给水处理厂铁铝泥对正磷酸盐的吸附效果

通过批量实验和柱状实验并结合磷的分级提取探究了给水处理厂废弃铁铝泥(ferric-alum water treatment re-siduals,FARs)吸附正磷酸盐的效果。批量实验结果表明,Langmuir和Freundlich方程均能较好地描述FARs对磷的等温吸附过程,且当pH从5增至9时,FARs磷的饱和吸附量从41.68 mg/g减小到17.08 mg/g。pH越低,磷与FARs的结合能力越强。柱状实验结果表明,FARs具有显著的磷吸附能力,在运行的89 d里,磷的去除率保持在80%以上。出水pH与进水相比略有增加,但增加量不会对地表水体造成影响。磷的分级提取结果进一步说明,被吸附的磷主要以释磷风险小的铁铝结合态存在。综合实验结果表明,FARs可以作为高效磷吸附剂应用于地表水除磷。

Effectiveness of ferric-alum water treatment residuals in removing orthophosphate

Effectiveness of orthophosphate adsorption by ferric-alum water treatment residuals (FARs) were studied using batch test and column test. Fractionation of the absorbed P from the FARs was also conducted after the column test. The results of batch test showed that the adsorption process can be described by both Langmuir and Freundlich isotherms. With the solution pH increasing from 5 to 9, the phosphorus saturated adsorption capacity of FARs decreased from 41.68 mg/g to 17.08 mg/g. The phosphorus binding capacity of FARs was stronger with lower pH. The results of the column test showed an effective phosphorus adsorption throughout the 89 d operation. The outflow pH was slightly higher than that of the inflow but it could not affect surface-water quality. During the operation, the adsorption efficiency kept above 80%. Fractionation of the absorbed P indicated that adsorbed phosphorus existed mainly in Fe-bound and Al-bound forms, whose risk of phosphorus release is low. FARs can be an efficient phosphorus adsorbent for surface water.