ISO 20304-2:2024
Fine bubble technology — Water treatment applications — Part 2: Test methods using Escherichia coli as a test micro-organism
- Standard No.
- ISO 20304-2:2024
- Release Date
- 2024
- Published By
- International Organization for Standardization (ISO) IX / ISO
- Latest
- ISO 20304-2:2024
- Introduction
Analysis of the core content of the standard
This part of the standard specifies the bactericidal efficacy test method using a hydraulic cavitation microbubble generator to generate microbubbles, using Escherichia coli as the indicator microorganism and quantifying the bactericidal efficiency through the ATP bioluminescence method.
Comparison of technical frameworks
Dimensions Test group (microbubble treatment) Control group (conventional treatment) Bactericidal mechanism OH radical chemical action + physical shear force Physical turbulence action only Bactericidal rate in 30 minutes 82.9% (average) 32.2% (average) Key equipment Hydraulic cavitation unit+125L test tank Conventional circulation pump group
Key experimental requirements
1. Microbial preparation
ATCC standard strains (such as ATCC 11775) should be used, with an initial concentration ≥1×105 CFU/mL, and LB medium should be used for three-generation subculture.
2. Test system configuration
- Volume: 125L stainless steel test tank
- Circulation pump: 0.4kW multistage centrifugal pump
- Detection equipment: ATP bioluminescence instrument (detection limit 10-12 mol/L)
3. Test parameter control
The contact time is divided into three groups: 1 minute, 10 minutes and 30 minutes, and the water temperature is controlled at 15-24±1℃.
Technology evolution analysis
Compared with the early ultrasonic disinfection technology, the nano-scale bubbles (average diameter 247nm) produced by microbubble technology through hydraulic cavitation have a larger specific surface area, which increases the OH radical yield by 3-5 times. International laboratory comparison data show that a 10-minute contact time can achieve a 77.3% sterilization rate (P value 0.00126).
Implementation recommendations
- Equipment verification: Regularly calibrate the bioluminescence instrument to ensure RLU measurement consistency
- Biosafety: Operations must be performed in a BSL-2 laboratory
- Data recording: The initial ATP concentration (N value) and final value (Na value) must be recorded to calculate the sterilization efficiency D=R/Rc
ISO 20304-2:2024 history
- 2024 ISO 20304-2:2024 Fine bubble technology — Water treatment applications — Part 2: Test methods using Escherichia coli as a test micro-organism
- 2023 ISO 20304-2:2023 Fine bubble technology
