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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:
September - October 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report date:
1992

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.6 (Degradation: Chemical Oxygen Demand)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Polyglycerin
IUPAC Name:
Polyglycerin
Details on test material:
- Name of test material (as cited in study report): Polyglycerin (synonym = Polyglycerol)
- Substance type: light brown, viscous liquid
- Physical state: liquid
- Analytical purity:
20.78% diglycerin
42.27% triglycerin
20.75% tetraglycerin
- Purity test date: not stated
- Lot/batch No.: 4648200291
- Expiration date of the lot/batch: not stated
- Stability under test conditions: not stated
- Storage condition of test material: not stated

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: RWZI Horstermeer in Nederhorst den Berg, The Netherlands

The inoculum was taken from activated sludge plant. The sludge was preconditioned to reduce endogenous respiration rate. The sludge was aerated for one week (200 mg dry weight/l). The sludge was diluted to a concentration in the BOD bottles of 2 mg d.w./l.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
2 mg/L
Based on:
test mat.
Initial conc.:
5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
other: ratio of BOD or COD to the TOD
Details on study design:
TEST CONDITIONS
- Composition of medium: aqueous solution of mineral salt
- Test temperature: 20 +/- 1 °C
- pH: 6.3 - 6.7
- pH adjusted: no
- Aeration of dilution water: the sludge was aerated 1 week before the test
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 280 ml BOD bottles, completely filled to avoid headspace
- Number of culture flasks/concentration: 7
- Measuring equipment: oxygen meter and pH meter
- Test performed in open system: no


SAMPLING
- Sampling frequency: oxygen content was measure on day0, 5, 15, and 28. pH was measured on day 0 and 28.
- Other:


CONTROL AND BLANK SYSTEM
A: mineral salt solution
B: mineral salt solution and inoculum (2.8 ml of the preconditioned sludge)
C: mineral salt solution, inoculum and sodium acetate (6.7 mg/l)
D: mineral salt solution, inoculum and test substance (2 mg/l)
E: mineral salt solution, inoculum and test substance (5 mg/l)
Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
6.7 mg/l

Results and discussion

% Degradation
Key result
Parameter:
other: % degradation
Remarks:
calculated from ratio of BOD or COD to the TOD
Value:
> 60
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
Inoculum activity is good: 60 % of sodium acetate was degraded within 5 days and 75 % within 28 days.

Any other information on results incl. tables

Percentage of biodegradation of sodium acetate and the test substance.

 

% Biodegradation

 5 days  15 days  28 days
sodium acetate  60  75  75
polyglycerins (2 mg/l)  10  50  60
polyglycerins (5 mg/l)  < 5  40  55

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The biodegradability of Polyglycerol was examined in a closed bottle test. Polyglycerol (2 mg/l and 5 mg/l) was added to an aqueous solution of mineral salt and exposed to unadapted microorganisms (activated sludge) under aerobic conditions. In the test, 60% of the test substance was degraded within 28 days. It is concluded that Polyglycerol can be classified as readily biodegradable.