A study of the physical and chemical characteristics of Ca-rich materials for use as phosphate removal filter media: A process based on laboratory-scale test

摘要

Urban and industrial wastewaters flowing into the environment as a consequence of the behaviour of the modern societies, it is an unavoidable problem. Different activities responsible for the release of large quantities of nutrients into wastewater, such as phosphate, contribute to the eutrophication of the water bodies by accelerating the extraordinary growth of algae. This paper aims to select and analyse Ca-rich materials that are categorised as natural materials and used as filter media in an upflow sand filter to enhance the understanding of filter media characteristics related to phosphate adsorption. Dolomite and limestone with specific gravity (2.8 and 2.6 respectively) were selected; sieve analysis was applied to categorise the physical properties of the selected materials' particles. Scanning electron microscopy (SEM) analysis showed that the limestone had higher porosity and larger total surface area in comparison to the dolomite. The chemical composition of media plays a vital role in phosphate adsorption; the x-ray fluorescence analyser (XRF) indicated high calcium oxides (CaO) for both selected media, but the (CaO) content for the limestone was higher than for the dolomite. Phosphate retention capacity is related to physical and chemical media properties which will be studied in Lab-scale systems as batch experiments. Both candidate materials will be applied in the test and the Freundlich isotherm model will be applied to determine the phosphate removal over time and estimate which materials' properties have a significant influence on the phosphate adsorption process. Further work will include constructing an upflow filter and using the promising material according to the results of the batch experiment as filter media, to determine the maximum phosphate removal from prepared synthetic wastewater. In addition, the media lifespan for phosphate removal will be studied and the results will be reported upon in a future publication.