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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline / GLP Study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Non adapted activated sludge from the sewage municipal plant at D-31137 Hildesheim. The activated sludge was washed twice with autoclaved tap water and maintained in an aerobic condition by aeration for 4 hours and then homogenized with a mixer for 2 min. Thereafter the sludge was filtered with folded filter and aerated with C02-free air for 5 days. 25 mL/L were used to initiate inoculation.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
15 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
1
Sampling time:
6 d
Remarks on result:
other:   test item, 1streplicate 15 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
0
Sampling time:
14 d
Remarks on result:
other:   test item, 1streplicate 15 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
12
Sampling time:
21 d
Remarks on result:
other:   test item, 1streplicate 15 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
35
Sampling time:
28 d
Remarks on result:
other:   test item, 1streplicate 15 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
0 - 1
Sampling time:
28 d
Remarks on result:
other:   test item, 2ndreplicate 15 mg/L
Details on results:
The 10 % level (beginning of biodegradation) was only reached by one replicate after a long lasting adaptation period of 20 days, the degradation came to a maximum of 35 % after 28 days. The biodegradation of the other replicate remained at a level of 1 % after 28 days.
In the toxicity control 30 % biodegradation occurred within 14 days and came to a maximum of 47 % after 28 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

BOD5 / COD results

Results with reference substance:
To check the activity of the test system sodium acetate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 8 days. In the toxicity control containing both test and reference item a biodegradation rate of 30 % occurred within 14 days and came to a maximum of 47 % after 28 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

Any other information on results incl. tables

            

Biodegradation [%]

study day [d]

   6 14   21  28

  test item, 1streplicate 15 mg/L

 1

 0

 12

 35

  test item, 2ndreplicate 15 mg/L

 0  0  0  1

  functional control 35 mg/L

 50

 74

 83

 95

 toxicity control

15 mg/L test item +

35 mg/L reference item

 15

 30

 34

 47

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The test item must be regarded as not readily biodegradable in the 10-d-window and after 28 days.
Executive summary:

The ready biodegradability was determined with a non adapted activated sludge for the test item Hostavin N20 P according to OECD 301 B / C02 evolution test. The test item was tested with a concentration of 15 mg/L in duplicates, corresponding to a carbon content (TOC) of 10.9 mgC/L in the test vessels. The biodegradation of the test item was followed by titrimetric analyses of the quantity of C02 produced by the respiration of bacteria. The degradation was finished on day 28 by acidification, the last titration was made on day 29, after the soluble C02 was turned out over a period of 24 h. The percentage C02 production was calculated in relation to the theoretical CO2 (ThC02) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system sodium acetate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 8 days. In the toxicity control containing both test and reference item a biodegradation rate of 30 % occurred within 14 days and came to a maximum of 47 % after 28 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

The biodegradation of the test item is shown graphically in Figure 1 in comparison to the readily degradable functional control and the toxicity control. The 10 % level (beginning of biodegradation) was only reached by one replicate after a long lasting adaptation period of 20 days, the degradation came to a maximum of 35 % after 28 days. The biodegradation of the other replicate remained at a level of 1 % after 28 days. The validity criteria according to the guideline are fulfilled.