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Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From January 25, 2021 to February 23, 2021

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

17th July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: CN0190301
Purity: 98.4%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A fresh sample of activated sludge was collected from the aeration tank of Shenyang North Sewage Treatment Plant 1 day before the test exposure was started.
- Laboratory culture:
- Method of cultivation: On the day of sludge collection, coarse particles were removed by filtration through a fine sieve and the sample was settled. After the supernatant was discarded, the sludge was washed twice with mineral medium and the concentrated sludge was suspended in mineral medium. Four replicates of 10 mL suspended sludge were weighed and dried at 105 C for 1 hour and 30 minutes and reweighed to calculate initial sludge concentration. The measured concentration of suspended sludge was 5.515 g/L as suspended solids (SS). The suspended sludge was prepared with mineral medium to yield a concentration of 4.0 g/L as SS.
- Storage conditions: The suspended sludge was kept at 22.0 - 23.5oC, under aerobic conditions until the start of the test.
- Storage length: 1 day
- Preparation of inoculum for exposure: About 900 mL mineral medium were added to a 1 L flask, followed by the addition of 7.680 mL of the prepared activated sludge and the mixture was made up to a volume of 1000 mL to give a suspended solid concentration of 30 mg/L. The 1 L inoculated mineral medium was brought into each test vessel.

Duration of test (contact time):

28 d

Initial conc.:

29.3 mg/L

Based on:

test mat.

Details on study design:

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Measuring equipment: Oxygen uptake was measured by respirometer system.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Test vessels containing only 1 L inoculated mineral medium were prepared in duplicate and served as inoculum controls identified as IC-1 and IC-2.
- Abiotic sterile control:
- Toxicity control: Toxicity control test vessel contained both test item and reference item.
- Other:

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

1.4

Sampling time:

28 d

Details on results:

The average biodegradation of test item was 1.4% af ter 28 days (2 replicates). The test item did not exhibit a percentage biodegradation exceeding the pass level of 60% within the 28-day period.

Results with reference substance:

The biodegradation of the reference substance (Sodium benzoate) attained 61.2% after Day 4, 83.1% after Day 14 and 94.3% after Day 28.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The average biodegradation of test item was 1.4% af ter 28 days (2 replicates). The test item did not exhibit a percentage biodegradation exceeding the pass level of 60% within the 28-day period. The test item did not meet the criteria for “ready biodegradability” under the described test conditions.

Executive summary:

The ready biodegradability study is performed according to OECD Guideline 301F under GLP. The average biodegradation of test item was 1.4% af ter 28 days (2 replicates). The test item did not exhibit a percentage biodegradation exceeding the pass level of 60% within the 28-day period. The test item did not meet the criteria for “ready biodegradability” under the described test conditions.

Description of key information

The ready biodegradability study is performed according to OECD Guideline 301F under GLP. The average biodegradation of test item was 1.4% af ter 28 days (2 replicates). The test item did not exhibit a percentage biodegradation exceeding the pass level of 60% within the 28-day period. The test item did not meet the criteria for “ready biodegradability” under the described test conditions.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater