SIST EN ISO 5815-1:2019 PDF

Overview

EN ISO 5815-1:2019 - "Water quality - Determination of biochemical oxygen demand after n days (BODn) - Part 1: Dilution and seeding method with allylthiourea addition" - specifies a standardized laboratory procedure to determine biochemical oxygen demand (BODn) using dilution and seeding with suppression of nitrification. The method covers incubation times of 5 days (BOD5) or 7 days (BOD7) and is applicable to waters with expected BOD typically in the 1 mg/L to 6 000 mg/L range (with special handling advised above 6 000 mg/L). It is widely used for wastewaters and applicable to natural waters where BOD assessment is required.

Key Topics and Requirements

• Principle: Measurement of oxygen consumption by microbial activity in diluted, seeded samples with nitrification suppressed by adding allylthiourea.
• Scope: Applicable to a broad BOD range (1–6 000 mg/L); for very low BOD values see ISO 5815-2 (undiluted sample methods).
• Incubation: Standardized incubation periods of 5 d or 7 d; Annex A documents incubation/temperature influence.
• Dilution & Seeding: Procedures for preparing dilution series and selecting suitable seeding (including direct seeding options); empirical and calculation-based dilution approaches (including use of COD, TOC or permanganate index factors).
• Interferences: Guidance on sample interferences such as free/combined chlorine, algae, peroxides and peroxide compounds that can bias results.
• Dissolved oxygen measurement: Accepts iodometric titration (ISO 5813) or electrochemical/optical probes (ISO 5814, ISO 17289).
• Quality control: Blank determinations, CGA control solution performance limits, control analysis batches and validity criteria for result acceptance.
• Documentation: Requirements for test reporting and conditions for result validity.
• Annexes: Normative and informative annexes on incubation effects, multitesting, direct seeding, and performance data.

Practical Applications and Users

• Who uses it: Environmental testing laboratories, wastewater treatment plant operators, regulatory agencies, consultants in water quality and environmental compliance, and research organizations.
• Why use it: Provides a recognized, reproducible method for monitoring organic pollution, verifying treatment plant performance, complying with permits, and assessing ecological impacts.
• Typical applications: Effluent compliance testing, influent/effluent monitoring, process control in treatment plants, baseline environmental surveys, and comparative studies of organic load.

Related Standards

• ISO 5815-2 - BOD determination for low-BOD samples (undiluted methods)
• ISO 5813 - Iodometric determination of dissolved oxygen
• ISO 5814 / ISO 17289 - Dissolved oxygen probe methods
• EN 1899-2:1998 - superseded by EN ISO 5815-1:2019

EN ISO 5815-1:2019 is a key reference for standardized BODn testing (BOD5/BOD7) using the dilution and seeding approach with allylthiourea to suppress nitrification, ensuring consistent water quality assessment across laboratories and regulatory frameworks.