Odor control with essential oils and waterless
vaporizer
□ GE Water Technologies : www.gewater.com
KM M Swamy, Regional Technical Support Manager,
65-6267-4882, Singapore
Jucheol Heo, Technical Manager
82-52-223-5300, Korea
ABSTRACT
Almost any manufacturing process can generate odor. Since the Clean Air
Act Amendment (CAAA) went into effect, the onus has been placed on
industries to reduce their odor emissions. It can cost millions of dollars to
companies and shut the facilities if not handled properly. A complete
understanding of the odor and the process in which it shall be dealt with are
absolutely essential to face any situation that might arise even in the most
environment friendly industrial establishment. This paper discusses the eco
friendly odor control chemistries, based on essential oils marketed by GE
Betz.
INTRODUCTION
Odors are difficult to define with scientific form compounds that have a
strong smell that can affect our olfactory nerves. Bad odors can indicate
danger; the addition of mercaptans to natural gas is to insure that any gas leak,
however small, is detected even before the odorless LPG causes deaths.
ODOR GENERATION AND CONTROL
Odor can be generated either by oxidation or reduction. While oxidized odors
are distinguished by their musty nature, reduced odors are unique with their
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putrid and rotten smell. Not all
odors are noxious or toxic in
nature. Hydrogen Sulfide is the
most common odor-causing
chemical,
followed
by
mercaptans and much other
chemistry. These gases can have
lethal consequences when their
levels exceed the threshold limits
in atmosphere. Concern for
public
health
and
safety,
improving employee working
conditions, property values and
governmental legislation are reasons for industrial odor control. Other nonreduced odors, such as those formed by certain compounds containing
amines and other groups, also contribute to odor emissions and need to be
controlled.
The specific need for odor control arises out of the following situations:
 Odoriferous substances such as Hydrogen Sulfide cause corrosion and
thereby machinery or equipment failure.
 Consumer rejection of consumable goods because of unpleasant odor.
 Safety concerns that people may be overcome by odor at the workplace
and in the neighborhood.
 Negligence of an odorous area within a working premise typically results
in lowered productivity and or development of another unsafe situation.
Many chemistries, both inorganic and organic, are available for odor control,
specific to the nature of the odor, source and location of concern. The
inorganic chemistries are limited by their area of performance, whereas
organic chemistries have a wide range of application.
PROGRAMS AND SOLUTIONS TO CONTROL ODORS
Mechanical solutions such as Scrubbing, Incineration and other traditional
methods are quite common in odor control, but they are either too expensive
in their capital investment or offer little respite when retrofitted or when the
installed capacity is exceeded by the operating capacity. A chemical program
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will normally have a lower impact on the bottom line than immediate upfront capital expenditures. In addition, the time lapse between odor control
conception and installation is shorter. Oftentimes, a chemical program can
begin within days of inception.
Success of any Odor control program is dependant on three factors:
 Good understanding of the source of odor, its spread and site conditions
under which the odor needs to be combated.
 A strategic and tactical plan (as there could be unforeseen deviations in
process and wind directions, etc) with the site personnel and
neighborhood who are potentially affected by odor.
 Chemistry that is most suited for the abatement of odor at its source or
during its spread. At least four chemical means of controlling odors are
generally used in the industrial setting:
1. Organic scavenging - Primary amines
2. Chemical oxidation - Chlorination, hydrogen peroxide,
permanganate, ozone
3.
4.
Precipitation - Iron salts
Control by pH - Lime, soda caustic
Other solutions that are included in a successful odor control program are:
5. Proprietary organic scavenger
6. Biomodifiers - nitrates and proprietary inhibitors
7. Masking agents
8. Neutralizers
Organic scavengers are typically comprised of primary amines that react
with reduced sulfur compounds that have acidic protons, as shown in the
figure below:
H2S ←→ HS- +; H+;
HS- ←→ S= + H+
Such nonproprietary compounds are not selective and will react with carbon
dioxide as well, and in so doing will have a higher use cost than more
selective compounds.
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Proprietary organic scavengers such as ProSweet™ are more specific in
their reaction and will selectively react with the reduced species of sulfur
compounds such as hydrogen sulfide and certain mercaptans. These organic
scavengers tend to form side reactions; therefore, their use cost will tend to
be lower. Of course, proper treatment levels for scavengers depend on many
factors such as stream flow rate, temperature, H2S concentration, desired H2S
removal efficiency and pH.
The benefits of using an organic scavenger include:



