Avaliação da tolerância de poáceas (gramíneas) a elevadas concentrações de sais em diferentes tempos de detenção hidráulico

Abstract

A great part of the Earth’s soil is influenced by salt concentrations, along with other natural causes like weathering source materials and its subsequent deposition in the soil solution, the anthropic salinization is responsible for a large part of the salinization process, primarily occurring in agro-industrial activities, which produce excessive quantities of effluents highly concentrated in sodium and potassium. The goal of this research was to evaluate the tolerance of aquatic Poaceae grass to elevated salt concentrations, at “wetland environments” built to accommodate various hydraulic retention times. During this research two different species of Poaceae grass were tested, Hemarthria altissima (H. altissima) and Brachiaria subquadripara (B.subquadripara). The Effluent was synthesized with an approximately 10,5 sodium adsorption ratio and the hydraulic retention times established were of 2,5 days as wells as 5 days. The concentration of sodium and potassium were also evaluated. The results demonstrated the plants performed best under the 100% HRT. The results for the 2,5 days HRT cycle showed a sodium reduction level of 47,06% and 90,00% of potassium reduction for the H. altissima and for the B. subquadripara the sodium reduction level was of 55,88% and 90,00% of potassium reduction. The results for the 5 days HRT cycle showed a sodium reduction level of 90,50% and 95,00% of potassium reduction for the H. altissima and for the B. Subquadripara the sodium reduction level was of 70,59% and 90,00% % of potassium elimination. The sodium absorption by the plants took an average of 250% of the HRT tested while the potassium levels required 650% of the HRT to reach similar reduction levels. Therefore, the research concluded the evaluated grasses presented a reduced ability to absorb sodium and potassium overtime; however they showed to be a promising solution to effluent treatment systems due to their hig salt toleration and would be specifically beneficial to absorb potassium from the soil.