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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Nov. 18, 2002-Dec. 19, 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Marl-Ost municipal sewage treatment plant
- Initial cell/biomass concentration: 3.94 g/l dry matter
Duration of test (contact time):
29 d
Initial conc.:
34.3 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Test temperature: 19.7-21.9 degree C
- pH: 7.4-7.5
- Aeration of dilution water: yes, overnight
- Suspended solids concentration: 26.3 mg/L

TEST SYSTEM
- Culturing apparatus: 5000 ml Woullf flasks
- Number of culture flasks/concentration: 2 flasks

SAMPLING
- Sampling frequency: 0, 2, 5, 9, 12, 14, 21, 28, and 29 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks

STATISTICAL METHODS: Results were calculated using the EXCEL computer program.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
85
Sampling time:
29 d
Details on results:
The test substance was 85% degraded on day 29.
Results with reference substance:
The reference substance was 89% degraded in 29 days.

% Degradation

Test Duration
(days)
Sodium Benzoate Test Vessel 1 Test Vessel 2 Test Vessel Mean
0 0 0 -1 -1
2 32 1 -5 -2
5 59 24 19 22
9 76 57 46 52
12 84 73 66 70
14 84 72 67 70
21 93 76 79 78
28 95 86 80 83
29 89 84 85 85
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance was 85% degraded in 29 days, and is considered readily biodegradable.
Executive summary:

This study examined the biodegradability of the test substance. 34.3 mg/L of test substance was added to flasks containing activated sludge. The amount of CO2 evolved was then measured over the next 29 days. Sodium benzoate was used as a reference substance. The reference substance was 89% degraded in 29 days. Therefore the test is valid. The test substance was 85% degraded in 29 days. The test substance is readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Principles of method if other than guideline:
ISO 7827, Directive 79/831, V
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
activated sludge, domestic, non-adapted (community: Lambsheim, federal state: Baden Württemberg, Germany)
Duration of test (contact time):
21 d
Initial conc.:
20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST SYSTEM
- Number of culture flasks/concentration: 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
> 90
Sampling time:
21 d
Interpretation of results:
readily biodegradable

Description of key information

MEA-LAS dissociates in water to its constituents MEA and LAS, both of which are readily biodegradable. MEA-LAS can therefore be considered to be readily biodegradable.

Study 1:

A study was conducted to examine the biodegradability of C10-13 LAS, sodium salt, according to OECD Guideline 301B, in compliance with GLP. 34.3 mg/L of test substance was added to flasks containing activated sludge. The amount of CO2 evolved was then measured over the next 29 d. Sodium benzoate was used as a reference substance. The reference substance was 89% degraded in 29 d, therefore the study was valid. The test substance was 85% degraded in 29 d and can be considered readily biodegradable (Anon, 2002).

Study 3:

A DOC die away test according to OECD Guideline 301A was conducted with MEA. The substance (20 mg/L in the test system) was degraded by >90% within 21 d and is therefore considered to be readily biodegradable (BASF, 1995).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information