Modeling phosphate adsorption of semi-intensive shrimp pond sediment
Models to simulate phosphate adsorption could be useful for predicting water quality and for controlling eutrophication of ponds and lagoons. The different models of phosphate adsorption of aquaculture pond sediment were investigated, including kinetic adsoqjtion models and adsorption isotherm models. Five sediment samples were collected from 5 different semiintensive shrimp ponds and analyzed physical and chemical properties. We measured the p adsorption under different conditions of pH and PO4-P concenfration (pH 5, 7, and 8.5; 0.5-5 mg L ') in batch tests at a sediment-to-solution ratio of 1:10 and then the experimental data was simulated by using several adsorption models . Results showed that p adsorption was not greatly affected by pH (p>0.05). This is probably atừibuted to the high proportion of sand in sediment (>60%) which would have a low specific surface area and less reactive adsorption sites. The adsorption of p with initial concentrations of 0.5 and 5 mg L ' increased within the first 10 and 30 minutes of incubation, respectively. The Langmuir model satisfactorily described the properties of p adsorption isotherms of aquaculture pond sediment. According to the Langmuir model the maximum adsorption capacity was 0.275 ± 0.011 mg g' .