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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Species/Origin: Aerobic activated sludge, micro organisms from a domestic waste water treatment plant was supplied by the sewage plant Hildesheim, Germany.
Conditioning: The aerobic activated sludge used for this study was filtered with folded filter. The first 200 mL of the filtrate were not used. The second filtrate efluent from domestic waste water was used to initiate inoculation. The concentration of suspended solids was not greater than 30 mg/L. Colony forming units in the test vessels was 10.E4 - 10.E6 CFU/L. Based on the ThOD of the test item the test concentration of 65 mg/L corresponding to a oxygen deman of 101.4 mgO2/L in the vessel was selected.
Inoculum control: Nutrient solution and inoculum
Toxicity control: 65.0 mg/L test item + 75 mg/L functional control item + nitrient solution and inoculum
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
65 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The purpose of this study was to determine the ready biodegradability of the test item . The test item was exposed to aerobic activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium acetate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.
This type of study is recognized by the international test guidelines and should provide a rational basis to assess the ready biodegradation properties of the test item when incubated with aerobic activated sludge.

Test Units
Type and Size: Manometric Test System with test flasks containing a volume of approximately 250 mL.
Apparatus: OxiTop-Control Measuring System, WTW
pH-meter "Corning" pH 240
Thermohygrograph, LUFFT FELLBACH
Frequency and duration of the application: Once per setting up over 28d
Test vessels: Brown glass bottles (volume 500 ml)
2 bottles containing test item and inoculum (test suspension)
2 bottles containing only inoculum (inoculum control)
2 bottles containing reference item and inoculum (functional control)
2 bottles containing test item and rference item and inoculum (toxicity control)
Inoculum control: Nutrient solution and inoculum
Toxicity control: 65.0 mg/L + 75 mg/L functional control item + nutrient solution and inoculum
Tets temperature: 20 +/- 1 °C

Principle: The appropriate amount of test item was given into brown glass bottles as incubation vessel.Afterwards the test medium was filled into overflow measuring flasks and given into brown glass bottles:
2 incubation vessels for the test compound (P1,P2)
2 incubation vessels for the functional control (R1,R2)
2 incuhbation vessels for the toxicity control (T1,T2)
The test series was accompanied by a complete parallel series for the determination of the O2 demand of the inoculated control medium (C1,C2).
All test solutions were made by directly weighing of the test item into incubation vessels. The test medium was inoculated with 10 mlL/L inoculum. The inoculated test medium was filled into overflow measuring flask and given into the brown glass bottles. A rubber sleeve with soda lime was hung into the opening of the bottles. The bottleas were closed with OxiTop measuring heads and the measuring system was activated.
The measuring principle of BOD was manometric with a pressure sensor in the OxiTop head. Incubation took place in thermostat boxes to ensure the necessary temperature of 20 +/-1 °Cin the dark. All vessels were stirred continuously on stirring platform.
The oxygen consumption was determined by the OxiTop measuring system continuously.
The temperature in the incubator was documented continuously by a thermo-hygrigraph. At the end of the test the pH-value of the solutions was determined.
The oxygen consumption was determined in theincubation vessels by the OxiTop measuring system at 360 measuring points (every 112 minutes) during the 28d incubation period.
Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
Test conc.75 mg/L; ThOD = 0.78 mg O2/mg

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
22
Sampling time:
28 d
Details on results:
The biodegradation rate of the test item reached iwithin 10-day window only 22%.
Conclusion:
The degradation rate of test item did not
reach 60% within the 10-day window or after 28 days (see Table 1).. Therefore, the test item is considered to be not readily biodegradable.



BOD5 / COD results

Results with reference substance:
Biodegradation of Reference Item Sodium Acetate
Percentage Biodegradation: The reference item sodium acetate was sufficiently degraded to 100% after 14 days and to 100% after
28 days of incubation.
Conclusion: The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Any other information on results incl. tables

 

Table3. Biochemical Oxygen Demand (mg O2/L) in during the Test Period of 28 Days (test item and toxicty control)

 Study day                                Biological oxygen demand (BOD) [mg O2/L]
          Test item 65 mg / L           Toxicity control 65 + 75 mg / L
    P1     P2     T1     T2
 gross  net  gross  net  gross  net  gross  net
 1  1.5  1.2  0.7  0.4  8.7  8.2  7.3  7.1
 2  0.3  0.3  0.0  0.0  27.1  27.1  29.1  29.1
 3  3.7  3.7  0.0  0.0  36.9  36.9  40.1  40 .1
 4  8.0  8.0  0.0  0.0  40.9  40.9  44.9  44.9
 5  11.4  11.4  0.0  0.0  45.0  45.0  49.5  49.5
 6  15.3  15.3  0.0  0.0  48.9  48.9  49.5  49.5
 17.8  17.8  0.0  0.0  51.9  51.7  51.2  51.0
 8  20.0  18.6  0.0  0.0  54.0  52.6  54.0  52.6
 9  21.5  19.7  0.0  0.0  55.5  53.7  54.3  52.5
 10  24.1  21.1  0.0  0.0  57.9  54.9  56.5  53.5
 11  26.1  21.8  1.4  0.0  60.0  55.7  58.4  54.1
 12  25.9  22.5  1.0  0.0  61.1  57.7  58.7  55.2
 13  27.4  22.4  1.0  0.0  61.6  56.5  65.6  60.5
 14  28.7  22.5  1.8  0.0  63.6  57.4  64.0  57.8
 15  32.2  23.4  4.8  0.0  67.5  58.8  63.5  54.8
 16  39.8  23.4  12.2  0.0  75.6  59.2  72.3  55.9
 17  40.6  24.3  12.4  0.0  76.7  60.5  71.7  55.4
 18  40.7  24.7  12.1  0.0  76.3  60.4  71.9  55.9
 19  41.8  24.5  13.0  0.0  78.3  61.0  73.4  56.2
 20  42.6  24.2  14.0  0.0  80.6  62.2  80.6  62.2
 21  43.1  23.7  14.4  0.0  83.8  64.4  83.8  64.4
 22  45.2  21.0  16.5  0.0  88.5  64.3  88.5  64.3
 23  46.3  20.9  17.1  0.0  90.3  64.9  90.3  64.9
 24  46.5  20.7  17.8  0.0  91.0  65.2  91.0  65.2
 25  46.4  20.8  17.3  0.0  90.9  65.3  90.9  65.3
 26  47.4  20.6  18.3  0.0  91.9  65.2  91.9  65.2
 27  48.9  20.1  19.5  0.0  94.3  65.5  94.3  65.5
 28  49.3  19.8  19.7  0.0  95.7  66.2  95.7  66.2

       

            

  Table 2. Biological oxygen demand (BOD) of control and functional control
 Study day                       Biological Oxygen Demand (BOD) [mg O2 / L]
 Control              Functional control 75 mg/L
    R1     R2
 mean  gross  net  gross  net
 1  0.4  6.0  5.8  5.6  5.5
 2  0.0  26.7  26.7  25.9  25.9
 3  0.0  32.2  35.2  35.0  35.0
 4  0.0  41.4  41.4  40.7  40.7
 5  0.0  45.5  45.5  45.2  45.2
 6  0.0  50.1  50.1  48.4  48.4
 7  0.2  53.4  53.2  51.7  51.5
 8  1.4  56.1  54.7  54.4  53.0
 9  1.8  58.9  57.1  56.9  55.1
 10  3.0  61.1  58.1  59.0  55.9
 11  4.3  62.7  58.4  60.7  56.4
 12  3.4  62.5  59.1  60.3  56.9
 13  5.0  64.3  59.2  65.3  60.3
 14  6.3  66.1  59.8  65.4  59.2
 15  8.7  69.0  60.3  67.1  58.3
 16  16.4  77.5  61.1  74.8  58.4
 17  16.2  77.6  61.4  74.7  58.5
 18  16.0  77.3  61.3  74.6  58.6
 19  17.2  78.8  61.6  76.1  58.9
 20  18.5  80.5  62.1  77.7  59.3
 21  19.4  82.3  62.9  79.7  60.3
 22  24.2  89.0  64.8  86.7  62.5
 23  25.4  90.3  64.9  88.8  63.4
 24  25.8  90.5  64.8  89.6  63.8
 25  25.6  90.2  64.6  89.2  63.6
 26  26.7  91.2  64.4  90.4  63.7
 27  28.8  93.8  64.9  93.5  64.7
 28  29.5  94.6  65.1  95.0  65.5


            

Table5.pH-Values at the End of the Test

Treatment

pH-value

Test item

7.31

Test item

7.31

Functional control

7.28

Inoculum control

7.25

Toxicity control

7.20

 

 

 

 

 

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Degradation of test item was 22% after 28 days.
Therefore, test item is considered to be not readily biodegradable.

The biological oxygen demand (BOD) of the test and refernce item was calculated out of the difference of the test and control replicates.The mean biodegradation rate was calculated for each study day from the respective measuring points. The tabulated results represent rounded results calculated on the axact raw data.

Biodegradation [%] = BOD [mg O2/L] / ThOD [mg O2/L] x 100
BOD=biological oxygen demand
ThOD=theoretical oxagen demand
Executive summary:

Title:

Test item: Ready Biodegradability in a Manometric Respirometry Test

 

 

Guidelines:

-     OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted

 

 

Material and Methods:

 

Test Item:

EMULSOGEN TO

Test Species:

Aerobic activated sludge (microorganisms from a domestic waste­water treatment plant) was supplied by the sewage treatment plant of Hildesheim, Germany.

Test Design:

The test item EMULSOGEN TO was investigated for its ready biodegradability in a manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium acetate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

Endpoints:

Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

Test Item Loading Rate (initial concentration in medium C0):

65 mg/L corresponding to an oxygen demand of 101.4 mg/L.

Reference Item:

Sodium Acetate

Reference Item Loading Rate:

75 mg/L corresponding to an oxygen demand of about 0.78 mg O2/mg (ThOD).

Test Conditions:

20°C ± 1°C, darkness

 

 

Results:

Biodegradation of Emulsogen TO:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the 10-day window, describing the period between reaching at least 10% degradation and 60% degradation. This period should not exceed 10 days.

The mean biodegradation at test end after 28 days was 22%.

 

 

 

Biodegradation of Sodium Benzoate:

The reference item sodium acetate was sufficiently degraded to 100% after 14 days and to 100% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

 

Biodegradation of the Toxicity Control:

In the toxicity control containing both, the test item and the reference item sodium acetate, 36% (ThOD) biodegradation was noted within 14 days and 41% (ThOD) biodegradation after 28 days of incubation. According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was approx.22% within 14 days.

This study is classified acceptable and satisfies the guideline requirements for ready biodegradability studies.