ISO 20468-9:2025

Overview

ISO 20468-9:2025 - "Performance evaluation of treatment technologies for water reuse systems - Part 9: Guidelines and requirements for electro‑chlorination" provides structured guidance to evaluate the production of sodium hypochlorite (NaOCl) by electro‑chlorination (EC) and to assess its disinfection performance in water reuse applications. The standard sets out a system for verifying EC performance using general water‑quality parameters, most notably residual/free chlorine concentrations produced by electrolysis.

Key topics and technical requirements

• System components and principles
  • Describes the NaOCl generating system (NaCl storage and dissolution, electrolyser, DC power supply, control panel), NaOCl storage/injection, and monitoring points.
  • Explains electrochemical reactions at the anode (oxidation of chloride to chlorine) and cathode (reduction of water to hydrogen and hydroxide); example electrode potentials are included in the document.
• Performance requirements and evaluation methods
  • Functional evaluation procedures and monitoring protocols for verifying disinfection performance (measurement points for chlorine and water quality before/after disinfection).
  • Safety requirements and procedures for evaluating disinfection by‑products (DBPs).
• Non‑functional/economic evaluation
  • Energy consumption considerations (related to DC power supply usage).
  • Material usage metrics, including NaCl consumption (document references assessment of kg NaCl per kg Cl produced).
• Terminology and references
  • Uses standardized vocabulary (normative reference: ISO 20670) and defines key terms such as electrolysis, electrolyser, free chlorine (NaOCl), etc.
• Supporting information
  • Informative annexes cover main treatment technologies and EC mechanisms.

Practical applications and users

Who benefits from ISO 20468-9:2025:

• Water reuse treatment designers and process engineers implementing on‑site NaOCl generation via electro‑chlorination.
• Plant operators and maintenance teams responsible for monitoring residual chlorine, DBPs, hydrogen management, and NaOCl storage/injection systems.
• Regulatory bodies, certification bodies and testing laboratories assessing EC system performance and compliance for reclaimed water distribution.
• Technology vendors and integrators producing electrolysers, DC power systems, and automated monitoring solutions.

Practical uses:

• Establishing test and monitoring protocols to verify EC disinfection efficacy.
• Comparing energy and chemical consumption (operational cost) across EC systems.
• Designing safer storage, injection and hydrogen venting arrangements consistent with performance verification.

Related standards

• ISO 20468-1 (water reuse - general chlorination context) - referenced in the introduction.
• ISO 20670 (water reuse - vocabulary) - normative reference for terms and definitions.

Keywords: ISO 20468-9:2025, electro-chlorination, NaOCl, sodium hypochlorite, water reuse, residual chlorine, electrolyser, DC power, disinfection by-products, performance evaluation.