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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:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Modified guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
NH4Cl omitted from medium (to prevent nitrification); fewer bottles/treatment than recommendation
Qualifier:
equivalent or similar to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
yes
Remarks:
NH4Cl omitted from medium (to prevent nitrification); fewer bottles/treatment than recommendation
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Cereclor 50LV
- Substance type: technical product
- Physical state: clear liquid
- Analytical purity: approx 100%
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: C10-13 chlorinated n-alkanes (50% chlorinated)
- Isomers composition: no data
- Purity test date: no data
- Lot/batch No.: 716984
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: no data
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
none

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
other: secondary activated sludge, domestic (non adapted) and river water
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
- (i) Nieuwgraaf domestic wastewater treatment plant, Duiven, The Netherlands.
- (ii) River water was sampled from the Rhine near Heveadorp, The Netherlands
- Preparation of inoculum for exposure: River water and activated sludge (400 mg dryweight/l) were preconditioned by aeration for 1 week
- Concentration of sludge: 2 mg dry weight/l
- Initial cell/biomass concentration: no data
- Water filtered: no
Duration of test (contact time):
56 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: KH2PO4 (8.5 mg/l); K2HPO4 (21.75 mg/l); Na2HPO4.2H2O (33.4 mg/l); MgSO4.7H2O (22.5 mg/l); CaCl2 (27.5 mg/l); FeCl3.6H2O (0.25 mg/l) in deionised water
- Additional substrate:
- Solubilising agent (type and concentration if used): silicone oil AR20 (2 ml/l); polyalkoxylate alkylphenol (2 ml/l)
- Test temperature: 22-24oC
- pH: (i) activated sludge on day 0 - 7.0; (ii) river water day 0 - 8.0
- pH adjusted: no
- CEC (meq/100 g): no data
- Aeration of dilution water: no data
- Continuous darkness: no data
- Other:

TEST SYSTEM
- Culturing apparatus: 0.3L BOD bottles
- Number of culture flasks/concentration: 3
- Measuring equipment: oxygen electrode/meter - WTW Trioxmatic EO 200/WTW Oxi 530

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes


STATISTICAL METHODS: none
Reference substance
Reference substance:
not specified

Results and discussion

Preliminary study:
none
Test performance:
no data
% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
72
Sampling time:
28 d
Remarks on result:
other: activated sludge; Cereclor 50 LV emulsion with agnique
Parameter:
% degradation (O2 consumption)
Value:
47
Sampling time:
56 d
Remarks on result:
other: activated sludge; Cereclor 50 LV added in DCM
Parameter:
% degradation (O2 consumption)
Value:
75
Sampling time:
42 d
Remarks on result:
other: activated sludge; Cereclor 50LV added in agnique
Parameter:
% degradation (O2 consumption)
Value:
37
Sampling time:
56 d
Remarks on result:
other: river water; Cereclor 50LV added in DCM
Parameter:
% degradation (O2 consumption)
Value:
64
Sampling time:
56 d
Remarks on result:
other: river water; Cereclor 50LV added in agnique
Details on results:
% degradation at 28 days when added in DCM - 36% (activated sludge) and 18% (river water)
% degradation at 28 days when added in agnique - 72% (activated sludge) and 42% (river water)
% degradation at 28 days when added in silicone oil - 7% (activated sludge) and 10% (river water)
% degradation at 42 days when added in agnique - 75% (activated sludge) and 63% (river water)
% degradation at 28 days when added in DCM - 47% (activated sludge) and 37% (river water)
% degradation at 56 days when added in silicone oil - 25% (activated sludge) and 38% (river water)
% degradation at 56 days when added in agnique - 64% (river water).

The biodegradation of the C10 -13 chlorinated paraffin (50% chlorinated) reached the pass level (>60% within a 10-day window in no more than 28 days), indicating ready biodegradability when incubated as an emulsion with activated sludge.

The test material did not inhibit endogenous respiration by either inoculum.

BOD5 / COD results

Results with reference substance:
none

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
oxygen concentration >0.5 mg/l in all bottles during the test
Interpretation of results:
other: only readily biodegradable when introduced as an emulsion in activated sludge
Conclusions:
In a closed bottle ready biodegradability test, carried out using a modified OECD Guideline 301D/EU Method C.4-E approach, the biodegradation of Cereclor 50LV (a C10-13 chlorinated paraffin; 50% chlorination) after 28 days by activated sewage was shown to be between 7 and 72% and by river water, 10-42%, depending on the method of introduction of the test material into the incubation medium (volatile solvent, silicone oil, surfactant solution). Biodegradation in excess of 60% was only obtained with test material emulsified with surfactant (72% at 28 days with activated sludge and 63% at 42 days with river water).
Executive summary:

In a closed bottle biodegradability test (considered the most relevant test for poorly-soluble compounds), conducted according to a modified OECD Guideline 301D/EU Method C.4 -E, the biodegradation of Cereclor 50LV (a C10-13 chlorinated paraffin; 50% chlorination) was assessed by measuring oxygen consumption during incubation with either secondary activated sewage sludge or river water for up to 56 days. The test material was introduced in to the incubation medium at a nominal concentration of 2 mg/L either as a thin film on the bottle surface deposited from a volatile solvent (dichloromethane), as a solution in silicone oil or as an emulsion in a polyalkoxylate surfactant (agnique).

The biodegradation of the test material by activated sludge at 28 days was 36, 7 and 72% after introduction by volatile solvent, silicone oil and as an emulsion, respectively. The corresponding values for incubation in river water were 18, 10 and 42%, respectively. The biodegradation of test material introduced as an emulsion increased to 75% by day 42 with activated sludge and 63 and 64% by days 42 and 56 respectively in river water. The biodegradation of solvent-introduced material by 56 days was 47 and 37% in activated sludge and river water respectively , the corresponding values following introduction in silicone oil were 25 and 38% respectively. The test material did not inhibit endogenous respiration by either inoculum.

The biodegradation of the C10 -13 chlorinated paraffin (50% chlorinated) reached the pass level (>60% within a 10-day window in no more than 28 days), indicating ready biodegradability when incubated as an emulsion with activated sludge.