Oxidation products of D-Glucose with nitric acid, sodium salts

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-05-15 to 2015-06-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Collection and transfer of the inoculum and analysis of oxidised inorganic nitrogen were not performed by the test facility or to GLP.

Specific details on test material used for the study:

- Source and lot/batch No. of test material: Rivertop Renewables,
- Lot/batch number: 150330EA
- Expiration date of the lot/batch: 2017-03-15
- Purity - 97.7%
- Water solubility: Soluble in water
- Physical state: Dark brown liquid
- Empirical formula: Na1.5 C3.8 H4.9 N0.1 O5.4
- Mean molecular weight: 173.02

Oxygen conditions:

aerobic

Inoculum or test system:

other: Settled secondary treated effluent from a sewage treatment plant

Details on inoculum:

A sample of effluent from the secondary treatment stage at Guelph Watewater Treatment Plant (Ontario, Canada) was pre-conditioned by continuous aeration at 22 +/- 2 degrees C during the 6d interval between collection and use. The effluent sample was settled for 0.5h prior to use and the clear supernatant was used to inoculate the test medium without prior filtration.

Duration of test (contact time):

28 d

Initial conc.:

15.8 mg/L

Based on:

test mat.

Remarks:

[Nominally equivalent to ca. 4 mg COD/L].

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Inoculated mineral salts medium dosed with the test substance, KHP (reference) or test substance combined with KHP (toxicity control) was dispensed to series of 14 BOD bottles to permit sacrificial measurements of dissolved oxygen (DO) concentration in duplicate vessels at each measurement point. Further series of BOD bottles were also set up with uninoculated medium containing no other addition (contol) and inoculated medium, with single and duplicate vessels per measurement point, respectively.

Reference substance:

other: potassium hydrogen phthalate (KHP)

Preliminary study:

Not performed.

Test performance:

Initial DO measurements were made on Day 0 and the remaining vessels were incubated at 22 +/- 2 degrees C for up to 28 days.  After each DO determination, samples of media were transferred to vials for analysis of oxidised N and the sacrificed test vessels provided no further mreasurements.

The extent of biodegradation was determined by expressing the DO uptake since the initial Day 0 measurement as a percentage of the theoretical quantity required for the complete oxidation of the test and/or reference substance, represented by COD.  

Parameter:

% degradation (O2 consumption)

Value:

30

Sampling time:

4 d

Parameter:

% degradation (O2 consumption)

Value:

48

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

50

Sampling time:

11 d

Parameter:

% degradation (O2 consumption)

Value:

56

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

58

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

67

Sampling time:

28 d

Details on results:

Degradation of the test substance reached 67% after 28 days, however the level of biodegradation achieved at the closure of the 10-day window (i.e. 10 days after crossing the 10% threshold) was 51%. The test substance therefore fulfilled the criteria for classification as readily biodegradable, but not within the 10-day window.

Degradation of the test substance was calculated on the basis of an initial loading equivalent to 0.25 mg chemical oxygen demend (COD)/L. The COD concentration was based on the results of preliminary COD analysis performed with a HACH reagent kit and spectrophotometer system.

Results with reference substance:

Degradation of KHP was as follows. D0: 0%; D4: 66%; D7: 78%; D11: 81%; D14: 84%; D21: 85%: D28: 86%.
Oxygen uptake as %COD exceeded 60% within 14 days and degradation conformed to expectation for a readily

Oxygen uptake recorded in the toxicity control series exceeded 25% of COD by Day 4 and at all subsequent measurements. There was consequently no evidence that Oxidation Products of d-Glucose with nitric acid, Sodium salts was inhibitory to the inoculum at the applied test concentration.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The ready biodegradability of the Oxidation Products of d-Glucose with Nitric acid, Sodium salts was determined by measurement of oxygen consumption in accordance with the Closed Bottle Test (OECD TG 301D). Oxygen uptake expressed as a percentage of chemical oxygen demand (COD) exceeded 60% within 28 days, but did not reach 60% within 10 days of reaching 10%. Oxidation Products of d-Glucose with Nitric acid, Sodium salts therefore qualifies for classification as readily biodegradable, but not within the 10-day window.

Executive summary:

The ready biodegradability of the Oxidation Products of d-Glucose with Nitric acid, Sodium salts was determined by measurement of oxygen consumption in accordance with the Closed Bottle Test (OECD TG 301D).  The inoculum was an acclimatised (not adapted) effluent obtained from the secondary stage of a municipal wastewater treatment plant. The test design included a reference treatment dosed with potassium hydrogen phthalate to provide a check on the adequacy of the test system and the activity of the inoculum, and a toxicity control treatment dosed with a combination of the test and reference substances to check for possible auto-inhibition of the degradation of the test substance due to toxicity. Measurements of dissolved oxygen were made in incubation vessels sacrificed on days 0, 4, 7, 11, 14, 21 and 28 and samples from the test substance and inoculated control series were analysed for oxidised nitrogen to facilitate correcion for oxygen consumed by nitrification.

Oxygen uptake expressed as a percentage of chemical oxygen demand (COD) for the test substance exceeded 60% within 28 days, but did not reach 60% within 10 days of reaching 10%.  Oxidation Products of d-Glucose with Nitric acid, Sodium salts therefore qualifies for classification as readily biodegradable, but not within the 10-day window.  

Description of key information

The ready biodegradability of the Oxidation Products of d-Glucose with Nitric acid, Sodium salts was determined by measurement of oxygen consumption in accordance with the Closed Bottle Test (OECD TG 301D).  Oxygen uptake expressed as a percentage of chemical oxygen demand (COD) exceeded 60% within 28 days, but did not reach 60% within 10 days of reaching 10%.  Oxidation Products of d-Glucose with Nitric acid, Sodium salts therefore qualifies for classification as readily biodegradable, but not within the 10-day window.  

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window