Registration Dossier

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:
22 Sep - 21 Oct 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
Jul 1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Württemberg, Karlsruhe, Germany

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge was sampled on 20 Sep 2016 from the municipal wastewater treatment plant Breisgauer Bucht, Freiburg, Germany treating predominantly domestic wastetwater.
- Storage length: 2 d
- Preparation of inoculum for exposure: The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.
- Concentration of sludge: The dry solid content of the activated sludge was 3.6 g/L by weight measurements after 3 h drying at 105 °C (mean of triplicates).
- Initial cell/biomass concentration: 30 mg dry solids/L
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
ca. 100 mg/L
Based on:
test mat.
Initial conc.:
>= 97.9 - <= 102 mg/L
Based on:
COD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium: KH2PO4, K2HPO4, Na2HPO4 * 2 H2O, NH4Cl, CaCl2*2H2O, MgSO4 * 7H2O, FeCl3 * 6H2O
- Test temperature: 21.9 - 22.4 °C
- pH: 7.6 (initial pH of dilution water)
- pH adjusted: No
- Aeration of dilution water: Before use, the mineral medium is aerated for about 1 h.
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Narrow-necked glass bottles with rubber sleeve inserts for NaOH pellets (in which the evolved CO2 is absorbed) and OxiTop-C pressure measuring heads.
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: Aeration of mineral medium for 1 h before use.
- Measuring equipment: OxiTop-C pressure measuring heads
- Test performed in open system: No, the bottles were sealed tightly with the measuring heads.
- Details of trap for CO2 and volatile organics if used: NaOH pellets inserted in rubber sleeve inserts in the test flasks were used.
- Other: Magnetic stirrers were added to the bottles, which were placed on a stirrer platform.
- Other: The calculated theoretical oxygen demand (ThOD) was 97.9 and 102 mg/L in the test flasks, 202 mg/L in the toxicity control and 100 mg/L in the reference flasks.

SAMPLING
- Sampling frequency: Every 112 minutes the current pressure was measured and stored by the measuring head.
- Sampling method: At the end of the experiment the pressure data were read out via an infrared interface to the controller unit and exported to Excel for analysis via the RS232 interface using the Achat OC software of WTW. Additionally, several measured values were randomly read out and recorded by hand and were afterwards compared with the printed Excel table for quality control.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, 3 flasks contained 164 mineral medium and inoculum.
- Toxicity control: Yes, 9.9 mg of the test item were added to 164 mL of the sodium acetate stock solution (128.3 mg/L in mineral medium).
- Other: Reference substance: 164 mL of sodium acetate stock solution (128.3 mg/L) in mineral medium.
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
41.8
Sampling time:
28 d
Details on results:
The degradation in the toxicity control reached 33% within 4 d and was thus above the criterion for inhibition effects to the inoculum (< 25% on Day 14). Therefore, the test item had no toxic effect to the inoculum according to the validity criteria of OECD 301.

Any other information on results incl. tables

PH VALUES

The pH values on Day 28 were 7.6 in the flasks containing the test item, 8.9 - 9.1 in the flasks containing the reference item, 8.7 in the toxicity control and 7.5 in the inoculum blanks.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable