A modified attapulgite clay for controlling infiltration of reclaimed water riverbed

Reusing reclaimed water is considered an effective way to abate water shortages in mega cities and protect the ecological status of rivers and lakes. Controlling of riverbed infiltration is an important way to protect the water environment, as it ensures the recycle of groundwater and maintained the groundwater quality in the recharge zone. The composite of attapulgite clay (AC) and modified-AC (MAC), named three-dimensional network adsorbent, was selected as the infiltration reduction materials, and the ability of controlling infiltration and purification were tested. Results showed that the permeability coefficient reached 10(-6) cm/s when AC and MAC were mixed at a ratio of 95:5 and 97:3, respectively. And when the layer thickness was 2-10 cm, the infiltration reduction capacity improved with the increased layer thickness and MAC content. The result of fine particles was greater than coarse particles. As the larger average pore diameter of coarse particles, the cumulative infiltration quantity and permeability coefficient of the AC and MAC coarse particles were lower, in the range of 10.98-11.16 %. The adsorption of ammonium nitrogen (NH4 (+)) was linear while phosphate (PO4-P) adsorption was nonlinear. Reusing reclaimed water could significantly inhibit the adsorption of NH4 (+) and PO4-P by AC and MAC.