SIMPLE TWO-STEP PROCESS FOR MAKING AGRICULTURAL CULTIVATION SOLUTION FROM SEAWATER USING CALCINED HYDROTALCITE AND NATURAL ZEOLITE

We attempted to make agricultural cultivation solution from seawater with a two-step process using calcined hydrotalcite and natural zeolite. Commercial calcined hydrotalcite was used in first step to reduce Cl^- content in seawater. Two types of Japanese natural zeolite, mordenite-type zeolite (Iizaka mine, Fukushima prefecture) and clinoptilolite-type zeolite (Koriyama mine, Kagoshima prefecture) were used in second step to reduce Na^+ concentration. Cl^- in seawater can be reduced by calcined hydrotalcite to obtain anion-reduced solution; Na^+ can be reduced by ion exchange with both types of natural zeolite. The obtained solution was neutral, and included the nutrients K^+, Mg^, and Ca^, and low levels of Na^+ and Cl^-. Higher concentrations of K^+, Mg^ and Ca^ in the solution can be obtained by mordenite-type Iizaka natural zeolite than those by clinoptilolite-type Koriyama natural zeolite. Radish sprouts did not grow in seawater and anion-reduced solution, but they grew in both solutions after zeolite treatment