Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From January 15 to February 17, 1991
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 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Inoculum: a mixed population of activated sewage sludge microorganisms.
- Source: the aeration stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
- Preparation: the activated sludge was washed by repeatedly settling and resuspending with the test water.
- Amount: usage rate equivalent to 0.75 g dry weight/I.
Duration of test (contact time):
28 d
Initial conc.:
255 mg/L
Based on:
test mat.
Remarks:
(=100 ppm C)
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Test temperature: 22 ± 1 °C
- Continuous darkness: yes; the test was conducted in darkness.
- Agitation: by magnetic stirrers and compressed air via narrow bore glass tubes.
- pH: pH values did not drop below 5.3 in any culture vessel during the course of the study and were adiusted to pH 7.3 daily.
- Dissolved oxygen: dissolved oxygen levels remained at approximately 7.8 mgO2/l or above in all cultures at all times.

SAMPLING
- Sampling preparation: losses by evaporation were made good by the addition of de-ionised water immediately prior to sampling.
- Sampling amount: 20 ml samples were withdrawn from each vessel and filtered through 0.45 um disposable filters; the first 10 ml was discarted.
Reference substance:
diethylene glycol
Remarks:
220 mg/l (= 100 ppm C)
Parameter:
% degradation (DOC removal)
Value:
18
Sampling time:
28 d
Details on results:
Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.
Results with reference substance:
The Standard Substance, diethylene glycol, attained 93 % degradation within 8 days and 100 % degradation by day 27, thereby confirming the suitability of the inoculum and culture conditions.

Details on test results

Day DOC* value mg/l (Mean of 2 Assays) % biodegradation
Test item Reference Test item Reference
0 Hours 130 88 0 0
3 Hours 130 88 0 0
1 130 91 0 <3>
2 132 94 <2> <6>
3 132 93 <2> <5>
6 131 74 <1> 17
8 126 6 3 93
10 130 5 0 95
14 116 2 11 97
16 117 1 10 99
21 115 3 11 96
23 114 3 12 96
27 108 0 17 100
28 107 0 18 100

<increase>

Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.
Executive summary:

The biodegradability of test item, exposed to activated sludge, was investigated under aerobic static conditions. The assessment was performed in accordance with Zahn-Wellens test method.

Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

The Standard Substance, diethylene glycol, attained 93 % degradation within 8 days and 100 % degradation by day 27, thereby confirming the suitability of the inoculum and culture conditions.

Conclusion

Based on the test results, the substance resulted to be not biodegradable under the test conditions, since less than 20 % degradation was attained after 28 days of contact time.

Description of key information

Neither readily, nor inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

The biodegradability of Acid Violet 048, exposed to activated sludge, was investigated under aerobic static conditions, in accordance with Zahn-Wellens test method. Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

Categories Display