UV/Peroxide treatment and therefore lessened the chance
of fouling due to the oxidation of organics.
Overall, the research procedure was deemed very useful. An initial design was tested, and based
on the results a modified system was implemented, which is the whole basis of research. The
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initial UV/Ozone/Peroxide demonstration system served as a stepping stone in developing the
modified UV/Peroxide process and clearly treated the saturated hydrocarbon contamination.
As with most ex-situ treatment processes, especially pump and treat methods, much of the VOC
mass is removed from the subsurface and treated with UV/Peroxide or UV/Ozone/Peroxide, but
there is still some in-situ groundwater VOC concentrations that will remain untreated. This
therefore limits most ultraviolet treatment systems, unless improved extraction procedures are
utilized.
FUTURE CONSIDERATIONS
The future of this treatment technology includes continuing to learn more about the process and
how to improve it. Higher intensity ultraviolet lamps are already being produced to reduce the
space and cost requirements for this process (5). Another innovation currently being studied is a
way to reduce the number of solid particles in the aqueous stream, so the amount of UV light
reaching the particles is greater. An electron-beam accelerator can be used to “zap” the aqueous
stream and oxidize organic contaminants to form harmless substances, like carbon dioxide and
salts (8). The UV/Ozone/Peroxide treatment technology is still new and advances are constantly
being discovered to improve the process.
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REFERENCES CITED
1. O’Brien & Gere Engineers, Inc. Innovative Engineering Technologies for Hazardous
Waste Remediation. New York: Van Nostrand Reinhold; 1995.
2. LaGrega, M.; Buckingham, P.; Evans, J. Hazardous Waste Management. New York:
McGraw-Hill, Inc.; 1994.
3. U.S. Filter/Zimpro, Inc. (Ultraviolet Radiation and Oxygen).
http://clu- in.com/site/complete/democomp/usfilzim.htm
4. Ultraviolet (UV) Oxidation. http://www.frtr.gov/matrix2/section4/4_56.html
5. Chin, K.; Fouhy, K.; Kamiya, T. Chemical Engineering. “Advanced Oxidation
Mission: Search and Destroy;” July 1997.
6. Encyclopedia of Environmental Science and Engineering. 3rd edition. Vol. 2.
Philadelphia: Gordon and Breach Science Publishers; 1992.
7. The New Encyclopedia Britannica. 15th edition. Vol. 2. Chicago: Encyclopedia
Britannica, Inc.; 1998.
8. Pump and Treat of Contaminated Groundwater at U.S. Department of Energy, Kansas
City Plant, Kansas City, Missouri.
http://denix.cecer.army.mil/denix/library/Remedy/Kansas/ksplnt02.html
9. Black, P. Business Week. “Zapping Toxic Waste with 1.5 Million Volts,” February
3, 1992.
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