Charcoal

Biodegradation in water: screening tests

Administrative data

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: The study was conducted accroding to the respective OECD guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

1. Temperature was slightly lower (18.4 to 23.7°C) than stated in the guidelin (22±2°C). 2. Air supply was interrupted for 90 min, because of a technical problem.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

yes

Remarks:

1. Temperature was slightly lower (18.4 to 23.7°C) than stated in the guidelin (22±2°C). 2. Air supply was interrupted for 90 min, because of a technical problem.

Principles of method if other than guideline:

A measured volume of inoculated mineral medium, containing a known concentration of the test substance (10-20 mg DOC or TOC/l) as the nominal sole source of organic carbon is aerated by the passage of carbon dioxide-free air at a controlled rate in the dark or in diffuse light. Degradation is followed over 28 days by determining the carbon dioxide produced.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Charcoal

EC Number:

240-383-3

EC Name:

Charcoal

Cas Number:

16291-96-6

IUPAC Name:

Carbón vegetal

Details on test material:

Name: Charcoal (Probe 2: C-Fix =80.5%)
Batch no.: 29004
Appearance: Charcoal typic
CAS no.: 16291-96-6
EINECS-no.: 240-383-3
Purity: C-Fix: 80.5%
Expiry date: Dec. 2030
Storage: Room temperature 20 ± 5 °C, keep away from humidity

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no aplicable

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Specification:
Activated sludge from a biologic sewage treatment plant was used. The chosen plant is predominantly treating domestic sewage.

Source:
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 03. Sept. 2010, batch no.: 20100903.

Pre-Treatment:
The sludge was filtrated, washed with tap water twice, then washed with and resuspended in test medium. It was then aerated for ≥ 12 hours. The dry matter was determined with 4520 mg suspended solids/L.

Duration of test (contact time):

ca. 28 d

Initial test substance concentration

Initial conc.:

ca. 25 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The temperature was in a range of 18.4 to 23.7°C and therefore slightly lower than stated in the guideline (22 ± 2°C). As all validity criteria were met, this deviation can be stated as uncritical.

Reference substance

Reference substance:

aniline

Remarks:

73.3%

Results and discussion

Preliminary study:

no aplicable

Test performance:

Samples were collected on day 0, 2, 4, 9, 11, 14, 18, 23, 29. The sample volume was 1 mL. The emitted CO2 was determined by IC measurement using a carbon analyser. Each sample was measured at least in duplicate.

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

< 2

Details on results:

no aplica

BOD5 / COD results

Results with reference substance:

The degradation of the reference substance was 64% after 9 d.

Any other information on results incl. tables

The percentage biodegradation in the test flasks was calculated from:

 

% degradation = ((emitted C (test flask) in mg/L – mean emitted C (inoculum controls) in gm/L) x 100)/ added C in mg/L

Degradation in the positive control and toxicity control was calculated analogously.

Abiotic degradation was calculated from:

% abiotic degradation = (mg emitted C (abiotic) x 100)/ added C in mg/L

Results:

Emitted carbon (emittC) in mg/L

Day	Inoculum Control 1	Inoculum Control 2	Positive Control 1	Positive Control 2	Test Flask1	Test Flask 2	Abiotic Control	Toxicity Control
2	0.30	0.13	0.05	0.23	0.06	0.09	0.17	0.24
4	0.28	0.23	3.15	3.38	0.11	0.09	0.04	4.09
7	0.81	0.94	13.33	9.76	0.69	0.78	0.10	13.35
9	1.16	1.25	15.89	12.12	0.96	1.11	0.01	16.06
11	1.29	1.08	16.88	15.49	1.18	1.36	-0.01	16.81
14	1.93	1.51	18.41	18.17	1.57	1.81	-0.04	18.52
18	2.02	1.93	19.76	19.51	1.91	2.43	-0.10	20.04
23	2.44	2.37	19.69	20.15	2.15	2.38	-0.21	19.11
29	2.80	2.10	18.42	19.66	2.47	2.93	-0.03	19.23

 

Degradation Values

In the following table the percentage biodegradation (% degradation, calculated according to the equation given above) is presented

Biodegradation values in %

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test Flask 1	Test Flask 2	Test Mean	Abiotic Control	Toxicity Control
2	-0.8	0.0	-0.4	-0.8	-0.6	-0.7	0.9	0.0
4	14.2	15.4	14.8	-0.7	-0.8	-0.8	0.2	9.5
7	61.4	43.8	52.6	-0.9	-0.5	-0.7	0.5	30.9
9	72.3	53.8	63.1	-1.2	-0.5	-0.9	0.1	36.8
11	77.3	70.5	73.9	0.0	0.9	0.4	-0.1	38.8
14	82.3	81.1	81.7	-0.7	0.4	-0.2	-0.2	41.7
18	87.7	86.4	87.0	-0.3	2.3	1.0	-0.5	44.8
23	85.2	87.5	86.3	-1.3	-0.1	-0.7	-1.1	41.4
29	78.7	84.8	81.7	0.1	2.4	1.2	-0.2	41.6

 

 

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item charcoal (Probe 2:C-Fix = 80.5%) is not readily biodegradable according to OECD 301B.