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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:
1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: according to GLP and OECD guideline, with deviation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report date:
1995

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
only 1 CO2 scrubber used
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Triphenyl phosphite
EC Number:
202-908-4
EC Name:
Triphenyl phosphite
Cas Number:
101-02-0
Molecular formula:
C18H15O3P
IUPAC Name:
triphenyl phosphite
Details on test material:
- Physical state: liquid
- Storage condition of test material: room temperature

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Activated sludge collected from the sewage treatment plant of CH-4153 Reinach on 16/01/95. The pH after collection was 7.8.
The preparation was carried out according to the method described in the guideline.
Duration of test (contact time):
29 d
Initial test substance concentrationopen allclose all
Initial conc.:
22.4 mg/L
Based on:
test mat.
Initial conc.:
22 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- vessels: 2 liter flasks (dark brov^m glass) equipped with gas inlet and magnetic stirrer
- Composition of medium: according to guideline
- Test temperature: 22-+2°C
- Aeration of dilution water: ca 25 ml/min purified from carbon dioxide
- CO2 Scrubbers: approx 250 ml scrubbers with gas inlet tubes equipped with sintered glass tips containing 200 ml 0.05 N sodium
hydroxide. Only one CO2 scrubber was used per test bottle. Theoretically, a solution of 0.05 M NaOH is siifficient to trap at least two times more CO2 than the maximum ThC02 which can evolve in each test bottle (including CO2 possibly evolved from the bacteria e.g., endogenous respiration). Moreover, experimentally it was confirmed that no measurable CO2 carry over has ever occured with the scrubbers used.

For the toxicity control, where the test substance and reference were applied together, the reference amount was 15.0 mg DOC/L and the test substance amount was 16.6 mg ThOC/L. Before application, the inoculum was pre acclimated to the test medium over night.
The aeration was performed inside 1.21 water, containing the amount of mineral salts for 1.5 L. The final volume was made up to 1.51 with a 300 ml mixture made from: the test substance (the above mentioned amount) in 285 ml bidistilled water and 15 ml (4.5 mg) vehicle Polyoxyethylen -Sorbitan monooleate : TWEEN 80 (Fluka 93781),which was applied as a stock solution of 300 mg/l. This mixture was homogenized by polytron for 5 minutes and added to the test vessel, which was immediately connected to the CO2 scrubber.


SAMPLING
- Sampling frequency: the evolved CO2 trapped by the 0.05 N NaOH solution of the blank and test substance was measured at 0, 3,6,8,10,13,17,20, 24,28 and 29 days.
- Sampling method: At each sampling day the CO2 trapped in the scrubbers was measured as inorganic carbon with a carbon analyzer (Shimadzu TOC-500).


Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (CO2 evolution)
Value:
63
Sampling time:
29 d
Parameter:
% degradation (CO2 evolution)
Value:
60
Sampling time:
6 d
Details on results:
readily biodegradable
pass level (60 % ) : 6 days
time window : 6 days
In the toxicity control (test substance + reference substance + inoculum) no inhibition of degradation was observed.

BOD5 / COD results

Results with reference substance:
93% after 20 days

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable

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