Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

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:
20 July 1994 to 18 August 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
not specified
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Fresh activated sludge was collected from a biological wastewater treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until used on the same day.
- Storage conditions: Sludge was kept aerobic.
- Storage length: Sludge was used on the same day as collection.
- Concentration of sludge: 2.988 g/L dry weight
- Water filtered: no
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: Mineral components for Solutions A (8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4x2H2O, 0.5 g NH4Cl), B (27.5 g CaCl2), C (22.5 g MgSO4x7H2O) and D (0.25 g FeCl3x6H2O, one drop concentrated HCl) were dissolved in water and made up to 1 L each. The mineral medium was prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 L with deionised water.
- Test temperature: 20°C
- pH: 7.36 to 8.54
- pH adjusted: Yes, to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide
- Suspended solids concentration: 30 mg/L dry weight

TEST SYSTEM
- Culturing apparatus: SAPROMAT test flask
- Number of culture flasks/concentration: 2
- Measuring equipment: SAPROMAT D 12
- Test performed in open system: No, closed system
- Details of trap for CO2 and volatile organics if used: Evolved carbon dioxide was absorbed in soda lime pellets.

SAMPLING
- Sampling frequency: The oxygen consumption of each flask was recorded daily and the pH of each flask was measured at the start and end of the test period.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: Yes

STATISTICAL METHODS: No statistical analysis was performed. Oxygen uptakes were corrected by deducing the basic oxygen uptake of sludge and to account for the differences between actual and nominal concentrations of the test substance.
Reference substance:
aniline
Preliminary study:
Not performed.
Test performance:
The test is considered valid as the degradation of aniline was > 40% after 7 days and > 65% after 14 days.
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
-1
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
-1
Sampling time:
10 d
Parameter:
% degradation (O2 consumption)
Value:
-2
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
-2
Sampling time:
21 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
-2
Sampling time:
28 d
Details on results:
The test substance is not readily biodegradable, possibly due to its physical state (solid) and the low water solubility.
Key result
Parameter:
ThOD
Value:
2.89 mg O2/g test mat.
Results with reference substance:
ThOD of aniline: 2.41 mg O2/g

Table 1. Biodegradability results

 Parameter  Flask  Biological Oxygen Demand (BOD, mg O2/L, adjusted to nominal concentrations)               
     Day 5  Day 7  Day 10  Day 14  Day 21  Day 28
 BOD Sludge  1 23.0   25.0  26.0  29.0  33.0  33.0
   2  23.0  25.0  26.0  29.0  33.0  33.0
   Mean  23.0  25.0  26.0  29.0  33.0  33.0
BOD Test substance  1  20.0  22.0  23.0  23.1  24.1  24.1
   2  24.0  24.0  26.0  26.1  28.1  28.1
   1C  -3.0  -3.0  -3.0  -5.9  -8.9  -8.9
   2C  1.0  -1.0  0.0  -2.9  -4.9  -4.9
 % degradation  1  -1  -1  -1  -2  -3  -3
   2  0  0  0  -1  -2  -2
   mean  0  -1  -1  -2  -2  -2

C: BOD results were corrected for the mean oxygen uptake of sludge

Validity criteria fulfilled:
yes
Remarks:
The degradation of aniline was > 40% after 7 days and > 65% after 14 days.
Interpretation of results:
not readily biodegradable
Conclusions:
The test substance is not readily biodegradable, as no degradation was observed after 28 days.
Executive summary:

The biodegradability of the test substance was tested according to OECD Guideline 301F. A nominal concentration of 100 mg/L test substance was incubated with activated sludge for 28 days under aerobic conditions, alongside an inoculum blank and a toxicity control. Oxygen consumption was measured electrolytically daily. The test substance is not readily biodegradable, as no degradation was observed after 28 days. This result may be due to the physical state (solid) and low water solubility of the test substance. This study is considered to be reliable without restriction (Klimisch 1).

Description of key information

The test substance is not readily biodegradable, as no degradation was observed after 28 days.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The biodegradability of the test substance was tested according to OECD Guideline 301F (1994). A nominal concentration of 100 mg/L test substance was incubated with activated sludge for 28 days under aerobic conditions, alongside an inoculum blank and a toxicity control. Oxygen consumption was measured electrolytically daily. The test substance is not readily biodegradable, as no degradation was observed after 28 days. This result may be due to the physical state (solid) and low water solubility of the test substance. This study is considered to be reliable without restriction (Klimisch 1).