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| Screening of phosphate-removing filter media for use in constructed wetlands and their phosphorus removal capacities |
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Abstract According to the characteristics of swine wastewater, physico-chemical properties of oyster shell (OS), broken bricks, volcanics, and zeolite were determined, as well as their phosphorus removal capacities. The results showed that, broken bricks and zeolite showed more suitable potential environments for biofilm bacterial growth, whereas OS and broken bricks possessed of high potential capacities for phosphorus removal. OS had the highest phosphorus adsorption value by isothermal adsorption tests, followed by broken bricks, volcanics, and zeolite, the type of adsorption of PO43- on OS was defined as chemical adsorption, the types of adsorption of PO43- on broken bricks, volcanics, and zeolite were defined as physical adsorption, and the process that occurred during phosphorus adsorption on broken bricks was understood to be chemical adsorption. OS was most effective at phosphorus removal in the dynamic adsorption experiments, followed by broken bricks, volcanics, and zeolite. Besides, the main phosphorus removal pathway of each filter medium was determined by the contents and chemical forms of elements in the filter medium. In conclusion, OS should be the ideal filter medium used in constructed wetlands treating swine wastewater.
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Received: 15 May 2012
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