Eliminating Microbiological Contamination in Ozone Fruit Wash Water

Location:

South Africa

Date:

May 2025

Background

At a leading fruit processing facility, Arc Aqua ozone washers were deployed to sanitize fruit surfaces before entry into high-care zones. Initial expectations were that combining ozone with standard filtration would meet hygiene standards. However, the facility faced ongoing challenges:

  • Persistent microbial contamination (E. coli, coliforms, and total bacteria)

  • Organic residue accumulation

  • Biofilm formation in wash systems

  • Unsustainable water losses in early-stage solutions

Filtration System Overview

To remove physical contaminants, a multi-stage filtration system was implemented:

  • Settler: Removed sand, soil, and large debris

  • Carbon Filter: Adsorbed organic compounds

  • Sand Filter: Removed suspended solids

  • Bag Filters (25μm): Captured fine particles

  • Treatment Tank: Enabled water recirculation

  • UV Lamps: Provided baseline disinfection

  • Waboost Ozone Ultrafine Bubble Generator: Trial focus

  • Ultrafiltration: Reserved for future integration

Filtration Performance Metrics:

ParameterRemoval EfficiencySuspended Solids98%Organic Matter76%Chemical Oxygen Demand57%Microbial Contamination0% (no removal)

Despite strong physical performance, filtration alone could not resolve microbial contamination, requiring advanced disinfection.

Disinfection Trials Overview

Objectives:

  • Eliminate microbial contaminants

  • Enable water reuse in a closed-loop system

  • Avoid harmful residues and surface effects on produce

  • Suppress biofilm formation and regrowth

Treatment Methods Trialed:

  1. Total Loss System – Effective but unsustainable (6,000 L/hr water loss)

  2. Sodium Hypochlorite – Reduced bacteria but introduced chemical residues

  3. Hydrogen Peroxide – Effective but costly

  4. Peracetic Acid – Strong disinfectant, but caused odor and residue issues

  5. Chlorine Dioxide – High efficacy but corrosive to infrastructure

  6. Ozone Injection via Ultrafine Bubbles – ✅ Highly effective, chemical-free, sustainable

  7. Reverse Osmosis (RO) – Excellent microbial removal, but overengineered and expensive

  8. Long Water Loop Simulation – Promising closed-loop model incorporating ozone + filtration

Why Ozone via Nanobubbles Was the Optimal Solution

Among all methods tested, ozone injection using ultrafine bubbles provided the best balance of efficacy, sustainability, and cost:

  • Complete microbial and biofilm control

  • No chemical residues or impact on fruit quality

  • Compatible with closed-loop systems

  • Minimal infrastructure upgrades required

  • Lowest cost per liter of treated water

  • Breaks down naturally into oxygen—no toxicity

Scientific Advantages of Ozone:

  • 50% stronger oxidizer than chlorine

  • Broad-spectrum action against bacteria, viruses, and spores

  • Penetrates biofilms that resist conventional agents

Recommended Future Strategy: Long Water Loop Model

To achieve best-in-class sanitation and sustainability, the facility should adopt a Long Water Loop model by recirculating wash water through a centralized treatment plant featuring:

  • Multi-stage filtration (sand, carbon, bag, cartridge, glass media)

  • UV disinfection

  • Centralized ozonation (primary method)

  • Optional chlorine dioxide dosing for periodic sanitation

Expected Benefits:

  • Regulatory compliance through full microbial control

  • Reduced chemical procurement, handling, and storage

  • Improved water sustainability metrics

  • Prolonged equipment lifespan due to chemical-free treatment

Conclusion

The use of ozone ultrafine bubble technology emerged as the only method that effectively unified food safety, sustainability, and economic efficiency. In the context of increasing regulatory and environmental pressures, ozonation offers a future-proof standard for produce sanitation—delivering complete microbial control without chemical compromise.

Want to learn more how Waboost can help your business?
Book a free introductory call with us today.
Want to learn more how Waboost can help your business?
Book a free introductory call with us today.
Want to learn more how Waboost can help your business?
Book a free introductory call with us today.

Revolutionizing Water Quality with Smart Ultrafine Bubble Solutions

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Central European Business Hours

Tehnološki park 19, 1000 Ljubljana

© 2025 by Waboost

Revolutionizing Water Quality with Smart Ultrafine Bubble Solutions

Connect on LinkedIn

Central European Business Hours

Tehnološki park 19, 1000 Ljubljana

© 2025 by Waboost

Revolutionizing Water Quality with Smart Ultrafine Bubble Solutions

Connect on LinkedIn

Central European Business Hours

Tehnološki park 19, 1000 Ljubljana

© 2025 by Waboost