人工快渗系统关键运行参数与除磷机理研究

Study on key operational parameters of constructed rapid infiltration system and phosphorus removal mechanism

采用人工快速渗滤(CRI)系统对氧化沟出水进行深度处理试验研究,在水力负荷为2.0 m/d、水力负荷周期为24 h、湿干比为1:1条件下运行2个多月后出水稳定,系统对COD(化学需氧量),NH_(4)^(+)-N,TN(总氮),TP(总磷)的平均去除率分别为46.30%,73.89%,55.94%,94.24%.在不同湿干比(1:1,1:2,1:3)、不同水力负荷(1.5,2.0,2.5 m/d)和不同水力负荷周期(8,12,24 h)下进行正交试验,结果表明:CRI系统在水力负荷为2.0 m/d,湿干比为1:3,水力负荷周期为8 h时处理效果最好,为最优运行参数.对试验前后的海绵铁填料进行XRD(X射线衍射)、XRF(X射线荧光)和XPS(X射线光电子能谱)的材料表征,结果表明:海绵铁缓释的Fe^(3+)与水中PO_(4)^(3-)结合,并在填料表面形成沉淀,是CRI系统具有良好除磷效果的主要原因.

The constructed rapid infiltration(CRI) system was established for advanced treatment of the oxidation ditch effluent under the operational condition of a hydraulic load of 2.0 m/d,a hydraulic retention time(HRT) of 24 h,and a wet-to-dry ratio of 1:1,and the effluent of the CRI system reached stability after over two-month operation.The average removal rates of chemical oxygen demand,ammonia nitrogen,total nitrogen and total phosphorus were 46.30%,73.89%,55.94%,and 94.24%,respectively.Moreover,the orthogonal tests were carried out with different wet-to-dry ratios(1:1,1:2,1:3),different hydraulic loads(1.5,2.0,2.5 m/d),and different HRTs(8,12,24 h).Results show that the CRI system has a better removal performance with the hydraulic load of 2 m/d,the wet-dry ratio of 1:3,and the HRT of 8 h,indicating it could be the optimal operational parameters.In addition,the sponge iron fillers were characterized by X-ray diffraction,X-ray fluorescence,and X-ray photoelectron spectroscopy before and after the test,the results show that the slow-release Fe^(3+) in sponge iron combines with PO_(4)^(3-) in water and forms precipitation on the surface of the filler,which is the main reason for the good phosphorus removal effect of the CRI system.