EN 1899-2-1998 pdf download.Water quality Determination of biochemical oxygen demand after n days (BOD,) Part 2: Method for undiluted samples.
3 Definition
For the purposes of this Eurnpean Standard, the following definition applies:
biochemical oxygen demand after n days
(BOD)
the mass concentration of dissolved oxygen consumed under specified conditions by the biochemical oxidation of organic and/or inorganic matter in water n is the incubation time; it is equal to 5 or 7.
NOTE For the purpose of this European Standard. ‘biochemical oxidaiion is taken to mean tiologicai oxidation . This definition is similar to the definition of ISO 6 107-2.
4 Principle
Equilibration of the sample of water to be analyzed to 20 °C followed by, if neces.saiy, aeration. lncibation at 20 °C for a defined penod, 5 or 7 days, in the (lark, in a completely filled and stoppered bottle. Deternunation of the (lLssolved oxygen concentration before and after incubation. Calculation of the mass of oxygen (Ofl.Stlmed iwr litre of S11111)k’.
5 Apparatus
5.1 Incubalum bottles, BOD bottles, with glass stoppers.
For exunple, preferably 250 ml to 300 ml or 100 ml to 125 ml, with stoppers and preferably with straight shoukiers, or any e(Ituvalent bottles.
It is important that the bottles are thoroughly cleaned before use. If the icxlonwtnc metllo(l (iii accordance with EN 25813) for detennhüng dissolved oxygen is used, it is, for example, normally sufficient to rinse the bottle several times with tap water then deionized water. however, if the electn)de nleth(xl (iii accordance with EN 25814) is used, a niore sthngent cleaning procedure, for example, as follows, is required. Add to the empty bottle 5 ml to 10 ml of a wash SOILItlOn (for example 2,5 g of iodine plus 12,5 g of potassium iodide per litre of 1 % (V/I’) sulfuric acid) shaking well to coat the bottle walls. Let stand for 15 mm, pour off the solution and rinse thoroughly with tap water and finally (leloluzed water.
5.2 Inru&itoi; capable of being maintained at
(20±1)°C.
5.3 Equ ijiiiient for deter??? in jug (Iis.soired o.rygen
CU? wenlrnt Ion, in accordance with EN 25813 and
EN 25814.
5.4 Metins of rçfrigenithm, (0 to 4) °C, for transport
811(1 storage of the sample.
5.5 Aerit ion equ ipmcnt, a bottle of compressed air or a compressor The air quality shall be such that the aeration does not lead to any contanunation.s., especially by the a(khuion of organic matter, oxidizing or reducing materials, or metals. If contamination is SLLSpected, the air shall be filtered or wasiwd.
6 Storage of the sample
Store the sample at a temperature (0 to 4) °C in a filled and hermetically stoppere(t bottle immediately after sample collection and until the analysis is perfomwd. Begin (he (k’teflhlliiatIOfl of the HOD11 as sxnl as possible and within 24 h alter completion of sample collection.
7 Procedure
7.1 Preparation of test solutions
Bring the test sample to a temperature of (20±2) °C and aerate if necessary. In case of aeration, let the sample stand about 15 mm. Remove air bubbles and possible supersaturation of oxygen.
7.2 Determination
7.2.1 Determination na measurement of dissolred oxygen-iodometric method (in accordance with EN 25813)
Using each sample (see 7.1), flil two incubation bottles (5.1) allowIng them to OVeTt1OW slightly. Dining filling operations, precautions shall be taken to prevent changing the oxygen concentration of the medium.
Allow any air bubbles adhering to the walls to escape. Stopper the bottles, taking care to avoid trapping air bubbles.
Divide the bottles Hlt() tWo SCfles, each contamnmg 01W’ bottie of each sample.
Put one series of bottles (the first) in the incubator (5.2) and leave in darkness for n (lays ±4 h.
In the second series of bottles measure the dissolved oxygen concentration in each of the bottles at time zero after 15 miii. using the method specified in EN 25813 with the addition of azide in the alkaline lodide—azide reagent.
After the incubation, determine the dissolved oxygen concentration in each of tue first series of bottles, using the method specified in EN 25813.
7.2.2 Determination iw measurement of dissolved oxygcn—electrochen. ical probe method (in accordance with EN 25814)
Using each SamI)le (see 7.1) fill an incubation bottle (5.1), allowing it to overflow slightly. During filling operations, j)recautiols shall be taken to prevent changing the oxygen concentration of the medium. Allow any air bubbles adhering to the walls to escape. Measure the diss1ved oxygen concentration in each of the bottles at time zero, using the method specified in
EN 25814.
Stopper the bottles, taking care to avoid trapping air bubbles.
Put the bottles in the incubator (5.2) and leave in darkness for n days ±4 h.
After the incubation, determine the dissolved oxygen concentration in each of the bottles, using the method .specified in EN 25814.EN 1899-2-1998 pdf download.