Pollution
Humain
Environnement
Economique

At around 5:00 p.m., pungent odours were detected during ethanol was being distilled at an ethanol processing plant. Prior to distillation, the dry matter is removed from the ethanol to be processed and then allowed to rest in a settling tank. The impurities, which are lighter, rise to the top of the mixture and the heavy phase containing the ethanol is sent to the distillation column. In the case at hand, the processed ethanol had been used to wash equipment and lines used in the manufacture of cosmetics. It contained 7% impurities consisting mainly of essential oils and 1% perfume essence.

The technician overseeing the transfer to the distillation column also sent the impurities. Realising his mistake, he drained the column’s contents into an intermediate bulk container (IBC). A malfunction of the heat exchanger (incorrectly adjusted water flow rate) used to cool the column’s contents allowed the ethanol to be transferred for 10 hours at 50 °C. The perfume essence evaporated, leaving offensive odours. The technician closed the IBC. The perfume essence was sent to the incinerator.

An estimated 1 kg of perfume essence was released. The odour disappeared 30 minutes after the IBC was closed.

The technician had been working at the factory for four months. Following the accident, he was again reminded of the importance of reporting all issues to his superiors. The operator amended the production procedure so that the supernatant in the settling tank is removed before distillation is started.