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EC number: 235-517-2 | CAS number: 12262-25-8 This substance is identified in the Colour Index by Colour Index Constitution Number, C.I. 53430.
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
- Endpoint:
- biodegradation in water: ready biodegradability
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 22 February 2017 - 14 June 2017
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
- Version / remarks:
- 1992
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
- Version / remarks:
- 2008
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EPA OPPTS 835.3110 (Ready Biodegradability)
- Version / remarks:
- 1998
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Oxygen conditions:
- aerobic
- Inoculum or test system:
- activated sludge, industrial, non-adapted
- Details on inoculum:
- Species:
Activated sludge, microorganisms from a domestic waste water treatment plant.
Origin:
The (controlled) activated sludge was supplied by the sewage plant for domestic sewage in Balatonfüred, Hungary, on 17 February 2017 (six days before the main test). The prepared activated sludge was continuously aerated (2 L/minute) at the test temperature of 22 ± 2°C, for about 6 days.
Preparation of Activated Sludge Inoculum:
The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution with shaking and again centrifuged. This procedure was repeated twice.
An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to dry weight determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 5 g dry material per litre was mixed with mineral medium (see Section 5.4) and then aerated under test conditions (for 6 days) until use. The pH of the activated sludge inoculum after preparation was 7.69, just before use the pH was: 7.28. A pH adjustment of activated sludge inoculum was not performed.
Pre-conditioning of Activated Sludge Inoculum:
Pre-conditioning consisted of aerating (2 L/minute) activated sludge (in mineral medium ) for 6 days (from February 17 to February 23, 2017) at test temperature (the actual temperature: 20.3 – 21.4°C). During the aeration the cell count of inoculum was checked as follows: the viability of the cultured sludge was determined by plating 0.1 mL of the different, 10^-1, 10^-2, 10^-3 and 10^-4 dilutions of cultures on nutrient agar plates. Plates were incubated at 37 °C for 24 hours.
The viable cell number of the cultures was determined by manual colony counting. The approximately cell count of aerated inoculum was ~10^8/L; therefore on the day of the test this inoculum was diluted 1000x with mineral medium to reach the necessary 10^5-10^6 cells/L cell concentration. After preparation the sludge was filtered through cotton wool. Pre-conditioning (see above) improves the precision of the method.
The inoculum was not pre-adapted to the test chemical.
The chose test item concentration of 4.0 mg/L to be investigated in the main test was based on the available information about the solubility and toxicity of the test item (based on preliminary toxicity test results). - Duration of test (contact time):
- 28 d
- Initial conc.:
- 4 mg/L
- Based on:
- test mat.
- Remarks:
- The test item concentration used in the main test was based on the results of the preliminary solubility and toxicity tests.
- Parameter followed for biodegradation estimation:
- O2 consumption
- Details on study design:
- Preparation of Test Solutions
The test solutions used in the test were prepared by mechanical dispersion freshly, at the beginning of the experiment, in the testing laboratory as follows:
For the preparation of test item test solutions, at first the suitable amount (80 mg) of Leuco Sulfur Blue 9 was suspended (using ultrasonic bath for about 10-15 min.) in the respective volume (1000 mL) of aqueous test medium (mineral medium, see Section: 5.4) to prepare a 80 mg/L stock solution (suspension). Before the preparation of the test item suspension the test item was ground with a pestle and mortar (as fine as possible).
The test item stock solution (suspension) was continuously stirred until use to ensure a good dispersion and homogeneity (extra care was taken to avoid air bubbles in the stirred solution). During the incubation period the test solutions were not stirred further.
Stock Solutions for Mineral Medium
In purified, deionized water analytical grade salts were added to prepare the following stock solutions:
A) Solution: KH2PO4 8.50 g
K2HPO4 21.75 g
Na2HPO4 x 12H2O 67.16 g
NH4Cl 0.50 g
Water ad 1000 mL
B) Solution: CaCl2 x 2 H2O 36.40 g
Water ad 1000 mL
C) Solution: MgSO4 x 7 H2O 22.50 g
Water ad 1000 mL
D) Solution: FeCl3 x 6 H2O 0.125 g
Water ad 500 mL
(The “D” stock solution was prepared on the day of the mineral medium preparation and was not further stored).
