Comparative study of parameters to evaluate and monitor the rate of a composting process

Physicochemical, and biological parameters of a composting system were compared to each other with respect to their potential use for the monitoring and evaluation of the rate of field-scale processes. The drying tendency was assumed to be the ''exemplar parameter'' against which the various process parameters were evaluated for their ability to reveal the process evolution. The organic matter content decrease, moisture content decrease, temperature induced-aeration demand, and respiratory activity were utilized to express the composting rate. The study of these expressions indicated significant correlation of the moisture content removal with the volatile solids decrease, and the respiratory activity. A mathematical model used to describe the profile of these rate indicators during processing. The data analyzed have been derived from a composting process involving a solid substrate (olive-mill solid residues) of which the moisture content was, systematically, corrected by applying olive-mill wastewater.