Introduction
Stožice Stadium, a premier football venue in Ljubljana with a capacity exceeding 15,000 spectators, faced critical challenges in turf maintenance due to its reliance on untreated rainwater for irrigation. The water, while sustainable, carried high levels of pathogenic microorganisms and had low dissolved oxygen content—posing both agronomic and public health risks.

To address these issues, a nanobubble-based disinfection and oxygenation system was installed in March 2022. The solution dramatically improved irrigation water quality, enhanced turf resilience, and ensured uninterrupted operations during Slovenia’s hottest summer on record.

Nanobubble Technology Overview

Nanobubbles—ultrafine gas bubbles under 200 nanometers in size—remain suspended in water and provide two vital benefits:

• Ozone Nanobubble Disinfection: Ozone nanobubbles offer powerful oxidative disinfection, effectively neutralizing pathogens and making rainwater safe for public use.

• Oxygen Nanobubble Enrichment: Oxygen nanobubbles elevate dissolved oxygen (DO) levels to over 15 mg/L, enhancing turf root development and plant resilience.

This two-stage treatment transforms stormwater into high-quality irrigation water, aligning sustainability with safety and turf performance.

Implementation at Stožice Stadium

• Start Date: March 2022

• Installation Type: Central irrigation water tank

• Pre-Installation Conditions:

  • Pathogens: High levels in stormwater

  • Dissolved Oxygen: Low DO values, inadequate for optimal turf health

• Post-Installation Results:

  • Water Quality: Nearly complete pathogen reduction

  • Dissolved Oxygen: >15 mg/L sustained levels

Process Overview

1. Ozone Nanobubble Disinfection
   The system was first used to infuse ozone nanobubbles into rainwater stored in the irrigation tank. This step virtually eliminated harmful microorganisms, reducing the risk of waterborne illnesses among athletes and spectators.

2. Oxygen Nanobubble Oxygenation
   Following disinfection, oxygen nanobubbles were added to enrich water with high DO levels. Within 14 days, turf root health improved visibly, with deeper, denser roots and enhanced nutrient uptake.

3. Seamless Integration
   The system was installed directly into the stadium’s existing water tank, requiring no major infrastructure overhaul and enabling consistent delivery of treated water to the turf.

Key Outcomes and Benefits

Direct and Indirect Financial Benefits

• Pathogen Elimination
  Near-total removal of waterborne pathogens minimized public health risks and liability, creating a safer venue for staff and spectators.

• Turf Root Improvement
  Deeper, healthier roots reduced the need for frequent turf repair or replacement, generating long-term cost savings in maintenance.

Operational and Environmental Benefits

• Heat Stress Mitigation
  July 2022 marked the hottest month in 50 years of record-keeping in Ljubljana, with average daily temperatures over 3°C higher than normal. Thanks to the oxygen-rich irrigation, the turf resisted heat shock and survived the extreme conditions—preserving the playing season and avoiding emergency turf replacement.

• Lower Maintenance Burden
  A healthier turf system reduced the frequency and severity of interventions required by groundskeeping staff, streamlining operations and preserving match-readiness.

Discussion

Agronomic Impact
The introduction of nanobubble technology addressed both biological contamination and physiological turf stress. By improving oxygen availability in the root zone and eliminating harmful microorganisms, the system helped develop a more resilient, disease-resistant turf capable of withstanding extreme climate conditions.

Economic and Operational Advantages

• Cost Savings
  Healthier turf means fewer repairs, lower chemical use, and reduced water waste. These translate into direct budget savings and enhanced resource efficiency.

• Safety and Facility Reputation
  Upgrading to safe, high-quality irrigation water reinforces Stožice Stadium’s reputation as a modern, responsible, and sustainable sports venue. The commitment to public safety boosts trust among teams, fans, and regulators.

Conclusion

Stožice Stadium’s adoption of ozone and oxygen nanobubble technology has transformed its irrigation system into a model of modern turf management. The system:

• Nearly eliminated pathogenic microorganisms in reused rainwater.

• Raised dissolved oxygen levels to >15 mg/L, promoting healthy turf growth.

• Protected turf from fatal heat stress during record-breaking summer temperatures.

This case highlights how nanobubble technology not only ensures player and public safety but also delivers tangible agronomic and financial benefits. The Stožice Stadium success story serves as a blueprint for other sports venues aiming to enhance field quality, operational resilience, and environmental responsibility.