Removal of ammonium nitrogen in the subsiding water from cropland in the Yellow River irrigation area of Ningxia by natural zeolite

摘要

Aimed at the distinguishing features, namely, high salinity, high pH value, unstable water quality and quantity, of the subsiding water from cropland in the Yellow River irrigation area of Ningxia, static adsorption experiments were carried out to remove ammonium nitrogen from the aqueous solution by natural zeolite. The ammonium adsorption onto natural zeolite is a pH-dependent process, and the appropriate range of pH value for ammonium removal by zeolite is from 5 to 9. The presence of co-existing ions in the solution could reduce the uptake of ammonium onto the zeolite. The orders of cations and anions effect on ammonium removal are K~+>Na~+>Ca~(2+)>Mg~(2+) and SO_4~(2-)>NO_3~->Cl~->H_2PO_4~-, respectively. Based on the obtained experimental results, it can be concluded that the natural zeolite has great potential in cost-effective removal of ammonium of the irrigation drainage in the Yellow River irrigation area of Ningxia.