Preparation of Mineral Medium (Ratio of Ingredients)
The mineral medium was prepared in the following ratio: 1 mL of the stock solutions A - D) were combined per 1000 mL total volume, filled with water (purified deionized) . The test medium was aerated for 20 minutes and allowed to stand for about 20 hours at the test temperature. The dissolved oxygen concentration was checked and found 8.97 mg/L. The pH of the mineral medium was 7.32.
Environmental Conditions
The test was carried out in a controlled environment room (during the preparation, aeration and incubation of the mineral medium, preparation of test bottles (units), during the formulation, oxygen and pH measuring) at a temperature of 22 +/- 2°C according to the guideline. The actual temperature range was 20.7 21.3°C.
The test bottles were incubated in an incubator at 22 +/- 2°C, in the dark. During the incubation (28 days) of the test units the temperature range was 20.0-20.1°C.
During the pre-conditioning of activated sludge inoculum the temperature was 20.3-21.4°C.
Temperature was measured continuously using min/max thermometer (in controlled environment room) or built-in thermometer (in incubator) and recorded at least once a day.
The oxygen concentration of test water (mineral medium) was in the range of 8-9 mg/L. It was measured at the start of the test and found to be 8.97 mg/L.
The pH was checked prior study start and found to be 7.32; further pH adjustment was considered as not necessary.
The test conditions were measured with suitable instruments and documented in the raw data.
Equipment
Large glass tank (volume:~30 L) and
Large glass bottles (volume: 5L),
Narrow necked, Winkler bottles with glass stoppers,
Funnels and coarse filter papers,
Oxygen and pH meter with appropriate O2 and pH electrode,
Aeration system, Moisture analyzer,
Temperature controlled (in the range of 22 ± 2 °C with a temperature deviation of ±1 °C) environment room (and/or incubator) with thermometer with exclusion of light,
Balance, Centrifuge.
Test Units
Type and Size: Winkler bottles (300 mL, coded) with special neck and glass stoppers.
Identification: Each test bottle was uniquely identified with study number, test group, days of measurement and replicate number.
Description of the Test Procedure
Preliminary Experiments
The pre-experiments on solubility of the test item, and the 14-day toxicity test for the determination of the test concentration for the main test were conducted non-GLP, and these pre-experiments are excluded from the Statement of Compliance in the final report, The raw data of these tests will be archived under the study code of the present study.
Preliminary Toxicity Test
The test item solubility, behavior, and toxicity were tested in a 14-day preliminary experiment. The test design was the same as described at the main experiment. In the preliminary experiment the test item was investigated at the concentration of
4 mg/L. No toxic effect of the test item was found at this investigated concentration.
COD Determination
The COD value of the test item was determined in parallel samples using a COD Cell Test (MERCK) and CombiCheck 50.
The COD expresses the amount of oxygen originating from potassium dichromate that reacts with the oxidizable substances contained in 1L of water under working conditions of the specified procedure. 1 mol K2Cr2O7 is equivalent to 1.5 mol O2. The results are expressed as mg/L COD (mg/L O2). The mg O2/mg test item unit is calculated from the known test item solution concentration.
For determination of the COD of the test item a solution with a concentration of 10 mg/L was prepared and measured. The COD of the test item solution was determined in parallel samples with the appropriate controls (CombiCheck 50).
The measured values for a 10 mg/L solution: 25.1 mg O2/L; 24.6 mg O2/L and 24.4 mg O2/L, in average 24.7 mg O2/L.
For the mg O2/mg test item unit the above value was divided with the known test item solution concentration (10 mg/L).
In summary the COD of the test item was measured and calculated as: 2.47 mg O2/mg test item. - Reference substance:
- benzoic acid, sodium salt
- Preliminary study:
- The test item solubility, behavior, and toxicity were tested in a 14-day preliminary experiment. The test design was the same as described at the main experiment. In the preliminary experiment the test item was investigated at the concentration of 4 mg/L. No toxic effect of the test item was found at this investigated concentration.
- Test performance:
- The chosen test item concentration of 4.0 mg/L investigated in the main test was based on the results of the preliminary solubility and toxicity tests. The chemical oxygen demand (COD) of 2.47 mg O2/ mg test item of Leuco Sulfur Blue 9 was determined at the start of the main experiment.
