Kinetic analysis of forced aeration composting - I. Reaction rates and temperature

The kinetics of the forced aeration composting process operated under different aeration modes was studied using two specifically designed heat insulated closed pilot-scale reactors. Five pilot scale composting tests using fresh mixture of organic solid waste were performed. The modes of aeration applied were upflow, downflow, alternate upflow/downflow, and internal air recirculation. Temperatures at different heights of the composting mass and air velocity were continuously monitored. Air flow was continuous or intermittent depending on temperature. Kinetic analysis showed that (i) temperature dependence of the reaction rates of all different aeration mode composting tests clearly followed the Arrhenius equation; (ii) the degradation of organic solids could be quantitatively predicted using the first order reaction model; and (iii) extent of degradation in the composting mass could be predicted on the basis of outlet air temperature instead of internal temperature of the composting mass.