Computational Simulation of Filters Used in the Removal of Heavy Metals Using Rice Husks

The biofiltration technique is of great importance for the removal of heavy metals. In the present work, a laboratory-scale biofilter was modeled using rice husk as a filter material. The Wolborska model was used to know the dimensions necessary for the biofilter to function. The Langmuir and Freundlich isotherms were performed to quantify the filter adsorption process, showing that the Langmuir isotherms are the ones that present the highest correlation coefficient and best represent the removal process of $\mathrm{Cd}\left(\mathrm{II}\right)$, $\mathrm{Cu}\left(\mathrm{II}\right)$ and $\mathrm{Cr}\left(\mathrm{VI}\right)$. According to the Langmuir isotherms, the maximum operating temperature allowed for this model was chosen, which was 303.15 K, because it presents the maximum removal of heavy metals. Regarding the pH variations for Cd (II) and Cu (II), the maximum removal was presented with a pH = 9.0 and for Cr (VI) with a pH = 3.0 the maximum removal was presented. According to the rupture curves, the blocking times were obtained for each height: for Cd (II) the highest ${\mathrm{t}}_{\mathrm{b}}$ for h = 0.55, Cu (II) the highest ${\mathrm{t}}_{\mathrm{b}}$ for h = 0.40 and for Cr (VI) the highest ${\mathrm{t}}_{\mathrm{b}}$ for h = 0.40.