Formic acid, manufacture of, by-products from

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:

2013-05-29 - 2013-06-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: 434009173
Expiry date: 2014-03-01

Appearance: Brown liquid
pH at 20°C (solution): <1
Solubility: Fully miscible
Stability: Stable under normal conditions of use and storage
Density: 1.28 g/cm³

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge from Kävlinge wastewater plant, Sweden, was used as inoculum. The inoculum was not pre-adapted. The final concentration of suspended solids in the mediums was 30 mg/l.

Duration of test (contact time):

28 d

Initial conc.:

49.9 mg/L

Based on:

COD

Initial conc.:

52.5 other: µl/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
Stock solutions (a)-(d) were prepared by dissolving the following salts in 1 litre of deionised water:

(a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2H2O, 0.5 g NH4Cl
(b) 22.50 g MgSO4 x 7H2O
(c) 36.4 g CaCl2 x 7H2O
(d) 0.25 g FeCl3 x 6H2O, three drops of HCl

The test medium was prepared by mixing 10 mL of solution A, 1 mL of each of the solutions B to D, 10.5 mL stock solution 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid (5 ml/l), and 6.2 mL of inoculum, making up to 1 L with deionised water.

The control medium was prepared by mixing 10 mL of solution A, 1 mL of each of the solutions B to D, 10 mL stock solution reference compound (sodium acetate anhydrous), and 6.2 mL of inoculum, making up to 1 L with deionised water.

The blank medium was prepared by mixing 10 mL of solution A, 1 mL of each of the solutions B to D, and 6.2 mL of inoculum, making up to 1 L with deionised water.

The inhibition test medium was prepared by mixing 10 mL of solution A, 1 mL of each of the solutions B to D, 10.5 mL stock solution 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid (5 ml/l), 10 mL stock solution reference compound (sodium acetate anhydrous), and 6.2 mL of inoculum, making up to 1 L with deionised water.

TEST METHOD
A manometric respirometer was used. Measured volumes of inoculated mineral medium, containing a known concentration of test substance (50-100 mg/L theoretical Oxygen Demand, ThOD) as the nominal sole source of organic carbon, were stirred in closed flasks at a constant temperature (22 ± 1°C) for a 28-day period. The pH of each flask was measured and, if necessary, adjusted to 7.4.
Oxygen consumption was determined from changes in pressure within the flask, since evolved carbon dioxide was absorbed in potassium hydroxide solution. Resulting decreases in pressure were monitored by the manometer. The amount of oxygen taken up by the microbial population (corrected for uptake by blank inoculum, run in parallel) was expressed as percentage of ThOD or Chemical Oxygen Demand (COD).

Reference substance:

acetic acid, sodium salt

Preliminary study:

No details supplied

Test performance:

Degradation of Sodium acetate was 71% after 7 days and 86% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid.

Parameter:

% degradation (O2 consumption)

Value:

ca. 66

Sampling time:

28 d

Details on results:

2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid was tested for Ready Biodegradability according to the OECD 301F Guideline method, and was shown to be degraded by approximately 66% within the 10-day window. 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid can therefore be regarded as readily biodegradable.

Results with reference substance:

Degradation of Sodium acetate was 71% after 7 days and 86% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid.

The biodegradation of the inhibition test, containing both sodium acetate and 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid was >25% (based on total ThOD) within 14 days, and therefore show no toxic effect of 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid on the micro-organisms at the test concentration.

Table 1: BOD (mg/L) for 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid

Day	Control	Test 1	Test 2	Inhibition test
2	23	10	9	29
7	41	39	38	67
12	50	51	51	83
14	52	52	54	86
21	54	56	57	86
28	56	59	59	89

Table 2: Percentage biodegradation of ThOD and COD (%) of 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid

Day	Control	Test 1	Test 2	Inhibition test
2	47	11	9	28
7	71	51	49	60
12	81	65	65	73
14	86	67	71	76
21	86	71	73	74
28	85	72	72	74

Validity criteria fulfilled:

yes

Remarks:

The criteria for validity of the test according to OECD TG no. 301F were fulfilled

Interpretation of results:

readily biodegradable

Conclusions:

The ready biodegradability of 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid has been determined according to the OECD guideline 301F. Under the conditions of the test, 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid was degraded by approximately 66% within the 10-day window.

2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid should therefore be regarded as readily biodegradable according to this test.

At the concentration used in the test (52.5 µl/L), 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid is not inhibitory to the micro-organisms.

Executive summary:

The ready biodegradability of formic acid technical 50% has been determined according to the OECD guideline 301F. Under the conditions of the test, formic acid technical 50% was degraded by approximately 66% within the 10-day window.

Formic acid technical 50% should therefore be regarded as readily biodegradable according to this test.

At the concentration used in the test (52.5 µl/L), formic acid technical 50% is not inhibitory to the micro-organisms.

Description of key information

An experimental study was conducted according to the OECD guideline 301F which found that 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid was readily biodegradable, having shown approximately 66% degradation within the 10-day window.
Moreover, the read-across substances formic acid and pentaerythritol were found to be readily biodegradable, while  propylidynetrimethanol (trimethylolpropane, TMP) was found to be inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

An experimental study was conducted according to the OECD guideline 301F which found that 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid was readily biodegradable, having shown approximately 66% degradation within the 10-day window.

In addition, supporting studies are available on the biodegradability of formic acid, pentaerythritol, and propylidynetrimethanol (trimethylolpropane, TMP), which are components of 2,2-bis(formyloxymethyl)propane-1,3-diyl diformate and formic acid, and therefore provide additional weight of evidence. 

The ready biodegradability of formic acid under aerobic conditions was determined in an 11-day test according to EU guideline C.4 -B. It was found that there was a 99% removal of DOC by day 11, hence formic acid is considered to be readily biodegradable.

The recommended inoculum concentration for ready biodegradability is in the range of 10^4 to 10^8 cells per litre. When given at least 0.05% vol/vol of secondary effluent (~ 3 x 10^ 5 viable cells/litre), within the recommended range, pentaerythritol will biodegrade by >70% after 27 days and with 5.0% vol/vol secondary effluent, the biodegradation is up to 86% after 27 days, indicating that pentaerythritol is readily biodegradable.

From the results of the study it is clear that after an initial lag period (of around 10 days) biodegradation of the test substance occured rapidly and within the 10 day window from day 10 to day 20. During this time biodegration rates progressed well beyond the 80% level. As such the substance meets the classification criteria for ready biodegradability.

The inherent biodegradability of TMP was tested in a 28-d Zahn-Wellens test following the OECD Guideline 302B (draft from 1989). With an initial test substance concentration of 100 mg/L and an activated sludge concentration of 0.4 g dry weight/L, 70 % degradability of TMP was determined within 7 days and 100% on test end by DOC-removal. 100% of the reference substance aniline degraded within the test period.

TMP was shown to be 100% inherently biodegradable after 28 days and fulfilled the criterion for inherent, ultimative biodegradability (70% degradability within 7 days).