Ruthenium, dichloro[1,3-dihydro-4,5-dimethyl-1,3-bis(2,4,6-trimethylphenyl)-2H-imidazol-2-ylidene](2-thienylmethylene)(tricyclohexylphosphine)-, (SP-5-41)-

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:

2016-05-11 to 2016-09-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

not soluble in water, slow decomposition by hydrolysis

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

inoculum concentration: 30 mg dry solid per litre
The treatment plant clarifies predominantly domestic wastewater and has a capacity of 600.000 inhabitant equivalents
Sampling date: 17 May 2016
Dry solid of the activated sludge was determined as 4.95 g/l by weight measurements after drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice with tap water by setting the sludge, decanting the supernatant and re-suspending the sludge

Duration of test (contact time):

28 d

Initial conc.:

ca. 20 mg/L

Based on:

TOC

Remarks:

corresponds to 47.6 - 47.8 mg of the test item per test vessel

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: according to the guideline
- Additional substrate: no
- Test temperature: 22.3-23.6 C
- pH adjusted: no
- suspended solid: 4.95 g/l
- Aeration of dilution water: yes
- Continuous darkness: diffuse light

TEST SYSTEM
- Culturing apparatus: gas wash bottles (200 ml volume) with lateral connecting pieces for butyl rubber septums
- Number of culture flasks/concentration: 3 containing test substance and inoculum; 3 containing inoculum (blanc), 3 containing refernce compound and inoculum, 1 containing test substance and reference substance and inoculum (toxicity control)
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used:
- Other:

SAMPLING
- Sampling frequency:
- Sampling method:
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank:
- Abiotic sterile control:
- Toxicity control:
- Other:

STATISTICAL METHODS:

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Remarks on result:

other: no biodegradation occured during 28 days

Details on results:

Test Substance: There was no degradation within 28 days, the degradation extend at the end of the test was slightly negative which is caused by a slightly higher CO2-evolution in the blank than in the test vessel
Reference substance: The reference compound sodium benzoate reached the pass levels for ready biodegradability within 4 days.
Toxicity control: The degradation in the toxicity control after 14 days was 44.7%. According to the guideline criteria OECD 301, the test substance had no toxic effect to the inoculum.
Blank: The mean CO2-evolution of the blank flask was 29.5 mg/l on day 28 after acidification
Before adding the test substance, the IC in the reactor was determined, only insignificant amounts of IC < 5% were found.
The temperature was 22.3-23.6°C throughout the whole study. The aeration rate was in the tolerated range of 1.6-5.5 bubbles/second
The difference of extremes of replicate values at the end of the test and at the end of the 10-d window was less than 20%

Results with reference substance:

Reference substance: The reference compound sodium benzoate reached the pass levels for ready biodegradability within 4 days.

Table 1: Ultimate biodegradation after x days[% of ThCO2]

Reactor	Day	0	4	8	11	14	21	28	29
15	Test flask	0	1.0	-0.1	0.1	0.8	-0.7	-0.9	-0.5
16		0	0.8	0.0	0.0	0.7	-1.5	-1.7	-1.7
17		0	0.1	-1.0	-1.5	-1.5	-4.3	-5.2	-5.0
4	Reference	0	71.1	83.0	86.6	92.0	93.9	94.3	94.2
5	flask	0	77.3	89.0	94.9	100.8	105.4	107.4	107.2
6		0	74.7	86.8	87.9	92.1	96.6	98.4	98.4
	Toxicity control
18	test item	0	37.8	42.7	43.2	44.7	48.0	46.3	45.6
	reference item

Table 2: Mean CO2 -evolution of blank flasks after x days

Day	0	4	8	11	14	21	28	29
CO2-evolution [mg/l]	0	8.9	13.8	16.3	18.6	24.9	28.6	29.5

 

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The substance is not readily biodegradable under the test condition

Executive summary:

The substance was tested in a valid CO2 evolution test according to OECD 301 B and under GLP. The substance is not readily biodegradable under the test condition.

Description of key information

The substance was tested in a valid CO2 evolution test according to OECD 301 B and under GLP. The substance is not readily biodegradable under the test condition.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed