Bontron E-108

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:

16 November 2000 to 20 December 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material: S178207
- Physical state: white powder
- Analytical purity: 75.1% +/- 0.8%
- Purity test date: 10 January 2001
- Lot/batch No.: 10295557
- Storage condition of test material: stored in the dark, at ambient temperature
- Other:

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Buckland Sewage Treatment Works, Newton Abbot, Devon, UK
- Storage conditions: aerated at room temperature, pH maintained at 7.0 +/- 1.0.
- Storage length: 6 days
- Preparation of inoculum for exposure: Diluted in medium, added to test bottles and stirred until required for use.
- Pretreatment: centrifuged, washed and resuspended in the test medium and the solids concentration determined.
- Concentration of sludge: 30 mg/l
- Initial cell/biomass concentration: Not stated
- Water filtered: Not stated
- Type and size of filter used, if any: Not applicable

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

other: calculated as a percentage of Chemical Oxygen Demand (COD)

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

other: measurement of Biochemical Oxygen Demand (BOD)

Details on study design:

TEST CONDITIONS
- Composition of medium: The test medium contained the following nutrients per litre of deionised water: 85 mg of KH2PO4, 217.5 mg of K2HPO4, 334 mg of Na2HPO4.2H2O, 5 mg of NH4Cl, 22.5 mg of MgSO4.7H2O, 36.4 mg of CaCl2.2H2O, 0.25 mg of FeCl3.6H2O and 0.40 mg of EDTA (disodium salt)
- Test temperature: 22 +/- 2°C
- pH: 6.9-7.5
- pH adjusted: no
- Suspended solids concentration: 30 mg/l
- Continuous darkness: dark glass bottles


TEST SYSTEM
- Number of culture flasks/concentration: 15
- Measuring equipment: Hach manumetric biochemical oxygen demand apparatus


SAMPLING
- Sampling frequency: day 5, 9, 15, 20 and 28
- Sampling method: Hach manumetric biochemical oxygen demand apparatus


CONTROL AND BLANK SYSTEM
- Inoculum blank: contained reference substance or no test material
- Abiotic sterile control: Test material and HgCl2

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

Parameter:

other: Biochemical Oxygen Demand (BOD)

Value:

< 5

Sampling time:

28 d

Details on results:

CHEMICAL OXYGEN DEMAND
The measured COD value of S178207 was 1.34 g O2 g -1 of substance.

pH AND TEMPERATURE MEASUREMENTS
At the end of the 28 day test period, the pH values ranged from 7.0 to 7.1 in the blank control bottles, from 7.2 to 7.5 in the sodium acetate bottles and from 6.9 to 7.2 in the bottles containing S178207.

Temperature measurements recorded in several of the test bottles on days 0 and 28 indicated the temperature was within the range 22 +- 2 deg C.

BIOCHEMICAL OXYGEN DEMAND (BOD)
The BOD value for S178207 after 28 days indicated negligible biodegradation (<5%), and may therefore be classified as not readily biodegradable.

BOD5 / COD results

BOD5 / COD

Parameter:

COD

Value:

1.34 g O2/g test mat.

Results with reference substance:

CHEMICAL OXYGEN DEMAND (COD)
The measured COD value of sodium acetate was 0.68 g O2 g-1 of substance. The COD obtained for sodium acetate compares favourably with its expected maximum oxygen demand of 0.68 g O2 g-1 thus demonstrating the validity of the analytical techniques.

BIOCHEMICAL OXYGEN DEMAND (BOD)
The results which are summarised in Table 2 (below), show that sodium acetate attained a maximum level of biodegradation. (Based on the BOD:COD ratio of 72%).
Over 60% biodegradation was acheived within the 10 day window, as expected for a biodegradable substance, thus confirming that the activated sludge contained viable organisms.
The following phases (approximate) were observed:

PHASE TIME PERIOD
Lag phase days 0 to 1
Degradation phase days 1 to 5
10-day window days 1 to 11

where;

Lag phase: is the period from inoculation until the degradation has increased to 10%
Degradation phase: is the time from the end of the lag phase to the time when 90% of the maximum level of degradation has been reached
10-day window: the 10 days immediately following the attainment of 10% biodegradation.
The sodium acetate data are displayed graphically in Figure 1. (attached).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

other: negligible biodegradation, not readily biodegradable

Conclusions:

The BOD value for S178207 after 28 days indicated negligible biodegradation (<5%), and may therefore be classified as not readily biodegradable.

Executive summary:

The test was conducted using activated sludge as the inoculum. The biodegradation was measured over a 28 day period in a manometric respirometer.

Oxygen uptake was recorded regularly during the 28 day experimental period. The readings were corrected for the blank and the volume of test solution. The biodegradation was calculated as a percentage of the chemical oxygen demand for the susbtance under test and as a percentage of the chemical oxygen demand for the reference substance.

The reference substance used was sodium acetate.

S178207		Sodium acetate
Day	Percentage biodegradation	Day	Percentage biodegradation
5	<5	5	69
9	<5	9	72
15	<5	15	72
20	<5	20	72
28	<5	28	72

The COD of the test substance was determined as 1.34 g O2 g-1 and the BOD values after 5 and 28 days were both <5 g O2 g-1. The percentage degradation was calculated as (BOD/COD) x 100.

The BOD value for S178207 after 28 days indicated negligible biodegradation (<5%), and may therefore be classified as not readily biodegradable.