3-nitrotoluene

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Principles of method if other than guideline:

batch system (comparable to Zahn-Wellens Test OECD TG 302B)

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): m-Nitrotoluene
- Analytical purity: no data

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): from a sewage plant, activated sludge, adapted for 20 days.
- Laboratory culture: cultivated in a 1000 ml cilinder
- Method of cultivation: The mixture is aerated with pressure air. Every day 200 ml of the mixture is driven off so that sludge age
is 5 days.
- Preparation of inoculum for exposure: After sedimentation ca. 600 ml of the liquid phase is driven off. The residue (200 ml of the thickened activated sludge) is diluted with tap water to the volume of ca. 800 ml and 600 mg/L of starch or glucose, 600 mg/L of pepetone, 25 ml of a phosphate buffer and the solution of the tested compund are added.
- Pretreatment: The mixture in the cilinder (see above) is made up to 1000 ml with tap water and aerated for 23 h. After this period the procedure is repeated, and the concentration of the test substance is gradually increased so that after 20 days of adaptation it reaches the value of 200 mg/L COD.
- Concentration of sludge: 100 mg/L (dry matter)

Duration of test (contact time):

120 h

Initial conc.:

200 mg/L

Based on:

COD

Details on study design:

The initial value of COD or organic carbon of the liquid phase are determined.
Samples (ca. 50-80 ml), filtered or centrifugated before analysis, are taken at suitable intervals.
The decrease of the test substance in the liquid phase is evaluated by determining COD
or organic carbon. The results are compared with those of a blank test and standard
compound decomposition.
With the degree of degradation also the average specific rate of degradation is determined,
expressed in terms of mg COD (or organic carbon) removed by a gramme of dry matter of the
activated sludge per hour.
The experiment is carried out till there is no decrease of COD. After that time the total percentage
of COD removed and the rate of degradation are evaluated.

Key result

Parameter:

other: based upon COD

Value:

98.5

Sampling time:

5 d

Details on results:

Degradation result based on COD removal; degradation rate: 21.0 mg COD/g/h

Validity criteria fulfilled:

not specified

Interpretation of results:

inherently biodegradable

Conclusions:

A test on inherent biodegradability was conducted. The test design is comparable to the Zahn-Wellens-test (OECD TG 302 B).
The test substance m-nitrotoluene in a concentration of 200 mg/l COD was the sole source of carbon. Activated sludge from a sewage treatment plant adapted for 20 days to m-nitrotoluene was used as inoculum in a concentration of 100 mg/l dry matter. Based on COD measurement, a removal of 98.5 % within 5 days was obtained.

Executive summary:

Pitter, 1976

A test on inherent biodegradability was conducted. The test design is comparable to the Zahn-Wellens-test (OECD TG 302 B).
The test substance m-nitrotoluene in a concentration of 200 mg/l COD was the sole source of carbon. Activated sludge from a sewage treatment plant adapted for 20 days to m-nitrotoluene was used as inoculum in a concentration of 100 mg/l dry matter. Based on COD measurement, a removal of 98.5 % within 5 days was obtained.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

14 day-test

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): m-Nitrotoluene
- Analytical purity: >99%

Oxygen conditions:

aerobic

Inoculum or test system:

other: sludge sampling from different sewage plants, natural waterbodies and soil

Details on inoculum:

1. Sludge sampling sites and time

1.1. Time: in March, June, September, and December, sludge was sampled
1.2. Sites (Japan): 1. Fukogawa city sewage plant, 2. Fukashiba industry sewage plant, 3. Nakahama city sewage plant, 4. Ochiai city sewage plant, 5. Kitakami river, 6. Shinano river, 7. Yoshino river, 8. Lake Biwa, 9. Hiroshima bay, 10. Dookai bay
A mixture composed of city and industry sewage and river, lake and sea surface water and soil was tested.

2. Sludge sampling method

2.1. City sewage: Returned sludge from sewage plants was taken.
2.2. Rivers, lake and sea: Surface water and surface soil which were in contact with atmosphere were collected.

