# Regulation (EC) No 648/2004 of the European Parliament and of the Council of 31 March 2004 on detergents (Text with EEA relevance), Division 1.6: Checking measuring equipment

Extent: E+W+S+N.I.

The surfactant content (in mg/l) of the synthetic sewage is determined immediately before use.
The surfactant content (in mg/l) of the effluent collected over twenty-four hours in vessel F should be determined analytically by the same method, immediately after collection: otherwise the samples must be preserved, preferably by freezing. The concentrations must be determined to the nearest 0,1 mg/l surfactant
As a check on the efficiency of the process, the chemical oxygen demand (COD) or the dissolved organic carbon (DOC) of the glass fibre filtered effluent accumulated in vessel F and of the filtered synthetic sewage in vessel A is measured at least twice per week.
The reduction in COD or DOC should level off when a roughly regular daily surfactant degradation is obtained at the end of the running-in period shown in Figure 3.
The content of dry matter in the activated sludge contained in the aeration vessel should be determined twice a week in g/l. If it is more than 2,5 g/l, the excess activated sludge must be discarded.
The degradation test is performed at room temperature; this should be steady and kept between 19-24 ° C.

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Source: https://www.legislation.gov.uk/eur/2004/648/annex/VIII/division/1/division/1.6 (the official version)
Page: https://openlegislation.uk/eu-regulation-2004-648/annex-VIII/division-1/division-1.6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.