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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: screening test, other
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1969

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Activated sludge was exposed to chemicals, oxygen uptake was measured during 24h using the Warburg respirometer.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
L-isoleucine
EC Number:
200-798-2
EC Name:
L-isoleucine
Cas Number:
73-32-5
Molecular formula:
C6H13NO2
IUPAC Name:
L-isoleucine
Test material form:
solid: crystalline

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): 3 sources of activated sludge
Source 1: Columbus, Ohio, municipal treatment plant, combined domestic and industrial wastewater
Source 2: Hilliard, Ohio, municipal treatment plant, domestic wastewater
Source 3: Brookside estates, Linworth, Ohio, residential wastewater
- Storage length: sample taken from aeration tank on day experiment started
- Preparation of inoculum for exposure: sludge suspension was blended for 10 sec and 20 ml was pipetted into the Warburg flasks
- Concentration of sludge: 2500 mg/L
- Water filtered: no
Duration of test (contact time):
24 h
Initial test substance concentration
Initial conc.:
500 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 20 °C

TEST SYSTEM
- Measuring equipment: Warburg respirometers, readings 0.5 to 5 h intervals

CONTROL AND BLANK SYSTEM
- Inoculum blank: control flask included with each run

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
14.8
Sampling time:
24 h

Applicant's summary and conclusion

Conclusions:
L-isoleucine showed good biodegradation within 24h, i.e. 14.8% of the initial test material was biodegraded within 24h. This study indicates that L-isoleucine has a potential to readily biodegrade.
Executive summary:

This study investigated the ability of activated sludges from 3 municipal waste treatment plants to oxidise amino acids. The activated sludge (concentration 2500 mg/L) was exposed to L-isoleucine at a concentration of 500 mg/L. The biodegradation was assessed during 24h by measurement of the O2 consumption using Warburg flasks.

The average biodegradation (as % of theoretical oxygen demand) over the 3 activated sludges was 14.8 %. Eventhough this study does not allow conclusion on ready biodegradability of L-isoleucine, the study clearly shows that rapid biodegradation can be expected since within 24h nearly 15 % of the substance is biodegraded.