ISO 5815-1:2019

ISO 5815-1:2019 pdf free.Water quality – Determination of biochemical oxygen demand after n
days (BOD,)一Dilution and seeding method with allylthiourea addition.
4 Principle
The BOD, with inhibition of nitrification is determined, using the dilution method. A batch series with different dilutions of a sample is prepared and examined. The dilution water is enriched with oxygen and seeded with adapted aerobic microorganisms.
The sample is incubated at (20 ± 1) °C for a specified period (n), S d or 7 d, in the dark, in a completely filled and stoppered bottle. The dissolved oxygen concentration is determined before and after incubation. The mass of consumed oxygen per litre sample is calculated.
5 Reagents
Use only reagents with the degree of purity “for analysis”.
5.1 Water, at least grade 3 in accordance with Iso 3696.
The water shall not contain more than 0,01 mg/I of copper, nor chlorine or chioramines.
5.2 Seeding water, which can be obtained in one of the following ways:
a) municipal waste water, decanted or coarsely filtered;
b) surface water containing municipal waste water;
c) settled effluent from a waste water treatment plant;
d) water taken downstream from the discharge of the water to be analysed, or water containing microorganisms that are adapted to the water to be analysed;
e) commercially available seeding material.
Use seeding water with a COD of about 300 mg/I or a TOC of about 100 mg/I (see 5.5). If the COD or TOC are higher, adapt to these concentrations with dilution water (SA) before preparing the seeded dilution water (55) or use a correspondingly changed volume of the seeding waters for seeding the dilution water (SA).
lithe sample comes from a process that has been subjected to disinfection treatment (chlorination, UV, ozone or other), use inoculum, even when there is no residual disinfectant present.
For commercially available seeding material consider respective application recommendations.
The selected seeding material can be checked in advance by running the procedure with a control analysis (91Z) batch only to prove its suitability for the analysis of samples.
5.3 Salt solutions
5.3.1 General
The following solutions can be kept for at least six months in glass bottles in the dark at (5 ± 3) °C.
Discard the solutions at the first signs of precipitation or opaqueness.
5.3.2 Phosphate-buffer solution
Dissolve 8,50 g of potassium dihydrogen phosphate (KH2PO4), 21,75 g of dipotassium hydrogen phosphate (K2HPO4), 33,4 g of disodium hydrogen phosphate-heptahydrate (Na2[1P04.7H20) and 1,70 g of ammonium chloride (NH4CI), in about 500 ml of water (5Jj. Dilute with water (&1) to 1 000 ml and mix. Measure the pH value. If the pH value is outside the range pH 7 to pH 8, prepare a new solution.
5.3.3 Magnesium sulfate heptahydrate solution, p = 22,5 g/l.
Dissolve 22,5 g of magnesium sulfate heptahydrate (MgSO4•7H20) in water (Si). Dilute with water (5..1) to 1 000 ml and mix.
5.3.4 Calcium chloride solution, p = 27,5 g/l.
Dissolve 27,5 g of anhydrous calcium chloride (CaCI2) (or an equivalent amount, if the hydrate is used (for example 36,4 g CaC12.2H20) in water (Si.), dilute with water (Si.) to 1 000 ml and mix.
5.3.5 Iron (III)-chloride-hexaliydrate solution, p = 0,25 g/l.
Dissolve 0,25 g of iron (lll)-chloride-hexahydrate (FeC13•6H20), in water (5.1). Dilute with water (Si) to 1 000 ml and mix.
5.4 Dilution water
Determine the total volume of dilution water required for the actual test. Pour about half the required volume of water (5Jj into the feed vessel (f3) for the dilution water and add 1 ml of each of the salt solutions (5.3.2. 5.3.3. 5.3.4 and 5.3.5) for each litre of the total volume. Then fill to the required total volume with water (51) and mix by stirring, aeration or shaking. Bring the dilution water obtained in this way to a temperature of (20 ± 2) °C, keep at this temperature and aerate slightly by mixing. If, for example, specially adapted seeding water or seeding material is necessary, the procedure according to Annex C can be followed.
EXAMPLE If 201 of dilution water are required, prepare 101 of water (5i). Stirring continuously, add 20 ml of each of the salt solutions individually and fill up with water (Sd) to 20 1.ISO 5815-1 pdf download.

Leave a Reply

Your email address will not be published. Required fields are marked *