After the removal process the acute toxicity of post-removal solutions was determined by means of AMPHITOX bioassay. Phenol solutions treated with rapeseed HR showed a lower level of toxicity than at the beginning of the treatment. Moreover, PEG addition reduced the toxicity of these solutions. On the contrary, tomato HR could only be applied to reduce the level of toxicity in solutions initially containing low phenol concentrations (100–150 mg/L), without adding PEG. From these results, it is relevant to point out the importance of studying different plant systems and their reaction capacity to find the more suitable ones for removal purposes.