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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1991 - 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
Read across justification is attached in section 13.
Guideline:
other: Not specified
Principles of method if other than guideline:
CO2 evolution test
GLP compliance:
not specified
Specific details on test material used for the study:
Name of test material (as cited in study report): [14C]-triethanolamine
- Analytical purity: >= 98 %
- Specific activity (if radiolabelling): 17.61 mCi/mmol
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Remarks:
mixed liquor (secondary effluent)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): West Bay County WWTP, Bay City, Michigan, treating primarily municipal sewage up to 4 mio gallons per day
Duration of test (contact time):
6 d
Initial conc.:
ca. 600 µg/L
Based on:
test mat.
Remarks:
Lower concentration
Initial conc.:
ca. 5 700 µg/L
Based on:
test mat.
Remarks:
Upper concentration
Parameter followed for biodegradation estimation:
CO2 evolution
Remarks:
14CO2 was trapped and quantified
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
Ion exchange HPLC, with radiochemical detection.
Details on study design:
TEST CONDITIONS
- TEST CONDITIONS
- Composition of medium: minimal salts basal medium according to Stainer et al. (1966; J Gen Microbiol 43: 159-271)
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 25 °C
- pH:
- pH adjusted: yes/no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration:
- Continuous darkness: yes
- Other:

TEST SYSTEM
- Culturing apparatus: 500-mL polypropylene Erlenmeyer flasks, sealed with rubber stoppers and fitted with CO2 traps
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used: glass tubular CO2 traps (4 mL 1N KOH)
- Other: test material amended with 14C-TEA to yield 0.7 µCi/mL

SAMPLING
- Sampling frequency:
- Sampling method:
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank:
- Abiotic sterile control: yes, via addition of formaldehyde (final concentration: 2.8%)
- Toxicity control:
- Other: performed in duplicate
Reference substance:
not specified
Preliminary study:
Not specified
Key result
Parameter:
% degradation (test mat. analysis)
Remarks:
experimentally determined first-order half-life for test substance
Value:
ca. 100
Sampling time:
5 d
Remarks on result:
other: Primary biodegradation of 5.7 mg/l TEA in a test with 164 mg/l municipal activated sludge
Key result
Parameter:
% degradation (test mat. analysis)
Remarks:
experimentally determined first-order half-life for mineralisation
Value:
ca. 100
Sampling time:
1 d
Remarks on result:
other: Primary biodegradation of 0.6 mg/l TEA in a test with 164 mg/l municipal activated sludge
Details on results:
The rate constants in all test batches for degradation and mineralization are >0.359. According to GHS legislation, the substance is rapidly biodegradable. Therefore it can be assumed that the substance is also readily biodegradable.
Results with reference substance:
n/a

Summary of TEA primary biodegradation and mineralisation in activated sludge


Matrix 

Initial TEA

Concentration

(µg/L

 Biodegradation

Rate Constant

(kb)a

(d-1)

Biodegradation

Half-life

(d) 

Mineralisation

Rate Constant

(km)a

(d-1

Mineralisation

Half-life

(d) 

% Theorectical

CO2 Yield

(mean +/- SD,

n = 2) 

 164 mg/L   

MLSSb

600

(4.0  µmol/L)

6.86  0.10  1.92  0.36  56 +/- 10 

5,700 

(38.2µmol/L)

1.36 

0.51 

1.04 

0.67 

54 +/- 3 

 818 mg/L   

MLSS

600

(4.0µmol/L) 

30.0 

0.02 

2.86 

0.24 

55 +/- 1 

5,700

(38.2µmol/L) 

6.70 

0.10 

1.69 

0.41 

52 +/- 0 

akbandkmrepresent first-order rate constants for primary biodegradation and mineralisation, respectively.

bMixed liquor suspended solid (MLSS)

Mineralisation (activated sludge):

 
 Activated sludge, mg/L MLSS  Test Item concentration, mg/L  Mineralisation rate constant, day^-1  Mineralisation half-life, day
 164  0.6  1.92  0.36
 164 5.7 1.04  0.67
 818  0.6  2.86  0.24
 818  5.7  1.69  0.41
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Measurement of TEA and its transformation products was achieved through use of a [14C] radiolabelled test material in the biodegradation studies, carried out within an activated sludge system using biomass as mixed liquor suspended solids (MLSS). Duplicate reactions containing each combination of test material and mixed liquor solids concentrations were prepared in 500 mL polypropylene Erlenmeyer flasks. Radiolabelled TEA was added to the activated sludge system to yield approximately 0.7 µCi/mL activity. Additional TEA was added as a concentrated aqueous solution to yield total concentrations of 4.0 and 38.2 µmol/L (600 and 5700 µg/L). Evolved 14C-CO2 was trapped and quantified. The dissipation of [U14C]-TEA over time was followed by HPLC coupled with radiochemical detection.
Degradation of TEA was found to be rapid, with a first-order half-life ranging from 0.10 to 0.51 days, depending on initial concentration of TEA and concentration of MLSS.
Based on the physical–chemical properties of TEA and the results of this experiment, biodegradation would indeed be the dominant process controlling the fate and lifetime of this material in aquatic environments, and TEA can be considered as being rapidly biodegraded by activated sludge. Ready biodegradability can be assumed.
Executive summary:

The degradation of radiolabelled TEA ([U-14C]TEA) within an activated sludge system was investigated using biomass in the form of mixed liquor suspended solids (MLSS), collected from a Wastewater Treatment Plant. Duplicate samples containing different combinations of test material and MLSS concentrations were incubated in the dark for up to 144 hours at 25C, with gentle agitation. The dissipation of  [U14C]-TEA over time was followed by HPLC coupled with radiochemical detection, and evolved 14CO2 was also trapped and quantified.

