What changed between the adopted text of 27 Feb 2024 and the adopted text of 22 Jan 2026

Removed:3.3.3. Dissolution of the precipitate

Removed:Dissolve the precipitate in the filter crucible by the addition of hot ammonium tartrate solution (about 80 ° C) (point 3.2.8) in three portions of 10 ml each. Allow each portion to stand in the crucible for some minutes before being sucked through the filter into the flask.

Removed:Put the contents of the filter flask into the beaker used for the precipitation. Rinse the sides of the beaker with a further 20 ml of tartrate solution to dissolve the rest of the precipitate.

Removed:Carefully wash the crucible, adapter and filter flask with 150-200 ml water, and return the rinsing water to the beaker used for the precipitation.

Removed:3.3.4. The titration

Removed:Stir the solution using a magnetic stirrer (point 3.2.16), add a few drops of bromocresol purple (point 3.2.5) and add the dilute ammonia solution (point 3.2.9) until the colour turns violet (the solution is initially weakly acid from the residue of acetic acid used for rinsing).

Removed:Then add 10 ml standard acetate buffer (point 3.2.10), immerse the electrodes in the solution, and titrate potentiometrically with standard ‘carbate solution’ (point 3.2.11), the burette tip being immersed in the solution.

Removed:The titration rate should not exceed 2 ml/min.

Removed:The endpoint is the intersection of the tangents to the two branches of the potential curve.

Removed:It will be observed occasionally that the inflection in the potential curve becomes flattened; this can be eliminated by carefully cleaning the platinum electrode (by polishing with emery paper).

Removed:3.3.5. Blank determinations

Removed:At the same time run a blank determination through the whole procedure with 5 ml methanol and 40 ml water, according to the instructions in point 3.3.2. The blank titration should be below 1 ml, otherwise the purity of the reagents (points 3.2.3, 3.2.7, 3.2.8, 3.2.9, 3.2.10) is suspect, especially their content of heavy metals, and they must be replaced. The blank must be taken into account in the calculation of the results.

Removed:3.3.6. Control of the factor of the ‘carbate solution’

Removed:Determine the factor for the carbate solution on the day of use. To do this, titrate 10 ml of the copper sulphate solution (point 3.2.12) with ‘carbate solution’ after the addition of 100 ml water and 10 ml standard acetate buffer (point 3.2.10). If the amount used is a ml, the factor f is:

Removed:and all the results of the titration are multiplied by this factor.

Removed:3.4. Calculation of results

Removed:Every non-ionic surfactant has its own factor, depending on its composition, particularly on the length of the alkene oxide chain. The concentration of non-ionic surfactant is expressed in relation to a standard substance — a nonyl phenol with ten ethylene oxide units (NP 10) — for which the conversion factor is 0,054.

Removed:Using this factor the amount of surfactant present in the sample is found expressed as mg of NP 10 equivalent, as follows:

Removed:(b — c) xfx 0,054 = mg non-ionic surfactant as NP 10

Removed:where:

Removed:3.5. Expression of results

Removed:Express the results in mg/l as NP 10 to the nearest 0,1.

Removed:Figure 1 Activated sludge plant: overviews

Removed:Figure 2 Activated sludge plant: detail (dimensions in millimetres)

Removed:Figure 3 Calculation of biodegradability - Confirmatory test

Removed:Annex VIII

Removed:CORRELATION TABLE