Abstract: A method to remove toxic heavy metals soluble in wastewaters of household or industrial origin that comprises the phases of: Providing lignocellulosic material with low moisture (10% or less) which is subject to grading reduction with a size below 1 mm; Defining a solid-liquid ratio in an adsorption reactor where its value depends on the liquid residue composition to be treated within a 3 and 50 g/L interval. Placing the liquid to be treated and the lignocellulosic material in said adsorption reactor at room temperature. Stirring and adjusting the pH value during the process, where said pH depends on the composition of the liquid residue to be treated. The pH value is adjusted within an interval of pH 3 through pH 8. Keeping the liquid to be treated under turbulent stirring with the vegetal substrate inside the reactor until the concentration values desired for the metallic composition of the aqueous composition are achieved.