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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

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:
other: Guideline study with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 4,4'-diaminostilbene-2,2'-disulfonic acid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): In March, June, September, and December, sludge was sampled at the following 10 places in 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; sampling: 1. City sewage: Returned sludge from sewage plants was taken. 2. Rivers, lake and sea: Surface water and surface soil which were in contact with atmosphere were collected.
- Method of cultivation: 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 a concentration of 0.1% (w/v). This procedure was repeated once every day. The culturing was carried out at 25 ± 2 °C. 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. 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.
- Concentration of sludge: 30 mg/L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of 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: 7.0
- pH adjusted: yes
- Suspended solids concentration: determined according to Method Japanese Industrial Standards (JIS) K 0102-1986-14.1

TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (Coulometer: Ohkura Electric Co., Ltd.); 300 mL vessel, absorbent for evolving carbon dioxide Soda lime No .l (extra pure reagent, Wako Pure Chemical Industries, Ltd.).
- Number of culture flasks/concentration: 1
- Measuring equipment: Coulometer, Okhura Electric Co., Ltd.
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: soda lime, extra pure, Wako Pure Chemical Industries, Ltd.)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: no

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d

Applicant's summary and conclusion

Interpretation of results:
readily biodegradable