No pH change
Ease of handling and simple feed equipment
No sludge generation
Biomodifiers such as nitrate are commonly used in facultative and anaerobic
lagoons to aid in controlling odors. Anaerobic bacteria use nitrate in
preference to sulfate as an electron acceptor during their metabolism of
organic substances. When nitrate is present, these sulfide-producing bacteria
use it rather than sulfate. Thus the by-product of their activity becomes
odorless nitrogen rather than objectionable H2S. Some of the disadvantages
of using nitrates are the limitation in effluent waterways and the necessity of
significant contact time in order for proper utilization to occur.
Masking agents are increasingly being viewed negatively. Primarily, this
negativity derives from the fact that in order to mask an odor the masking
agent must create a significantly higher odor level. Once done, the perception
is that something is being hidden. The masking of odors can present a severe
health risk when H2S is being masked. Masking does not mitigate the
hazardous health effects of H2S.
Oxidizers such as chlorine donating material have safety and handling
problems. In addition, chlorine donors may contribute to the formation of
carcinogenic tri-halomethanes (THM).
Hydrogen peroxide oxidizes H2S, and depending upon the pH of the water
system will yield different products as shown below:
pH < 8.5
H2O2 + H2S ←→ S + 2H2O
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pH > 8.5
4H2O2 + S-2 ←→ SO4-2 + 4H2O
At pH < 8.5, the stoichiometric H2O2 requirement is 1 gram H2O2 for each 1
gram of H2S. In actual use, however, more H2O2 is required because H2O2 is
not selective in what it attacks and therefore oxidizes other materials and
organic matter in addition to H2S. Many oxidizers have similar usage
characteristics to that of H2O2.
Metal salts such as ferric chloride react as follows and precipitate the sulfide
from water as ferric sulfide salts. In addition to sludge formation, handling of
the iron salts presents a corrosion problem of its own.
2FeCl3 + 3H2S
----> Fe2S3+ 6HCl
Neutralizers function in a complex manner. This is because of the makeup of
the neutralizers. Those neutralizers that contain essential oils primarily
function by capturing odor molecules in a charge film that surrounds the
essential oil-water complex. Neutralizers that contain other large organic
molecules created by certain fermentation and blending processes function by
absorbing odor molecules, by radical reaction, or by condensation reaction
between the odor molecules and the neutralizer.
Oftentimes, the latter compounds produce a neutralizer reaction product that
does not create or leave a detectable odor. Within the neutralizer grouping,
the essential oils tend to control a wider range of odors. However, there may
be a detectable odor of the essential oil present after odor neutralization
The use of chemical neutralizers to control these odors is regarded as an
acceptable treatment option because of the minimal amount of capital
investment required. Other acceptable technologies, including combustion,
oxidation and stripping, are also very efficient, but require considerable
capital equipment investment. In many industrial applications odor control
methods such as incineration, carbon adsorption, wet scrubbing, source
modifications and odor masking may be found.
ODOR NEUTRALIZATION WITH ESSENTIAL OILS
When it comes to control of non-specific odors from Municipal waste, food
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industries, pharmaceutical units, automotive lines, flavors and fragrances,
nothing works better than neutralizing with essential oils.
Essential oils are liquids extracted from plant material by pressing, solvent
extraction, or steam distillation. These organic, naturally occurring essential
oils are extracted from the seeds, bark, roots, leaves, flowers, wood, balsam,
resin, and fruit of plants. The oils are then redistilled or rectified to remove
any unwanted materials. Essential oils easily evaporate, infusing the air
without leaving an oily residue behind. They are extremely complex organic
compounds consisting of hundreds of components and trace elements.
Essential oils contain many constituents. The predominant components are
terpenes and esters, aldehyde, ketones, phenols, terpenes, oxides, and
alcohols but a large number of trace elements are also present. It is these trace
elements that give the essential oil its character and enhance its ability to
blend with the other oils. The orange peel oil in ProSweet™ OC2533, for
example, contains over 200 trace elements at concentrations of less than one
percent. As in all natural oils, trace elements provide the delicate, extremely
complex nuances that provide the unique odor neutralizing quality. The
synergistic effect of trace elements enhances the blending and performance
of the odor-neutralizing product. The blended product actually becomes
greater in effectiveness and allows for a broader range of applicability than
the oils individually.
Unlike scavengers, those odor neutralizing products do not REACT with
odor-causing chemicals to remove them from the air phase, hence, whatever
health hazard related to the odor-causing chemicals, still remains. On the
other hand, odor-neutralizing agents are different from masking agents,
which covers unpleasant smells with another rather pleasant scent.
These oils will behave somewhat like a solvent. The odorous material can
be considered the solute. The essential oils are fed to the air in a fashion
that would initiate and optimize two physical processes that occur in the
vapor phase, Absorption and Adsorption, between the essential oil and the
odorous material. Surface area, contact time, particle size, temperature, and
concentration of both materials will be important in optimizing the efficiency
of the physical processes. The essential oil will physically combine with the
odorous material to form a new physical compound. This new combined
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product will have a net zero odor. Certain odors will be easily neutralized,
and certain hydrocarbons (heavy and/or saturated) will be difficult. H2S,
most mercaptans, NH3 and most amines can be neutralized. A property of
the essential oil is being able to trick the human olfactory system to not smell
something that is there.
HOW ODOR NEUTRALIZERS WORK:
Zwaardemaker in 1900 found that two odors get neutralized if introduced in
each nostril. The neutralizing effect was for specific chemical pairs (now
called Zwaardemaker pairs or Z-pairs) and was concentration dependent.
The exact means of the neutralization reaction between the essential oils and
the odiferous compounds is not completely understood. Studies to isolate the
exact mechanism are being done. In the process of odor neutralization there
is no chemical interaction involved. Neutralization is achieved when no
resultant odor, pleasant or unpleasant, is sensed. There exists an optimal
concentration of the counter-actant depending on the type and concentration
of the pollutant. Examples of Z-pairs include:





