2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one

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:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3220 (Porous Pot Test)

Deviations:

not specified

GLP compliance:

yes

Remarks:

Springbom Smithers Laboratories 790 Main Street Wareham, Massachusetts 02571-1037

Radiolabelling:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on source and properties of surface water:

- Details on collection: prepared from a Sybron/Bamstead NANOpure® water purification system (meets ASTM Type II requirements)

Details on source and properties of sediment:

- Details on collection: reference sludge

Details on inoculum:

- Source of inoculum/activated sludge: Wareham wastewater treatment
- Laboratory culture: no
- Preparation of inoculum for exposure: Exactly 1400 mL of activated sludge was added to the porous pots within four hours of collection and was aerated throughout the acclimation period. Dissolved oxygen (DO) levels were generally maintained at greater than 2 mg/L and averaged 4.5 and 4.6 mg/L for the test item and control units, respectively. Activated sludge was characterized at least three times during the work week (e.g. Monday, Wednesday, Friday) by measurement of pH, ammonia (NH3), MLSS, mixed liquor volatile suspended solids (MLVSS), and DO. Activated sludge was acclimated to the natural feed for one week prior to test initiation. After this one week acclimation period, two porous pot reactors were chosen for the definitive study.
- Concentration of sludge: 3.0 L of sewage

Duration of test (contact time):

3 wk

Initial conc.:

3 720 mg/L

Based on:

test mat.

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: 1.5-L glass cylinder bioreactors each containing a porous mesh stainless steel cylinder (tube)
- Test temperature: 22 ± 3 °C
- pH: 6.41 to 7.11
- pH adjusted: no
- Aeration of dilution water: yes
- Continuous darkness: yes (away from direct light)


TEST SYSTEM
- Culturing apparatus: 1.5-L glass cylinder bioreactors each containing a porous mesh stainless steel cylinder (tube)
- Number of culture flasks/concentration: 2


SAMPLING
- Sampling frequency: three times weekly in the sewage, activated sludge, influent and effluent:

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes

Reference substance:

benzoic acid, sodium salt

Key result

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

2 d

Transformation products:

not specified

Evaporation of parent compound:

not specified

Volatile metabolites:

not specified

Residues:

not specified

TEST CONDITIONS

The minimum/maximum temperature in environmental chamber ranged from 21.5 to 22.5 "C during the 21-day study, which was within the guideline value of 22 ± 3 °C. All parameters (D.O., pH, DOC, ammonia, percent moisture, total solids, MLSS and MLVSS) remained stable and within expectations and requirements throughout the study.

Ammonia levels remained very low indicating that ammonia was being oxidized to nitrate because of satisfactory DO levels. Biomass (MLVSS) was also increasing throughout the study. The data also indicates that the effluent DOC values for the test substance bioreactor averaged approximately 2 mg/L higher that the control unit receiving sodium benzoate. Since sodium benzoate is readily biodegradable, there is probably little if any residual DOC from the sodium benzoate in the control unit, and the excess 2 mg/L in the test substance unit may reflect degradation products. The DOC analysis results for the influent sewage which range from 42 to 82 ppm carbon throughout the 21-day study.

TEST SUBSTANCE BIODEGRADATION

The average test substance concentration in the sewage influent over the course of this study was 4.52 mg/L.

Almost complete primary biodegradation (98.6%) occurred by day 1 of the study, and complete primary biodegradation (100%) occurred by day 2 and the remainder of the study.

The chromatograms show the test substance at a retention time of 7.5 minutes. The day 9 influent sample is the same as the sewage feed sample but it was collected just before it dropped into the sludge. The influent also shows the test substance peak at 7.5 minutes and proved that the test substance was being transferred from the feed storage container to the activated sludge. The day 8 and 9 sludge and effluent chromatograms do not show the test substance, but do show some very small peaks at 5.1 through 5.7 minutes. These peaks do not appear in the raw sewage or in the reference control sludge or reference control effluent.

Validity criteria fulfilled:

yes

Conclusions:

The results of the study indicate that the test substance, when added to the sewage influent at 5 mg/L (3.70 mg C/L), underwent essentially complete primary biodegradation by day 2 of the study. DOC effluent levels from the test susbtance unit were consistently 2 to 3 mg/L higher than the control unit receiving sodium benzoate. This observation suggests that the test substance was transformed to several water-soluble organic compounds that were possibly detected by the HPLC/UV analytical method at retention times ranging from 5.1 to 5.7 minutes.

Executive summary:

In this study conducted to generally accepted scientific standards the test material (EC 444-860-9) was determined to be X.

Description of key information

Study conducted to generally recognised scientific standards with GLP.

Additional information

The test substance underwent essentially complete primary biodegradation by day 2 of the study.

A Porous Pot Test according OPPTS method 835.3220 and GLP has been conducted (Springborn Smithers Laboratories 2006). The purpose of this study was to determine the biodegradation of the non-radiolabeled test substance in activated sludge contained in a porous pot bioreactor under conditions simulating an actual wastewater treatment plant. The test substance (i.e., 5.00 mg a.i./L) was exposed to a concentration of microorganisms typical for conventional domestic activated sludge wastewater treatment plants and monitored for biodegradation via dissolved organic carbon (DOC) disappearance and chemical specific analysis. At each sampling interval, the concentration of the test substance in solution and adsorbed to activated sludge was determined by high performance liquid chromatography with ultraviolet detection (HPLC/UV) to evaluate potential biodegradation and adsorption of the test substance.

The results of the study indicate that the test substance, when added to the sewage influent at 5 mg/L (3.71 mg C/L), underwent essentially complete primary biodegradation by day 2 of the study. DOC effluent levels from the test substance unit were consistently 2 to 3 mg/L higher than the control unit receiving sodium benzoate. This observation suggests that the test substance was transformed to several water-soluble organic compounds that were possibly detected by the HPLC/UV analytical method at retention times ranging from 5.1 to 5.7 minutes.