EFFECT OF THE THERMAL ALKALINE PRETREATMENT ON THE MESOPHILIC AND THERMOPHILIC ANAEROBIC DIGESTION OF WASTE ACTIVATED SLUDGE

This study is focused on the effect of thermo alkaline pretreatment on velocity of anaerobic hydrolysis mesophilic and thermophilic of waste activated sludge (WAS), separating the hydrolysis of suspended solids (SS) and dissolved solids (SD). In order to research the hydrolysis of SS, the Sander's surface model was used, and for the hydrolysis of SD, the God's model of saturation was employed. The pretreatment increased the superficial area available for the enzymatic action, due to the reduction of the solids size. The effect of the pretreatment in the anaerobic digestion of the SD in thermophilic conditions, resulted in competitive inhibition over the anaerobic hydrolysis rate, whereas that in mesophilic conditions, resulted in non competitive inhibition. Mathematical simulation of SS to SD and methane consecutive reactions, showed that a 4 % increase in initial thermal-alkaline treated sludge diminished the inhibition of SD hydrolysis in the thermophilic anaerobic digestion.