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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 23, 2018 - December 21, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
July 17, 1992; §14 corrected July 26, 1993
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
dated 22 November 2017

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Laboratory preparation:
A filtration through a fine sieve (about 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by decantation in a mineral medium until sludge was considered free from excess substrate or inhibitor.

Inoculum pre-conditioning:
Pre-conditioning consisted in aerating sludge (in mineral medium) for 5-7 days before the test and at the test temperature.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST ITEM PREPARATION
The test item “BiCAT 8842” was tested at 100 mg/L in mineral medium.
The test item was directly introduced with sludge into each test vessels.
The test medium was the mineral medium, a weakly saline aqueous medium

PROTOCOL
Principle:
A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days.
Microbial respiration consumes O2 and releases CO2 which was absorbed by soda lime pellets present in the headspace of flasks. This produces a decrease in pressure in the flask proportional to the amount of oxygen taken up by the microbial population during biodegradation, which was expressed as a percentage of ThOD (Theoretical Oxygen Demand).
Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item.
Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L + inoculum) and a toxicity control (sodium benzoate + inoculum + test item) were run in parallel.
The pH of the contents was measured at the start and the end of the experiment.

Tes system: The inoculum was a fresh sample of activated sludge and was collected from the aeration tank of a sewage treatment plant receiving predominantly domestic sewage.

Incubation:
The test was performed in darkness between 20 to 24°C (constant temperature ±1°C).

MATERIAL AND METHOD
Inoculum preparation:
Sample site = Water treatment plant 'STEP de Lille', 33290 Blanquefort (France) - Tank 1
Date of sampling = May 31, 3018
Inoculum physico-chemical characteristic at the beginning of the test:
Suspended solid = 2.75 g/L
pH = 6.0
Dissolved oxygen = 9.1 mg/L
Activated sludge preparation:
1. Filtration through a 1 mm sieve
2. 3 successive decantations into mineral medium
3. Activated sludge aeration during 5 days

Preparation of the test solutions:
The test item “BiCAT 8842” was tested at 100 mg/L in mineral medium.
The test item was directly introduced with sludge into each test vessels.
The test medium was the mineral medium, a weakly saline aqueous medium.

Reference solution:
Solution of Sodium Benzoate at 1 g/L: weighing of 500.02 mg in 500mL mineral medium.
A solution of sodium benzoate was produced: weighing of 200.15 mg in 200 mL (final volume) mineral medium.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
The theorical Oxygen Demand ThOD(NH4) is 1.922 mg O2 per mg of test item.
The theorical Oxygen Demand ThOD(NO3) is 2.197 mg O2 per mg of test item.
Test performance:
All validity criteria were successful.
% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
9.04
Sampling time:
28 d
Remarks on result:
other: See 'Remarks'
Remarks:
Evaluation of biodegradation based as ThOD(NH4).
Parameter:
% degradation (O2 consumption)
Value:
7.9
Sampling time:
28 d
Remarks on result:
other: See remarks
Remarks:
Evaluation of biodegradation based as ThOD(NO3).
Details on results:
The test item “BiCAT 8842” contains nitrogen according to the elementary analysis, the evaluation of biodegradation has to be based in the following expressed as ThODNH4 and ThODNO3.
Based on ThODNH4, the 10-Day window failed and the degradation rate of the test item “BiCAT 8842” reached 9.04% after 28 days of incubation.
Based on ThODNO3, the 10-Day window failed and the degradation rate of the test item “BiCAT 8842” reached 7.90% after28 days of incubation.
According to the OECD guideline 301F, the test item is not considered to be biodegradable whatever the ThOD.

Biodegradation of the reference item: “Sodium benzoate”:
The reference item “Sodium benzoate” was degraded up to 93.02% after 14 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Biiodegradation of the Toxicity Control:
A biodegradation of 30.51 and 31.20% after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item) based on ThODNH4. At the end on the test, 28 days of incubation, the result was 37.83% and 41.25% respectively for both replicates.
A biodegradation of 27.89 and 28.52% after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item) based on ThODNO3. At the end on the test, 28 days of incubation, the result was 34.58 and 37.71% respectively for both replicates.
Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro-organism whatever the nitrification because degradation was higher than 25% within 14 days (validity criterion).

