There are a number of existing treatment chemicals and
systems used world wide in the disinfection of water and surfaces. These
based sanitation systems are by far the most commonly used. Chlorine products
are available in the form of gas, or as the hypochlorite of sodium or
Chlorine is a powerful oxidizing compound capable of reacting with both organic
and inorganic matter in water. The chemical’s strong oxidizing properties
reduces the level of biocide remaining to be available to inactivate micro-organisms
(the goal of any biocide). As a result, systems using chlorine must be continuously
monitored in any direct process flume wash operation where fresh fruit and
vegetables are washed prior to further processing.
The disadvantages of chlorine systems surround maintenance of effective dosage
levels, monitoring, safety and corrosivity issues. Chlorine is only effective
in a very narrow pH range of 6.5 to 7.5. Chlorine solutions will not naturally
remain in this range requiring constant monitoring and adjustment by addition
of acid or alkaline solutions. It is difficult to accurately measure free
available chlorine in the form of hypochlorous acid (the only biocidal active
specie) in line automatically above 8ppm chlorine. Other manual systems of
measurement are often inaccurate and time consuming.
Chlorine sanitiser compounds have the potential to form deadly chlorine gas
if the pH of the water decreases below 4.0 or if the temperature rises
significantly. Chlorine is corrosive to numerous metals, increasing plant maintenance
Additionally, chlorine can be irritating to the skin and mucous membranes.
Chlorine produces carcinogenic trihalomethane (THM) by-products which have
been the subject of governmental maximum limits in the USA and EU. These
limits have recently been reduced due to increased concerns.
The US FDA is currently reviewing the health and environmental impacts
of the ability of chlorine sanitisers to form toxic organic chlorine
by-products, such as the suspected THM compounds. These issues have created
opportunity for Ioteq’s much environmentally and labour safe Isan System
to be introduced into the market.
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Ammonium Compound Systems
quarternary ammonium compounds (Quats) benefit from their ability
to leave a residual anti-microbial film on the food surface. These
systems are not designed for flume wash water treatments unlike
the Isan System. However they are used predominately for sanitising
process equipment and conveyers as well as food surfaces Which
The disadvantages of Quat systems is that they are unsuitable
for food processes using starter cultures, such as yoghurt, cheese,
beer or wine operations. They also have a low tolerance to hard
water, and are incompatible with most cleaners and detergents.
Additionally, Quat systems cannot be used within the organic
industry due to the formation of a residual film.
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Chlorine Dioxide Systems
Chlorine dioxide is a gas that is soluble in water and
these systems are often used for drinking water disinfection.
The major disadvantages of chlorine dioxide systems are the high
initial capital cost to install an on-site generator, electrical
energy costs and worker safety. Chlorine dioxide gas is ten times
more toxic than chlorine gas and is sensitive to light at temperatures
greater than 30 degrees celsius (or 86 degrees fahrenheit). Chlorine
dioxide systems are not ideal for sanitising in the fruit and vegetable
market as most systems are required outdoors or in regions where
temperatures exceed 30 degrees celsius. Additionally, chlorine dioxide
is highly explosive when in contact with ammonia compounds.
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Peroxyacetic Acid Systems
Peroxyacetic acid is a fast acting sanitiser that
works on the same basis as chlorine based sanitisers.
The major disadvantage of peroxyacetic acid is its sensitivity
to metal ions. Peroxyacetic acid is corrosive to soft metals such
as brass, copper and galvanized steel, with the corrosive properties
accelerated at higher temperatures. Additionally, peroxyacetic
acid is known to have a bleaching effect on certain fruit and vegetables
if the dosage range deviates outside of a narrow range.
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Calcium Hypochlorite Systems
Calcium hypochlorite sanitation systems predominately use
tablets which disolve in water and deliver chlorine solution
into the water stream. Whilst these systems are comparatively
easy to install, it is difficult to regulate the chlorine release
rate, due to issues such as pressure and flow rates.
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Ozone is a powerful oxidising agent that is naturally unstable.
Because of ozone’s inherent instability, it cannot be stored
and must be produced on site at the location where the sanitation
is required. Whilst ozone systems have been shown to be more
effective at killing bacteria and viruses than chlorine systems,
they are more expensive than most other systems.
There are also
significant worker safety issues with ozone since the gas is
a powerful respiratory irritant. As a result, ozone
systems have not been widely employed in the food industry
and results to date have been mixed.
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Ultra Violet Light (UV) Systems
Invisible part of the spectrum which can’t be seen
by human eyes;
To produce ultraviolet radiation, low-pressure mercury gases
in quartz crystal are ignited between two electrodes with a large
current of electricity;
There are three categories of UV radiation based on their wavelengths:
UV-A, UV-B and UV-C. UV-C is of a shorter wavelength (in the
range of 254 nm);
Regular maintenance of UV lights is required on an ongoing basis;
For drinking water and other applications, a disinfectant can
be required to support the UV system as the UV system by itself
cannot provide residual protection;
TSS (Total Suspended Solids) can shield the micro-organisims
from the UV light, leaving harmful bacteria and other micro-organisms
unharmed from the UV light;
- TDS (Total Dissolved Solids) can form a coating which fouls
the lamp sleeve and reduces the effectiveness of the UV lamp;
The indirect effect of TDS on water quality can impact the lamp’s
performance, and has the potential to increase fouling of the
quartz sleeve that protects the UV lamp from moisture;
Temperature is also a consideration as the water must be between
40 and 80 degrees fahrenheit (4.5 degrees celsius, and 26.5 degrees
In summary, UV disinfection works only when Total Suspended
Solids are low and the water is clear. UV disinfection systems
also require a “line of sight”, meaning it cannot
penetrate cracks and solid objects. Additionally, running and
capital costs can be high.
Summary of Competitors
Chlorine systems currently dominate the market. However, the market is also
in urgent need for a more effective, automated system that can provide a guaranteed
accountability to owners, auditors and customers in an environmentally clean
process. Ioteq’s Isan System is the only system on the market that can
deliver all of these solutions.
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