Toxicity test for fuller’s earth contaminated with dielectric oil using eisenia foetida earthworms and soils with different carbon contents

Abstract

Fuller’s earth is an adsorbent material used in the electric industry for dielectric oil regeneration. The high amount of polyaromatic hydrocarbons removed from oil and adsorbed in the Fuller’s earth makes this material a hazardous waste. It is necessary to implement a toxicity test and apply a suitable treatment to safely dispose of this waste in a landfill or repurpose it for reuse. In this paper, the toxicity of Fuller’s earth contaminated with dielectric oil is assessed before and after treatment. The toxic potential of the Fuller’s earth and the dielectric oil extracted through decontamination processes was evaluated in two types of soil with different carbon contents, analyzing the effects on the test organisms, Eisenia foetida earthworms. These tests showed that decontaminated Fuller’s earth is non-toxic, and that the toxicity of the contaminated Fuller’s earth, or its extracts after treatment, represented by the median lethal concentration (LC50) depends significantly on the type of soil used.