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EC number: 257-913-4
CAS number: 52434-90-9
The pH, oxygen consumption rate and percent inhibition of total respiration and heterotrophic respirations of the definitive test are presented in the tables 1 and 2, respectively.
pH of mixture at the end of incubation
Oxygen consumption rate (mg/L min)
Oxygen consumption rate (mg/L h)
Specific respiration rate a (mg/g h)
Percent inhibition, total respiration
Blank control at start of test
Blank control at end of test
Percent inhibition, heterotrophic respiration
Note: a: oxygen consumed per g dry weight of sludge per hour.
The toxic effect of AP 729 on microorganisms (largely bacteria) from activated sludge of a well operated wastewater treatment plant receiving predominantly domestic sewage was studied according to OECD Guideline 209.
A range finding test was performed to determine the range of concentrations of test item to be used in the definitive test. Based on the results of the range finding test, the tested concentration of AP 729 in the definitive test was at the limit concentration of 1000 mg/L in triplicate and in two sets, along with blank control (without test item) and reference substance (3,5-Dichlorophenol) at concentrations of 2, 8 and 32 mg/L. One set of all test groups was used to determine total respiration and another set of all test groups added with N-allylthiourea at 11.6 mg/L was used to determine the heterotrophic respiration and the nitrification potential of the sludge.
The test item mixtures and the reference substance mixtures were prepared by adding the required quantity of test item and reference substance directly into the test vessels to obtain different nominal concentrations, respectively.
Blank control, test mixtures and reference substance mixtures were aerated for the exposure time of 3 hours at a temperature between 21.4 and 21.8°C. The oxygen consumption rate in the mixture was measured for 10 minutes using dissolved oxygen electrode and the respiration rate was calculated.
No significant inhibition of AP 729 was observed in both total respiration and heterotrophic respiration.Moreover, the nitrification respiration rate was found to be not significant: hence the inhibition of AP 729 due to nitrification respiration was not calculated.
The validity criteria of the test were fulfilled as:
Therefore, the EC50 and NOEC (No Observed Effect Concentration) value for total respiration inhibition and heterotrophic respiration inhibition of AP 729 are higher than 1000 mg/L.
The toxic effects of AP 729 on microorganisms from activated sludge of a well operated wastewater treatment plant receiving predominantly domestic sewage were studied according to OECD Guideline 209. The tested concentration of AP 729 was at the limit concentration of 1000 mg/L in triplicate and in two sets, along with blank control and reference substance (3,5-Dichlorophenol). One set of all test groups was used to determine total respiration and another set of all test groups added with N-allylthiourea at 11.6 mg/L was used to determine the heterotrophic respiration and the nitrification potential of the sludge.Blank control, test mixtures and reference substance mixtures were aerated for the exposure time of 3 hours. No significant inhibition of AP 729 was observed in both total respiration and heterotrophic respiration.Therefore, the EC50 and NOEC value for total respiration inhibition and heterotrophic respiration inhibition of AP 729 are >1000 mg/L.
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