ISO 7827:2010

Overview

ISO 7827:2010 defines a laboratory method for assessing the “ready” and “ultimate” aerobic biodegradability of organic compounds in water by measuring dissolved organic carbon (DOC). The test evaluates how readily an organic substance is biodegraded by aerobic microorganisms under controlled conditions (typically 22 °C ± 2 °C, dark or diffuse light) by tracking DOC removal over time (start, several intermediate points, and end - usually 28 days or longer if needed). The standard provides definitions for “ready” and “ultimate” biodegradability and sets practical limits for test substances and conditions.

Key topics and requirements

• Test substance suitability: compounds must be soluble at test concentrations, non‑volatile (negligible vapour pressure), not strongly adsorbable on glass or sludge, and non‑inhibitory to microorganisms.
• DOC concentration range: standard test range is 10 mg/L to 40 mg/L of DOC (higher concentrations may be used if justified).
• Test medium and inoculum: detailed preparation of mineral test medium and guidance on inoculum sources (secondary effluent, activated sludge, surface water), inoculum volumes, and pre‑exposure considerations.
• Analytical methods & apparatus: DOC analysis per ISO 8245; equipment includes DOC analyzer, centrifuge, incubator (22 °C ± 2 °C), filters (0.2–0.45 µm), pH meter and aeration/mixing devices.
• Procedure and data interpretation: calculate percent DOC removal at intervals, determine lag time, degradation time and maximum biodegradation level; Annex B provides interpretation guidance for “ready” vs “inherent/ultimate” biodegradability.
• Limitations & safety: not suitable for wastewaters containing water‑insoluble organic carbon (not measured as DOC); handle activated sludge carefully due to pathogenic organisms.

Applications and users

ISO 7827:2010 is used for:

• Environmental and analytical laboratories performing biodegradability testing.
• Chemical manufacturers assessing environmental fate during product development and regulatory submissions.
• Regulatory bodies evaluating claims of rapid biodegradability for aquatic compartments.
• Wastewater and treatment plant researchers studying biodegradation kinetics of specific compounds (note: the method is not suitable for raw wastewaters).
• Ecotoxicology and environmental consultants preparing compliance and environmental risk assessments.

Practical benefits include reproducible DOC‑based biodegradation data, clear pass/fail interpretation for “ready biodegradability,” and compatibility with other aerobic tests for holistic assessment.

Related standards

• ISO 8245 - Water quality: determination of TOC and DOC
• ISO 9408 - Closed respirometer oxygen demand test
• ISO 9439 - Carbon dioxide evolution test
• ISO/TR 15462 - Alternative biodegradation methods
• ISO 9887 / ISO 9888 - Reference methods cited for inoculum pre‑exposure examples

Keywords: ISO 7827:2010, DOC method, dissolved organic carbon, ready biodegradability, ultimate biodegradability, water quality, aerobic biodegradation.