| Summary: | 碩士 === 國立成功大學 === 環境工程學系碩博士班 === 94 === Phosphate is an essential factor for eutrophication of reservoirs in Taiwan due to the high N concentration in water. In this study, sludge cake and iron oxide (goethite) were used as adsorbent to remove phosphate. The preparation and the characterization of adsorbent, the kinetics and isotherm of adsorption, and the competitive adsorption experiment were carried out. In order to compare the difference between prepared phosphate solution and real water sample, the water sample from Fengshan water treatment plant was conducted for the further adsorption experiment.
According to the average concentration in reservoirs, the solution was prepared with the phosphate concentration of 1 mg P/l in deionized water. At pH7, the adsorption capacity of raw sludge cake was as low as 0.042 mg P/g. After the modification of sludge with NaOH, the adsorption capacity raised to 1.2 mg P/g within 52 hours. The adsorption capacity of goethite at pH7 was found to be 32 mg P/g within 24 hours.
The results of the adsorption isotherm experiments showed that the adsorption capacities of the both adsorbent increase with the decreasing pH-value. By comparing the adsorption behaviors of the both adsorbent in prepared solution and real water sample from Fengshan water treatment plant, the high concentration of HCO3- was found to be the limiting factor so that the adsorption capacities were reduced by 50% in the real water sample.
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