给水厂污泥改良生物滞留填料除磷效果的研究

通过静态吸附实验研究了土壤、给水厂污泥对磷的吸附特性,采用生物滞留模拟柱,考察生物滞留技术对城市径流中磷的去除效果,评价以给水厂污泥改良填料的可行性.结果表明,给水厂污泥对磷的吸附能力远大于土壤.在进水磷浓度为1.0 mg·L-1条件下,传统填料模拟柱出水总磷随着进水量的增加浓度逐渐增大,而改良填料模拟柱表现出稳定的长期去除效果,经7个月的连续运行,改良填料模拟柱出水总磷的浓度仍小于0.050 mg·L-1,满足地表水Ⅲ类水质标准.根据静态吸附实验估算结果,相同的控制条件下,添加4%给水厂污泥的改良填料对磷的吸附能力约为传统填料的4倍.无定型铁铝的沉淀、吸附作用是改良填料截留进水中磷的主要机制,工程应用中可在填料中添加4%~5%比例的给水厂污泥以提高生物滞留设施控制受纳水体富营养化的效果.

Water Treatment Residual as a Bioretention Media Amendment for Phosphorus Removal

The characteristics of phosphorus adsorption of both soil and water treatment residual (WTR) were investigated through batch tests. The removal of phosphorus in runoff by bioretention column was evaluated. Furthermore, the feasibility of taking the WTR as a bioretention amendment was discussed. The results indicated that the phosphorus adsorptive capacity of WTR was significantly higher than that of soil. With a high influent phosphorus concentrations(1.0mg·L^-1), the columns with amended media showed a better long-term removal efficiency than the columns with traditional media. The concentrations of TP in effluent from columns with amended media were less than 0.050mg·L^-1 after 7 months' continuous operation. According to batch test results, it was estimated that the phosphorus adsorptive capacity of amended media, which was mixed with 4% of WTR, was 4 times as high as the traditional media under same conditions. Adsorption and precipitation by amorphous iron and aluminum is the main mechanism for phosphorus removal in amended media. It is recommended that the mixture with 4%-5% of WTR by mass in media would improve the phosphorus removal of bioretention in engineering practice.