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BS EN ISO 9509:2006

Current
Current

The latest, up-to-date edition.

Water quality. Toxicity test for assessing the inhibition of nitrification of activated sludge microorganisms
Available format(s)

Hardcopy , PDF

Language(s)

English

Published date

31-07-2006

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents and materials
6 Apparatus
7 Procedure
8 Calculation and expression of results
9 Validity of results
10 Precision
11 Test report
Annex A (normative) Determination of the nitrifying
        activity of an activated sludge
Annex B (normative) Example for preparation of the test
Annex C (informative) Apparatus for culturing nitrifying
        activated sludge
Bibliography

States a method for assessing the short-term inhibitory effect of waters, wastewaters or test substances on nitrifying bacteria in activated sludge.

This International Standard specifies a method for assessing the short-term inhibitory effect of waters, waste waters or test substances on nitrifying bacteria in activated sludge. The inhibitory effect is estimated over an exposure period of usually 3h or up to 24h with weakly nitrifying sludge.

The method is applicable to nitrifying activated sludge derived from domestic and synthetic sewage and also to sludges from industrial and mixed domestic and industrial waste waters.

The nitrifying activity of the sludge is verified by testing in the presence and absence of a specific inhibitor (e.g. N-allylthiourea; see AnnexA). If the nitrification rate is within a suitable range for the test, i.e. 2mg of nitrogen per gram of suspended solid and hour to 6,5mg of nitrogen per gram of suspended solids and hour, the sludge may be used directly. If not, adjustments are necessary (see Clause9).

The method is applicable to water-soluble, non-volatile chemicals, and to waste waters

Sludges from different sources respond differently to a given concentration of an inhibitor mainly due to reaction between the inhibitor and components of the sludge. This results in a partial neutralisation of the toxic effect. Also, since the test lasts only hours, any inhibitory effects may diminish or increase over a longer period, e.g. in the continuous activated sludge system (see ISO5667-16).

Committee
EH/3/5
DevelopmentNote
Renumbers and supersedes BS 6068-5.9(1990) 1995 version incorporates amendment 8456 to BS 6068-5.9(1990) Supersedes 88/52165 DC (09/2005) Supersedes 05/30039357 DC. (07/2006)
DocumentType
Standard
Pages
24
PublisherName
British Standards Institution
Status
Current
Supersedes

ISO 9888:1999 Water quality Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium Static test (Zahn-Wellens method)
ISO 6777:1984 Water quality — Determination of nitrite — Molecular absorption spectrometric method
ISO 11733:2004 Water quality — Determination of the elimination and biodegradability of organic compounds in an aqueous medium — Activated sludge simulation test
ISO 5667-16:2017 Water quality — Sampling — Part 16: Guidance on biotesting of samples
ISO 8192:2007 Water quality Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation
ISO 7150-1:1984 Water quality — Determination of ammonium — Part 1: Manual spectrometric method
ISO 6107-1:2004 Water quality Vocabulary Part 1:

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