A light-weight aggregate (LWA) made of expanded clay used as a filter media in wastewater treatment, was tested for sorption of phosphorus (P) in laboratory experiments. The objectives were to investigate the different P retention pools and how grain size, time, temperature and changed P concentration influenced the P binding mechanisms in this type of filter. Three different grain sizes (0-2 mm, 2-4 mm and 0-4 mm) were tested in a batch experiment. The isotherm for the P sorbed by the contact medium (including retention and fixation) was obtained under laboratory conditions. Fifty percent of the P sorption occurred in the first 4-8 hours. Temperature did not substantially influence P sorption for 0-2 mm grain size LWA. In the LWA suspension system, P desorption did not occur when the P content in the loading solution decreased. Fractionation analysis indicated that Ca-bound P, loosely-bound P, and Al-bound P were the predominant P retention pools. The loosely-bound P pool was determined primarily by the equilibrated P concentration in the system. Fe-bound P was negligible in the P sorption of LWA.
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Research Article| September 01 2003
Phosphorus sorption characteristics of a light-weight aggregate
Water Sci Technol (2003) 48 (5): 93–100.
T. Zhu, T. Maehlum, P.D. Jenssen, T. Krogstad; Phosphorus sorption characteristics of a light-weight aggregate. Water Sci Technol 1 September 2003; 48 (5): 93–100. doi: https://doi.org/10.2166/wst.2003.0290
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