By-product from Guanidinoacetic acid manufacturing

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:

2020-02-19 - 2020-06-04

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)

Version / remarks:

1992-07-17

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

200116MA1 liquid
Total dissolved solids: 18 %

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Aerobic activated sludge, microorganisms from a
domestic waste water treatment plant was supplied
by the sewage treatment plant Rossdorf, Germany.

The aerobic activated sludge used for this study was
deposited for 15 min, washed by centrifugation and
the supernatant liquid phase was decanted. The solid
material was re-suspended in test water and
centrifuged again. This procedure was done three
times. An aliquot of the final sludge suspension was
weighed, dried and the ratio of wet sludge to its dry
weight was determined. Based on this ratio,
calculated aliquots of washed sludge suspension,
corresponding to 3.5 g dry material per litre were
mixed with test water and aerated. This
suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial conc.:

92.3 mg/L

Based on:

test mat.

Remarks:

total dissolved solids

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 10

Sampling time:

28 d

Results with reference substance:

The reference item sodium benzoate was degraded to more than 60 % after 6 days of incubation.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation rate of By-product from GAA manufacturing neither reached 60 % within the 10-
day window nor after 28 days.
Therefore, Guanidinoacetic acid - Mother liquor is
considered to be not readily biodegradable.

Executive summary:

Nitrogen is part of the molecular structure of the test
item; therefore nitrification (ThODNO3) was
considered for the evaluation of the results. The
criterion for ready biodegradability under the
conditions of a manometric respirometry test is the
degradation of the test item of at least 60 %, reached
within a 10-day window; the 10-day window starts
when the degradation of the test item reaches at
least 10 % degradation.
The mean biodegradation of 10 % of By-product from GAA manufacturing was reached at day 6, when
based on ThODNH4 and was never reached during the
incubation time of 28 days when based on ThODNO3.
At the end of the 10-day window at day 16, the mean
degradation of By-product from GAA manufacturing
was 10 % (ThODNH4) and therefore the 10 day window
criterion was not passed. The mean biodegradation
at test end after 28 days was 12 % (ThODNH4) and 3 %
(ThODNO3).

The nitrite-N+nitrate-N formation rate after 28 days
of incubation in the controls was 1.651 mg/L (mean).
The nitrite-N+nitrate-N formation rate in the test
item treated vessels was 1.616 mg/L (mean). The
degradation considering the nitrification process was 12 % and in the same range as the degradation based
on ThODNH4. Therefore it is assumed that the
nitrification process was inhibited.

Description of key information

By-product from Guanidinoacetic acid manufacturing was tested for ready biodegradability in GLP study acording to OECD Testguideline 301F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992.

Unter the conditions of the test the test item is not ready biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater