Melamine

Mode of degradation in actual use

Administrative data

Endpoint:

mode of degradation in actual use

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication. No GLP.

Data source

Reference

Title:

Unnamed

Year:

2013

Materials and methods

Test guideline

Qualifier:

no guideline required

Principles of method if other than guideline:

The objective of this study was to determine the fate and toxicity of melamine in activated sludge systems and to evaluate whether long-term sludge adaptation can improve melamine degradation.

GLP compliance:

not specified

Type of study / information:

Degradation of melamine in 2 common activated sludge processes.

Test material

Test material information

Constituent 1

Reference substance name:

Melamine

EC Number:

203-615-4

EC Name:

Melamine

Cas Number:

108-78-1

Molecular formula:

C3H6N6

IUPAC Name:

1,3,5-triazine-2,4,6-triamine

Test material form:

not specified

Details on test material:

Purity: 99 %Supplier: Acros Organics.

Results and discussion

Any other information on results incl. tables

Even after 100 days of sludge adaptation, melamine appeared not to be easily biodegradable. The average melamine removal efficiencies in the Modified Ludzack-Ettinger (MLE) process and the continuous stirred tank reactor (CSTR) process were 14 ± 10 % and 20 ± 15 %, respectively. There was no significant difference in melamine removal between the two different activated sludge processes.

The long-term input of melamine resulted in a decrease in the nitrifying bacterial activities (by 82 ± 8 %) and population in both systems.

Short-term microtiter assay results also showed that melamine reduced activated sludge growth by 80 % when supplied at a concentration of 75.6 mg/L. These results suggest that sludge adaptation plays a minimal role in melamine degradation, as the enzymes responsible for hydrolytic deamination of melamine in activated sludge are not easily induced.

The insignificant biodegradation of melamine is also attributed to bacterial growth inhibition under long-term dosing conditions with melamine, resulting in a significant decrease in effluent water quality.

Applicant's summary and conclusion

Conclusions:

Melamine is not easily biodegradable even after a long period of sludge adaptation.
The long-term input of melamine resulted in a decrease in the nitrifying bacterial activities.

Executive summary:

The degradation of melamine and its impact on activated sludge operations by employing two common activated sludge processes, namely the Modified Ludzack-Ettinger (MLE) process and the continuous stirred tank reactor (CSTR) process was investigated. Melamine was dosed continuously from day 125 in both activated sludge treatment systems at an influent concentration of 3 mg/L for about 100 days. Even after such a long period of sludge adaptation, melamine appeared not to be easily biodegradable. The average melamine removal efficiencies in the CSTR and MLE systems were 14 ± 10 % and 20 ± 15 %, respectively. There was no significant difference in melamine removal between the two different activated sludge processes. The long-term input of melamine resulted in a decrease in the nitrifying bacterial activities (by 82 ± 8 %) and population in both systems. Short-term microtiter assay results also showed that melamine reduced activated sludge growth by 80 % when supplied at a concentration of 75.6 mg/L. These results suggest that sludge adaptation plays a minimal role in melamine degradation, as the enzymes responsible for hydrolytic deamination of melamine in activated sludge are not easily induced. The insignificant biodegradation of melamine is also attributed to bacterial growth inhibition under long-term dosing conditions with melamine, resulting in a significant decrease in effluent water quality.