ISO 23043:2021

Overview

ISO 23043:2021 - Evaluation methods for industrial wastewater treatment reuse processes provides a structured, multi‑criteria framework to comprehensively evaluate industrial wastewater treatment and reuse options. The standard defines the principles, procedure and recommended indicators for comparing, selecting, upgrading and continuously improving industrial wastewater treatment–reuse processes. It describes calculation approaches and recommended indicators (technology, environment, resource, economy) but does not prescribe methods for single indicator measurements.

Key topics and requirements

• Scope and goals: Establish clear goals and scope for the evaluation; intended uses of results must be defined up front (selection, upgrade, continuous improvement).
• Evaluation principles: Emphasizes comprehensiveness, operability, relevance and transparency so assessments are practical, meaningful and auditable.
• Evaluation procedure:
  • Preparation: request evaluation, collect baseline documents and data, and organize a project committee.
  • Preliminary screening: identify feasible vs. infeasible treatment–reuse processes.
  • Comprehensive evaluation: apply the multi‑indicator framework to shortlisted options.
• Indicator framework: Four main indicator groups with sub‑indicators:
  • Technology indicators (process performance, reliability, treatability)
  • Environment indicators (emissions, pollutant load, GHG potential)
  • Resource indicators (water recovery, resource reuse, energy use)
  • Economy indicators (costs, life‑cycle economic factors)
• Supporting methods and annexes: Includes lists of indicators/sub‑indicators, approaches to quantify qualitative measures, guidance on weighting (e.g., Delphi method) and an example evaluation case to illustrate application.
• Transparency: Calculation steps and data sources must be recorded and available for verification.

Practical applications

• Evaluating and comparing alternative industrial wastewater treatment and reuse process designs.
• Supporting selection of treatment trains for specific reuse applications (cooling water, boiler feed, process water, irrigation, toilet flushing).
• Guiding upgrades and retrofits to improve performance and resource recovery.
• Informing continuous improvement programs and regulatory or permit assessments.
• Structuring multi‑criteria decision making where environmental, technical and economic trade‑offs exist.

Who should use ISO 23043:2021

• Process engineers, water reuse designers and plant operators
• Environmental managers and sustainability teams
• Regulatory and permitting authorities, local governments
• Consultants and project committees conducting comparative evaluations or feasibility studies

Related standards

• ISO 20670 (Water reuse - Vocabulary) - normative reference for terms
• Other methods referenced in the standard for context include ISO 14040 (Life Cycle Assessment), ISO 20468‑1 and ISO 14046 (water footprint concepts) where relevant

Keywords: ISO 23043:2021, industrial wastewater, wastewater reuse, evaluation methods, treatment reuse indicators, industrial water reuse, evaluation procedure.