BOD5 / COD results

Results with reference substance:
The reference item “Sodium benzoate” was degraded up to 93.02% after 14 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Any other information on results incl. tables

Percentage (%) Biodegradation during 28 days with ThOD(NH4) = 1.922 mg O2/mg test item

 Time (days)  Toxicity control     Test item         
 Measuring system  25  17  35  24  7  Average
 0  0.00 0.00  0.00  0.00  0.00  0.00 
 1 0.00 0.00  0.00 0.00 0.00 

 0.00

 2 20.72 20.72  0.00  0.00  0.00  0.00 
 3 23.12 23.60  0.00 0.00  0.00  0.00 
 4 26.66 26.66  0.00  0.00  0.00  0.00 
 5 28.10 27.62  0.00  0.00  0.00  0.00 
 6 28.61 28.13  0.00  0.00  0.00  0.00 
 7 29.09 29.09  0.00  0.00  0.00  0.00 
 8 29.57 29.57 0.00  0.00  0.00 0.00
 9 30.02 29.55 0.00  0.00  0.00  0.00 
 10  29.69 29.69  0.00  0.00  0.00  0.00 
 11 29.69 30.17  0.00  0.00  0.00  0.00 
 12 30.17 30.17  0.00 0.00  0.00  0.00
 13 30.33 30.67  0.00  2.19  0.00  0.73 
 14 30.51 31.20  0.00  4.13  0.49  1.54 
 15 30.51 31.54  0.00  4.13  3.40  2.51 
 16 31.90  31.22 0.00  4.37  4.37  2.91
 17 33.11  33.11 0.00  4.86  4.86 3.24 
 18 35.16 35.51 1.94 5.64  5.64  4.41 
 19 35.51 38.24  4.86  6.36  5.64  5.62 
 20 36.24 38.63 4.67  6.12  6.12  5.64 
 21 36.08 39.50  5.88  7.34  5.88  6.36 
 22 36.24  40.00 6.12  8.31  6.12  6.85 
 23 37.08  39.82  6.36  8.55  7.09  7.34 
 24 36.96 40.70   7.09 9.28  7.09  7.82
 25 37.28  41.39  7.09  9.28  8.55  8.31 
 26 37.28  41.39  7.09 10.01  8.55  8.55 
 27 38.15 41.23   6.85 9.76  9.76  8.79 
 28 37.83  41.25  7.09  10.01  10.01  9.04 

Percentage (%) Biodegradation during 28 days with ThOD(NO3) = 2.197 mg O2/mg test item

 Time (days)  Toxicity control     Test item         
 Measuring system  25  17  35  24  7  Average
 0  0.00 0.00  0.00  0.00  0.00  0.00 
 1 0.00 0.00  0.00 0.00 0.00 

 0.00

 2 18.94 18.94  0.00  0.00  0.00  0.00 
 3 21.13 21.57  0.00 0.00  0.00  0.00 
 4 24.37 24.37  0.00  0.00  0.00  0.00 
 5 25.68 25.24  0.00  0.00  0.00  0.00 
 6 26.15 25.71  0.00  0.00  0.00  0.00 
 7 26.59 26.59 0.00  0.00  0.00  0.00 
 8 27.03 27.03 0.00  0.00  0.00 0.00
 9 27.44

27.01

0.00 

0.00 

0.00 

0.00 

 10

 27.14

27.14 

0.00 

0.00 

0.00 

0.00 

 11

27.14

27.58 

0.00 

0.00 

0.00 

0.00 

 12

27.58

27.58 

0.00

0.00 

0.00 

0.00

 13

27.72

28.04

0.00 

1.91 

0.00 

0.64 

 14

27.89

28.52

0.00 

3.61 

0.42 

1.35 

 15

27.89

28.83 

0.00 

3.61 

2.97 

2.19 

 16

29.16

28.54

0.00 

3.82 

3.82 

2.55

 17

30.27 

30.27

0.00 

4.25 

4.25

2.83

 18

32.14

32.45

1.70

4.93 

4.93 

3.85 

 19

32.45

34.96 

4.25 

5.57 

4.93 

4.92 

 20

33.12

35.31

4.08 

5.36 

5.36 

4.93 

 21

32.98

36.10 

5.14 

6.42 

5.14 

5.57 

 22

33.12

36.56

5.36 

7.27 

5.36 

5.99 

 23

33.89

36.39

5.57

7.48 

6.21 

6.42 

 24

33.77

37.21 

6.21

8.12 

6.21 

6.84

 25

34.08 

37.83 

6.21 

8.12 

7.48 

7.27 

 26

34.08

37.83 

6.21

8.75 

7.48

7.48 

 27

34.87

37.68 

 5.99

8.54 

8.54

7.69 

 28

34.58 

37.71 

6.21 

8.75 

8.75 

7.90 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under conditions of OECD Guideline 301F, the test item is not considered to be biodegradable.
Executive summary:

The aim of this study was to determine the effects of the test item according to the OECD 301F guideline, ready biodegradability within an experimental period of 28 days by respirometric method.

The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank

inoculum, run in parallel) was determined from the change in pressure in apparatus and will be expressed as percentage of theoretical Oxygen Demand (ThOD).

All the validity criteria were successful.

Based on ThODNH4, the 10-Day window failed and the degradation rate of the test item “BiCAT 8842” reached 9.04% after 28 days of incubation.

Based on ThODNO3, the 10-Day window failed and the degradation rate of the test item reached 7.90% after

28 days of incubation.

The results obtained show that the test item is not considered to be readily biodegradable whatever the ThOD, after 28 days of incubation.

Under conditions of OECD Guideline 301F, the test item is not considered to be biodegradable.