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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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The results of a CAS test (OECD 303A, GLP, reliability 1) demonstrate that the substance is removed by > 99.99% from the waste water in conventional biological waste water treatment plants. Chemical analysis of the test substance confirmed that removal occured primarily via biodegradation.

In accordance with column 2 (9.2.1.2) of REACH (Regulation 1907/2006/EC) Annex IX, simulation testing on biodegradation in water and sediment is not needed as the substance is readily biodegradable.

Key value for chemical safety assessment

Additional information

Removal in STP (OECD 303A)

Behavior of organic substances in biological wastewater treatment systems is mainly determined by their biodegradability, capacity to adsorb, and evaporation.SimpleTreat does integrate adsorption, stripping and biodegradation (Struijset al., 1991, Struijs, 1996). The justification of read-across of removal of organic substances from wastewater in biological treatment systems should therefore be based on these properties. The fate of Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl in wastewater treatment systems is assessed through read across with di (2-hydroxy ethyl) oleyl amine. The removal of di (2-hydroxy ethyl) oleyl amine has been determined in a CAS test.

The removal of the readily biodegradable di (2-hydroxyl ethyl) oleyl amine (CAS no: 25307-17-9) in biological treatment plants was assessed in continuously-fed activated sludge (CAS) unit fed with domestic wastewater spiked with di (2-hydroxyl ethyl) oleyl amine (Akzo Nobel, 2010). Di (2-hydroxyl ethyl) oleyl amine was exposed to micro-organisms maintained by addition of domestic wastewater in the CAS test. Di (2-hydroxyl ethyl) oleyl amine was spiked at nominal influent concentrations of 50 mg/L (37.0 mg/L carbon; calculated) for a period of 48d and included a control fed with domestic wastewater only.

The mean carbon removal percentage of di (2- hydroxyl ethyl) oleyl amine calculated over 15 measurements of the test was 102± 0.8% (95% confidence interval). These high removal percentages strongly indicate that di (2-hydroxyl ethyl) oleyl amine is biodegraded completely. Formation of water soluble compounds during biological treatment of di (2-hydroxyl ethyl) oleyl amine can be excluded. An accurate assessment of the removal of di (2-hydroxyl ethyl) oleyl amine was established with specific analyses. The mean removal percentage of di (2-hydroxyl ethyl) oleyl amine in the test unit was >99.999% using octadecenyl di (2-hydroxyethyl) amine as most representative component. These analyses demonstrate that the removal of di (2-hydroxyl ethyl) oleyl amine is complete. Mean removal percentages of octadecenyl bis(2-hydroxyethyl) amine from the influent through adsorption onto sludge assessed in two samples was 0.16% demonstrating that octadecenyl bis(2-hydroxyethyl) amine is primarily removed by biodegradation.

In conclusion, the CAS test demonstrates that di (2-hydroxyl ethyl) oleyl amine is almost completely removed from the wastewater in conventional biological wastewater treatment plants. Di (2-hydroxyl ethyl) oleyl amine is primarily removed by biodegradation.

The biodegradability, capacity to adsorb and evaporation of the two ethoxylated amine derivatives are given in the Table below. Both derivatives have been classified as readily biodegradable. The Henry’s Law constants of the surfactants demonstrate that evaporation is negligible. The Log Koc indicates that the potential of Quaternary ammonium compounds, C12 -18 -alkylbis(hydroxyethyl)methyl to a

dsorb onto activated sludge is lower than observed for di (2- hydroxy ethyl) oleyl amine. The properties of di (2- hydroxyl ethyl) oleyl amine (CAS no: 25307-17-9) and Q

uaternary ammonium compounds, C12 -18 -alkylbis(hydroxyethyl)methyl

demonstrate that read across is justified.

A total removal percentage of >99.9 is adopted as a worst-case for Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl. The adopted worst-case removal via sorption is <0.16% based on the lower sorption of Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl when compared to di (2- hydroxyl ethyl) oleyl amine.

Table: Biodegradability test results (OECD 301 D), Henry’s law constant and the Log Koc of the ethoxylated fatty amine derivatives and removal percentages of di (2- hydroxy ethyl) oleyl amine determined in CAS tests (OECD 303A). The removal percentages of Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl as registered obtained through read across are indicated in bold.

 

Substance

Biodegradability

Henry’s Law constant

Pa. m3/mol

(Evaporation potential*)

Log Koc

L/kg

(Potential to adsorb)

Total removal in CAS test

%

Removal via sorption in CAS test

%

Di (2- hydroxy ethyl) oleyl amine

(CAS no: 25307-17-9)

Readily

1.215 * 10-5(calculated EPI)

 

0.071 (calculated from ratio measured VP/CMC)

Log Koc = 3.70 (calculated, EPI)

 

Log Koc = 4.96 (measured, range 4.61 – 4.97)

>99.999

(measured)

0.16

(measured)

Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl, chloride(CAS no: 71808-53-2)

Readily

1.453 * 10-12(calculated EPI)

 

7.8 * 10‑4(calculated from ratio measured VP/CMC)

 

Log Koc = 2.16 (calculated, EPI)

 

Log Koc = 4.6

(measured, range 3.88 – 4.81)

>99.9(worst-case)

<0.16(worst-case in relation to measured Koc)

*If the Henry’s law constant is in the range 10-2< H < 1 Pa.m3/ mol, the test substance volatilizes slowly at a rate dependent on the Henry’s law constant. If the Henry’s law constant is in the range 1 < H < 102Pa.m3/mol, the test substance volatilizes not rapid but possibly significant.