涂铁砂滤料吸附过滤去除城市污水厂二级处理出水中磷的研究

PHOSPHATE REMOVAL FROM MUNICIPAL SECONDARY EFFLUENT BY IRON-OXIDE-COATED SAND ADSORPTION AND FILTRATION

研究了涂铁石英砂(IOCS)的表面性质和吸附过滤对城市污水厂生物二级处理出水中PO43--P的去除性能。扫描电镜(SEM)和X射线衍射(XRD)的表面分析表明,IOCS表面粗糙、比表面积大且附有α-Fe2O3晶体、吸附能力增强。静态吸附试验表明,pH、接触时间和涂铁砂量等均会影响IOCS对溶液中PO43--P的吸附。通过非线性回归得出的Langmuir、Freundlich和Temkin吸附等温线均可较好地拟合IOCS对溶液中PO43--P的吸附。拟合曲线的相关性大小顺序为:Langmuir>Temkin>Freundlich(R2>0.9130)。与石英砂(QS)相比,IOCS过滤对PO43--P的平均去除率提高约5%,去除效果提高明显,但运行过程中IOCS过滤的水头损失比QS大。

Phosphate removal from municipal secondary effluent by iron-oxide-coated sand（IOCS）adsorption and filtration was studied. Scanning electron microscopy （SEM）and X-ray diffraction spectroscopy （XRD）were used to observe the surface properties of the coated layer.Results showed that IOCS had significantly rougher surfaces, more micropores, and accordingly larger specific surface area than quartz sand（QS）, and iron oxide mineral hematite（α-Fe2O3）existed on the surface of IOCS resulting in better ability to adsorb phosphate. Removal of phosphate was studied in batch experiments conducted as a function of pH, contact time and dose of IOCS. Three isotherm equations（Langrnuir,Freundlich and Temkin）were used for data fitting, and fitting-correlation of isotherm equations for present experimental data followed the order： Langrnuir〉Temkin〉Freundlich （R^2〉 0.9130）. Compared with QS filtration,average phosphate removal efficiency by IOCS filtration increased 5% and the improving of removal efficiency was evident. Moreover, during runtime, head losses of IOCS filtration were generally higher than those of QS filtration.