Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April – August, 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
conducted under GLP conditions

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: Ministry of environmental protection of the people's Republic of China, The Guidelines for the Testing of Chemicals-Degradation and Accumulation, 2013, 301F Ready Biodegradability: Manometric Respirometry Test
Version / remarks:
2013
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry 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)

Test material

Constituent 1
Chemical structure
Reference substance name:
4-(dodecylthio)-4-methylpentan-2-one
Cas Number:
855737-35-8
Molecular formula:
C18H36OS
IUPAC Name:
4-(dodecylthio)-4-methylpentan-2-one
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
activated sludge, from a domestic sewage treatment plant is normally used as the microbial inoculums based on "Ministry of environmental protection of the people's Republic of China, The Guidelines for the Testing of Chemicals-Degradation and Accumulation, 2013, 301F Ready Biodegradability: Manometric Respirometry Test." and "OECD, Guidelines for the Testing of Chemicals. Ready Biodegradability 301F: Manometric Respirometry Test, 1992". The activated sludge is suitable for the ready biodegradability test because of its higher cell densities, no pre-adaption and good repetitive results.
Sludge collection: a fresh sample of activated sludge was collected on May 17, 2018 from the aeration tank of the Long Hua Wastewater Treatment Plant in Shanghai which treats predominantly domestic sewage with Anaerobic-Oxic process(A/0). The activated sludge was kept by aeration until used (non-aeration during transport from the wastewater treatment plant to the laboratory was kept to a minimum).

When back to the laboratory, the sludge was washed with mineral medium. After centrifugation, the supernatant was decanted. This procedure was repeated three times (4000 rpm, 4°C, centrifuge 20 minutes). Then, 0.406g of the concentrated sludge was weighed, dried at 105°C for 1h and then measured by moisture meter for 1h to determine the dry weight. The dry weight of concentrated sludge was 6.90%.
Sludge suspension: According to the dry weight, 43.48g of concentrated sludge was calculated and suspended in 1L mineral medium to yeild a concentration of 3g suspended solids/L. The final concentrationof the activated sludge in the test medium was 30mg/L.
The definitive study began on May 17, 2018 when the fresh sewage sludge sample was collected at the same day.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
17 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
When the test system was prepared completely, Respirometer (WTW, OxiTop 11OC, Weilheim, Germany) the following operational procedure was performed as follows:
1) Evaluate the BOD range of the test substance and prepare the test systems
2) Insert a magnetic stirrer bar into the flasks.
3) Place 2 sodium hydroxide pellets in the rubber sleeve.
4) Insert the rubber sleeves into the flasks.
5) Screw the OxiTop® measuring head tightly.
6) Start the measurement on the OxiTop® head.
7) Place the measuring flask on the inductive stirring system, then set the temperature of the incubator at 22°C. The temperature fluctuation was recorded as 21.9-22.3°C during 28 days. Samples were incubated in the dark.
8) Auto-read the results once per 112min during 28 days.
9) Determine pH at the beginning and the end of the study.
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
CAS number 532-32-1, purity: 99%, lot SLBP6327V

Results and discussion

Test performance:
The results are checked once per 112min during 28 days.
% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
83
Sampling time:
28 d
Remarks on result:
other: Average of two flasks (Flask 1 BOD = 85% on Day 28, Flask 2 BOD = 80% on Day 28)
Parameter:
% degradation (O2 consumption)
Value:
62
Sampling time:
11 d
Remarks on result:
other: Day 11 is the end of the 10-day window. Average of two flasks (Flask 1 BOD = 63% on Day 11, Flask 2 BOD = 61% on Day 11)
Details on results:
Results showed that under the experimental conditions, biodegradation of test substance attained an average of 62% at Day 11 (10-d window) and 83% at Day 28 which met the 10-d window criteria.
Therefore, the test substance can be considered to be readily biodegradable under the experimental conditions according to this test method.
Since biodegradation in the toxicity control was greater than 25% within 14 days, the test substance was considered not to have a toxic or inhibitory effect on the activity of the microbial inoculum.

BOD5 / COD results

Results with reference substance:
In the toxicity control, within 14 days of exposure, biodegradation amounted to 80%.

Any other information on results incl. tables

The mean BOD of the inoculum blanks was 25.45mg 02/L in 28 days, which was less than 60mg/L, meeting the guideline requirement. During the 28 days, the pH values of the solution in test substance flasks were in the range of 7.81-7.96, which met the requirement of pH 6.0-8.5 of the test substance solution.The difference between replicate values of the removal of the test substance during 28d test period was less than 20%.


The mean biodegradation of the reference substance (Sodiumbenzoate) was 93% by Day 14, reaching the pass level of the ready biodegradation test (>60% within 14 days).


The biodegradation percent of the toxicity control was 80% by day14, > = to 25%ThOD, which met the guideline requirement.


Thus,the test is considered valid.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance Scentaurus Juicy was readily biodegradable under the test conditions.
Executive summary:

The study was conducted according to the guidelines of "Ministry of environmental protection of the people's Republic of China,The Guidelines for the Testing of Chemicals-Degradation and Accumulation, 2013, 301F Ready Biodegradability Manometric Respirometry Test","OECD, Guidelines for the Testing of Chemicals. Ready Biodegradability 301F:Manometric Respirometry Test,1992","Part C.4-D(ManometricRespirometryTest) of EC Methods for the Determination of Ecotoxicity" and "Annex to Council Regulation (EC), L142 (2008) and Fate, Transport and Transformation Test Guidelines, OPPTS 835.3110, Ready Biodegradability. EPA 712-C-98-076, January 1998".


Under specific experimental conditions, the ready biodegradability of Scentaurus Juicy (QHDL 20180402 -2220) was determined in a 28 -day dissolved oxygen depletion test using activated sludge from a domestic waste water treatment plant.


The tested concentration of test substance were 17.12mg/L and 17.04mg/L (i.e.51.02mg ThOD/L and 50.78mg ThOD/L).The concentration of sludge inoculum in test system was 30mg/L, and the tested concentration of sodium benzoate used as reference substance was 100 mg/L (i.e.167.00mgThOD/L). A toxicity control was also included.


During the test,the temperature was maintained at 21.9 -22.3°C. The mean total 02 uptake in the inoculum blanks at the end of the test was less than 60mg 02/L in 28 days meeting the guideline requirement. Biodegradation of the reference substance (sodium benzoate) reached the pass level of the ready biodegradation test (>60% within 14 days). Biodegradation of the reference substance (sodium benzoate) reached an average of 93% by Day 14. The difference of extremes between replicate values of the removal of the test substance during the 28d test period was less than 20%. The results of the toxicity control showed that the test substance met the criteria for not being inhibitory to the microbial inoculum.Thus, the test is valid.


Results showed that under the experimental conditions, biodegradation of test substance attained an average of 83% at Day28. Biodegradation of the test substance attained at the end of the 10-day window attained an average of 62% on Day 11, and met the 10-d window criteria.


Therefore, the test substance can be considered to be readily biodegradable under the experimental conditions according to this test method.