ISO 20304-4:2026

Description

This document specifies a method for assessing the impact of ultrafine bubbles (UFBs) on membrane antifouling using the crossflow filtration system as the evaluation setup. The evaluation compares the membrane fouling behaviour of the original wastewater (control) with that of the same wastewater after UFB generation under specified operating conditions. This document is applicable to dispersions containing UFBs, including dispersions in which microbubbles (MBs) are present in combination with UFBs.

The method employs the crossflow membrane fouling index (CMFI), measured under constant transmembrane pressure during crossflow filtration as the evaluation criterion.

This method is applicable to various membrane treatment systems including ultrafiltration, nanofiltration, and reverse osmosis and can be used for different types of wastewater containing particulates, colloids, and soluble organic matter.

This method is primarily intended for dispersions containing UFBs (see Annexes A to C and E); however, it is equally applicable, by analogy, to dispersions containing MBs (see Annex D).

This document can guide the design and optimization of industrial processes that integrate FB technologies for enhanced membrane antifouling.

NOTE 1        This method is intended for waters that contain a measurable amount of either particulate matter or colloidal matter, or both. It is not applicable to essentially particle-free waters, such as permeate from reverse osmosis or ultrafiltration systems.

NOTE 2        Users can record supplementary information, e.g., turbidity, total suspended solids, and particle-size distribution; however, such data are not required in this document.