DESALINATION OF SEAWATER USING NATURAL ZEOLITE FOR AGRICULTURAL UTILIZATION

Abstract

The aim of this studyis to provide an agricultural cultivation solution from seawater with a simple process using natural zeolite. In the 21st century, the demand for food is increasing due to the global population growth, and securing farmland is one of the most important factors in food production. Approximately 20 % of farmland in the world is salt-damaged soil with unsuitable properties for agriculture by high salinity water, and simple desalination methods of high salinity water to improve salt-damaged soil is desired. Natural zeolite has a cation exchange ability and is available in large quantities at low cost. In this study, desalination of seawater, as high salinity water, using Japanese clinoptilolite zeolites with typical exchangeable cation, Na⁺, K⁺, NH₄⁺, Mg^2+,and Ca²⁺, were examined. Ca²⁺-type zeolite indicates the highest reduction of NaCl from seawater among these ion-exchanged natural zeolites. The column experiment using Ca²⁺-type natural zeolite shows that pH can be controlled to neutral and salinity can be reduced by the reaction between Ca²⁺ in zeolite and other ions in seawater. Although Radish sprouts did not grow in seawater, they could be grown in the solution treated with column process of Ca²⁺-type natural zeolite.