Butyric acid - Oil of juniper
Chlorine - Vanillin
Ammonia - Ionone
Tobacco odors - Oil of wintergreen
Rancid butter, milk fats - Juniper oil
ODOR NEUTRALIZATION WITH PROSWEET™ OC2533 AND
OC2534
Some site-specific situations offer very few choices other than vapor phase or
air contact treatment. GE Betz ProSweet™ OC2533 is a waterless vaporizer
that works by air contact. This needs a special equipment to vaporize the
chemical into the air, enabling reaction between its many constituents and the
odorous gases. This may be in either indoor or outdoor situations, and
requires corresponding equipment and technology, depending on the exact
situation. GE Betz ProSweet™ OC2534 works by surface contact. It can be
sprayed or misted in liquid phase with dilution.
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The advantages of air ProSweet™ OC2533, waterless vaporizing application
are :






Can be used anywhere, inside buildings and in open yards compact and portable
Immediate impact
Covers a wide variety of odors, including H2S up to 10 PPM
Completely water-free, hence does not cause any rainy effect.
Very effective with ease of operation and application
Capital equipment needs are minimal.
CASE HISTORY
Challenge : A leading refinery in South East Asia experienced noxious
mercaptans and non-specific odor from their large light crude storage tanks.
The light crude processed while it did not affect the process did emanate
odoriferous compounds as vapors while in the crude holding tanks triggering
environmental concern from the neighborhood. Legislation on Industrial
8
and Vehicular Emissions forced the refinery to continue to process light
distillate crude.
Four of these storage tanks were fitted with ring main spraying high-pressure
water around the periphery to contain the odor spreading from source.
Despite this measure, the odor spread into the nearby community. While the
refinery was evaluating other chemistries, the concern from the community
was snow balled to a point that there was a serious threat of closure order
from the local municipal government.
Solution : GE Betz took this challenge and offered a demo on the first day of
visit. Neutralizers based on essential oils, vaporizer ProSweet™ OC2533 and
ProSweet™ OC2534, a portable misting device proved their might on
samples of strong odorous compounds and on odors similar to site conditions.
The USDA certification and the eco friendly nature of the chemicals were
features the customer was keen with. GE Betz was awarded a month long
trial on the existing water misting facility. GE Betz reviewed the engineering
aspects and presented a modified misting system with better nozzles that can
enhance product performance and save extensively on water consumption.
Within a week’s time, one drum of the ProSweet™ product together with a
dosing pump was airlifted, delivered, set-up and the trial commenced at the
problem location.
Results : The refinery has not received a single complaint from the
neighborhood on nuisance and noxious odor from the day the trials started
with GE Betz ProSweetTM technology. Work environment have as well
significantly improved. The number of complaints from neighborhood fell
from 32 a week, prior to the commencement of GE Betz’ trial became ZERO
since the start of the odor control treatment program.
The refinery was likewise pleased, as they were able to apply an
environmentally complying true solution to the problem and not a masking
agent. The benefit to the plant is that the threat of closure order was
eliminated and the Refinery personnel work at a more pleasant working
environment what with the removal of the odor. Water consumption was
likewise reduced considerably with the completion of installation of the
misting nozzles.
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INTRODUCTION OF GE WATER TECHNOLOGIES
GE Water Technologies is the new global platform that brings together GE
Betz, GE Osmonics and GE Glegg to create the most comprehensive single
source of products and services for the treatment of water and process
systems available anywhere in the industry.
The integration of these three business components creates a powerful and
unified force for helping customers improve performance while reducing
