Phosphate recovery using calcium zeolite in ultrafiltration pilot plant
Tutor / director / evaluatorCortina Pallás, José Luís
Document typeBachelor thesis
Rights accessOpen Access
One of the most important ecological problems is the eutrophication, this process consist in the uncontrolled growing of algae and phytoplankton, which can destroy entire aquatic ecosystems. The reason of this process is the excess of nutrients, as for example, phosphate coming from human activities. This project focus on the study of synthetic zeolites capacity to absorb phosphate from wastewater. Zeolites are porous minerals of the alumina-silicates family with high capacity of cations exchange. They can be natural or synthetic and present a tetrahedral structure that can include alkali or alkaline earth metals, those metals can improve the capacity to absorb determinates contaminants. The zeolite used for this work is a calcium zeolite (Ca-Ze) obtained from a synthetic sodium zeolite (NaP1). The NaP1 is produced using fly ashes as raw material, by hydrothermal process. The objective of the project is to evaluate: the elimination of phosphate, the equilibrium and kinetic data, using agitated reactors, and the integration of the sorption process with a separation process, using ultrafiltration membrane in different operating conditions. The evaluated operation conditions are designed to simulate the treatment of residual waters coming from industries, households and agricultural fields. Other experiments as kinetic, isotherms and point zero charge are done to characterize the zeolite used in the ultrafiltration plant and to make a comparison with other zeolites and adsorbents used for phosphate removal. Analysis results of phosphate loaded samples give information about the phosphate adsorption mechanisms and the adsorption capacity in different working conditions. The formation of calcium-phosphate minerals, brushite, is the principal phenomena during adsorption, it is favoured by low pH as seen in the results. The analytical techniques used are UV-visible spectrophotometry for phosphate analysis, ionic chromatography for the analysis of different ions presents in the water, X ray diffraction for zeolite sample analysis.