3. Method of cultivation

3.1. Mixing of fresh and old activated sludge: 5 L of the filtrate of the supernatant of old activated sludge was mixed with 500 mL of the filtrate of the supernatant of new sludge and cultured at pH 7.0 ± 1.0 under sufficient aeration using prefiltered open air.

3.2. Culture: About 30 minutes after ceasing aeration to the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed. Then the equal volume of dechlorinated water was added to the remaining portion and aerated again, followed by addition of synthetic sewage at aconcentration of 0.1% (w/v). This procedure was repeated once every day. The culturing was carried out at 25 ± 2 °C.

3.3. Control: During the cultivation, appearance of the supernatant, precipitability, formation of flock, pH, dissolved oxygen concentration in the solution and temperature were checked and necessary adjustments were made, Microflora in the activated sludge was microscopically observed and sludge with no abnormal symptom was used for the test.

4. Inspection of activity

Activity of the sludge was inspected to use reference substance. And the relation between new and old activated sludge was taken account.

5. Adaptation

There is no specific statement about the adaptation of the used microorganisms but the sampling sides and culture conditions suggest not adapted microorganisms.

6. Concentration of sludge: 30 mg/L

Duration of test (contact time):

14 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test performed in open system: no
Preparation of basal culture medium (sludge):
- Suspended solids concentration: determined according to Method Japanese Industrial Standards (JIS) K 0102-1986-14.1
- Composition of basal culture medium: 3 mL each of four stock solutions, as described in JIS K 0102-1986-21, are diluted to 1000 mL with purified water
- pH of basal culture medium: 7.0
- pH adjusted: yes
Test system:
- Abiotic sterile control: 300 ml purified water + 30 mg test substance
- Test solution: 300 ml basal culture medium (sludge) + 30 mg test substance
- Reference: 300 ml basal culture medium (sludge) + 30 mg aniline
- Inoculum blank: 300 ml sludge
Test instruments and conditions:
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (Coulometer: Ohkura Electric Co., Ltd.)
- Vessel size: 300 mL in volume
- absorbent for evolving carbon dioxide: Soda lime No .l (extra pure reagent, Wako Pure Chemical Industries, Ltd.).
- stirring method: test solution was stirred by a magnetic stirrer
- cultivating temperature: 25 ± 1°C
- reference substance: aniline
Analysis after termination of the test:
- TOC
- test substance
- pH

Degradation (%) was obtained from the following equations:
BOD: Degradation (%) = (BOD-B)/ThOD x 100 BOD (mg):
BOD in (sludge + m-Nitrotoluene system)
B (mg): BOD in sludge blank
ThOD: theoretical oxygen demand
required when m-Nitrotoluene was completely oxidized.

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

14 d

Results with reference substance:

Degradation of aniline: 77%.

Validity criteria fulfilled:

not specified

Remarks:

Normally, the test lasts for 28 days. Tests however may be ended before 28 days, i.e. as soon as the biodegradation curve has reached a plateau for at least three determinations.

Interpretation of results:

not readily biodegradable

Conclusions:

In a modified MITI I test according to OECD guideline 301 C a non adapted mixed microbial inoculum mineralised 2 % of the initial test substance concentration within 14 days (MITI, 1992).

Executive summary:

In a modified MITI I test according to OECD guideline 301 C a non adapted mixed microbial inoculum mineralised 2 % of the initial test substance concentration within 14 days (MITI, 1992).

Description of key information

MITI, 1992 (ready biodegradability)

In a modified MITI I test according to OECD guideline 301 C a non adapted mixed microbial inoculum mineralised 2 % of the initial test substance concentration within 14 days.

Pitter, 1976 (inherent biodegradability)

A test on inherent biodegradability was conducted. The test design is comparable to the Zahn-Wellens-test (OECD TG 302 B).
The test substance m-nitrotoluene in a concentration of 200 mg/l COD was the sole source of carbon. Activated sludge from a sewage treatment plant adapted for 20 days to m-nitrotoluene was used as inoculum in a concentration of 100 mg/l dry matter. Based on COD measurement, a removal of 98.5 % within 5 days was obtained.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater