This study aimed to determine some transport parameters of potassium in soil columns by miscible displacement of effluent from a Sewage Treatment Plant (STP). This effluent was collected at different stages of treatment, and potassium chloride solutions were prepared with the same K pulse concentration as the effluent. They were used to conduct a miscible displacement experiment of potassium in soil columns of dystrophic Red Latosol. Both types of solutions contained concentrations of 30 and 32 mg L-1 of potassium. STANMOD software was used to obtain the retardation factor (R) and the Peclet number (Pe) from pore volume and relative concentration. Both retardation factor and solid-water partition coefficient of the soil showed significant results by ANOVA. When assessing KCl solutions, retardation factor was higher than that observed for the effluent, resulting in higher soil-solute interaction. The presence of other competitor cations in the effluent caused less potassium adsorption by the soil. Based on the results, potassium provided a greater groundwater pollutant potential when applied via effluent than solutions of potassium chloride with the same ion concentrations.

The substrates composition can take place from different raw materials, being an influencer of the water and nutrient retention capacity, an important dynamic in the management of the cultivation in containers due to the possibility of nutrient leaching. It was aimed to quantify the Potassium adsorption to substrates with different proportions of vermiculite and peat, in addition to determining adsorption isotherms which would best fit the observed adsorption data, for contact periods of one and seven days. We carried out batch adsorption essays, using as an adsorbent media substrate prepared with different proportion of vermiculate and peat, and as adsorbate, solutions with concentrations of 0, 25, 50, 75 and 100 mg/L of K. The substrate that showed the highest adsorption capacity, then less leaching potential, was the one constituted with the largest amount of peat. The Freündlich’s isotherm best represents the K adsorption phenomenon in all the studied treatments.