Under the test conditions ready biodegradation of this test item was not noticed. The percentage biodegradation of Leuco Sulfur Blue 9 reached a mean of 9.3 % after 28 days based on its COD. Based on the dissolved oxygen depletion, the resulting biodegradation values reached a plateau on about the 7th day of the experiment. From this day the slight changes were considered as being within the biological variability range of the applied test system. The highest biodegradability value of 9.5 % was noticed on the 21st day of the test.
The concurrently conducted analytical determination of possible nitrite and nitrate development demonstrated that no nitrification occurred (the slight changes in nitrite and nitrate concentrations in the 21-day and 28-day samples were caused likely by a technical effect: turbidity and/or discoloration). Therefore the biodegradability value of the test item was calculated based on its COD; any correction, based on the measured nitrite and/or nitrate content was not performed.
The reference item Sodium benzoate was sufficiently degraded to a mean of 80.9 % after 14 days, and to a mean of 80.2 % after 28 days of incubation, based on ThODNH3, thus confirming the suitability of the used activated sludge inoculum.
In the toxicity control containing both, the test item and the reference item, a mean of 29.6 % biodegradation was noted within 14 days and 32.0 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to not inhibit the activated sludge microorganisms (higher than 25 % degradation occurred within 14 days). - Key result
- Parameter:
- % degradation (O2 consumption)
- Remarks:
- mean
- Value:
- 9.3
- Sampling time:
- 28 d
- Parameter:
- % degradation (CO2 evolution)
- Remarks:
- mean
- Value:
- 9.5
- Sampling time:
- 21 d
- Parameter:
- % degradation (CO2 evolution)
- Remarks:
- mean
- Value:
- 8.9
- Sampling time:
- 14 d
- Details on results:
- Under the test conditions the percentage biodegradation of Leuco Sulfur Blue 9 reached a mean of 9.3 % after 28 days based on its COD. Based on the dissolved oxygen depletion, the resulting biodegradation values reached a plateau on about the 7th day of the experiment. From this day on, the slight subsequent changes were considered as being within the biological variability range of the applied test system. The highest biodegradability value of 9.5 % was noticed on the 21st day of the test. The test item can be considered to be not readily biodegradable.
In the toxicity control containing both, the test item and the reference item, a mean of 29.6 % biodegradation was noted within 14 days and 32.0 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to not inhibit the activated sludge microorganisms (higher than 25 % degradation occurred within 14 days). - Key result
- Parameter:
- COD
- Value:
- 2.47 other: mg O2/ mg test item
- Results with reference substance:
- The reference item Sodium benzoate was sufficiently degraded to a mean of 80.9 % after 14 days, and to a mean of 80.2 % after 28 days of incubation, based on ThODNH3, thus confirming the suitability of the used activated sludge inoculum.
- Validity criteria fulfilled:
- yes
- Interpretation of results:
- under test conditions no biodegradation observed
- Conclusions:
- The test item was considered to be not readily biodegradable (9.3 % biodegradation on day 28). According to the test guidelines the pass level for ready biodegradability is 60 % of COD.
- Executive summary:
The purpose of this study was to determine the ready biodegradability of the test item. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant. The biodegradation was followed by oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate (at a concentration of 3.0 mg/L) was tested simultaneously under the same conditions as the test item, and functioned as a procedure control (reference control). Additionally inoculum (containing the filtered inoculum only) and toxicity (containing both the test item and reference item) controls were examined. The chosen test item concentration of 4.0 mg/L investigated in the main test was based on the results of the preliminary solubility and toxicity tests. The chemical oxygen demand (COD) of 2.47 mg O2/mg test item was determined at the start of the main experiment. Under the test conditions ready biodegradation of this test item was not noticed. The percentage biodegradation of the test item reached a mean of 9.3 % after 28 days based on its COD. Based on the dissolved oxygen depletion, the resulting biodegradation values reached a plateau on about the 7thday of the experiment. From this day the slight changes were considered as being within the biological variability range of the applied test system. The highest biodegradability value of 9.5 % was noticed on the 21st day of the test. The concurrently conducted analytical determination of possible nitrite and nitrate development demonstrated that no nitrification occurred (the slight changes in nitrite and nitrate concentrations in the 21-day and 28-day samples were caused likely by a technical effect: turbidity and/or discoloration). Therefore the biodegradability value of the test item was calculated based on its COD; any correction, based on the measured nitrite and/or nitrate content was not performed. The reference item Sodium benzoate was sufficiently degraded to a mean of 80.9 % after 14 days, and to a mean of 80.2 % after 28 days of incubation, based on ThODNH3, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a mean of 29.6 % biodegradation was noted within 14 days and 32.0 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to not inhibit the activated sludge microorganisms (higher than 25 % degradation occurred within 14 days).
