Introduction: Biosolids generated in the treatment of wastewater are an environmental problem due to their inadequate handling and disposal. Objective: To know the effects when varying substrate ratios and pile weight on quality and time of biosolid compost. Materials and Methods: The mixture of biosolids (BS) with clay soil (CS) and equine degraded manure (DM) was evaluated in the following ratios: 70:30:00, 65:30:05, 60:30:10 and 50:30:20 to determine the optimum ratio in piles of 250 kg and evaluate it in 500 and 2 000 kg. The parameters of quality were temperature, Ph, humidity, organic matter (OM), total Kjeldahl nitrogen (TKN), C/N ratio, K/Na ratio and phosphorus (P). Results and Discussion: the ratio 65:30:05 had higher temperature (63.8 °C) and lower composting time (21 days). Significant differences ( P < 0.05) were found in the parameters of quality with respect to the substrates and pile weight. The treatments of 250 kg had the shortest processing time (28 days) with higher OM, TKN, C/N and P. Conclusion: The DM and CS favor BS composting by reducing the process to a maximum of 32 days. The ratio 65:30:05 in 250 kg increases the agronomic quality of the compost.