Scale-up evaluation of the anaerobic digestion of food-processing industrial wastes

This work proposes a semi-pilot scale procedure for the evaluation of biogas production potential and the employment of its results for the scale-up of the process. AD tests were performed at 35 C in 6 L reactors, feeding 3e6% w/w TS in a fed-batch mode. Several substrates, generated by food-processing industries, were considered in the study. Assuming solubilization as the limiting step, a theoretical model was proposed and the values of the disintegration kinetic constant (kdis) were calculated from the experimental data. The obtained model was employed as a control tool during tests afterward performed on pilot scale in a 300 L digester fed in a semi-continuous mode. Biogas yields between 0.5 and 0.9 Nm3/kgVS, and methane contents of 55e63% v/v were obtained on both scales. The model derived from the results of the proposed procedure appeared adequate for a consistent evaluation of the scale-up of the AD process.