Ozone For Odour Control
A serious problem for sewage plant operations
is the generation of foul smelling odors, especially when they are located
within an enclosed area. Studies have shown that air pollution from odors is
the greatest problem that these installations must deal with and for which
they receive the most complaints from the local population.
Ozone treatment for deodorization of odiferous gases has been acknowledged
as a technically effective method for many years. During the past
twenty-five years, hundreds of ozone installations for the treatment of
sewage plant odors have been erected. Ozone is one of the strongest oxidants
known and quickly breaks down odors compounds.
In the elimination of obnoxious odors', Ozone reacts with malodorous
substances to produce oxidized products having better olfactory
characteristics. Ozone has been found to be very effective on many
contaminants including sulfides, mercaptans, amines, phenols, and similar
chemical compounds. In addition, ozone is a very powerful germicide and
destroys most airborne bacteria.
What is required?
What is needed is a way to quickly and
economically maintain a reasonably good environment by eliminating the foul
smell generated by different biological sources, mustiness from mold and
mildew and oxidize organic harmful gases into harmless gases and the
products.
For improving the environment either the internal air of the plant should be
replaced on a continuous basis to maintain a very low concentration of
harmful gases and foul odor. However, this is an uneconomical and
inconvenient proposition. Ozone is capable of oxidizing various organic
odors, VOC, Organic Gases and destroys viruses and bacteria present in the
air that are not only offensive but very harmful.
What is the solution?
Ozone treatment is a proven & a viable
solution to purify & de-odorize air in the Sewage Treatment Plants or
similar locations that suffers from foul odor and organic harmful gases.
Ozone the nature's most powerful purifying agent oxidizes the harmful
organic foul odors and the presence of different types of VOC's (Volatile
Organic Compounds) and eliminates them through intensive oxidation.
Treatment Process
Ozone is usually generated from "Oxygen as
Feed Gas " in ozone systems used for odor control. In our OZ-AIR®
ODOFREE Ozone Systems special contact systems are designed as per site
requirements so that the odiferous gas is collected and continuously reacted
with ozone. To insure proper distribution and increase the reactivity Ozone
gas is usually introduced through a perforated pipe or diffuser placed
across the duct carrying the odiferous gas. In case we have to deodorize
Area our ODOFREE Wall Mounted units are ideal solution in which controlled
amount of gas is diffused in the odiferous area.
Ozone Dosage Control
Ozone systems are usually designed for fully
automatic operation to minimize personnel requirements. The ozone dosage can
be controlled by two different methods.
- The control method usually employed automatically adjusts the ozone
production rate to balance the residual ozone content of the contactor
off gases to a preset ozone level. As a result, ozone is not wasted and
less operator attention is required. However, a residual ozone analyzer
is required.
- The second type of control method that can be used is to manually set
the level of ozone production. Thus, whenever the blower is working, the
Ozonator will produce a constant amount of ozone. The main disadvantage
of this system is that even if the odor level increases the ozone
production level will remain the same.
Typical Ozone Dosages
In the treatment of sewage plant odors, ozone
requirements are well established and experimental work is usually not
necessary. An ozone dosage in the range of one to two ppm by volume is
usually adequate to deodorize exhaust gases from standard, covered, sewage
treatment plants. Other applications have varying ozone requirements, since
odors usually differ both qualitatively and quantitatively. Table 1 suggests
general ozone dosages for various applications. This is based on an air
change in the collection chamber once every five minutes and a contact time
of thirty seconds.
| Ozone Dosage in Odor Control |
| APPLICATION |
PPM (Vol.) |
| Wastewater Air treatment |
1-2 |
| Sludge storage facilities |
10 |
| Paper mills |
10-50 |
| Rendering plants |
10 |
| Chemical plants |
3-10 |
| Food processing plants |
20-30 |
| Fermentation plants |
1-50 |
Note: If precise data is required,
testing can be performed on-site. This is usually advisable when specific
odor contaminants are not precisely known. All data are believed to be
correct. However, this should not be accepted as a guarantee of their
accuracy, and confirming tests should be run in each plant since local
conditions may vary.
Limit Of Ozone Concentration
Ozone Concentration should not exceed more than
0.1 PPM where persons are present, for eight hours or more per work day, and
no person be exposed to a ceiling concentration of Ozone in excess of 0.6
mg/m³ (0.3 PPM by volume) for more than ten minutes. This limit is set
as per OSHA standards.
Safety information regarding product is contained in its Material Safety
Data Sheet provided along with the system when supplied. When properly
applied for odor control resulting residual ozone concentrations will be
negligible. They will be below the Maximum Allowable Concentration (MAC)
established for most jurisdictions as the maximum level to which an
individual may be continuously exposed during an eight hour working day.
Ozone destruction is achieved through the oxidation of odor producing
compounds prior to release to the atmosphere with a controlled system.
Types Of Ozone Purification &
De-Odourisation System
Controlled quantity of Ozone is diffused
into the environment:
- Through a network of diffusers into the affected area, the diffusers
are connected to a Central Ozonator, which can be located at a suitable
place and connected to the diffuser network.
- Through special Online Ozone Generators, Ozone can be injected into
the Plant through Pipelines while the Ozone Generator can be located on
the top, taking input from the fresh air for the production of Ozone.
- Incase Plant has an Air Handling System; it is better to inject Ozone
at the inlet of AHU. The injected Ozone gets mixed with the total air
stream and provides a uniform distribution and effective deodorization
and cleaning of the place.
- Ozone Air purification is a continuous and safe process.
Monitoring And Control Of Ozone
Concentration
Concentration of Ozone in air is monitored by
Ozone Monitors manufactured by "OZ-AIR". For Automatic regulation
a feedback loop can be used. The monitoring system can be equipped with two
steps output, which can be set at a desired Ozone Concentration levels. The
System will provide Ozone output correction from the Ozone Generator and if
required, warnings or control signals for operation of any other equipment.
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