Decamethylenediamine

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of activated sludge: municipal wastewater treatment plant Breisgauer Bucht, sampled on 26 May 2008, dry solid content 5.21 g/L after 3 h drying at 105 °C
- Preparation of inoculum for exposure: the activated sludge was washed twice by settling teh sludge, decanting the supernatant and re-suspending the sludge in areated tap water; 8.6 ml was filled up to 1500 ml with 1491.4 mineral medium
- Pretreatment: The system was sealed and aerated with CO2-free air at a rate fo 30-100 ml/min overnight
- Concentration of sludge: 30 mg/l dry solids
- Initial cell/biomass concentration:
- Water filtered: yes/no
- Type and size of filter used, if any:

Duration of test (contact time):

29 d

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock solution A:
8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 * 2 H2O, 0.5 g NH4Cl were dissolved in demineralised water and made up to 1 L
Stock solution B:
36.4 g CaCl2 * 2 H2O were dissolved in deminaralised water and made up to 1 L
Stock solution C:
22.5 g MgSO4 * 7 H2O were dissolved in demineralised water and made up to 1 L
Stock solution D:
0.25 g FeCl3 * 6 H2O were dissolved in deminaralised water, stabilised with one drop of concentrated HCl and made up to 1L

10 ml of solution A was mixed with 800 ml demineralised water, 1 ml of each solution B, C and D were added and made up to 1 L

- CO2 absorption medium: 72 g NaOH were dissolved in 9000 ml deionised water (0.2 M NaOH)
- Test temperature: 21-22 °C
- pH adjusted: no
- Aeration of dilution water: with CO2-free air at a rate of 30-100 ml/min
- Suspended solids concentration: 30 mg/l


TEST SYSTEM
- Culturing apparatus: Gas wash bottles (2000 ml) with lateral connecting pieces for butyl rubber septums were used as reactors and contained
1500 ml medium each. The CO2 produced in the reactors was adsorbed in two 250 ml gas wash bottles, each filled with 200 ml 0.2 M NaOH
- Number of culture flasks/concentration: see below table
- Method used to create aerobic conditions: aeration with CO2 free air (air produced by a compressor was passed through three gas wash bottles
containing soda lime followed by one bottle filled with 0.1 M NaOH
- Measuring equipment: Total Carbon Analyser TOC-5000A.
- Details of trap for CO2: CO2 produced in the reactors was absorbed to 0.2 M NaOH (200 ml).


SAMPLING
- Sampling frequency:
- Sampling method: 4 ml NaOH from the first of two CO2-absorber flasks were sampled through lateral connecting pieces through butyl rubber
septums by using 5 ml PE syringes

CONTROL AND BLANK SYSTEM
- Inoculum blank: mineral medium + inoculum
- Toxicity control: mineral medium + inoculum + test item + sodium benzoate


STATISTICAL METHODS:
The percentage of biodegradation was caculated with the following formula:
Biodegradation [%] = 100*(CO2 test reactor [mg] - CO2 blank reactor [mg]) / ThCO2 [mg]

Reference substance:

other: sodium benzoate

Parameter:

% degradation (inorg. C analysis)

Value:

41.2

Sampling time:

7 d

Parameter:

% degradation (inorg. C analysis)

Value:

65.3

Sampling time:

11 d

Parameter:

% degradation (inorg. C analysis)

Value:

76.8

Sampling time:

14 d

Parameter:

% degradation (inorg. C analysis)

Value:

92.9

Sampling time:

21 d

Parameter:

% degradation (inorg. C analysis)

Value:

90.1

Sampling time:

28 d

Details on results:

The mean degradation of the test item after 28 days (after acidification) was 96.9 %. The end of the 10-d-window was reached on day 15 when the calculated degradation extent was 79.1 %. The test item reached the pass level for ready biodegradability (60 % ThCO2)

Results with reference substance:

The reference substance sodium benzoate reached the pass level for ready biodegradability within 4 days. After 28 days, biodegradability was observed to be 100 %

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Executive summary:

The biodegradability of the test item was studied in a "CO2 Evolution Test (Modified Storm Test)" according to OECD 301 B. The results indicate that the test item is readily biodegradable under the present test conditions. 96.9% of the test item degraded within a period of 28 days.

The study was classifed as "reliable without restrictions".

Description of key information

The biodegradability of the test item was studied in a "CO2 Evolution Test (Modified Storm Test)" according to OECD 301 B. The results indicate that the test item is readily biodegradable under the present test conditions. 96.9% of the test item degraded within a period of 28 days.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable