reaction time conditions (overliming).At the end of the process, the pH of the mixture is adjusted to that required by the microorganism with H2SO4 and the precipitate formed is removed by filtration or centrifugation. This method has some advantages as: low cost, partial removal of acetic acid and phenolic compounds, precipitation of toxic metal ions as Fe, Ni, Cr,and conversion of furfural to less toxic compounds (such as furfuryl acid), metabolizable by microorganism fermentation [27].