ISO 20468-5:2021

Overview

ISO 20468-5:2021 - "Guidelines for performance evaluation of treatment technologies for water reuse systems - Part 5: Membrane filtration" provides standardized guidance for assessing the performance of membrane-based water reclamation processes. The document focuses on evaluating treated wastewater quality at the membrane permeate outlet and on methods to assess environmental and economic performance of membrane filtration (MF, UF, NF, RO) within water reuse systems. It is intended to help plant designers, operators and end users design, operate and verify membrane-based water reclamation systems.

Key topics and technical requirements

The standard organizes performance evaluation into functional and non-functional requirements and includes practical measurement and monitoring guidance:

• Concepts of membrane filtration technology:
  • Definitions and membrane types (MF, UF, NF, RO, MBR) and their treatment objectives.
  • Filtration unit processes, flux, permeability, fouling and transmembrane pressure concepts.
• Performance evaluation principles:
  • Water quality–based evaluation (finished permeate quality at membrane exit).
  • Process-based evaluation (process parameters, flux, TMP, fouling indicators).
  • Integrity monitoring:
    • Direct integrity monitoring (non-destructive tests correlated to retention capability).
    • Indirect integrity monitoring (operational signs and surrogate measurements).
• Non‑functional performance metrics:
  • Energy consumption and efficiency of membrane systems.
  • Chemical consumption for cleaning and maintenance.
  • Brine (concentrate) disposal or treatment and solid waste management.
  • Life cycle cost (LCC) analysis and economic performance indicators.
• Supporting materials:
  • Specification sheet parameters (Annex A).
  • Recommended frequency of data collection (Annex B).
  • Normative references such as ISO 20670:2018 (Water reuse - Vocabulary).

Practical applications and who uses it

ISO 20468-5:2021 is practical for stakeholders involved in water reuse projects who need to ensure reliable membrane performance and regulatory compliance:

• Plant designers and process engineers - to select membrane types, specify performance parameters, and design integrity testing strategies.
• Operators and plant managers - to implement monitoring programs, establish cleaning/backwash regimes, and evaluate energy/chemical consumption.
• Regulators and water reuse end users - to assess whether membrane-treated water meets required quality targets and to review environmental/economic implications.
• Consultants and asset owners - for comparative evaluation of membrane technologies and life cycle cost assessments.

Use cases include design verification, commissioning checks, routine operational monitoring, troubleshooting membrane fouling, and project-level environmental/economic assessments.

Related standards

• ISO 20468 series (other parts for overall water reuse system performance evaluation)
• ISO 20670:2018 - Water reuse vocabulary

Keywords: ISO 20468-5:2021, membrane filtration, water reuse, performance evaluation, membrane integrity, UF, MF, NF, RO, life cycle cost, water reclamation systems.