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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

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Based on the article (Luo, Xia, Fan, Chen and Peng, 2010) the biodegradability of some fat liquors has been tested in order to establish the environmental impact and the efficiency of the tratment plant. the degradation order is oxidised sulphited castor oil > fish oil > rape oil > mineral oil. In degradation kinetics studies (Luo et al 2010) the degradation rate constant (k) of sulphated castor oil, fish oil and rape oil are 0.87, 0.84, and 0.81 d-1, respectively. These degradation rate constants are slightly faster for the sulfited fatliquor substances where castor, fish and rape were 0.95, 0.93, and 0.85 d-1, respectively.). The higher content of unsaturated fatty acids and hydroxyl groups, the faster is the biodegradability of fatliquors.

In a similar article of 2008 ( Sun Danhong, He Qiang, Zhang Wenjun, Xin Liu, Shi Bi, 2008), The biodegradation behaviours of the six fatliquors at different concentrations were investigated. The respiration of activated sludge in fatliquor solutions was measured and used to assess the

biodegradability of fatliquors. Sulfated castor, neat foot and fish oils) and lecithin fatliquor exhibit good biodegradability when their concentrations range from 125 mg/L to 750 mg/L

A 1976 aerobic biodegradation study with the sodium salt of sulfated castor oil (CAS 68187-76-8) in an activated sludge inoculated system, documented DOC removal consistent with 96% biodegradation in 45 days.

For the assessment of the end point further evaluations can also be made. The QSAR predictions for the substance and the two analogues fish and vegetable sulphited derivatives used as analogues within the dossier have been performed, taking into account all potential components of the three substances, demonstrating that there is a tendency towards a higher and quicker biodegradability for castor oil derivative in respect to the sulphited fish and vegetable derivative.