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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-11-10 to 2016-12-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
July 1992
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Bis(N,N-dimethylpropane-1,3-diamine-N)[29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32]cobalt(1+) chloride
EC Number:
284-943-5
EC Name:
Bis(N,N-dimethylpropane-1,3-diamine-N)[29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32]cobalt(1+) chloride
Cas Number:
84989-53-7
Molecular formula:
C42H44CoN12.Cl
IUPAC Name:
hydroxylamine
Test material form:
solid: particulate/powder

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: municipal wastewater treatment plant Breisgauer Bucht Germany, 600,000 inhabitant equivalents, predominantly domestic wastewater.
- Concentration of sludge: 4.2 g/L after drying at 105°C for 3h
- Initial cell/biomass concentration: 30 mg d.s./L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
>= 20.1 - <= 20.2 mg/L
Based on:
TOC
Remarks:
calculated based on molecular structure
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium according to guideline
- Additional substrate: no
- Solubilising agent: no
- Test temperature: room temperature - 20.5 to 23.1 °C
- pH: not registered
- pH adjusted: no
- Aeration of dilution water: 2.5 - 4.3 bubbles/second or 30-100 mL/min with CO2-free air
- Suspended solids concentration: 30 mg dry solids/L
- Continuous darkness: no, diffuse light


TEST SYSTEM
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: aeration with CO2-free air
- Measuring equipment: Total organic carbon analyser TOC-5050A with autosampler ASI 5000A, Shimadzu.
- Details of trap for CO2 and volatile organics if used: two 250 mL glass wash bottles in series each filled with 200 mL 0.2 M NaOH (IC = 4.4 mg/L), sampling through lateral connecting pieces, through butyl rubber septum using 5 mL PE syringes

SAMPLING
- Sampling frequency: on day 4, 7, 11 14, 21 and 28
- Sampling method: 4 mL of NaOH sampled from 1st CO2-absorber flasks
- Sample storage before analysis: samples immediately closed with sealing film
- Final sampling: on day 28, 2mL of 4M HCl is added to the reactor to release CO2 dissolved in water. IC-analysis on day 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 replicates
- Abiotic sterile control: no
- Toxicity control: yes, 1 replicate at 40.0 mg/L TOC (1:1 test substance and reference substance)
- Reference substance: 3 replicates at 20 mg/L

Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
-3.8
St. dev.:
3.38
Sampling time:
28 d
Remarks on result:
other: as measured after acidification of the reactor flasks to release CO2 dissolved in water on day 29
Remarks:
mean of 3 replicates
Details on results:
Biodegradability remained very low. The maximum degradation reported was -3.8 % of ThCO2.

BOD5 / COD results

Results with reference substance:
The reference substance was rapidly biodegraded, with maximal degradation of 85.2 % ThCO2 after 28 days.

Any other information on results incl. tables

Ultimate biodegradation as % of ThCO2

Reactor day 0 day 4 day 7 day 11 day 14 day 21 day 28 day 29
Test item, rep 1 0 -6.7 -7.5 1.1 -4.8 -3.5 -2.5 -2.9
Test item, rep 2 0 -5.1 -7.3 -4.4 -4.3 -6.9 -6.6 -7.5
Test item, rep 3 0 -5.2 -6.4 -0.7 -4.3 0.3 -0.6 -0.9
Reference, rep 1 0 71 80.8 79.2 83 77.1 82.4 84
Reference, rep 2 0 77.6 79.1 80.5 85 80.2 86 87.1
Reference, rep 3 0 68.5 77.6 77.1 84.1 76.7 82.6 84.6
Toxicity control 0 -3.4 24.3 32.3 36.8 37.4 41.4 41.8

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The biodegradability of the test item was examined in a CO2-evolution test according to OECD 301B. The test item was found to be not readily biodegradable with on average -3.8 % of ThCO2 biodegradation after 28 days.
Executive summary:

The biodegradability of the test item was examined in a CO2-evolution test according to OECD 301B. After 28 days, the ultimate biodegradation was found to be -3.8 % (average of 3 replicates). The biodegradation never exceeded 10 % hence, the 10 -day window criteria was not met and the test item should be considered to be not readily biodegradable.

The reference substance degraded 85 % after 28 days. Up to 41.8 % degradation was observed in the toxicity control containing sodium benzoate and the test item. This result shows that the test item was not inhibitory to the inoculum.

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