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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:
1994-01-13 to 1994-02-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)
Version / remarks:
Cited as Directive 92/69/EEC, C.4-A
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
2,2,4(or 2,4,4)-Trimethyladipic acid of Hüls AG, produced 25 March 1992
Sample from continuous production, storage tank FA 975
Purity 90 % w/w
Sample ID 3630/81389, Sample No. 1324/920707

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
INOCULUM
- Sampling site: Municipal STP Marl-Ost, sampled 13 Jan 1994
- Preparation of inoculum: Sampling, centrifugation (15 min at 3000 rpm), discard supernatant and resuspend with mineral medium, repeat  
centrifugation as above, resuspension of sludge (3.07 g dry weight/l),  aeration through frit
- Initial inoculum concentration: 24.6 mg sludge/l (8.0 ml inoculum with 3.07  g/l dry weight content / l test solution)
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
10.6 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST SYSTEM
- Culturing apparatus: 2000 ml Erlenmeyer flask covered loosely with aluminum sheet, filled with 1000 ml test soln
-  Number of culture flasks per concentration: 2 with test substance (10.93 mg DOC/l) and inoculum; 2 with inoculum only (blank); 2 with control 
substance (10.47 mg DOC/l) and inoculum
- Aeration device: shaking for 28 days

METHOD OF PREPARATION OF TEST SOLUTION
- Stock solution: 558 mg DOC/l

TEST CONDITIONS
- Test temperature: 22.0 - 22.2 °C; dark
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
Purity > 99.5% (Fluka)

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (DOC removal)
Value:
25
Sampling time:
7 d
Parameter:
% degradation (DOC removal)
Value:
44
Sampling time:
14 d
Parameter:
% degradation (DOC removal)
Value:
56
Sampling time:
21 d
Parameter:
% degradation (DOC removal)
Value:
73
Sampling time:
28 d
Details on results:
Kinetic of test substance (in %):
= 25 after 7 day(s)
= 44 after 14 day(s)
= 56 after 21 day(s)
= 75 after 27 day(s)
Degradation products: not measured

BOD5 / COD results

Results with reference substance:
Kinetic of control substance (in %):
= 98 after 7 day(s)

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
2,2,4(or 2,4,4)-Trimethyladipic acid was observed to be readily biodegradable without passing the 10-day window.
Executive summary:

The biodegradability of 2,2,4(or 2,4,4)-trimethyladipic acid was investigated by Hüls AG (1994) in a DOC-DIE AWAY Test according to EU-method C.4 -A. The DOC removal was determined at weekly sampling intervals by using a carbon analyser (Shimadzu). Trimethyladipic acid was observed to be readily biodegradable, but the 10 -day window was not passed. 73 % degradation was determined over a period of 28 days.

The study was assessed as "reliable without restrictions".