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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Reason / purpose:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
Chemical oxygen demand (COD) was assessed by standard methods. The bio-chemical oxygen demand (BOD) was analysed using a Sapromat BOD measuring unit. Biological degradation-inhibition test was performed using the Offhaus method.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
not specified
Duration of test (contact time):
5 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
50
Sampling time:
5 d
Parameter:
BOD5
Value:
517 mg O2/g test mat.
Parameter:
COD
Value:
1 023 mg O2/g test mat.
Parameter:
BOD5*100/COD
Value:
50.54 other: %

The BOD5 test showed good biological degradation. The test item was degraded 50 % after a short exposure of 5 days.

Based on the observed respiration activity, it is expected that the biodegradation should take place undisturbed, even at higher concentrations and especially after certain adaptation.

Interpretation of results:
other: biodegradable according to Offhaus method
Conclusions:
The BOD5 was determined to be 517 mg O2/g for a substance with COD = 1023 mg O2/g.
The inhibition study showed negligible inhibition (5.4%), however not decreasing.
The test shows that after 5 days 50 % of the substance has degraded, but longer testing is needed to conclude on readily biodegradability.
Executive summary:

In this study, the biochemical oxygen demand (BOD) was analysed using a Sapromat BOD measuring unit and compared to the chemical oxygen demand (COD). Biological degradation-inhibition test was performed using the Offhaus method. It is not a GLP study and no OECD guideline was followed.

After 5 days, the BOD5 was determined to be 517 mg O2/g for L-histidine (COD = 1023 mg O2/g). The test is showing good biological degradation, i.e. 50 % after 5 days.

Based on the observed respiration activity, the degradation should take place undisturbed, even at higher concentrations and especially after certain adaptation.

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
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
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 conc.:
500 mg/L
Based on:
test mat.
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
Key result
Parameter:
% degradation (O2 consumption)
Value:
16.5
Sampling time:
24 h
Conclusions:
L-histidine showed good biodegradation within 24h, i.e. 16.5% of the initial test material was biodegraded within 24h. This study indicates that L-histidine 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-histidine 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 16.5 %. Even though this study does not allow conclusion on ready biodegradability of L-histidine, the study clearly shows that rapid biodegradation can be expected since within 24h nearly 17 % of the substance is biodegraded.

Description of key information

The study of Mueller and Neumann (1981) assessed the biodegradability of L-histidine in a Sapromat apparatus. The test was not performed according to GLP nor internationally accepted guidelines.

At a test concentration of ca. 200 mg/L, a BOD5 of 517 mg O2/g was determined. Histidine hase a COD value of 1023 mg O2/g. The test shows good biological degradation, i.e. 50 % biodegradation after 5 days.

Based on the observed respiration activity, the degradation should take place undisturbed, even at higher concentrations and especially after certain adaptation.

A second study on the biodegradability of L-histidine is available (Malaney and Gerhold). In this study dating back to

1969, the ability of activated sludges from 3 municipal waste treatment plants to oxidise amino acids

was investigared. The activated sludge (concentration 2500 mg/L) was exposed to L-histidine 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 16.5 %.

The test was not performed according to GLP nor internationally accepted guidelines.

Key value for chemical safety assessment

Additional information