Influence of Granularity of Sediment from a Water Reservoir on Phosphorus Sorption Processes

Abstract

This research was designed to investigate the mechanism of phosphorus adsorption behaviour on the fine- ( 0.063 mm) sediments of the Klusov water reservoir (Slovakia) due to the different particle cohesiveness. The study of the sediment physical parameters indicated that the clay/silt fraction dominates in fine-grained sediment sample and the silt/sand fraction in coarse-grained one. Based on the study of physico-chemical properties of sediments, it can be concluded that sediment particle size, specific surface area, organic content and aluminium content are the main sorption influencing factors. The Langmuir-Freundlich isotherm model was used to describe the phosphorus adsorption process of two different grain-size fractions of reservoir sediments. The R2 values of fitting (0.99 for fine- and 0.98 for coarse-grained sediments) revealed very well the description of the P sorption process by the Langmuir-Freundlich isotherm model. The results demonstrated a maximum phosphorus sorption capacity of 325 mg P/kg for fine-grained sediment and 207 mg P/kg for coarse-grained sediment. Reservoir sediments indicated maximum P sorption efficiency at low P content in solution and the release of phosphorus from sediment into water was observed without the addition of adsorbate. The results of this study indicate that the fine- and coarse-grained sediments of the Klusov water reservoir act as an efficient trap for phosphorus.