[No public or meaningful name is available]

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

see below

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Principles of method if other than guideline:

The following deviation from the study plan occurred:
On Day 18 of the test the temperature in a vessel containing water which was incubated under the same conditions as the test vessels was recorded as being 24.5 °C. This was a deviation from the Study Plan which states the test will be conducted at a temperature of 22 ± 2 ºC. This deviation was considered to have not affected the integrity or validity of the study given that all validation criterion were met.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was obtained on 15 August 2016 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

71

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Sodium benzoate attained 81% biodegradation after 14 days and 79% biodegradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item attained 71% biodegradation after 28 days and therefore can be considered to be readily biodegradable.

Executive summary:

Ready bioavailability of the test item was evaluated according to OECD Guideline 301b (Ready biodegradability; CO2 Evolution Test). The test item (10 mg carbon/L) was exposed to activated sewage sludge microorganisms with mineral medium in sealed culture vessels in the dark for 28 days. The test item degraded 71% after 28 days. This results in the test item being classified as readily biodegradable.