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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
experimental data of read across substances
Justification for type of information:
Data for the target chemical is summarized based on the structurally similar read across chemicals
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report is based on two biodegradation studies as- WoE-1. and WoE- 2.
GLP compliance:
not specified
Oxygen conditions:
other: 1. anaerobic 2. No data
Inoculum or test system:
activated sludge (adaptation not specified)
Duration of test (contact time):
56 d
Initial conc.:
100 mg/L
Based on:
test mat.
Remarks:
(1)
Initial conc.:
> 1 - < 15 mg/L
Based on:
test mat.
Remarks:
(2)
Parameter followed for biodegradation estimation:
other: 1. chromatography
Parameter followed for biodegradation estimation:
other: 2. HPLC
Details on study design:
TEST CONDITIONS
- Test temperature:
1. 35°C
2. 21-25°C

- pH:
1. No data
2. 7.0-8.0
Parameter:
other: chromatography
Value:
57
Sampling time:
56 d
Remarks on result:
other: Other details not known
Parameter:
other: HPLC
Value:
0
Remarks on result:
other: Other details not known
Details on results:
1. Test substance undergoes 57% degradation by appropriate chromatography method in 56 days. The metabolites identified by the appropriate chromatographic method were 3-amino-6-methylbenzene-N-phenylsulphonamid and 4-amino-3-methy1-1-[4'-sulphophenyl)pyrazolone, respectively.

2. No percentage degradation of test substance was determined by using HPLC parameter.

1. No data

2.

Table: Summary of operating conditions.

 

Parameter

Value

Influent flow rate, L/d

720

Primary sludge flow rate, L/d

6

Primary effluent flow rate, L/d

714

Mixed liquor wastage flow rate, L/d

67

Secondary effluent flow rate, L/d

647

Solids retention time, days

2.7

Hydraulic retention time, days

0.28

Dissolved oxygen, mg/

2.0-4.0

Target influent spike dosages, mg/L

Low

High

 

 

1

5

Influent pH, pH units

7.0-8.0

Aeration basin temperature, °C

21-25

   

Recovery for most dyes was within the targeted range of 80% to 120%; thus, it appeared that little or no chemical transformation occurred for these dyes because of contact with the variable wastewater and/or sludge matrix under these conditions.

 

Table:Percent Recovery of Test Dyes from Sample Matrices.

 

Dye compound name

 

Sample matrix

Org. free water

Wastewater

Mixed liquor

1 mg/l

5 mg/l

1 mg/l

5 mg/l

1 mg/l

5 mg/l

Test chemical

 

 

101

 

 

98

 

 

92

 

 

97

 

 

99

 

 

97

 

 

Where.

 

-         = Not tested

 

 

Table:Dye Concentrations Data Summary.

 

Dye

compound name

 

Low spike*

High spike*

INF

PE

ASE

SOL

RES*

INF

PE

ASE

SOL

RES*

 

Test chemical

 

0.97

 

0.95

 

 

0.92

 

 

0.93

 

 

< 0.06

 

4.58

 

 

4.51

 

 

 

4.55

 

4.45

 

< 0.05

 

 

Above table presents the mean concentrations for each of the dyes tested at each ASP sample location.

 

If a compound in Table below was recovered near the targeted range of 80% to 120%, then it was assumed that this compound was not biodegraded since most of the compound was recovered.Conversely, if the recovery was less than 20% to 30%, then it was assumed the compound was apparently biodegraded.Lastly, if the compound was recovered near the targeted range of 80% to 120%, then one must investigate the percentage adsorbed data..If these data indicated less than 20% adsorbed on the ML solids, then it was assumed that the compound was substantially untreated by the ASP. However, if these data indicated that the amount adsorbed was greater than 30%, then it was concluded that such a compound was removed by apparent adsorption.

 

Table:Mass balance data summary.

