What is ISO 5815‑1 - BOD with allylthiourea addition about?
ISO 5815‑1 is the first part of the ISO 5815 multi-series on water quality and focuses on biochemical oxygen demand after n days (BODn). ISO 5815‑1 specifies the determination of the biochemical oxygen demand of waters by dilution and seeding with suppression of nitrification after 5 d or 7 d incubation time. ISO 5815‑1 is applicable to all waters having biochemical oxygen demands usually between 1 mg/l and 6 000 mg/l. ISO 5815‑1 applies particularly to wastewaters but also suits the analysis of natural waters.
For biochemical oxygen demands greater than 6 000 mg/l of oxygen, the method is still applicable, but special care is needed taking into consideration the representativeness of subsampling for preparation of the dilution steps. The results obtained are the product of a combination of biochemical and chemical reactions in presence of living matter which behaves only with occasional reproducibility. The results do not have the rigorous and unambiguous character of those resulting from, for example, a single, well‑defined, chemical process. Nevertheless, the results provide an indication from which the quality of waters can be estimated.
Who is ISO 5815‑1 - BOD with allylthiourea addition for?
ISO 5815‑1 on BOD with allylthiourea addition is useful for:
- Government testing laboratories
- Industries that release wastewater into natural water bodies
- Geological scientists
- Nuclear power plants
- Public water supply systems
Why should you use ISO 5815‑1 - BOD with allylthiourea addition?
Substances that are toxic to microorganisms, for example bactericides and free chlorine inhibit biochemical oxidation and lead to reduced findings. Increased results can occur due to the presence of nitrifying microorganisms. The presence of algae can lead to an overestimation of BOD and disturb the determination. Allylthiourea prevents this overestimation.
ISO 5815‑1 specifies the determination of the BOD of waters with an expected BOD in the range of 1 mg/l to 6 000 mg/l using the dilution method. A lower limit of working range may result from validation data in the laboratory. For samples with an expected low BOD in the range of 0,5 mg/l to 6 mg/l ISO 5815-2 provides the option of the BOD of waters using undiluted samples.
ISO 5815‑1 discusses pre-treatment, neutralization of the sample, homogenization, preparation of test solutions, calculation of dilutions, empirical determination of the dilutions, determination of dilutions via the factors R of the TOC, the permanganate index or the COD, and calculation of dilution stages via the COD.
What’s changed since the last update?
BS EN ISO 5815‑1:2019 supersedes ISO 5815-1:2003, which is withdrawn. BS EN ISO 5815‑1:2019 includes some technical changes with respect to ISO 5815-1:2003.
These include:
- Change of working range: 1 mg/l instead of 3 mg/l as the lower limit
- Changes in test procedure
- Annex A: title changed and “normative” instead of “informative”
- Annex C "Direct seeding of the analysis batches" added
- New Annex D "Performance data" included