The pH value increased throughout the composting because of the decomposition of acid-type compounds and the mineralization of organic compounds to inorganic compounds, such as NH4+-N (Fig. 2-B) (Paredes et al. 2000). The value of electrical conductivity (EC) increased at the beginning and thermophilic phase because of the mineralization of OM, but decreased at the latter phase which might be due to the precipitation of mineral salts, the volatilization of NH3 and the stabilization of OM (Fig. 2-B).