2014 Volume 20 Issue 1 Pages 19-27
This paper investigated the possible use of agricultural wastes including rice husk, rice straw and rice bran for attenuation nitrate- or chloride-induced problems such as nitrate pollution or soil salinization in porous media. Column experiments with 30 cm in length were carried out under saturated flow conditions using two different solutions of KNO3 and NaCl. Each agricultural waste was mixed with silica sand and filled into the column homogeneously. Mixture percentages of the weight of each material to silica sand were varied in order to examine the change of the degree of solute dispersion, mobility and mass attenuation, which were identified using temporal moment analysis based on experimental breakthrough curves of the effluent. The results showed that use of agricultural wastes provides the slight increase of the dispersivity relative to the case without agricultural wastes except for the case with rice bran in chloride ion transport. Each anion showed its own degree of solute mobility associated with mixed agricultural wastes, due to the hydrophobic property of the surface of wastes. The results also revealed that the use of rice husk and rice bran leads to the degradation of total mass from the effluent, although the rice straw has an extremely low property attenuating the mass of nitrate and chloride. Furthermore, a new quantity index to synthetically evaluate the potential of agricultural wastes was proposed. The results indicated that rice straw has the highest potential in terms of the attenuation of nitrate- or chloride-induced adverse effects in porous media.
