Pesticide Degradation by Ozonation

High pH and low temperatures improve the degradation of pesticides by ozone.

Pesticides affected by low ozone doses:

Dimethoate

Chlortoluron

Diuron

Isoproturon

Metoxuron

Vinclozolin 

Increasing the ozone dose enhances the degradation of most pesticides.

Poorly degradable pesticides such as atrazine, propazine, simazine, and others react slowly with ozone, relying mainly on hydroxyl radicals.

Advanced Oxidation Processes and Pesticide Removal

• Combining ozonation with hydrogen peroxide significantly improves the degradation of persistent pesticides.
• Pesticides such as atrazine, propazine, simazine, chlorfenvinphos, and others are effectively degraded at higher ozone-to-peroxide ratios.
• Bromate formation is minimised (<2 µg/L) when using excess hydrogen peroxide during advanced oxidation.
• pH has a minor effect on pesticide degradation in advanced oxidation, with higher hydroxyl radical formation at increased pH.

Ozone Disinfection 

• Lower pH and temperature favour disinfection.
• Pesticide removal is limited at low ozone levels, with only a few pesticides degraded effectively.
• Higher ozone doses improve degradation. 
• To confirm disinfection and prevent exceeding safety limits, it is important to measure ozone levels continuously. 
  

Water Treatment Strategies for Pesticide Removal

• A three-barrier approach includes storage, ozonation, and activated carbon filtration to reduce pesticide levels.
• pH levels and temperature will affect pesticide removal wth ozone.
• For persistent pesticides, ozonation with hydrogen peroxide enhances degradation efficiency.
• The treatment process effectively decreases pesticide concentrations to meet water quality standards.

2. How Does Ozone Compare to Chlorine for Produce Washing?

Ozone eliminates the need for chlorine while achieving comparable microorganism control, offering a safer and more environmentally friendly alternative for water treatment professionals.

Ozone is produced on-site and is not classified as a pesticide or chemical, which simplifies regulatory compliance and enhances safety protocols for food and water treatment.

Rinse water must be ultra-clean and free of organisms. 

The oxidative properties of ozone ensure that organic contaminants in food-wash waters are destroyed.

The oxidative properties of ozone reduce reliance on chlorine, supporting environmentally responsible practices in food washing and recycling. 

Less chlorine means less equipment maintenance and fewer halogenated reaction products.

In turn, this can result in cost savings for the user.

3. Can Ozone Extend the Shelf Life of Fresh Produce?

Storage facilities dosed with ozone in transit and on the shelves will prevent the growth of bacteria and mould.

The old saying, “One bad apple spoils the bunch“, is very relevant when storing or transporting fresh vegetables or fruit.

Maintaining the freshness and quality of perishable goods using ozone helps distribution centres minimise spoilage and meet safety standards. 

4. Why Cold Chain Operators Are Using Ozone Technology

• Ozone gas treatment can be termed “organic”, unlike chemical treatment such as chlorine dioxide or formaldehyde, which, if used in food preparation, precludes the product from being labelled “ organically grown and prepared.” 
• Ozone is introduced into cold rooms to control fungus, mould, bacteria & ethylene, extending the shelf life of fresh food in transit or storage. 
• Ozone dramatically reduces the risk of spreading germs when handling foods such as meats, fish, fruits, and vegetables.
• Bacteria, moulds and yeast can grow in refrigerators, causing spoilage and reducing shelf life.
• Organic or bacterial “slime” grows on produce and refrigerator coils, pans, and drain lines, blocking or restricting flow and causing cross-contamination with other foods in the refrigerator.
• Ozone will eliminate ethylene. The presence of ethylene from higher plants, including the leaves, stems, roots, flowers, fruits, tubers, and seeds, will hasten ripening. Plant reactions to ethylene include stimulation of the ageing process in leaves & flowers, the shedding of leaves & flowers, the ripening of fruit and a climacteric rise in respiration in some fruit, which causes a release of additional ethylene.
• Ozone also neutralises Linuron carried over from herbicides. Commonly, the herbicide linuron, used for weed control in vegetable plantations, can leave residual linuron on plants, including the lower stems of baby carrots. The presence of linuron will condemn the entire container upon arrival at the final destination. Dosing ozone in the cold room will eliminate linuron.
• Cockroaches and other insects will not grow in the presence of ozone.
• Mould control, especially during cheese ripening or sausage curing, is challenging due to high condensation levels in the storage room. Ozone gas will prevent mould growth on all surfaces exposed to it. 
• The proliferation of Salmonella, especially in grain storage, can be curtailed by judiciously using ozone gas introduced into bins or onto conveyor belts or augers.
• The same applies to fungal growth, where introducing ozone will provide a fungus-free environment.
• Smells escaping, e.g. tannery
• Covid. At the height of the COVID-19 crisis, four instances of infection in New Zealand occurred, apparently due to pockets of the COVID-19 virus identified on the surface of packaged meat. These had remained on the product under cool conditions following an initial infection during food preparation.
• Commonly, ozone gas is used in shipping containers as part of a controlled environment where carbon dioxide, temperature and humidity monitors are crucial to ensure a safe and stable environment for fresh fruit and vegetables.

5. Food Sanitising for Export Compliance: What Processors Need to Know

• Contain ethylene to extend shelf life and prevent fungal growth.
• Straight disinfection of fungus and mould growth.​
• Mould containment in cheese factories/storage.
• Table grapes exporters need to prevent bacterial growth in transit
• Washing and rinsing of avocados will eliminate surface bacteria or mould.
• Control bacteria growth on the skins of pomegranates and citrus.
• Ozone will eliminate Lumarol, a residual herbicide introduced in plantations to prevent weed growth