The aims of this study were to perf

The aims of this study were to perform the anaerobic digestion of recycled pulp and paper sludge (RPPS) at laboratory scale, using a continuously stirred tank reactor (CSTR) digester, to determine the methane yield of this type of waste, and to control the physico-chemical parameters to maintain its stability during the experiment. Recycled pulp and paper sludge has an important organic matter with a COD/BOD5 ratio of 1.94, which is easily degradable. The result of anaerobic digestion experiment has given a methane yield coefficient of 159 N mL CH4/g VS, while biodegradability was found around 77% (in VS). The results obtained from the kinetic models studied in this work, mainly the modified Gompertz, first-order, Richards, and Logistic kinetic models show that the difference between the predicted and measured methanogenic potentials was higher in the modified Gompertz kinetic model (0.25–12.94%) than in the Logistic model (0.18–2.69%). The Logistic model showed the best fit for the substrates used. The Logistic, the modified Gompertz, Richards models fitted adequately to cumulative methane production (R2 was 0.9744; 0.9597 and 0.9655, respectively). Specifically, the Logistic model predicted the methane production volume like the experimental within loads added of 2.5 g VS/L.