Reference
Dissolved Oxygen Concentrations at Different Time Intervals during the Exposure Period of 28 Days
Treatment |
Concentration |
Bottle |
mg O2/L after n days of exposure |
||||
[mg/L] |
No. |
0 |
7 |
14 |
21 |
28 |
|
Test item |
|
1a |
8.71 |
7.08 |
6.95 |
6.76 |
6.63 |
4.0 |
1b |
8.62 |
7.02 |
6.83 |
6.59 |
6.50 |
|
|
mean |
8.67 |
7.05 |
6.89 |
6.68 |
6.57 |
|
Reference item |
|
2a |
8.69 |
4.07 |
3.87 |
3.70 |
3.58 |
3.0 |
2b |
8.76 |
4.05 |
3.69 |
3.65 |
3.49 |
|
|
mean |
8.73 |
4.06 |
3.78 |
3.68 |
3.54 |
|
Inoculum control |
– |
3a |
8.73 |
8.03 |
7.86 |
7.71 |
7.67 |
3b |
8.71 |
7.95 |
7.78 |
7.63 |
7.41 |
||
mean |
8.72 |
7.99 |
7.82 |
7.67 |
7.54 |
||
Toxicity control |
Test item: 4.0 |
4a |
8.65 |
3.63 |
3.49 |
2.81 |
2.70 |
4b |
8.62 |
3.57 |
3.40 |
3.02 |
2.94 |
||
mean |
8.64 |
3.60 |
3.45 |
2.92 |
2.82 |
Oxygen Depletion at Different Time Intervals during the Exposure Period of 28 Days
Treatment |
Concentration |
Bottle |
mg O2/L after n days of exposure |
|||
[mg/L] |
No. |
7 |
14 |
21 |
28 |
|
Test item |
4.0 |
1a |
0.90 |
0.86 |
0.90 |
0.90 |
1b |
0.87 |
0.89 |
0.98 |
0.94 |
||
Reference item |
3.0 |
2a |
3.89 |
3.92 |
3.94 |
3.93 |
2b |
3.98 |
4.17 |
4.06 |
4.09 |
||
Toxicity control |
Test item: 4.0 |
4a |
4.29 |
4.26 |
4.79 |
4.77 |
4b |
4.32 |
4.32 |
4.55 |
4.50 |
oxygen depletion : (mt0- mtx) - (mbo- mbx), where:
mt0: oxygen concentration (mg/L) of test group on day 0
mtx: oxygen concentration (mg/L) of test group on day x
mb0: oxygen concentration (mg/L) of inoculum blank on day 0
mbx: oxygen concentration (mg/L) of inoculum blank on day x
BOD at Different Time Intervals during the Exposure Period of 28 Days
Treatment |
Concentration |
Bottle |
BOD after n days of exposure |
|||
[mg/L] |
No. |
7 |
14 |
21 |
28 |
|
Test item |
4.0 |
1a |
0.23 |
0.22 |
0.23 |
0.23 |
1b |
0.22 |
0.22 |
0.25 |
0.24 |
||
Reference item |
3.0 |
2a |
1.30 |
1.31 |
1.31 |
1.31 |
2b |
1.33 |
1.39 |
1.35 |
1.36 |
||
Toxicity control |
Test item: 4.0 |
4a |
0.61 |
0.61 |
0.68 |
0.68 |
4b |
0.62 |
0.62 |
0.65 |
0.64 |
BOD = = mg O2/mg T.i and/or R.i.
