List of contaminants that are destroyed, inactivated, oxidized, or eliminated by ozone in
water purification
Iron (Fe2+) and Manganese(Mn)- one can readily oxidize iron in groundwater and water
of low organic content. Ozone has extremely fast kinetics when it comes in contact with
Fe. Basically 0.43O3/mg Fe and 0.88O3/mg Fe is needed. The presence of organic
material inhibits removal of iron and manganese. So you have to get rid of the organics
before you start oxidizing the manganese. This can be accomplished by using an acid pH
of 5. Ozone oxidizes most of the iron and turns it into vary stable iron complexes.
Manganese oxidation is most effective around a pH level of 8
Oxidation of metals such as iron and manganese is quick and efficient over a wide pH
range. Iron in the ferrous state will be rapidly oxidized by ozone to the ferric state
whereby gelatinous ferric hydroxide will precipitate. Soluble manganate occurs in the
divalent form and will be oxidized by ozone to the tetravalent form also very rapidly.
Tetravalent manganese hydrolyzes, and it will produce insoluble manganese
oxydehydroxide which can be precipitated over a filter bed.
Nitrites- they are quickly oxidized by ozone into nitrate at a rate constant of
3.3-3.7 x 105 M-1 s-1 which corresponds to 1.04mg ozone/mg nitrite
Ammonia- oxidation is slow with ozone especially at pH levels lower than 9.3. The
presence of bromide in the water catalyzes the degradation of ammonia. With the help of
bromide, ammonia can be oxidized in a neutral pH environment.
Giardia- Giardia lamblia cysts were inactivated in water with ozone at pH 7.0 and 5 and
25 degrees C. The concentration-time products for 99% inactivation were 0.53 and 0.17
mg-min/liter at 5 and 25 degrees C, respectively. There is a 2 minute contact time (CT)
to eliminate 99.99% of the giardia organism. Ozone is 60 times more effective than
Chlorine at killing Giardia viruses
Mold- Ozone can kill mold on contact, even the loose spores that other products such as
bleach leave behind. It even eliminates the unpleasant odors of mold. Scientific tests
show that mold is greatly reduced by the addition of as little as 50ppb (parts per billion)
Chlorite and Bromite- these chemicals are very reactive with Ozone while Chlorate and
Bromate are not very reactive with Ozone.
Iodide- can easily be oxidized by Ozone. Iodide can be transformed into hypoiodous
acid (HOI) which can then react with natural organic material or it can continue being
oxidized into iodate (IO3-). IO3- is the desired sink for iodine in drinking waters.
Cryptosporidium- Ozone is superior to Chlorine Dioxide and Chlorine for the
inactivation of water borne pathogens such as Cryptosporidium and Giardia
Arsenic- An ozone dose of 2 mg/L, contacted with the water for 1 minute prior to
filtration, has been shown to be effective in oxidizing arsenic and other metals to below
detection limits. For the same Ozone dose arsenite is shown to have a half life of
approximately 4 minutes
Taste and Odor of inorganic and organic contaminantsChanges Caused by Ozonation
Description of Taste and
Odor
Fruity
Musty
Muddy
Earthy
Fishy
Astringent
Pastic
Taste or Odor
Intensity
Both increase
Both decrease
Both decrease
Both decrease
Both decrease
No change
No change
Water Flow: 2.0 m3 /h (0.013 mgd)
O3 contact time: 10-20 minutes
Applied O3 dose: 0-5 mg/L
Hydrogen Sulfide (H2S)- is easily oxidized by Ozone ultimately to form sulfate.
3mgO3/mg H2S to oxidize into sulfate which is a soluble salt.
Organism
Virus
E-Coli
Streptococcus
Legionella
Total Coliform
CT
1.3
0.02-0.03
0.01-0.03
0.3-1.1
0.19
This table provides various CT values for different contaminants throughout the paper
Removal of Color of Textile Streams and Plants- Ozone is effective in removing the
color from all dyes used in textile processing. The amount of Ozone varies depending on
a number of factors. Tosik has shown that about 1 mg O3/mg of Tosik is required to
achieve 95% of color removal. The CT time is roughly 10 minutes.
Cyanide- The reaction time for complete cyanide oxidation is raped in a reactor system
with 10 to 30 minute retention times being typical. The second stage reaction is much
slower than the first stage reaction. The reaction is typically carried out in the pH range
of 10-12 where the reaction rate is relatively constant. Temperature does not influence the
reaction rate significantly. To complete the first reaction requires 1.8-2.0 lbs of ozone
per lb of CN.
The following is a list of several contaminants. The concentration is given for 99%
deactivation of the contaminant in 10 minutes. pH of 7 and at 10-15 ˚C
Escherichia-0.001mg/liter
Streptococcus faecalis- 0.0015mg/liter
Polio virus- 0.01mg/liter
Endamoeba histolytica- 0.1mg/liter
Bacillus megatherium- 0.03mg/liter
Mycobacterium tuberculosam- 0.005mg/liter
Spores- Under hospitable sterilization conditions and at ambient temperature and an
ozone concentration of about 10mg/L Bacillus and Clostridium spores are inactivated
within 10 minutes.
Metolachlor- a pesticide can be efficiently removed with ozone alone while for geosmin
and MIB (methylisoborneol) a complete removal can be obtained with the advanced
oxidation of ozone (with concentration of 1.5-3mg/L and contact time of 2-3 minutes
MicroganismsMicrorganisms
Naegleria gruberi
Acanthamoeba
Naegleria gruberi
flowleri
T (˚C)
25
25
Microrganisms
N. gruberi 1518
N. gruberi Paris
N. gruberi MO5
N. gruberi NEG
N. Foleri 0359
A. castellanii
A. species MR4
A. species Brest
T (˚C)
25
25
25
5
25
25
25
25
7.4
7.4
CT
(mg*min/L)
.1-.4
.1-.4
7.4
.1-.4
7.4
7.4
7.4
7
7.4
7.4
7.4
7.4
CT
(mg*min/L)
0.7
0.68
0.73
4.23
0.3
1
1.1
1.12
pH
25
pH