Degradation of TEA was found to be rapid, with a first-order half-life ranging from 0.10 to 0.51 days, depending on initial concentration of TEA and concentration of MLSS.

Based on the physical–chemical properties of TEA and the results of this experiment, biodegradation would indeed be the dominant process controlling the fate and lifetime of this material in aquatic environments, and TEA can be considered as being rapidly biodegraded by activated sludge. Ready biodegradability can be safely assumed.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
5/2/1999 - 16/3/1999
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)
GLP compliance:
yes
Specific details on test material used for the study:
Test Article: SYLVATAL 25/30S (distilled tall oil)
Low soluble liquid
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the municipal sewage treatment plant in Reutlingen, Germany.
- Preparation of inoculum for exposure: Washed 2 times with dechlorinated tap water and centrifuged at 3000 rpm for 1 minute. 1g of the wet centrifugate corresponds to approx. 60 mg suspended solids. Using a flask volume of 250 mL, 0.1 g of the centrifugate per flask is used (corresponds to 24 mg suspended solids per litre).
Duration of test (contact time):
28 d
Initial conc.:
102.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
* Dilution Water: Demineralised water is aerated for 1 day with oil-free compressed air. Before usage the water is allowed to stand for 0.5 hours at 20°C. This water is used as dilution water or as mineral water after adding the mineral stock solutions.
* Mineral Water: 1 litre of the medium contains 10 mL of solution 1 and 1 mL of solution 2-4 (dilution water: deionised water).
Solution 1: KH2PO4 (8.5 g/L); K2HPO4 (21.75 g/L); Na2HPO4 * 2 H2O (33.4 g/L); NH4CL (0.5 g/L)
Solution 2: CaCl2 * 2 H2O (27.5 g/L)
Solution 3: MgSO4 * 7 H2O (22.5 g/L)
Solution 4: FeCl3 * 6H2O (0.25 g/L)

TEST SYSTEM
- Culturing apparatus: BOD-digi (J. Otto GmbH), electrolytic oxygen supply with automatic data registration and temperature regulation.
- Number of culture flasks/concentration: 6 flasks
Flask 1: Test article in mineral medium + inoculum
Flask 2: Test article in mineral medium + inoculum
Flask 3: Mineral medium + inoculum (blank)
Flask 4: Mineral medium + inoculum (blank)
Flask 5: Reference substance in mineral medium + inoculum
Flask 6: Test article in dilution water, sterilised with 6 mL HgCl2 medium (C HgCl2 = 10 g/L; abiotic control)
*pH in flasks 1-2 at start of test was 7.6 and was 7.7 at the end of the test.

SAMPLING
- Other: Incubation: 28 days stirred culture at 22°C ± 2
Reference substance:
other: Sodium benzoate
Remarks:
c = 98.5 mg/L in mineral medium
Key result
Parameter:
% degradation (O2 consumption)
Value:
73.2
Sampling time:
28 d
Results with reference substance:
Test concentration: 98.5 mg/L
ThOD: 1.67 mgO2/mg substance
ThOD in flask 5:165 mgO2/L
BOD in flask 5 after 28 d: 1.691 mgO2/mg substance or 166.6 mgO2/L (icluding blank)
Biodegradation after 14 d (Required: >60%): 91.5%
Biodegradation after 28 d: 97.2%

Test Article

  • Test concentration: 102.2 mg/L
  • ThOD of the test article: 2.589 mgO2/mg test article
  • ThOD in the test flasks: 264.6 mgO2/L
  • BOD in flask 1 after 28 d: 198.7 mgO2/L (including blank)
  • BOD in flask 2 after 28 d: 202.6 mgO2/L (including blank)
  • Mean value: 200.7 mgO2/L (including blank)
  • BOD (test article) - BOD (innoculum blank): 1.896 mgO2/L (including blank) or 193.8 mg O2/L
  • BOD in flask 3 after 28 d (innoculum blank): 5.8
  • BOD in flask 4 after 28 d (innoculum blank): 8.0
  • Mean value (Innoculum blank, required: <60 mgO2/L): 6.9
  • Maximum BOD - difference in flasks 1 -2 at the end of the test (required: <20%): 2%
  • BOD in flask 6 after 28 d (abiotic degradation): 0 mgO2/L
  • Biodegradation after 28 d: 73.2%

General Notes

  • Volume of reaction mixture: 253.25 mL
  • Concentration of inoculum in the final medium: 24 mg suspended solids/L
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test article SYLVATAL 25/30S reported 73% degradation in 28 days in a Klimisch 1 OECD 301F study. It did not meet the stringent 10-day requirements for the 60% degradation but according to OECD guidance, the 10-day window does not apply to UVCB substances.
Executive summary:

In the ready biodegradability study conducted on distilled tall oil according to the Manometric Respirometry Test (OECD 301F), the test item reported 73% biodegradation after 28 days. It did not meet the stringent 10-day requirements for the 60% degradation but according to OECD guidance, the 10-day window does not apply to UVCB substances.  

The target substance, distilled tall oil, is thus considered to be readily biodegradable.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Description of key information

The biodegradability of Tall oil, compound with triethanolamine, was assessed by read-across from its two main components, distilled tall oil (DTO)and triethanolamine. Both these source substances are readily biodegradable and hence, the target substance is also assessed as readily biodegradable. The detailed read-across justification document covering this and other endpoints is attached in Section 13.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information