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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:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Data is from NTRL report
Justification for type of information:
Data is from NTRL report
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Biodegradation study was conducted for evaluating the percentage biodegradability of test chemical.
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Test inoculum activated sludge was taken from the bench-scale completely mixed activated sludge system (CMAS).
- Pretreatment: Activated sludge taken from the bench-scale completely mixed activated sludge system (CMAS) was settled, decanted, washed with 20 mM pH 7.0 phosphate buffer, and resuspended in the same buffer solution.
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Parameter followed for biodegradation estimation:
TOC removal
Details on study design:
TEST CONDITIONS
- pH: 6.9 to 7.2

TEST SYSTEM
- Culturing apparatus: 1 lt cylinder with bottom diffusers was used as a test vessel for the study.
- Measuring equipment: All the oxygen uptake tests were done with a 250-m1 BOO bottle and an Orbisphere oxygen probe equipped with an adapter. Endogenous rates were taken after 30-min aeration without feed. When substrate was included, the sludge was washed twice with 10 or 20mM pH 7 phosphate buffer.
The BOD5 and COO (dichromate) analyses were done according to the Standard Methods. TOC was analyzed with a Beckman TOCAMASTER Model 915-B. Sulfate was determined by ion exchange chromatography (Dionexl.

SAMPLING
- Sampling frequency: The removal of the test chemical and TOC were analyzed over several days.

Key result
Parameter:
% degradation (test mat. analysis)
Remarks:
and TOC removal
Value:
> 87 - < 100
Sampling time:
48 h
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 87-100% degradation by using Test material analysis & TOC removal parameter in 48 hrs. Inorganic sulfate has been identified as a degradation product of test chemical.

Table:Degradation of test chemical – Batch die away test.

Retention time (hrs)

pH

mg/l

Sulfur recovery as SO42-, *

Test chemical

TOC

SO4

0

24

48

7.2

6.9

6.9

100

˂ 1

˂ 1

36

5

5

57

146

163

-

87.2*

104*

 

where,

* = Total degradation of test chemical is assumed.

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The percentage degradation of test chemical was determined to 87-100% by using test material analysis & TOC removal parameter in 48 hrs. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in water.
Executive summary:

Biodegradation study was conducted for evaluating the percentage biodegradability of test chemical. The study was performedunder aerobic conditions at a pH range 6.9 to 7.2.1 lt cylinder with bottom diffusers was used as a test vessel for the study. Activated sludge taken from the bench-scale completely mixed activated sludge system (CMAS) was used as test inoculums for the study. Test inoculum was further settled, decanted, washed with 20 mM pH 7.0 phosphate buffer, and resuspended in the same buffer solution. Initial test substance conc. used in the study was 100 mg/l. The removal of the test chemical and TOC were analyzed over several days.Alltheoxygen uptake tests were done with a 250-m1 BOO bottle and an Orbisphere oxygen probe equipped with an adapter. Endogenous rates were taken after 30-min aeration without feed. When substrate was included, the sludge was washed twice with 10 or 20mM pH7 phosphate buffer. The BOD5 and COO (dichromate) analyses were done according to the Standard Methods. TOC was analyzed with a Beckman TOCAMASTER Model 915-B. Sulfate was determined by ion exchange chromatography (Dionexl.Inorganic sulfate has been identified as a degradation product of test chemical/ The percentage degradation of test chemical was determined to 87-100% by using test material analysis & TOC removal parameter in 48 hrs. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

Description of key information

Biodegradation study was conducted for evaluating the percentage biodegradability of test chemical (NTRL report, 1991). The study was performedunder aerobic conditions at a pH range 6.9 to 7.2.1 lt cylinder with bottom diffusers was used as a test vessel for the study. Activated sludge taken from the bench-scale completely mixed activated sludge system (CMAS) was used as test inoculums for the study. Test inoculum was further settled, decanted, washed with 20 mM pH 7.0 phosphate buffer, and resuspended in the same buffer solution. Initial test substance conc. used in the study was 100 mg/l. The removal of the test chemical and TOC were analyzed over several days.Alltheoxygen uptake tests were done with a 250-m1 BOO bottle and an Orbisphere oxygen probe equipped with an adapter. Endogenous rates were taken after 30-min aeration without feed. When substrate was included, the sludge was washed twice with 10 or 20mM pH7 phosphate buffer. The BOD5 and COO (dichromate) analyses were done according to the Standard Methods. TOC was analyzed with a Beckman TOCAMASTER Model 915-B. Sulfate was determined by ion exchange chromatography (Dionexl.Inorganic sulfate has been identified as a degradation product of test chemical. The percentage degradation of test chemical was determined to 87-100% by using test material analysis & TOC removal parameter in 48 hrs. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Experiment study of the test chemical and various supporting weight of evidence studies for its read across chemical were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from NTRL report (1991),biodegradation study was conducted for evaluating the percentage biodegradability of test chemical. The study was performed under aerobic conditions at a pH range 6.9 to 7.2.1 lt cylinder with bottom diffusers was used as a test vessel for the study. Activated sludge taken from the bench-scale completely mixed activated sludge system (CMAS) was used as test inoculums for the study. Test inoculum was further settled, decanted, washed with 20 mM pH 7.0 phosphate buffer, and resuspended in the same buffer solution. Initial test substance conc. used in the study was 100 mg/l. The removal of the test chemical and TOC were analyzed over several days. All the oxygen uptake tests were done with a 250-m1 BOO bottle and an Orbisphere oxygen probe equipped with an adapter. Endogenous rates were taken after 30-min aeration without feed. When substrate was included, the sludge was washed twice with 10 or 20mM pH7 phosphate buffer. The BOD5 and COO (dichromate) analyses were done according to the Standard Methods. TOC was analyzed with a Beckman TOCAMASTER Model 915-B. Sulfate was determined by ion exchange chromatography (Dionexl.Inorganic sulfate has been identified as a degradation product of test chemical. The percentage degradation of test chemical was determined to 87-100% by using test material analysis & TOC removal parameter in 48 hrs. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

In a supporting weight of evidence study from authoritative databases (2018) for the test chemical,biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test chemical. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of test chemical was determined to 106 and 89% by BOD, TOC removal and CE parameter in 28 days Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

For the test chemical, biodegradation study was conducted for 27 days for evaluating the percentage biodegradability of test chemical (from HSDB and PubChem authoritative databases and secondary source, 2017). The study was performed in accordance with the IS0 7827 "Evaluation in an aqueous medium of the 'ultimate' aerobic biodegradability of organic compounds -method by anlaysis of dissolved organic carbon (DOC)"under aerobic conditions. Initial test substance conc. used in the study was 162 mg/l. Acetic acid, sodium saltwas used as a reference substance for the study. The percentage degradation of test chemical was determined to 99% by Test material analysis parameter after a period of 27 days. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

On the basis of above results of the test chemical, it can be concluded that the test chemicalcan be considered to be readily biodegradable in nature.