Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The Zahn-Wellens test was conducted according to national standard (DIN 38 412, Part 25, 1984), which is similar to OECD 302B; limited documentation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1987
Report Date:
1987

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
yes
Remarks:
In the today's methods no industrial but only municipal wastewater sludge is used and the concentrations of test substance and sludge are lower
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
not specified
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Duration of test (contact time):
20 d
Initial test substance concentration
Initial conc.:
ca. 3 g/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
Preparation of the stock solution: 5 g/L test substance was stirred for 24 h in deionized water to prepare a saturated solution. The acidic pH was adjusted with 1 m NaOH solution from 3.4 to 7.0. The resulting suspension was filtered through a folded paper filter, the filtrate was used as stock solution.
DOC of the stock solution: 955 mg/L
COD of the stock solution: 4180 mg/L
Reference substance
Reference substance:
diethylene glycol
Remarks:
271.6 mg DOC/L

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
3 d
Parameter:
% degradation (DOC removal)
Value:
37
Sampling time:
6 d
Parameter:
% degradation (DOC removal)
Value:
94
Sampling time:
9 d
Parameter:
% degradation (DOC removal)
Value:
95
Sampling time:
20 d

BOD5 / COD results

Results with reference substance:
1 d: 6 %
3 d: 44 %
6 d: 100 %

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
The test item is inherently and completely biodegradable.
Executive summary:

Testing of 4 -nitrobenzoic acid for inherent biodegradability was performed in the Zahn-Wellens test. The results of testing revealed that the substance is inherently and completely biodegradable. The degradation of the reference substance was in the demanded range and caused a DOC reduction of 100 % within 6 days.