Overview
ISO 4240-2:2024 - Fine bubble technology - Environmental applications - Part 2: Test method for evaluating aeration performance of fine bubble jet devices - specifies a standardized laboratory method to measure and report the aeration performance of fine bubble jet devices. The standard focuses on quantifying oxygen transfer from gas to water by determining the oxygen mass transfer coefficient (K_L,a) and derived metrics such as SOTR (standard oxygen transfer rate), SAE (standard aeration efficiency) and SOTE (standard oxygen transfer efficiency). It is applicable to fine bubble jet devices used for aeration (including ejector/self-aspiration and injector/pressurized modes).
Key topics and technical requirements
- Test principle: Non‑steady‑state oxygen transfer measurements to obtain K_L,a from DO (dissolved oxygen) change over time using established mass‑transfer equations and temperature/pressure corrections.
- Test system components: fine bubble jet device, tank, DO monitor and optical DO sensor (accuracy ±0.5 %, response time <0.02 τ/K), oxygen flowmeter (mass or volumetric converted to mass), water flowmeter, pump/blower and pressure gauge.
- Test media and conditions: ultra‑pure or deionized water; test water temperature recommended 23.5 ± 3.5 °C; tank depth < 1 m; tank volume sized by cycle frequency (>10 h−1 requirement).
- Chemicals and method detail: sodium sulfite deoxygenation with cobalt catalyst for the non‑steady‑state method; standard formulas for converting measured K_L,a to standard conditions (20 °C, 101.325 kPa) and computing SOTR, SAE and SOTE.
- Measurements and reporting: DO concentration time series, oxygen mass flow, gross power input (including pump/blower), and triplicate tests for reproducibility (report average K_L,a).
- Annex: Annex A provides an example test method for pure oxygen aeration performance.
Practical applications and users
Who uses ISO 4240-2:2024:
- Manufacturers of fine bubble jet devices - to characterize and publish comparable aeration performance data.
- Environmental and process engineers - to size aeration systems for wastewater treatment, aquaculture, water restoration and ecological remediation using validated SOTR and SAE values.
- Independent test laboratories and certification bodies - to perform repeatable lab evaluations and support product claims.
- Procurement and regulatory bodies - to compare devices on a standardized basis for energy efficiency and oxygen transfer performance.
Benefits:
- Enables consistent comparison of fine bubble jet devices.
- Supports energy‑efficient design by linking oxygen transfer to power input.
- Reduces uncertainty when scaling laboratory performance to field systems.
Related standards
- ISO 20480-1 - Fine bubble technology - Terminology.
- ISO 20480-2 - Fine bubble technology - Categorization of fine bubble attributes.
Keywords: ISO 4240-2:2024, fine bubble technology, aeration performance, fine bubble jet devices, oxygen mass transfer coefficient, SOTR, SAE, SOTE, DO sensor, sodium sulphite test method.