Distillation residue, butyl alcohols production, rectification

Endpoint summary

Additional information

The substance distillation residue, butyl alcohols production, rectification is a UVCB-substance composing of several not easily identifiable substances. Only one of the constituent, 2 –ethylhexanol, can be analytically quantified (typical concentration range 20 -30 %). Due to the complex composition of the substance there are a lot of technical difficulties related to the testing. The biodegradation highly depends on the biodegradation of the individual components. Different constituents have different physical chemical properties (i.e. water solubility, vapour pressure, octanol/water partition coefficient) that might have an effect on the overall biodegradation of the substance in water and soil.

Because the composition of the substance is not easily identifiable, application of read-across method in order to evaluate the overall fate and pathways was regarded unsuitable. The need for further investigations of the substance biodegradation in soil, surface waters and sediments was evaluated based on the existing experimental physicochemical data ((1) water solubility, (2) vapour pressure, (3) K_owpartition coefficient and (4) hydrolysis). In addition, (5) ready biodegradation screening test results in water and (6) aquatic toxicity data were used to evaluate the biodegradation of the UVCB-substance.

1) The substance is water soluble (2-9 g/l) but most probably also contains constituents having low solubility in water.

2) The substance is non volatile at room temperature (< 0.01 Pa).

3) The substance indicated peaks corresponding the constituents having log Kow values of 1.8 to 5.8, but also constituents corresponding the log Kow values of 6.4 up to 7. (HPLC method).

4) The substance is hydrolytically stable and the half-life estimated by the preliminary study (OECD 111) at three pH-values is over one year.

5) The biodegradation of the substance in water was determined by using OECD guideline method 301B. According to the test results, the substance is inherently biodegradable. The substance was biodegradable (degradation within 28 days was 49.6 %) but was failing the 10 -days window. There might be some uncertainties related to the results. The differences in physical chemical properties of the constituents (i.e. solubility, vapour pressure) might have an influence on the overall biodegradation of the substance.

6) The substance was not an inhibitory to activated sludge microorganisms at maximum test concentration of 100 mg/l.

 

As a conclusion on the biodegradation, the substance might contain more easily biodegradable substances but also constituents that are not readily biodegradable. The one quantified constituent (at range of 20 -30%) is regarded as readily biodegradable. The possibility of the substance not being biodegradable in water or soil cannot be neglected when considering the environmental fate and pathways of the substance.