ISO 14592-2:2002

Overview

ISO 14592-2:2002 - "Water quality - Evaluation of the aerobic biodegradability of organic compounds at low concentrations - Part 2: Continuous flow river model with attached biomass" specifies a laboratory method to evaluate the aerobic biodegradability of organic test compounds in natural waters using a continuous-flow river simulation. The method is designed for low-concentration test compounds that act as a secondary substrate in the presence of natural organic carbon and where biodegradation follows first‑order (non‑growth) kinetics.

Key topics and technical requirements

• Test principle: Continuous-flow cascade (river model) with attached biomass on stationary surfaces; typical units contain multiple trays (commonly seven) and are run with a mean hydraulic retention time of about 24 h.
• Target measurements: Regular sampling of influent and effluent under steady-state conditions to determine the degree of primary biodegradation, degradation rate constant (k) and degradation half-life (T1/2).
• Applicability requirements: Test compounds must be
  • water‑soluble at test concentration,
  • quantitatively detectable by substance‑specific analysis or available in radiolabelled form,
  • non‑volatile from aqueous solution,
  • not significantly adsorbed, not photolyzed, and
  • not inhibitory to the test microorganisms.
• Kinetics: Designed to evaluate primary biodegradation and first‑order rate behavior (secondary substrate conditions). Not intended as proof of ultimate biodegradability (mineralization).
• Data and calculations: Mass balance across the cascade, inlet/outlet concentration differences, and derivation of rate constants and half‑lives from steady‑state data.
• Safety and quality: Use analytical‑grade reagents; handle activated sludge and radiolabelled compounds with appropriate biosafety and regulatory precautions.

Practical applications and users