Sodium 1-amino-9,10-dihydro-9,10-dioxo-4-[(2,2,4-trimethylcyclohexyl)amino]anthracene-2-sulphonate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From April 06th to September 27th, 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Version / remarks:

May 12, 1981

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Microorganisms (activated bacteria sludge) from a domestlc waste-water sewage plant (ARA, Sissach/Switzerland).

Duration of test (contact time):

28 d

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Sliudge amount: an amount of sludge from a domestic waste-water sewage plant corresponding to 7.5 mg dry material for the positive control and 25.0 mg dry material for the test article were added to 250 ml of the flnal test medium.
- Temperature: 22.5 - 25 °C
- Continuous darkness: flasks incubated protected from light.

TEST MEDIUM
Stock solution:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 44.6 g Na2HPO4 x 12H2O, 1.7 g NH4Cl dissolved in 1000 ml bidistllled water.
b) 22.5 g MgSO4 x 7H2O dissolved in 1000 ml water.
c) 27.5 g CaCl2 dissolved in 1000 ml water.
d) 0.25 g FeCl3 x 6H2O dissolved in 1000 ml water.
Three ml each of the stock solutlons (a-d) were added to 1000 ml bidistilled water (final test medium pH adjusted to 7.0).

CONTROL AND BLANK SYSTEM
- Inoculum blank: untreated inoculated control was run.

SAMPLEN PREPARATION
At the end of the incubation period, samples of at least 10 ml from all flasks were centrifuged and thereafter directly analysed.

Reference substance:

aniline

Remarks:

100 mg/l; ThOD of 241 mg O2 per 100 g aniline

Parameter:

% degradation (O2 consumption)

Value:

23.8 - 31.8

Sampling time:

28 d

Results with reference substance:

Degradation (28d): 73.2 % (BOD/ThOD).

Biodegradation of test item in activated sludge determined by means of DOC

Flask		mg DOC/l after 28 days	% BD
Test item flask 1	sb	2.2	-
Test item flask 2	sa	1.5	31.8
Test item flask 3	sa	1.4	36.4
Test item flask 4	sa	1.6	27.3
Mean		-	31.8

sa = remaining amount of test article after 28 days by means of DOC-analyses (mg)

sb = remaining amount of test article after 28 days in the control flask test article without inoculum.

Biochemical oxygen demand of test item and aniline

Concentration mg test article per 250 ml	mg Hg* after		BOD mg O2/100 ml test article after		% BD
	14 d	28 d	14 d	28 d	BOD/COD (28d)	BOD/ThOD (28d)
**Test item 7.5	0	0	0	0	0	-
Test item 7.5	0	2.5	0	41.7	34	-
Test item 7.5	1	1	16.7	16.7	13.6	-
Mean	-	-	-	-	23.8	-
Aniline 25	37.5	38.5	187.5	192.5	-	79.9
Aniline 25	32	32	160	160	-	66.4
Mean	-	-	-	-	-	73.2

* Corrected for control value (0 - 4.5 mn Hg) on the respective day.

** Flask leakage

Interpretation of results:

other: possible inherently biodegradable

Conclusions:

The test article was degradable to 23.8 %, based on BOD/COD assay, or 31.8 %, based on BOD/DOC assay, within 28 days.

Executive summary:

The biodegradability of test item exposed to activated sludge of a municipal sewage treatment plant was investigated under aerobic conditions. The procedures outlined into the OECD guideline 302 C were followed.

The biodegradation of the test article was determined by means of the biochemical oxygen demand (BOD) for 28 days. Results obtained were compared with those obtained with aniline tested simultaneously under the same conditions.

The test article was degradable to 23.8 %, based on BOD/COD assay, or 31.8 %, based on BOD/DOC assay, within 28 days.

The standard compound, aniline, was degraded within 28 days to 73.2 %, based on BOD/ThOD.

Conclusion

The test article was degradable to 23.8 %, based on BOD/COD assay, or 31.8 %, based on BOD/DOC assay, within 28 days.

Description of key information

Not readily biodegradable.

Additional information

The substance is an antrachinone derivative; it is not expected to be ready biodegradable because of its chemical structure and its specific function. Commonly, dyes undergo a primary transformation, i.e. discolourization due to the interrupting the conjugation. Nevertheless, the degradation process involves more steps and take more time.

The biodegradability of Acid Blue 278 was investigated according to the testing procedures outlined into the OECD guideline 302 C. The test article was degradable to 23.8 %, based on BOD/COD assay, or 31.8 %, based on BOD/DOC assay, within 28 days.

On the basis of the curve shape, a lag-phase of 7 - 15 days can be observed, followed by a period of ca 6 days during which the substance reached the ca 24 % of degradation. Then, from ca the 21st up to the 28th dys, the curve described a plateau.

Acid Blue 278 is deemed to be non-readily biodegradable. Although, biodegradation above 20 % of theoretical may be regarded as evidence of inherent, primary, biodegradability, a clear conclusion cannot be traced on the basis of the available information.