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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:
09 Jun - 07 Jul 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Staatliches Gewerbeaufsichtsamt Hildesheim

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage treatment plant, 31137 Hildesheim, Germany- Initial cell/biomass concentration: Approx. 1.30 x 10E+07 cfu/L in the final test solution- Pretreatment: Activated sludge was washed twice with chlorine free tap water; settled sludge resuspended in mineral salts medium; maintained under aerobic condition by aeration for 2 h; homogenized with a blender; after sedimentation the supernatant decanted and maintained under aerobic conditions by aeration with CO2-free air for 6 days; 10 mL/L used to initiate inoculation
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
36 mg/L
Based on:
test mat.
Remarks:
corresponding to an oxygen demand of 52.2 mg O2/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS- Composition of medium: Mineral salts medium according to OECD 301 F- Test temperature: 20 - 24 °C- pH: 7.57 - 7.83- pH adjusted: no- Dispersion treatment: Continuous stirring- Continuous darkness: yesTEST SYSTEM- Measuring equipment: OxiTop system- Test performed in closed vessels: yes- Details of trap for CO2 and volatile organics if used: Soda limeSAMPLING- Sampling frequency: Continuous measurement (360 measuring points during the 28 days; every 112 min one measurement)CONTROL AND BLANK SYSTEM- Inoculum control: yes (with 2 replicates)- Toxicity control: yes- Functional control: yes
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
32
Sampling time:
28 d
Details on results:
In the toxicity control (36 mg/L test item and 45 mg/L sodium benzoate) the biodegradation achieved 59% after 14 days. After 28 days the biodegradation came to 69%. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.

BOD5 / COD results

Results with reference substance:
The adaptation phase changed to degradation phase within 1 day (degradation > 10 %) and the biodegradation came to a maximum of 100 % on day 27. The pass level for ready biodegradation (> 60% degradation) was reached on day 2. The validity criterion that the degradation should be> 60% after 14 d was fulfilled.

Any other information on results incl. tables

Table 1: Degradation of test substance, functional- and toxicity control

 Biodegradation (%)

 

 

Day 7

 

Day 14

 

Day 21

 

Day 28

Replicate 1

Test Item 36 mg/L

Replicate 2

7

15

21

26

9

25

31

37

 

Functional Control

45 mg/L

87

94

97

100

 

Toxicity Control

36 mg/L Test Item +

45 mg/L Reference Item

46

59

66

69

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
not readily biodegradable: 32% after 28 d (OECD 301F)