DS/EN ISO 9509

Water quality - Toxicity test for assessing the inhibition of nitrification of activated sludge microorganisms

active, Most Current
Buy Now
Organization: DS
Publication Date: 13 July 2006
Status: active
Page Count: 23
ICS Code (Examination of biological properties of water): 13.060.70
scope:

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 4 h or up to 24 h with weakly nitrifying sludge.
The method is applicable with 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 Annex A). If the nitrification rate is within a suitable range for the test, i.e. 2 milligrams of nitrogen per gram of suspended solid and hour (mg of N per (g·h) to 6,5 milligrams of nitrogen per gram of suspended solids and hour (mg of N per (g·h) , the sludge may be used directly; if adjustments are not necessary (see Clause 9).
The method is applicable to water-soluble, non-volatile chemicals, and also to waste waters
Sludges from different sources respond differently to a given concentration of an inhibitor mainly due to a 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 ISO 5667-16 ).

Document History

DS/EN ISO 9509
July 13, 2006
Water quality - Toxicity test for assessing the inhibition of nitrification of activated sludge microorganisms
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...
May 24, 1996
Water quality - Method for assessing the inhibition of nitrification of activated sludge micro-organisms by chemicals and waste water
This standard specifies a method for assessing the short-term inhibitory effects of test substances on nitrifying bacteria in activated sludge. The inhibitory effect is estimated over an exposure...
Advertisement