Optimization of Process Conditions for Infected Animal Tissues by Alkaline Hydrolysis Technology

Alkaline hydrolysis represents a relatively new animal carcass disposal technology. It uses alkali, high temperature and high pressure to catalyze the hydrolysis of biological materials into a sterile aqueous solution and bone residues. The purpose of this work is to provide a complete study of the influence of operational parameters on alkaline hydrolysis process and to find an optimal combination of factors that maximize the disposal efficiency. In order to determine the optimal combination of the four factors viz. treatment time, temperature, the concentration of alkali solution and the ratio of alkali and tissue, single-factor and orthogonal experiments were used. The orthogonal experimental design included four variables (three levels) in L9 orthogonal array. Results showed that four factors all significantly (P < 0.01) increased the efficiency of alkaline hydrolysis. The order of significance decreased from temperature, alkali concentration, the ratio of alkali and tissue to treatment time. Optimum process conditions were found to be as follows: treatment time, 180 min; temperature, 150 °C; the concentration of alkali solution, 5% and the ratio of alkali and tissue, 3 mL/g. The optimum conditions was validated and proven to be reliable for achieving the complete hydrolysis of different animal tissues and the inactivation of Bacillus stearothermophilus. This study provides a biosafety disposal method of infected animal tissues and be useful to establish effective process conditions of alkaline hydrolysis.