[No public or meaningful name is available]

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-10-18 to 2007-11-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

certified by "Ministerium für Umwelt und Naturschutz, Landwirtschaft und Verbraucherschutz des Landes Nordrhein-Westfalen", Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Aeration tank of a wastewater plant treating
predominantly domestic sewage (Wupper area water authority, STP Odenthal, Germany)
- Laboratory culture: no
- Storage conditions: The inoculum was stored at room temperature under continuous shaking with aeration until use for max. 3 days.
- Preparation of inoculum for exposure: The sludge was washed twice by adding mineral
medium, centrifuging (10 min at 2000 rpm and 20 °C) and decanting off the supernatant. 1.354 g of the wet sludge was dried in order to calculate the amount of wet sludge to achieve a
concentration of activated sludge of 3 g/L (dry wet) suspended solids. The calculated amount of sludge was first dissolved in mineral medium and then filled up to a defined end volume
- Concentration of inoculum: 30 mg/L ss

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 22 ± 1 °C
- pH: 7.4 to 7.9
- pH adjusted: no
- Aeration of dilution water: yes, before test start
- Suspended solids concentration: 30 mg/L ss
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: closed flasks
- Number of culture flasks/concentration: 2 replicates for test item, 3 flasks as blanks, 2 flasks for reference compound (sodium benzoate), 1 toxicity control
- Test apparatus: Oxi Top System (WTW)
- Test volume: 250 mL
- Chemical analysis and measuring equipment:
NO3-N/NO2-N: Determination of nitrite nitrogen and nitrate nitrogen and the sum of both by flow analysis (CFA and FIA), Standard: EN ISO 13395, Test apparatus : Continuous Flow Analyser SKALAR SAN Plus System
COD: Determination of Chemical Oxygen Demand of solids and substances which are not water-soluble (COD), Calibration Standard: Potassium hydrogen phthalate, Test apparatus : Behrotest / Mettler DL 70 ES with Rondo 60 and spectrometric detection
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 flasks
- Abiotic sterile control: no
- Toxicity control: yes, 1 flask
- Other: Reference substance: yes, 2 flasks

STATISTICAL METHODS:

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

48.8

Sampling time:

28 d

Details on results:

Within 28 days, a degradation of 48.8 % was determined for the test substance.

Results with reference substance:

The reference compound sodium benzoate showed 86.3 % degradation after 14 days.

Table 1:

Study Day	Test substance, mean of 2 replicates [%]	Reference substance, mean of 2 replicates [%]	Toxicity control [%]
0	-	-	-
7	40.6	80.1	61.6
14	45.8	86.3	68.7
21	47.9	88.5	71.2
28	48.8	89.9	71.2

The toxicity control showed that the used concentrations of the test item did not show toxic effects to bacteria.

Validity criteria fulfilled:

yes

Remarks:

The reference compound reached the level for ready biodegradability within 14 days. No toxicity of the test item was observed in the toxicity control. The oxygen uptake of the inoculum blank was ≤ 60 mg/L.

Interpretation of results:

not readily biodegradable

Conclusions:

The study indicates that the test substance is not readily biodegradable (48.8 % after 28 d (O2 consumption), OECD 301F).

Executive summary:

A study was performed according OECD 301F to assess the ready biodegradability of Beta 30. The study was conducted in accordance with the Council Directive 92/69/EEC Method C.4-D “Manometric Respirometry Test“ (1992). This test method is in all essential parts identical with OECD Guideline 301 F.
A solution of Beta 30 in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation was followed by BOD determinations.
Beta 30 showed:
40.6 % degradation after 7 days
45.8 % degradation after 14 days
47.9 % degradation after 21 days
48.8 % degradation after 28 days
Therefore, Beta 30 is considered to be “Not Readily Biodegradable“.
The reference compound sodium benzoate showed 86.3 % degradation after 14 days.

Description of key information

Not readily biodegradable: 48.8 % after 28 days (O2 consumption, OECD 301F)

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

An experimental study was performed according to the OECD 301F (GLP). Activated sludge from a domestic sewage treatment plant was used as inoculum. 48.8 % degradation of the test substance was recorded based on O₂-consumption after 28 d. Thus, the test substance is not readily biodegradable according to the OECD criteria. A toxicity control containing both, reference substance and test substance, did not indicate inhibitory effects of the test substance to the inoculum (68.7 % degradation after 14 d; trigger value of 25% biodegradation in the toxicity control was reached).