Yoshiharu Mitoma, Kazuki Shishida, Yumi Katayama
In recent years of Japan, there have been reported cases of soil contamination with significantly overrun levels of arsenic than environmental standards, due to large-scale civil engineering works. Conventional remediation techniques for such contamination involve methods like washing soluble heavy metals from the soil or employing immobilization treatments. However, these conventional methods often require wastewater treatment and longer curing times, posing significant issue to be solved. Under these circumstances, we effectively tackled this challenge by introducing nano-particles of calcium, hereafter denoted as nCa, along with phosphorus compounds into soil contaminated with arsenic. This approach resulted in the swift formation of a hydroxyapatite coating on the soil's surface, effectively immobilizing arsenic. Notably, this groundbreaking technique obviates the necessity for wastewater treatment and enhances the potential for reusing the treated soil, courtesy of the incorporation of calcium-based materials. As the result of many investigations, the mixture of 2wt% nCa and 1.6wt% phosphorus compound are added and mixed to 5g of contaminated soil, in which total amount can reduce 60% compared to the conventional method. The treated concentration has reached less than the environmental standard values.
