4-hydroxybenzaldehyde

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:

2001-08-02 to 2002-06-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

standard activated sludge 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: basic culture medium prepared according to guideline
- pH: 7
- pH adjusted: yes, with 1N, H3PO4
- Aeration of dilution water: no
- Continuous darkness: yes/no

TEST SYSTEM
- Culturing apparatus: BOD bottles
- Measuring equipment: Total organic carbon meter (TOC Meter)
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: measured for 28 days
- Sampling method: the biological oxygen demand (BOD) associated with the degradation of the test substance in the presence of standard activated sludge was measured over time using a closed oxygen consumption measurement device

CONTROL AND BLANK SYSTEM
- Test substance degradation system: 2
- Inoculum blank: 2
- procedure control: 1
- Toxicity control: 1

Reference substance:

aniline

Remarks:

100 mg/L

Test performance:

For the degradation activity confirmation system (aniline + standard activated sludge + basic culture medium), the basic culture medium was added to a culture bottle, 30 mg of aniline was weighed in a glass cup, added and mixed to the medium, and standard activated sludge weighing between 30.0 – 30.2 mg/L was added to the culture bottle.
For the Basic sludge respiration system (standard activated sludge + basic culture medium), the basal medium was placed in a culture bottle and standard activated sludge was added.
For the test substance degradation system (test substance + standard activated sludge + basic culture medium), the basic culture medium was inserted into a culture bottle, then 30.0 mg of the test substance was weighed in a glass cup, added to the medium and mixed, then standard activated sludge was added to each culture bottle.
For the Aqueous stability system (test substance + Millipore water), 300 mL of Millipore water was inserted into a culture bottle and 30.0 mg of the test substance, which was weighed in a glass cup, was added.
Initially, the biological oxygen demand (BOD) associated with the degradation of the test substance in the presence of standard activated sludge was measured over time using a closed oxygen consumption measurement device over 28 days, and after BOD measurement was complete, the dissolved organic carbon concentration (DOC) and the residual test substance concentration were measured.

Key result

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

28 d

Details on results:

In the underwater stability system, DOC in test no. 1 was 64.2 mg/L, and DOC in test No. 3 was 72.0 mg/L. The degradation rate from DOC after 28 days was 100% in all cases. The degradation is considered to be favorable.

Results with reference substance:

The BOD degradation of aniline after 7 days was 56% in experiment 1 and 59% in experiment 3, and the activity of standard activated sludge was favorable in both cases.

Measured values (after 28 days)

Measurement items	Test substance degradation system*				Aqueous stability		Preparation
Test no.:	1		3		1	3	Theoretical
Bottle no.	4	5	4	5
BOD, mg	56.0	54.4	55.7	55.0	8.0	0.0	59.0
DOC, mg/L (TOC)	0.0	0.0	0.0	0.0	64.2	72.0	68.8
Test substance, mg/L (HPLC)	0	0	0	0	72.6	95.9	100.0

* Values after measured values were corrected using the sludge basic absorption system

 

Degradation after 28 days

Degradation		Test substance degradation system				Mean
	Test no.	1		3
	Bottle no.	4	5	4	5
Degradation from BOD, %		95	92	94	93	94
Degradation from DOC, %		100	100	100	100	100
Degradation from residual test substance concentration, %		100	100	100	100	100

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Since the mean decomposition from BOD is 94 %, the mean decomposition from DOC is 100 %, and the decomposition from the remaining concentration of the test substance is 100 %, the test substance is judged to exhibit favorable degradability.

Executive summary:

The Ready biodegradability of the test item was assessed in a Closed Bottle Test according to OECD Guideline for Testing of Chemicals No. 301 D over a period of 28 days at 24.9 - 25.0 °C in darkness. The biodegradation was followed by the DOC removal. As a reference item, Aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. pH values at before and after the BOD measurement did not change in both the test substance decomposition system and the underwater stability system. BOD degradation rate of aniline after 7 days was 56 % in the test no. 1 and 59 % in the test no. 3. The activity of the standard activated sludge was good. BOD after 28 days was 78.6 mg, 56.0 mg, 54.4 mg in test no. 1 and 34.6 mg, 55.7 mg, and 55.0 mg in test no.3 (corrected with the measurement value of the sludge basic respiration system, all of which are No. 3, 4, 5 in the same order as in this section) in the test substance decomposition system against the theoretical oxygen demand (59.0 mg). Although there is no abnormality in the device and operation, in test no. 1 BOD of the test substance decomposition system was abnormally high and in test no. 3 BOD of the test substance decomposition system was abnormally low. Since these were considered as outlier, these were rejected as outlier with a risk rate of 5 % as a result of a rejection test by the Grubbs method. Degradation rate from BOD after 28 days using the values not rejected in Experiments 1 and 3 were 95 % and 92 % in Experiment 1, 94 % and 93 % in Experiment 3, and the average was 94 %. Degradability of this substance is considered to be good. The structure of the test substance partially changes in water, but it is judged that both the test substance and the structurally changed substance are completely mineralized by the activated sludge. From the results that the degradation rates were average 94 % from BOD, 100 % from DOC and 100 % from the residual concentration of test substance, the test substance is judged to be readily biodegradable.

Description of key information

From the results that the degradation rates were average 94 % from BOD, 100 % from DOC and 100 % from the residual concentration of test substance, the test substance is judged to be readily biodegradable (reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The Ready biodegradability of the test item was assessed in a Closed Bottle Test according to OECD Guideline for Testing of Chemicals No. 301 D over a period of 28 days at 24.9 - 25.0 °C in darkness. The biodegradation was followed by the DOC removal. As a reference item, Aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. pH values before and after the BOD measurement did not change in both the test substance decomposition system and the underwater stability system. BOD degradation rate of aniline after 7 days was 56 % in the test no. 1 and 59 % in the test no. 3. The activity of the standard activated sludge was good. BOD after 28 days was 78.6 mg, 56.0 mg, 54.4 mg in test no. 1 and 34.6 mg, 55.7 mg, and 55.0 mg in test no. 3 (corrected with the measurement value of the sludge basic respiration system, all of which are No. 3, 4, 5 in the same order as in this section) in the test substance decomposition system against the theoretical oxygen demand (59.0 mg). Although, there is no abnormality in the device and operation, in test no. 1 BOD of the test substance decomposition system was abnormally high and in test no. 3 BOD of the test substance decomposition system was abnormally low. Since these were considered as outliers, these were rejected as outliers with a risk rate of 5 % as a result of a rejection test by the Grubbs method. Degradation rate from BOD after 28 days using the values not rejected in Experiments 1 and 3 were 95 % and 92 % in Experiment 1, 94 % and 93 % in Experiment 3, and the average was 94 %. Degradability of this substance is considered to be good. The structure of the test substance partially changes in water, but it is judged that both the test substance and the structurally changed substance are completely mineralized by the activated sludge. From the results that the degradation rates were average 94 % from BOD, 100 % from DOC and 100 % from the residual concentration of test substance, the test substance is judged to be readily biodegradable (reference 5.2.1-1).