Disodium piperazine-1,4-diethanesulphonate

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:

11 Sep 2017 to 12 Nov 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Appearance: White powder
Test item storage: At room temperature
Stable under storage conditions until: 30 November 2018 (retest date)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Source: The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
Treatment: The freshly obtained sludge was used immediately. The concentration of suspended solids was determined to be 4.9 g/L (data obtained from the sewage treatment plant. Before use, the sludge was allowed to settle (approximately 30 minutes) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.
Reason for selection: The test has been accepted internationally for determining the 'ready' biodegradability of test items under aerobic conditions.
Test duration: 28 days for the inoculum blank and test item (last CO2 measurement on day 29). 14 days for the positive and toxicity control (last CO2 measurement on day 15). During the test period, the test media were aerated and stirred continuously.
Test vessels: 2 litre brown coloured glass bottles.
Milli-RO water: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon.

Synthetic air (CO2 < 1 ppm)1: A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. The synthetic air was passed through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).
Illumination: The test media were excluded from light.

Preparation of Bottles
Pre-incubation medium: The day before the start of the test (day -1) mineral components, Milli-RO water (ca. 80% of final volume) and inoculum (1% of final volume) were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
Type and number of bottles: Test suspension: containing test item and inoculum (2 bottles). Inoculum blank: containing only inoculum (2 bottles)
Positive control: containing reference item and inoculum (1 bottle). Toxicity control: containing test item, reference item and inoculum (1 bottle).
Preparation: At the start of the test (day 0), test and reference item were added to the bottles containing the microbial organisms and mineral components. The volumes of suspensions were made up to 2 litres with Milli-RO water, resulting in the mineral medium described before.
Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit air line of each test bottle.

Duration of test (contact time):

28 d

Initial conc.:

43.5 mg/L

Based on:

test mat.

Remarks:

corresponding to 12 mg TOC/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Source: The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
Treatment: The freshly obtained sludge was used immediately. The concentration of suspended solids was determined to be 4.9 g/L (data obtained from the sewage treatment plant. Before use, the sludge was allowed to settle (approximately 30 minutes) and the supernatant liquid was used as inoculum at the
amount of 10 mL/L of mineral medium.
Reason for selection: The test has been accepted internationally for determining the 'ready' biodegradability of test items under aerobic conditions.

Test Procedure and Conditions
Test duration: 28 days for the inoculum blank and test item (last CO2 measurement on day 29). 14 days for the positive and toxicity control (last CO2
measurement on day 15). During the test period, the test media were aerated and stirred continuously.
Test vessels: 2 litre brown coloured glass bottles.
Milli-RO water: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon.
Stock solutions of mineral components: A)8.50 g KH2PO4
21.75 g K2HPO4
67.20 g Na2HPO4.12H2O
0.50 g NH4Cl
dissolved in Milli-RO water and made up to 1 litre, pH 7.4 ± 0.2
B)22.50 g MgSO4.7H2O dissolved in Milli- RO water and made up to 1 litre.
C)36.40 g CaCl2.2H2O dissolved in Milli-RO water and made up to 1 litre.
D)0.25 g FeCl3.6H2O dissolved in Milli-RO water and made up to 1 litre.
Mineral medium: 1 litre mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B) to (D) and Milli- RO water.
Barium hydroxide: 0.0125 M Ba(OH)2 (Boom, Meppel, The Netherlands), stored in a sealed vessel to prevent absorption of CO2 from the air.
Synthetic air (CO2 < 1 ppm)1: A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle, containing 0.5 - 1 litre 0.0125 M
Ba(OH)2 solution to trap CO2 which might be present in small amounts. The synthetic air was passed through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).
Illumination: The test media were excluded from light.

Reference substance:

other: Sodium acetate

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

based on ThCO 2

Value:

9

Sampling time:

28 d

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

based on ThCO 2

Value:

0

Sampling time:

28 d

Details on results:

Details of the results can be found in the attachment on the background section below.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In conclusion, 1,4 piperazinediethanesulfonic acid disodium salt was not readily biodegradable under the conditions of the modified Sturm test presently performed.

Executive summary:

The objective of the study was to evaluate the non-volatile test item 1,4 piperazinediethanesulfonic acid disodium salt for its ready biodegradability in an aerobic

aqueous medium with microbial activity introduced by inoculation with the supernatant of activated sludge; Carbon dioxide (CO2) evolution test (modified Sturm test).

The study procedures described in this report were in compliance with the OECD guideline No. 301 B, 1992. 1,4 piperazinediethanesulfonic acid disodium salt was a white powder with a purity of 100.6% (assay, titration). The test item was tested in duplicate at a concentration of 43.5 mg/L, corresponding to 12 mg TOC/L. The organic carbon content was based on the molecular formula. The Theoretical CO2 production (ThCO2) of 1,4 piperazinediethanesulfonic acid disodium salt was calculated to be 1.02 mg CO2/mg.

The study consisted of six bottles:  

- 2 inoculum blanks (no test item),

- 2 test bottles (1,4 piperazinediethanesulfonic acid disodium salt),

- 1 positive control (sodium acetate) and

- 1 toxicity control (1,4 piperazinediethanesulfonic acid disodium salt plus sodium acetate).

Since 1,4 piperazinediethanesulfonic acid disodium salt was easily soluble in water the test media were prepared using a stock solution of 1 g/L in Milli-RO water. Aliquots of 87 mL of the clear and colourless stock solution were added to the test item bottles A and B and to the toxicity control. These test bottles contained medium with microbial organisms. The volumes of suspensions were made up to 2 litres with Milli- RO water. The test solutions were continuously stirred during the test, to ensure optimal contact between the test item and the test organisms. Test duration was 28 days for the inoculum blank and test item (last CO2 measurement on day 29) and 14 days for the positive and toxicity control (last CO2 measurement on day 15). The relative biodegradation values calculated from the measurements performed during the

test period revealed no biologically significant biodegradation of 1,4 piperazinediethanesulfonic acid disodium salt (9% and 0%, based on ThCO2). In the toxicity control, 1,4 piperazinediethanesulfonic acid disodium salt was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. In conclusion, 1,4 piperazinediethanesulfonic acid disodium salt was designated as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater