| Phosphorus, as one kind of non-renewable resources, is an important element. The demand of phosphorus in our country will not be met after 2025, and it will turn to be in extremely shortage. However, its release to surface waters in industrial wastewaters and agricultural runoff has led to destruction of the ecological balance of water environment, and cause eutrophication of surface waters. Thus, pursuing of technologies for phosphorus removal and recovery from wastewaters can not only improve the water quality and lighten the contamination, but also realize the phosphorus recycling and sustainability, relieve the deficit of phosphorus resources, thus will greatly contribute to the harmony development of our society and economies.Preparing of one kind of magnetic phosphates adsorbent by surface modification on micron Fe3O4 powder was investigated in this thesis. This adsorbent can efficiently remove the phosphates from wastewaters, and the used adsorbent can release phosphates in magnetic field. Thus the recovery of phosphorus and Fe3O4 nuclei was easily achieved, and these nuclei still can be reused in preparing of the adsorbent.The optimum preparing conditions of the phosphates adsorbent was explored. Both orthogonal test and mono-factor analysis are employed in this discussion. Static adsorption test was performed with phosphate solutions which simulating the phosphorus content of domestic wastewaters and evaluated with both the amount of phosphates left in the supernatant fluid and the phosphates adsorption percentage as standards. The optimal preparing conditions is determined as follows: propionic acid (>99wt%, AR) and hydrochloric acid (36wt%, AR) mixed at cubage ratio 1:1, micron Fe3O4 powder added at the mixing rate of 1 ml mixed acid to 1g powder, smoothly intermix, then torrefy at 100℃for 7h, the highly efficient phosphates adsorbent is finally prepared after smashing the gotten black solid.The optimum adsorption conditions were also discussed. Adsorption test was executed at 20mg/L of which the phosphate concentration of simulating phosphate solutions is. The determined optimal adsorption conditions are as follows: the dosage of phosphate adsorbent is 0.4g/L, pH value is 9, and adsorption time is 9min. The equilibrium adsorption rate is 95% under the above conditions, and the removal of phosphates is up to 95% with the phosphate concentration of effluent less than 0.5g/L, which has met the first-level standard of Integrated wastewater discharge standard GB 8978-1996.According to features of the phosphate adsorbent, integrated continuous flow treatment device was designed and divided, following its difference operating technology, mainly into phosphate adsorption unit, sludge-water separation unit, phosphate-contained sludge off-nuclei unit, phosphates concentration unit and phosphates purify and recovery unit. The format, function and improvement of each unit were studied.Prepared phosphate adsorbent was characterized by SEM and XRD, the results show that it has a Fe3O4 nucleus which was covered with a hydrolyzate shell. The active sites which can adsorb phosphate come out when the adsorbent are preparing. At the same time, the Fe3O4 nucleus was covered with ferrous chloride, ferric oxyhydroxides and some unstable metal-hydroxide-complex, which can be hydrolyze and produce hydrolysate with high surface area, so, the adsorbent had excellent phosphate adsorption ability. Adsorption isotherm experiments show that the phosphate adsorbent adsorption is fit for the Langmuir adsorption isotherm.
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