Abstract
Decolorization using the purification capacity of soil is used as a cheap method in wastewater treatment. The problem of this method is its ease of clogging. The use of pumice soil is expected to induce no clogging since it is granular. In this study, the effect of heated pumice soil on the decolorization of secondary effluent from a swine livestock barn is examined, and the mechanism of decolorization using heated pumice soil is discussed. Furthermore, the improvement of the regeneration effect is examined by adding a thermal regeneration step to the handling of the soil used. As a result, the best decolorization rate is achieved at 300 degrees C, because this is the level at which adsorptive water which hinders to absorb pigments disappears mostly, the noncrystalline quality which induces the absorption of the main mineral ingredient of pumice soil i.e., allophone, is maintained at this temperature. Concerning the regeneration of the soil used, the color degree was successfully reduced below the desired value (100 color degrees); it was improved to 37 color degrees at the maximum by adding a thermal regeneration step at 400 degrees C heating. Moreover, it was clarified that with thermal regeneration, the soil can be repeatedly used for a maximum of 4 times, by which processed water can be pressed down below to the desired value.
