Overview
ISO 20304-1:2020 defines a standardized test method for evaluating ozone fine bubble water generating systems using the decolorization of methylene blue. The standard is focused on performance assessment for water treatment applications (e.g., wastewater and industrial water) and specifies test apparatus, environmental conditions, calibration, measurement and result expression. It does not address ozone impacts on health or the environment.
Key topics and technical requirements
- Test principle: introduce a measured ozone dose via an ozone fine bubble water generating system into methylene-blue‑coloured water and monitor the decrease in absorbance to determine the half-life of absorbance.
- Test equipment configuration: four-unit layout - Raw material gas supply (A), Ozone generator supply (B), Chemical reaction unit with fine bubble generator and tank (C), and Discharged ozone treatment (D).
- Ozone supply conditions: example parameters include 0.5 L/min ozone flow rate and 3 g/h ozone yield; material gas oxygen concentration ≥ 90 % (report gas gauge pressure).
- Test tank and water: recommended glass column ≥ 60 L, water depth 35 cm ± 1 cm; water quality per ISO 20480-2; methylene blue stock (0.15 g/L) and test water adjusted so pH is between ~5 and 8, test temperature ~20 °C ± 2 °C.
- Optical measurement: absorbance measured at 664 nm (colorimeter/spectrophotometer or inline absorbance meter), synchronized with fine bubble generation; measurement cycles and data-point requirements specified.
- Calibration & validation: prepare five concentration levels for calibration, validate ozone meters, photometric instruments and pH meters (references include ISO 10678, ISO 1431-3, ISO 20480 series).
- Data processing and uncertainty: procedures for functional processing, corrections to account for optical effects of bubbles, and uncertainty evaluation are specified.
- Additional measurements: includes measurement of fine bubble size and number concentration using air (Clause 6).
Applications and who should use this standard
- Manufacturers and suppliers of ozone fine bubble generators seeking objective performance verification and product comparison.
- Laboratories and test houses performing standardized decolorization tests for wastewater and industrial effluents.
- Wastewater treatment operators, dye-house and industrial water engineers evaluating advanced oxidation / decolorization technologies.
- R&D teams and consultants optimizing ozone utilization efficiency and demonstrating operational improvements (ISO notes ozone fine bubbles can improve efficiency vs diffuser systems).
- Procurement and compliance teams requiring reproducible, comparable test data.
Related standards
Keywords: ISO 20304-1:2020, fine bubble technology, ozone fine bubble, methylene blue decolorization test, water treatment, wastewater, industrial water, absorbance 664 nm, test method.
Open preview (PDF)Fine bubble technology — Water treatment applications — Part 1: Test method for evaluating ozone fine bubble water generating systems by the decolorization of methylene blue
