BS 6068-5.25:1999

1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Test environment
6 Reagents
7 Inoculum
8 Apparatus
9 Procedure
10 Expression of results
11 Interpretation or results
12 Reproducibility
13 Test report
Annex A (informative) Examples of contents of test
and control flasks
Annex B (informative) Typical growth curve using 3.5
dichlorophenol as test material
Annex C (informative) Determination of lowest
ineffective dilution of wastewater
Bibliography

Gives a method for assessing the potential toxicity of test material to the growth of aerobic bacteria present in activated sludge. Inhibitory effects are restricted to those microorganisms capable of growth on the chosen organic test medium. Give information on inhibitory effects on microorganisms over incubation periods up to 6 h. Applies to water, wastewater and chemical substances which are soluble under the test conditions. Special care is required with volatile or coloured materials and materials which form turbid suspensions or dispersions.

This International Standard specifies a method for assessing the potential toxicity of a test material to the growth of aerobic bacteria present in activated sludge. The inhibitory effect is restricted to those microorganisms capable of growth on the chosen organic test medium.

This method gives information on inhibitory effects on the microorganisms over incubation periods up to 6 h.

This method is applicable to water, wastewater and chemical substances which are soluble under the conditions of the test. Special care is needed with volatile or coloured materials and materials which form turbid suspensions or dispersions.

NOTE 1 Results with volatile test material should be interpreted with caution and are likely to underestimate any inhibitory effect because of the difficulties in maintaining the initial concentration in the test flasks.

NOTE 2 Coloured materials and materials of low water-solubility which form turbid suspensions or dispersions can be tested in many cases using colour/turbidity controls as blanks (see 9.4).

NOTE 3 Inhibitory effects on activated sludge microorganisms of test materials for which this test is not applicable can be determined by using an inhibition test based on respirometric measurements (see ISO 8192).