Application of sewage sludge to degraded soil has received considerable attention because of its potential for soil-fertilization and also as an effective, low-cost disposal method. An understanding of the decomposition of organic substrates in soil is essential to determine the relative worth of different materials for improvement of soil agrochemical properties. Therefore, this study aimed to evaluate the C mineralization of mining soil amended with dried sewage sludge and co-composted with olive pruning by response surface methodology. We carried out an aerobic incubation in the laboratory using varying doses of waste (0-100 g kg-1)following a D-optimal design over 30 days at 40% field capacity and 28ºC. The CO2 evolution pattern was monitored throughout the incubation time. The experimental design allows allowed to evaluate evaluating how the characteristics of the sludge affected the C mineralization process as showed by surface and contour plots and estimated the kinetic parameter of CO2-C production at several application doses. The dried sludge supplied an easily degradable C pool that produces 5 times higher CO2-C than that found for the co-composted one. Mineralization process, performed differently for each sludge, can be discriminated by mineralization and metabolic quotients. Additionally fluorescence spectrometry also discriminate the composition of dissolved organic matter from each substrate. In both cases, soil biological activity was enhanced.