 

Dye

compound name

 

Low spike

High spike

% recovered

% adsorbed

% recovered

% adsorbed

 

Test chemical

 

 

98

 

 

 

1

 

 

 

101

 

 

 

<1

 

Thus, from the above table, it indicates that the test chemical was substantially untreated by the activated sludge process (ASP).

Validity criteria fulfilled:
not specified
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be range from 0 to 57%, respectively in 56 days. Thus, based on this, test chemical is considered to be not readily biodegradable in nature.
Executive summary:

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the biodegradability of the test chemical . The studies are as mentioned below:

Biodegradation study was carried out to determine the biodegradability rate of the test chemical. Activated sludge was used as an inoculum and the study was performed under anaerobic conditions at a temperature of 35°C for a period of 56 days.Samples of the aqueous phase were analyzed either qualitatively or quantitatively by an appropriate chromatographic method for the presence of certain of the expected aromatic amine metabolites.The percentage degradation of test substance was determined to be 57% by appropriate chromatography method in 56 days. The metabolites identified by theappropriate chromatographic method were 3 -amino-6 -methylbenzene- N-phenylsulphonamid and 4 -amino-3 -methy1 -1 -[4'-sulphophenyl)pyrazolone, respectively. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

Another biodegradation study was conducted for evaluating the percentage biodegradation of test chemical. The study was carried outin pilot activated sludge process system using several wastewater and mixed liquor at a temperature of 21-25°C and pH range of 7.0-8.0, respectively. Mass balance calculations were made to determine the amount of the dye compound in the waste activated sludge (WAS) and in the activated sludge effluent (ASE). Activated sludge was used as test inoculum for the study. Test chemical conc. used for the study was 1 and 5 mg/l, respectively.Screened raw wastewater from the Greater Cincinnati Mill Creek Sewage Treatment Plant was used as the influent (INF) to three pilot-scale activated sludge biological treatment systems (two experimental and one control) operated in parallel. Each system consisted of a primary clarifier (33 L), complete-mix aeration basin (200 L), and a secondary clarifier (32 L). Each water soluble dye was dosed as commercial product to the screened raw wastewater for the two experimental systems operated in parallel at targeted active ingredient doses of 1 and 5 mg/L of influent flow (low and high spike systems, respectively). All systems were operated for at least three times.All samples were 24 hr composites made up of 6 grab samples collected every 4 hr and stored at 4°C. The possible removal mechanisms for a dye compound in the ASP system include adsorption, biodegradation, chemical transformation, photodegradation, and air stripping.Dye analytical recovery studies were conducted by dosing the purified dye compound into organic-free water, influent wastewater, and mixed liquor. These studies were run in duplicate and each recovery study was repeated at least once to ensure that the dye compound could be extracted. Purified dye standards were analytically prepared from the commercial dye product by repeated recrystallization. The INF, primary effluent (PE), and ASE were filtered, and the filtrate was passed through a column packed with resin. The filter paper and resin were soaked in an ammonia-acetonitrile solution and then Soxhlet extracted with ammonia-acetonitrile. The extract was concentrated and brought up to 50 mL volume with a methanol/dimethylformamide solution. The mixed liquor (ML) samples were separated into two components, the filtrate or soluble (SOL) fraction and the residue (RES) fraction. The SOL fraction was processed similar to the INF, PE, and ASE samples. The RES fraction and the filter paper were processed similar to these samples but the resin adsorption step was omitted. All extracted samples were analyzed by HPLC with an ultraviolet-visible detector. Total suspended solids (TSS) analyses were also performed on the INF, PE, ML, and ASE samples.Percentage recovery of test chemical was determined to be 98-101%,thus, it appeared that little or no chemical transformation occurred for test chemical because of contact with the variable wastewater and/or sludge matrix under these conditions. Also it was evaluated that the test chemical was adsorbed at a level of 1 -<1% on the ML solids, indicating that the compound was substantially untreated by the activated sludge process (ASP). Thus, based on % recovery of test chemical was can be considered to be not readily biodegradable in nature.

