6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide, potassium salt

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: sewage treatment simulation testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

February 2013 to July 2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Continous measurements were taken over a period of 6 month

GLP compliance:

not specified

Remarks:

It is a well conducted and documented study.

Radiolabelling:

no

Oxygen conditions:

aerobic/anaerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Remarks:

Approximately 90% of the wastewater was from municipal sources.

Details on inoculum:

Average operating parameters of the wastewater treatment plant:
- Mixed liquor suspended solids (MLSS): 1,756 mg/L
- Hydraulic retention time (HRT): 8.2 h
- Sludge retention time (SRT): 5.7 d
- Return activated sludge ratio: 35%
- Flow rate: 171,974 m³/d
Location: Ulu Pandan, Singapore

Initial conc.:

8 045 other: ng/L

Based on:

act. ingr.

Remarks:

Mean concentration in the influent

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

Between February 2013 and June 2013 samples were taken from wastewater before and after treatment in the sewage treatment plant. Samples were taken from the influent and from the secondary effluent. The samples were taken as grab samples and were filled in 1 L amber glass bottles and immediately transported to the laboratory in cooling containers. The samples were stored in the lab at 4°C in the dark. Samples were prepared for measurment within 10h after sampling to avoid any degradation.

Reference substance:

not required

Compartment:

wastewater

% Recovery:

100

St. dev.:

12

Remarks on result:

other: In the publication, a mean recovery of 119.5% and a relative standard deviation of 12.0% is reported.

Compartment:

activated sludge

% Recovery:

83.1

St. dev.:

9.7

Key result

% Degr.:

ca. 8

St. dev.:

8.8

Parameter:

test mat. analysis

Sampling time:

6 mo

Remarks on result:

other: given as "mean removal rate" during the measuring peroid (Feb-July). Total number of measurements: 6

Other kinetic parameters:

pseudo-first order rate constant

Transformation products:

no

Details on results:

Based on a lab experiment, the biodegradation rate constant kbio was determined to be 0.0448 and 0.0594 L/g MLSS d. Based on this, the authors conclude that Acesulfame K is persistent to biological treatment. A degradation in the sewage treatment plant takes place, if at all, only at a minor amount.

Validity criteria fulfilled:

not applicable

Conclusions:

Acesulfame K was rated as "persistent" as only a mean removal rate of 8% could be determined during the measuring period.

Description of key information

The mean removal rate of Acesulfame K in a wastewater treatment plant was determined over a period of 6 month. Samples were taken from the influent and the secondary effluent. Only a mean removal rate of 8% could be determined, indicating that the substance is persistent in the wastewater treatment plant.