Overview
ISO 5815-1:2019 is an international standard developed by ISO for assessing water quality by determining biochemical oxygen demand after n days (BODn), using the dilution and seeding method with allylthiourea addition. This standard defines procedures for highly reproducible BOD measurements after either 5 or 7 days of incubation, a critical metric for evaluating the presence and impact of biodegradable organic matter in water. ISO 5815-1:2019 applies to both natural waters and wastewaters, encompassing a BOD range typically between 1 mg/l and 6,000 mg/l.
The method is essential for laboratories, environmental agencies, and wastewater treatment facilities needing to evaluate the organic pollution of water samples. By suppressing nitrification during the test, the standard ensures that measured oxygen consumption reflects only carbonaceous biochemical demand, yielding more consistent results.
Key Topics
- Dilution and Seeding Method: The procedure involves preparing a series of diluted samples, seeding each with adapted aerobic microorganisms, and measuring dissolved oxygen before and after incubation.
- Allylthiourea Addition: This compound is added to suppress nitrification, isolating the oxygen demand attributable to carbonaceous matter.
- Incubation Periods: Provides procedures for both 5-day and 7-day incubation, accommodating regulatory and regional practice variations.
- Sample Types and Applicability: Suitable for a wide range of water matrices, especially wastewaters and natural water bodies, with adjustments for very high BOD values.
- Interferences and Quality Control: Guidance for handling interferences from toxic substances (e.g., chlorine, peroxides, algae) and utilizing control solutions for accurate results.
- Calculation and Validity: Outlines how to select dilution factors, calculate BODn, and validate results using specific criteria.
- Sampling and Storage: Offers instructions for collecting, preserving, and handling water samples to maintain sample integrity until analysis.
Applications
Implementation of ISO 5815-1:2019 is vital for:
- Wastewater Treatment Monitoring: Ensures effluent meets environmental discharge permits by quantifying organic pollutant loads.
- Surface Water Quality Assessment: Measures organic contamination in lakes, rivers, and reservoirs, aiding in freshwater management.
- Industrial Discharge Evaluation: Used by facilities to analyze and report the organic load in their wastewater discharges.
- Regulatory Compliance: Forms the basis for environmental reporting, permitting, and verifying compliance with national and international water quality standards.
- Research and Environmental Impact Studies: Provides reliable data for scientific analyses, environmental surveys, and pollution remediation assessments.
Related Standards
ISO 5815-1:2019 promotes cohesive water quality measurement when used alongside related international standards, including:
- ISO 5667-3: Water quality - Preservation and handling of water samples
- ISO 5813: Water quality - Determination of dissolved oxygen - Iodometric method
- ISO 5814: Water quality - Determination of dissolved oxygen - Electrochemical probe method
- ISO 17289: Water quality - Determination of dissolved oxygen - Optical sensor method
- ISO 6060: Water quality - Determination of the chemical oxygen demand (COD)
- ISO 8245: Water quality - Determination of total organic carbon (TOC) and dissolved organic carbon (DOC)
- ISO 10523: Water quality - Determination of pH
Practical Value
ISO 5815-1:2019 equips laboratories and practitioners with a trusted, standardized method for BOD determination. Reliable BODn results are central to environmental monitoring, operational control in wastewater treatment, and compliance reporting. By adopting this standard, users benefit from consistent methodologies, improved comparability of results, and enhanced water quality assessment capabilities, supporting the protection of aquatic ecosystems and public health.
For additional support or guidance in implementing ISO 5815-1:2019, consult the full standard or reach out to your national or local standards body.