Methenamine

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water and sediment: simulation testing, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: public available literature (non GLP, pH not indicated)

Qualifier:

according to guideline

Guideline:

EU Method C.10 (Biodegradation: Activated Sludge Simulation Test)

Deviations:

not specified

GLP compliance:

not specified

Radiolabelling:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on source and properties of surface water:

not indicated.

Details on source and properties of sediment:

not indicated.

Details on inoculum:

not indicated.

Duration of test (contact time):

9 wk

Initial conc.:

17.5 - 20 mg/L

Based on:

other: C

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The activated sludge simulation test was carried out as described by the EEC. Both Husmann and WRc porous pot units were used in the direct non-coupled mode treating Stevenage settled domestic sewage at a retention time of 3 h and a sludge age of 6 d. These conditions resulted in concentrations of suspended solids in the activated sludge mixed liquor of 3000 - 4000 mg/L. In most experiments the temperature was kept in the range 18-25°C, but in some it was deliberately maintained at 25°C.

Reference substance:

not specified

Test performance:

not indicated.

Key result

% Degr.:

>= 12 - <= 21

Parameter:

DOC removal

Sampling time:

3 wk

Transformation products:

not specified

No.:

#1

Details on transformation products:

not examined.

Details on results:

DOC-elimination rates of 12-21 % after 3 weeks were obtained in an activated sludge simulation test (hydraulic retention time: 3 h, sludge age: 6 d).

Results with reference substance:

no reference-substance.

Validity criteria fulfilled:

not specified

Conclusions:

In a statutory 9 -week simulation tests, the removal of methenamine was investigated and found to not exceed 21% DOC. Removal was not increased when the temperature was elevated to 23 -25°C instead of the standard temperature of 18 -20°C. Examination of the experiment a further week did also not affect the degradation rate.

Executive summary:

DOC-elimination rates of 12-21 % after 3 weeks were obtained in an activated sludge simulation test (hydraulic retention time: 3 h, sludge age: 6 d). As the stock solutions feeding the activated sludge unit were made up weekly, a certain degree of hydrolysis has to be assumed before the stock solution enters the simulation plant.

Description of key information

In a statutory 9-week simulation tests, the removal of methenamine was investigated and found to not exceed 21 % DOC. Removal was not increased when the temperature was elevated to 23 - 25 °C instead of the standard temperature of 18 - 20 °C. Examination of the experiment a further week did also not affect the degradation rate.