where:
T.i. =test item
R.i. =reference item
i.control=inoculum control
Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days
Treatment |
Concentration |
Bottle |
Percent of biodegradation after n days of exposure |
|||
[mg/L] |
No. |
7 |
14 |
21 |
28 |
|
Test item |
|
1a |
9.1 |
8.7 |
9.1 |
9.1 |
4.0 |
1b |
8.8 |
9.0 |
9.9 |
9.5 |
|
|
mean |
9.0 |
8.9 |
9.5 |
9.3 |
|
Reference item |
|
2a |
77.8 |
78.4 |
78.8 |
78.6 |
3.0 |
2b |
79.6 |
83.4 |
81.2 |
81.8 |
|
|
mean |
78.7 |
80.9 |
80.0 |
80.2 |
|
Toxicity control |
Test item: 4.0 |
4a |
29.6 |
29.4 |
33.1 |
32.9 |
4b |
29.8 |
29.8 |
31.4 |
31.1 |
||
mean |
29.7 |
29.6 |
32.3 |
32.0 |
Biodegradation % =
where:
T.i. =test item
R.i. =reference item
i.control=inoculum control
Nitrate Concentrations |
||||||
Analytical occasions |
Measured nitrate concentration (mg/L) in the test bottles |
|||||
1a |
1b |
3a |
3b |
4a |
4b |
|
0 day |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
7thday |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
14thday |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
<0.4 |
21stday |
0.6 |
0.5 |
0.7 |
0.6 |
<0.4 |
<0.4 |
28thday |
0.8 |
0.9 |
0.9 |
0.9 |
<0.4 |
<0.4 |
Remarks: LOQ of nitrate determination: 0.4 mg NO3/L
1a, 1b, 3a, 3b, 4a and 4b mean the bottle numbers.
|
Nitrite Concentrations |
||||||||
|
Analytical occasions |
Measured nitrite concentration (mg/L) in the test bottles |
|
||||||
|
1a |
1b |
3a |
3b |
4a |
4b |
|
||
|
0 day |
--- |
--- |
--- |
--- |
--- |
--- |
|
|
|
7thday |
--- |
--- |
--- |
--- |
--- |
--- |
|
|
|
14thday |
<0.03 |
<0.03 |
<0.03 |
<0.03 |
<0.03 |
<0.03 |
|
|
|
21stday |
0.69 |
0.55 |
0.67 |
0.73 |
0.12 |
0.08 |
|
|
|
28thday |
0.73 |
0.74 |
0.81 |
0.76 |
0.55 |
0.57 |
|
|
Remarks: LOQ of nitrite determination: 0.03 mg NO2/L 1a, 1b, 3a, 3b, 4a and 4b mean the bottle numbers, --- : nitrite concentrations were not detectable. |
|
Description of key information
The test item, Leuco Sulfur Blue 9, was considered to be not readily biodegradable (9.3 % biodegradation on day 28). According to the test guidelines the pass level for ready biodegradability is 60 % of COD.
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
- Type of water:
- freshwater
Additional information
A study according to OECD 301D was performed with to determine the ready biodegradability of the test item. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant. The biodegradation was followed by oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate (at a concentration of 3.0 mg/L) was tested simultaneously under the same conditions as the test item, and functioned as a procedure control (reference control). Additionally inoculum (containing the filtered inoculum only) and toxicity (containing both the test item and reference item) controls were examined. The chosen test item concentration of 4.0 mg/L investigated in the main test was based on the results of the preliminary solubility and toxicity tests. The chemical oxygen demand (COD) of 2.47 mg O2/mg test item was determined at the start of the main experiment. Under the test conditions ready biodegradation of this test item was not noticed. The percentage biodegradation of the test item reached a mean of 9.3 % after 28 days based on its COD. Based on the dissolved oxygen depletion, the resulting biodegradation values reached a plateau on about the 7thday of the experiment. From this day the slight changes were considered as being within the biological variability range of the applied test system. The highest biodegradability value of 9.5 % was noticed on the 21st day of the test. The concurrently conducted analytical determination of possible nitrite and nitrate development demonstrated that no nitrification occurred (the slight changes in nitrite and nitrate concentrations in the 21-day and 28-day samples were caused likely by a technical effect: turbidity and/or discoloration). Therefore the biodegradability value of the test item was calculated based on its COD; any correction, based on the measured nitrite and/or nitrate content was not performed. The reference item Sodium benzoate was sufficiently degraded to a mean of 80.9 % after 14 days, and to a mean of 80.2 % after 28 days of incubation, based on ThODNH3, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a mean of 29.6 % biodegradation was noted within 14 days and 32.0 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to not inhibit the activated sludge microorganisms (higher than 25 % degradation occurred within 14 days).
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