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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-03-09 to 2017-05-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
(1992)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
30 May, 2008
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany,
- Laboratory culture: after the arrival at the laboratory kept aerobic until use
- Storage length: freshly prepared
- Preparation of inoculum for exposure: The sludge was left for settlement for ca. one hour. Subsequently the supernatant was discarded and the concentration of suspended solids was measured in the remaining sludge. The concentration was adjusted to 3.2 g/L and verified by dry mass measurement. The concentration used in the test was 29.6 mg dry mass/liter (7.4 mg dry mass/250 mL).
- Water filtered: no, deionized water was used which was free from inhibitory concentrations of toxic substances
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Initial conc.:
48 mg/L
Based on:
test mat.
Initial conc.:
123 mg/L
Based on:
ThOD
Initial conc.:
59 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
( a ) KH PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 26.64 g/L
NH4Cl 0.50 g/L
pH 7.4 ± 0.2

( b ) CaCl2 x 2 H2O 36.40 g/L
( c ) MgSO 4 x 7 H2O 22.50 g/L
( d ) FeCl3 x 6 H2O 0.25 g/L.
The mineral medium applied in the test contained 10 mL/L of mineral stock solution a and 1 mL/L of the mineral stock solution b–d, respectively.
- Test temperature: 22°C ± 1°C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Suspended solids concentration: 29.6 mg dry mass/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500 mL glass vessels at a medium volume of 250 mL
- Number of culture flasks/concentration: 2
- Measuring equipment: The measurement and recording of the oxygen demand was carried out continuously using a SAPROMAT respirometer (VOITH Inc.)
- Test performed in closed vessels: yes


CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated mineral medium only
- Toxicity control: test item at 100 mg per liter and reference item (sodium benzoate) at 100 mg per liter mineral test medium (25 mg test item/250 mL and 25 mg reference item/250 mL)
- Procedural control: Vessels containing the reference item (sodium benzoate, 100 mg/L) and inoculum
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
77.3
St. dev.:
4
Sampling time:
14 d
Remarks on result:
other: Test suspension A (100 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
83
St. dev.:
3.6
Sampling time:
14 d
Remarks on result:
other: Test suspension B (48 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
71.3
St. dev.:
5.9
Sampling time:
14 d
Remarks on result:
other: Toxicity control
Key result
Parameter:
% degradation (O2 consumption)
Value:
86.2
St. dev.:
3.5
Sampling time:
28 d
Remarks on result:
other: Test suspension A (100 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
83
St. dev.:
2.4
Sampling time:
28 d
Remarks on result:
other: Test suspension B (48 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
82.9
St. dev.:
6.8
Sampling time:
28 d
Remarks on result:
other: Toxicity control
Key result
Parameter:
% degradation (O2 consumption)
Value:
72.4
Sampling time:
12 d
Remarks on result:
other: Test suspension A (100 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
78.8
Sampling time:
12 d
Remarks on result:
other: Test suspension B (48 mg/L)
Key result
Parameter:
% degradation (O2 consumption)
Value:
68.3
Sampling time:
12 d
Remarks on result:
other: Toxicity control
Details on results:
The biodegradation of the test item after 28 days of incubation in the static test was found to be 86 % (SD = 3.5 %) and 83 % (SD = 2.4 %) in the assays with 100 mg/L and 48 mg/L, respectively. The biodegradation within the 10-day-window was 72 % and 81 % in the assays with 100 mg/L and 48 mg/L, respectively. The 10-day-window started at day 2, independent from test item concentration.
The biodegradation of the item mixture in the toxicity control was found to be 71 % after 14 days of incubation. Thus, the demanded threshold value of 25 % is exceeded and the test item can be identified as non-toxic in a ready biodegradability test. The reference item sodium benzoate was degraded to 85 % within the first 14 days.
Results with reference substance:
The reference item sodium benzoate was degraded to 85 % within the first 14 days. The 10-day-window started at day 2 and the O2 consumption of the reference item was 82.9% at day 12.
Validity criteria fulfilled:
yes
Remarks:
Validity criteria as specified in guideline were fulfiled, see "any other information on material and methods"
Interpretation of results:
readily biodegradable
Conclusions:
In the present study according to OECD guideline 301F (1992) alpha methyl glucoside was incubated with activated sludge for 28 days. During that period the oxygen consumption of the inoculum was measured. At day 14 both concentrations (100 and 48 mg test item) exhibited a mean oxygen consumption of 77.3 and 83.0 %, respectively. After 28 days the respective degradation was 86.2 and 83.0%. Thus, the degradation of the substance is > 60% within the 10-days window after achieving 10% degradation. Hence, the test item is considered to be readily biodegradable.
Executive summary:

The biodegradation in water of alpha methyl glucoside was studied in unfiltered activated sludge (adjusted to pH 7.4, dissolved organic carbon: 3.2%) from the sewage treatment  plant  Ruhrverband  Kläranlage,  Schmallenberg,  Germany for 28 days under aerated conditions in the dark at 22 °C ± 1°C. The test material was applied at the concentrations of 100 mg and 48 mg/L, equivalent to 123 mg and 59 mg ThOD.

The experiment was conducted in accordance with the OECD guideline 301F (1992) and in compliance with the OECD GLP standards.  The test system consisted of 500 mL glass vessels at a medium volume of 250 mL, attached with traps for the collection of CO2  and volatile organic compounds.  Samples were analysed at 14 and 28 days of incubation. 

 For both concentrations ( 100 and 48 mg/L) the mean degradation (oxygen consumption) was 77.3 and 83.0 %, respectively, after 14 days and 86.2 and 83.0% after 28 days. The mean degradation in water of the reference item sodium benzoate at a concentration of 100 mg/L was 85.0 % after 14 days and 88.3 % after 28 days. Based on these results the test was considered valid and the test item was regarded as readily biodegradable.

Description of key information

- readily biodegradable, OECD TG 301F, GLP, RL1, 77 .3 and 83.0 % degradation for 100 and 48 mg/L, respectively, within the 10 -days-window

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The biodegradation in water of alpha methyl glucoside was studied in unfiltered activated sludge (adjusted to pH 7.4, dissolved organic carbon: 3.2%) from the sewage treatment  plant  Ruhrverband  Kläranlage, Schmallenberg, Germany for 28 days under aerated conditions in the dark at 22 °C ± 1°C. The test material was applied at the concentrations of 100 mg/L and 48 mg/L, equivalent to 123 mg and 59 mg ThOD.

The experiment was conducted in accordance with the OECD guideline 301F (1992) and in compliance with the OECD GLP standards.  The test system consisted of500 mL glass vessels at a medium volume of 250 mL, attached with traps for the collection of CO2  and volatile organic compounds.  Samples were analysed at 14 and 28 days of incubation. 

 For both concentrations (100 and 48 mg/L) the mean degradation (oxygen consumption) was77.3 and 83.0 %, respectively, after 14 days and 86.2 and 83.0% after 28 days. The mean degradation in water of the reference item sodium benzoate at a concentration of 100 mg/L was 85.0 % after 14 days and 88.3 % after 28 days. Based on these results the test was considered valid and the test item was regarded as readily biodegradable.

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