Glycerol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was conducted prior to GLP and test guidelines, but sufficient data is available for interpretation of results

Qualifier:

no guideline available

Principles of method if other than guideline:

The biological degradation of 123 organic compounds was studied.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

Activated sludge obtained from a sewage plant was used. Starch or glucose and peptone were the only chemicals added during the 20 day adaptation phase.

Duration of test (contact time):

ca. 24 h

Details on study design:

The tested substance is dissolved in a beaker in a biological medium in a concentration corresponding to 200mg/L COD. The tested substance is a sole source of organic carbon for the microbes of the inoculum. To the biological medium such amount of thickened adapted activated sludge is added to make dry matter of the inocuium 100 mg/L. The beaker is placed in a dark room with a roughly constant temperature of 20+/- 3 C on an electromagnetic stirrer. The initial value of COD or organic carbon of the liquid phase are determined. Samples. filtered or centrifuged before analysis, are taken at suitable intervals. The decrease of the tested substance in the liquid phase is evaluated by determining COD or organic carbon. The rest, Its are compared with those of a blank test and standard compound decomposition. With the degree of degradation also the average specific rate of degradation is determined, expressed in terms of mg COD (or organic carbon) removed by a gamme of dry matter of the activated sludge per hour.

Reference substance:

diethylene glycol

Reference substance:

aniline

Preliminary study:

Not applicable.

Test performance:

98.7% of the glycerol was removed within approximately 24 hours based on COD. The rate of biodegradation was 85.0 mg COD g-1 h-1.

Parameter:

% degradation (DOC removal)

Value:

98.7

Sampling time:

24 h

Details on results:

No additional information available.

Results with reference substance:

95% of the diethylene glycol was removed based on COD measurement (time interval not specified but less than 20 days)
94.5% of the aniline was removed based on COD measurement (time interval not specified but less than 20 days).

No additional information available.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In this study, glycerol was rapidly biodegraded. 98.7% of the glycerol was removed within approximately 24 hours based on COD. The rate of biodegradation was 85.0 mg COD/g/h.

Executive summary:

In this study, glycerol was rapidly biodegraded. 98.7% of the glycerol was removed within approximately 24 hours based on COD. The rate of biodegradation was 85.0 mg COD/g/h.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was not conducted according to guideline/s and GLP but the report contains sufficient data for interpretation of study results

Qualifier:

no guideline available

Principles of method if other than guideline:

The biodegradation potential of glycerin was examined using activated sludge from an industrial source.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
ethylene glycol was used as positive control

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial (adaptation not specified)

Details on inoculum:

- Inoculum (source/concentration): activated sludge
(industrial)
- pretreatment: washed with tap water
METHOD OF PREPARATION OF TEST SOLUTION: not indicated

Duration of test (contact time):

24 h

Initial conc.:

226 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

TOC removal

Details on study design:

INITIAL TEST SUBSTANCE CONCENTRATION: 88 mg C/L (=226 mg TS/L)

TEST SYSTEM
- Test apparatus: fill and draw type unit; one with two aeration cylinders, each with a volume of 7 L, the other with two aeration cylinders, each with a volume of 30 L (no more information available in this report, Nanbu(1971) is given as a reference)
- Number of replicates: not indicated
- Aeration: yes (5 L/min)
- Measuring equipment:
TOC: TOC analyser
COD-Mn: water sample was oxidised with KMnO4-H2SO4 at 100 C for 30 minutes (catalyst: Ag2SO4)

DURATION OF THE TEST: 24 hours
SAMPLING: 0, 2, 4, 24 hours
ANALYTICAL PARAMETER: TOC and COD-Mn
ThOD: 1.21 mg/g = 275 mg/L (COD = 238 mg/L)
TEST CONDITIONS
- Test temperature: 25 C
CONTROLS: not included
REFERENCE SUBSTANCE: ethylene glycol was also included in this test and can be used as a positive control

Reference substance:

ethylene glycol

Preliminary study:

No additional information available.

Parameter:

% degradation (TOC removal)

Value:

60

Sampling time:

2 h

Parameter:

% degradation (TOC removal)

Value:

86

Sampling time:

4 h

Parameter:

% degradation (TOC removal)

Value:

94

Sampling time:

24 h

Details on results:

Probably no blank was included in the test, but it was stated, that the contribution of TOC and COD-Mn from the activated sludge was negligible.

Removal test substance as %COD, %TOC respectively:
0 hour: 0, 0
2 hour: 50, 60
4 hour: 92, 86
24 hour: 97, 94

Results with reference substance:

REFERENCE SUBSTANCE
Removal test substance as %COD, %TOC respectively:
0 hour: 0, 0
2 hour: 14, 18
4 hour: 32, 38
24 hour: 92, 93

No additional information available.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test material was essentially biodegraded within 24 hours.

Executive summary:

The biodegradation of glycerin was examined using industrial activated sludge. Glycerin was nearly completely degraded within 24 hours. No indication is given in the report whether the microorganisms were pre-adapted. However, given that glycerin is considered a primoridial biomolecule from which many biomolecules are derived, pre-adaptation is probably minimal.

Description of key information

The biodegradation of glycerin was examined using industrial activated sludge. Glycerin was nearly completely degraded within 24 hours. No indication is given in the report whether the microorganisms were pre-adapted. However, given that glycerin is considered a primoridial biomolecule from which many biomolecules are derived, pre-adaptation is probably minimal.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation of glycerin was examined using industrial activated sludge. Glycerin was nearly completely degraded within 24 hours. No indication is given in the report whether the microorganisms were pre-adapted. However, given that glycerin is considered a primoridial biomolecule from which many biomolecules are derived, pre-adaptation is probably minimal.