operating costs in a broad range of applications.
GE Betz is a leading worldwide supplier of specialty chemicals and
engineered programs for the treatment of water, wastewater and process
systems in industrial, commercial and institutional facilities. Its products are
used in plant utilities, such as boilers, cooling towers and wastewater
treatment systems, to eliminate problems from corrosion, scale, deposits,
foam, odors and microbiological growth, as well as in manufacturing
operations to increase productivity, improve product quality, protect assets
and meet environmental requirements.
GE Betz is also a leading supplier of high-performance chemical treatments,
regeneration services and other support programs to increase the efficiency
and extend the useful life of membrane separation systems.
The primary industries served by GE Betz include automotive, chemical
processing, food and beverage processing, metal and plastic finishing,
microelectronics, minerals processing, petrochemicals, petroleum refining,
pharmaceuticals, power generation and primary metals.
GE Osmonics is a leading manufacturer and worldwide marketer of high
technology water purification systems; fluid filtration, separation and
handling equipment; controls; and replaceable components.


The Filtration and Separations Group supplies filtration and
separation products for customers in the beverage, municipal
drinking water, pharmaceutical, cosmetics, bioengineering, bottled
water, laboratory, power generation, food & dairy processing,
general industry, electronics manufacturing, acid recovery,
wastewater treatment, desalination, petroleum and gas extraction,
car wash and wine production businesses.
The Process Water Group offers standard and custom-designed
reverse osmosis water purification systems and components for the
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
beverage, municipal, pharmaceutical, medical (dialysis), power
generation, general industrial and controller/instrument segments.
The Household Water Group provides point-of-use filtration and
control valve products for residential and commercial markets.
GE Osmonics and GE Glegg bring GE Water Technologies a full line of
water purification and fluid handling equipment and design services for the
industrial, commercial, institutional and household water treatment markets,
including cartridge filters; reverse osmosis, nanofiltration, ultrafiltration and
microfiltration membranes; filtration lab products; industrial fluid recycling
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GE Water Technologies is headquartered in Trevose, Pennsylvania, USA, and
has worldwide operations. For more information, visit www.gewater.com.
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APPENDIX : THE RESUME OF THE SPEATER
Muthukumaraswamy K M
Regional Technical Support Manager, Asia Pacific
Industrial & Metals Process
GE Betz Singapore Pte Ltd

Graduated in 1981 with a First Class degree in Chemistry.

Graduated in 1994 with a Diploma in Management.

Worked with Petrochemicals and Fertilizers Industry for 13 years before joining
Betz in 1995. Experience includes erection, commissioning and operation of
medium size petrochemical plants, high-pressure boilers, turbines, utilities,
hazardous chemical storage and Hazop study.

Worked as a Field Sales & Service Engineer with Betz India Pvt. Ltd., before
moving to Singapore in 1999. Over the years, held various positions in Sales,
Marketing and Product Management.

Won four Technical Excellence awards.

Has one global patent and one patent pending technology related to steel
industry. Authored technical papers on treatment programs for Sinter Making,
Blast Furnaces, Coke oven and By-products plant, BOF practices, Water
treatment for Casters that are published in international conferences and within
the organization.

Currently Technical Support Manager, Asia Pacific with responsibilities for
engineering and marketing support in the Industrial & Metals Process
applications. Also Championing Odor Control and environmental compliance
opportunities within the region.

Member of Association of Iron & Steel Engineers and Toastmasters
International.
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