Rye, ext.

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:

June 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

One deviation to the study plan 16/1183F/a was observed in this study. This deviation has no incidence on study results.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Rye, ext.

EC Number:

290-271-3

EC Name:

Rye, ext.

Cas Number:

90106-48-2

IUPAC Name:

Oligosaccharides and polysaccharides of glucose from Rye

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: white powder
- Storage In darkness at room temperature
- Batch: 16 167
- Manufacturing date: June 2016
- Expiry date: June 2018

Specific details on test material used for the study:

ThOD(NH4) = 1.075 mg O2/mg test item
ThOD(NO3) = 1.102 mg O2/mg test item

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: the inoculum was a fresh sample of activated sludge and was collected from the aeration tank of a sewage treatment plant receiving predominantly domestic sewage.
- Sample site: Water treatment plant "STEP de Lille", 33290 Blanquefort (France) - Tank 2.
- Laboratory preparation: a filtration through a fine sieve (about 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by decantation in a mineral medium until sludge was considered free from excess substance or inhibitor.
- Inoculum pre-conditioning: pre-conditioning consisted in aerating sludge (in mineral medium) for 5-7 days before the test and at the test temperature.

Duration of test (contact time):

ca. 28 d

Initial test substance concentration

Initial conc.:

ca. 100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST ITEM PREPARATION:
- The test item was soluble in water; It was directly diluted with mineral medium and sludge was added directly in each test vessels (100 mg/L). The test medium was the mineral medium, a weakly saline aqueous medium. The test item was tested at 100 mg/L in mineral medium.

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301F guideline
- Test temperature: The test was performed in darkness between 21,9.0 to 22.4°C (constant temperature +/- 1°C).
- Mineral medium - pH: 7.6
- Inoculum pH: 6.4
- Dissolved oxygen: 8.6 mg/L
- Suspended solids concentration: 2.76 g/L
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: WTW Oxitop (FCBA reference: ACQU 1011)
- Test performed in closed vessels: Yes
- A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days.
- Details of trap for CO2: Microbial respiration consumes O2 and releases CO2 which were absorbed by soda lime pellets present in the headspace of flasks. This produced a decrease in pressure in the flask proportional to the amount of oxygen taken up by the microbial population during biodegradation, which was expressed as a percentage of ThOD (Theoretical Oxygen Demand).
- Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item. Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L + inoculum) and toxicity control (sodium benzoate + inoculum + test item) were run in parallel.

SAMPLING
- Sampling frequency: 0 to 28 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 flasks (inoculum only)
- Reference item: 2 flasks (Sodium benzoate and inoculum)
- Toxicity control: 2 flasks (test item, sodium benzoate and inoculum)



The medium was prepared from conœntrated stock solutions in ultrapure water as described in the guideline.
The test ws performed in darkness between 20 to 24°C.
Experimental plan:
-3 flasks for inoculum control (inoculum only)
-3 flasks for test item 100 mg/L (test item and inoculum)
-2 flasks for reference item (sodium benzoate and inoculum)
-2 flasks for toxicity control (test item, sodium benzoate and inoculum)

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

No preliminary study

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (O2 consumption)

Remarks:

ThODNH4

Value:

ca. 74.95

St. dev.:

1.94

Sampling time:

28 d

Remarks on result:

other: results with ThOD(NH4)=1.075 mg O2/mg test item

% Degradation 2

Key result

Parameter:

% degradation (O2 consumption)

Remarks:

ThODNO3

Value:

ca. 73.11

St. dev.:

1.89

Sampling time:

28 d

Remarks on result:

other: results with ThOD(NO3)=1.102 mg O2/mg test item

Details on results:

The test item contains a small quantity of proteins, so it contains nitrogen according to the elementary analyse, the evaluation of biodegradation had to be based in the following expressed as ThODNH4 and ThODNO3.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window (reaching at least 60%), on Day 6, the mean degradation was 60.31% following the ThODNH4 and therefore the D-day window was reached.
The degradation rate of the test item reached 74.95% ± 1.94% (between 73.40% and 77.12%), following the ThODNH4, after 28 days of incubation.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window, on Day 7, the mean degradation was 63.55% following the ThODNO3 and therefore the D-day window was reached
The degradation rate of the test item reached 73.11% ± 1.91% (between 71.60% and 75.23%), following the ThODNO3, after 28 days of incubation.

BOD5 / COD results

Results with reference substance:

The reference item “Sodium benzoate” was degraded up to 88.69% after 28 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under conditions of OECD Guideline 301F, the test item "COHELISS AT" can be considered readily biodegradable. Furthermore, the 10-day window was reached under the test conditions.

Executive summary:

The ready biodegradability of the test item has been determined by the Manometric Respirometry Test according to the OECD Guideline No. 301F with GLP compliance.

A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item. Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L+ inoculum) and toxicity control (sodium benzoate + inoculum +

test item) were run in parallel. The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank inoculum, run in parallel) was determined from the change in pressure in apparatus and will be expressed as percentage of theoretical Oxygen Demand (ThOD).

Based on ThOD_NH4,the 10-Day window was reached on Day 6 and the results obtained show that the test itemcan be considered readily biodegradableafter 28 days of incubation with a mean percentage of biodegradation rate of 74.95%. 

Based on ThOD_NO3,the 10-Day was reached on Day 7.The results obtained show that the test itemcan be considered readily biodegradableafter 28 days of incubation with a mean percentage of biodegradation rate of 73.11%.

A biodegradation of 75.18% (with ThOD_NH4) and 74.22% (with ThOD_NO3) after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item).

At the end on the test, 28 days of incubation, the results were respectively 83.48% and 82.40%.

Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro-organism because degradation was >25% within 14 days (validity criterion).

Under conditions of OECD Guideline 301F, the test item "COHELISS AT" is considered as readily biodegradable.