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be range from 0 to 57%, respectively in 56 days. Thus, based on this, test chemical is considered to be not readily biodegradable in nature.

Description of key information

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the percentage degradation of the test chemical is expected to be range from 0 to 57%, respectively in 56 days. Thus, based on this, test chemical is considered to be not readily biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the biodegradability of the test chemical . The studies are as mentioned below:

Biodegradation study was carried out to determine the biodegradability rate of the test chemical. Activated sludge was used as an inoculum and the study was performed under anaerobic conditions at a temperature of 35°C for a period of 56 days.Samples of the aqueous phase were analyzed either qualitatively or quantitatively by an appropriate chromatographic method for the presence of certain of the expected aromatic amine metabolites.The percentage degradation of test substance was determined to be 57% by appropriate chromatography method in 56 days. The metabolites identified by theappropriate chromatographic method were 3 -amino-6 -methylbenzene- N-phenylsulphonamid and 4 -amino-3 -methy1 -1 -[4'-sulphophenyl)pyrazolone, respectively. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

Another biodegradation study was conducted for evaluating the percentage biodegradation of test chemical. The study was carried outin pilot activated sludge process system using several wastewater and mixed liquor at a temperature of 21-25°C and pH range of 7.0-8.0, respectively. Mass balance calculations were made to determine the amount of the dye compound in the waste activated sludge (WAS) and in the activated sludge effluent (ASE). Activated sludge was used as test inoculum for the study. Test chemical conc. used for the study was 1 and 5 mg/l, respectively.Screened raw wastewater from the Greater Cincinnati Mill Creek Sewage Treatment Plant was used as the influent (INF) to three pilot-scale activated sludge biological treatment systems (two experimental and one control) operated in parallel. Each system consisted of a primary clarifier (33 L), complete-mix aeration basin (200 L), and a secondary clarifier (32 L). Each water soluble dye was dosed as commercial product to the screened raw wastewater for the two experimental systems operated in parallel at targeted active ingredient doses of 1 and 5 mg/L of influent flow (low and high spike systems, respectively). All systems were operated for at least three times.All samples were 24 hr composites made up of 6 grab samples collected every 4 hr and stored at 4°C. The possible removal mechanisms for a dye compound in the ASP system include adsorption, biodegradation, chemical transformation, photodegradation, and air stripping.Dye analytical recovery studies were conducted by dosing the purified dye compound into organic-free water, influent wastewater, and mixed liquor. These studies were run in duplicate and each recovery study was repeated at least once to ensure that the dye compound could be extracted. Purified dye standards were analytically prepared from the commercial dye product by repeated recrystallization. The INF, primary effluent (PE), and ASE were filtered, and the filtrate was passed through a column packed with resin. The filter paper and resin were soaked in an ammonia-acetonitrile solution and then Soxhlet extracted with ammonia-acetonitrile. The extract was concentrated and brought up to 50 mL volume with a methanol/dimethylformamide solution. The mixed liquor (ML) samples were separated into two components, the filtrate or soluble (SOL) fraction and the residue (RES) fraction. The SOL fraction was processed similar to the INF, PE, and ASE samples. The RES fraction and the filter paper were processed similar to these samples but the resin adsorption step was omitted. All extracted samples were analyzed by HPLC with an ultraviolet-visible detector. Total suspended solids (TSS) analyses were also performed on the INF, PE, ML, and ASE samples.Percentage recovery of test chemical was determined to be 98-101%,thus, it appeared that little or no chemical transformation occurred for test chemical because of contact with the variable wastewater and/or sludge matrix under these conditions. Also it was evaluated that the test chemical was adsorbed at a level of 1 -<1% on the ML solids, indicating that the compound was substantially untreated by the activated sludge process (ASP). Thus, based on % recovery of test chemical was can be considered to be not readily biodegradable in nature.

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be range from 0 to 57%, respectively in 56 days. Thus, based on this, test chemical is considered to be not readily biodegradable in nature.