Ozone Gas (O3) has as a long history of safe use in many fields as a strong oxidant such as controlling microorganisms in air and water sources, eliminating water-borne parasites and pathogens, and bleaching wood paper and pulp, eliminates odors, taste, and color. It is also used for bleaching different substances.
Due to the Quarantine measurement, pesticide resistance and residues, a High demand for organic grains, food manufacturing companies, and grain handlers are looking for new methods to control insects and pathogens in stored products.
Ozone (O3), three-atom of oxygen combine with each other through a covalent bond, it is highly unstable than O2. At room temperature it breaks down with a half-life of 20–50 min convert into normal O2 and a single atom of oxygen [O] that is highly reactive. This nascent oxygen reacts with the cell membrane of bacteria and virus. The normal cellular activity and cellular components are disturbed by attacking of nascent oxygen.
Researchers have been recently focused on the application of O3 as a fumigant in closed structure to control stored-grain insects and microorganisms and to overcome mycotoxins because it has an ability to clean the outer surface of grain kernel from contamination of fungal spores and toxins. Also, it can effectively use storage structures to kill adult stored-product pests and reduce off-odors producing volatile compounds present in the grain.
Generation of O3 by Artificial Methods.
Ozone (O3) is an allotrope of oxygen, which can be generated by electrical discharges in air and UV-light come from the sun. Artificially ozone can be generated by electrical discharge and has several advantages, like that greater sustainability of the unit, higher ozone production, and higher cost affectivity. Ozone has a half-life of 20-50 min, rapidly decomposing to molecular oxygen and nascent oxygen. Ozone can be generated easily at the treatment site by using only electricity and air, As compare to traditional post-harvest pesticides it provides several safety measures and benefits.
Various Methods for Ozone Treatment
At early stages treatment of fixed-bed ozonation was developed to treat grain in on-farm grain bins by introducing it through the grain mass using forced air at a minimum air velocity of 0.03 meters per second (m/s), until the right CTP is reached. During treatment of grain mass with ozone, a recirculation system is needed to help capture the gas and to keep it from exhausting into the environment. Due to the less availability of current ozone- producing generators, there is a limit to the size of grain bins that can be ozonated. Consequently, more efficient ozonation treatment systems were variable-speed fan equipped to deliver at least the minimum air velocity of 0.03 m/s to move ozone through a grain mass but without causing the ozone to become too diluted in the bottom grain layer.
• The efficient flow of ozone by new generators:
This is controlled by the ozone-producing generator. Presently, the only safe method to control this variable is by shutting down one or more of the four chambers of the ozone generator. By use of modern technology new types of generators build up to control ozone production and more efficient flow.
• Exposure time:
The exposure time depends on the concentration of ozone and at each grain layer depth needed for the desired treatment effect (e.g., odour removal, fungi sterilization, and insect mortality). Once the desired Concentration Temperature and Pressure is achieved and maintained, the bottom treated grain layer is removed by tapered unloading auger is programmed. Developed such as a semi-continuous counter flow ozonation system and a continuous-ozonation flow system, in order to treat grain at a continuous rate and sterilize any fungal spores and eradicate insects. As compared to the current fixed-bed treatment these systems offer a faster and safer treatment.
Hafiz Muhammad waqas Amjad 1*, , Hamza khaliq1, Muhammad Umer Saeed2 , Shahroz Khalid3
And Adnan Sohail4
1Department of Entomology, University of Agriculture
Hafiz Muhammad waqas Amjad