Protein hydrolyzates, rice bran

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:

March - April 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:

This deviation has no incidence on study results

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Protein hydrolyzates, rice bran

EC Number:

305-224-5

EC Name:

Protein hydrolyzates, rice bran

Cas Number:

94350-05-7

IUPAC Name:

Protein hydrolyzates of Oryza Sativa

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: beige powder
- Storage: in a dark place at room temperature
- Batch : 16 208
- Manufacturing date: July 26th 2016
- Expiry date: July 26th 2018

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 culture: 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 recantation in a mineral medium until sludge was considered free from excess substrate or inhibitor.
- Inoculum preconditioning: 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 is soluble in water; it was diluted with mineral medium at 1g/L and directly introduced with sludge into each test vessels.
The test item “NUTRIPEPTIDES AT” was tested at 100 mg/L in mineral medium.
The test medium was the mineral medium, a weakly saline aqueous medium.

TEST CONDITIONS
Composition of medium: Mineral medium according to OECD 301F guideline
- Test temperature: The test was performed in darkness between 20 to 24 °C (constant temperature +/- 1°C).
- Mineral medium - pH: 7.6
- Inoculum : pH: 6.8, Dissolved oxygen: 9.0 mg/L, Suspended solids concentration: 2.57 g/L
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: WTW Oxitop (FCBA reference: ACQU 1030)
- Number of culture flasks/concentration: 3 flasks (test item and inoculum)
- 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: Yes; 3 flasks (inoculum only)
- Reference item: 2 flasks (Sodium benzoate and inoculum)
- Toxicity control: Yes; 2 flasks (test item, sodium benzoate and inoculum)

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

none

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

With ThODNH4

Value:

ca. 119.08

St. dev.:

2.62

Sampling time:

28 d

% Degradation 2

Key result

Parameter:

% degradation (O2 consumption)

Remarks:

with ThODNO3

Value:

ca. 81.6

St. dev.:

1.79

Sampling time:

28 d

Details on results:

Biodegradation of the test item:
- The test Item contains nitrogen, therefore the evaluation of biodegradation is based in the following expressed as ThOD-NH4 and ThOD-NO3.
- The degradation for the 10-day window beginning was reached on Day 1, at the end of the 10-day window (reaching at least 60%), on Day 4, the mean degradation was 67.61% following the ThODNH4 and therefore the D-day window was reached.
- The degradation rate of the test item “NUTRIPEPTIDES AT” reached 119.08% (between 116.80% and 121.94%), following the ThODNH4, after 28 days of incubation.
- The degradation for the 10-day window beginning was reached on Day 1, at the end of the 10-day window (reaching at least 60%), on Day 7, the mean degradation was 67.30% following the ThODNO3 and therefore the D-day window was reached.
- The degradation rate of the test item “NUTRIPEPTIDES AT” reached 81.60% (between 80.04% and 83.56%), following the ThODNO3, after 28 days of incubation.
According to the OECD guideline 301F, the test item is readily biodegradable according to ThODNH4 and ThODNO3


Biodegradation of the Toxicity Control:
A biodegradation of 108.01% (with ThODNH4) and 86.61% (with ThODNO3) 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 110.54% with ThODNH4 and 88.64% with ThODNO3.
.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).

BOD5 / COD results

Results with reference substance:

The reference item “Sodium benzoate” was degraded up to 83.61% after 14 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 is considered as 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).

The degradation for the 10-day window beginning was reached on Day 1, at the end of the 10-day window (reaching at least 60%), on Day 4, the mean degradation was 67.61% following the ThOD_NH4and therefore the D-day window was reached. The degradation rate of the test item reached 119.08% (between 116.80% and 121.94%), following the ThOD_NH4, after 28 days of incubation.

 

The degradation for the 10-day window beginning was reached on Day 1, at the end of the 10-day window (reaching at least 60%), on Day 7, the mean degradation was 67.30% following the ThOD_NO3and therefore the D-day window was reached. The degradation rate of the test item reached 81.60% (between 80.04% and 83.56%), following the ThOD_NO3, after 28 days of incubation.

In addition, a biodegradation of 108.01% (with ThOD_NH4) and 86.61% (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 110.54% with ThOD_NH4and 88.64% with ThOD_NO3.

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 is considered as readily biodegradable.