There are several international regulations regarding trace elements. The use of ICP-MS for their determination is usually a difficult task, especially when Hg is one of the target elements.

Agricultural waste products can be used as biosorbents for bioremediation once they are low-cost and high-efficient in pollutants removal. Thus, waste products from mushroom farming such as cutting and substrate of Lentinula edodes (popularly known as shiitake) and Agaricus bisporus (also known as champignon) were evaluated as biosorbents for metallic contaminants copper (Cu) and lead (Pb). Shiitake and champignon stalks, and shiitake substrate (medium in which shiitake was cultivated) were dried, grounded, characterized and experimented to remove Cu and Pb from contaminated water. The Sips model was used to establish the adsorption isotherms. Regarding Cu, champignon stalks have the best removal efficiency (43%), followed by substrate and stalks of shiitake (37 and 30%, respectively). Pb removals were similar among three residues (from 72 to 83%), with the champignon stalks standing out. The maximum adsorption capacities (q_max) for Cu in shiitake and champignon stalks were 22.7 and 31.4 mg/g⁻¹, respectively. For Pb, q_max for shiitake and champignon stalks, and shiitake substrate were 130.0, 87.0 and 84.0 mg/g⁻¹, respectively. The surface morphology of the champignon stalks revealed an organized and continuous structure. After an interaction with metals, the stalk of champignon accumulated the metal ions into interstices. Mushroom residues showed a relevant adsorption efficiency, especially for Pb. Mushroom farming waste are a very low-cost and promising alternative for removing toxic heavy metals from aquatic environment.

Bioremediation is a promising technique for the removal and recovery of contaminated areas, which is based on the ability of organisms to convert toxic substances into less harmful or inert compounds. Here, we evaluate the capacity of the Bacillus subtilis (BS) bacteria to bioadsorved heavy metals such as lead (Pb), copper (Cu) and cadmium (Cd) in water samples. Water samples were laboratory contaminated Pb at 500 ppm, Cu and Cd at 100 ppm. First, the growth curve of BS was plotted using Tryptone Soy Broth (TSB) at 100% (TSB₁₀₀) and 33% (TSB₃₃). Later, BS was studied in water containing all three metals separately and simultaneously. All solutions were stirred at 150 rpm, 35 ℃ for periods that ranged from 1 to 144 h. The heavy metal analyses were performed by X-ray fluorescence and Inductively Coupled Plasma Mass Spectrometry. The results showed that BS was resistant to Cu, Cd and Pb in water, with active multiplication and reduction in the concentration of the metals. The highest removal efficiency, in the presence of each heavy metal, reached 100% with Pb, 92.3% with Cd and 89% with Cu. In the solution with the mixture of heavy metals, Cd and Pb levels reduced significantly. However, the mixture of metals negatively affected the removal of Cu. In conclusion, the implement using Bacillus-type bacteria can be efficient in the biosorption of heavy metals from aqueous solutions and can be employed as a cost-effective treatment for the bioremediation of industrial effluents and contaminated areas.