Investigating and Modeling the Process of Biogas Production while Utilizing the Wastes of Damask Rose Distillation

To study the potential of production of biogas, utilizing the wastes of rose distillation process, the wastes were mixed with cow manure at manure proportions of 5, 10, 15 and 20% and in temperatures at two levels of 35 and 45 °C. The treatments were carried out using a 2×4 factorial design (?=0.05). The volumes of produced gas and generated methane were recorded daily and modeled as functions of time, using three mathematical models; namely: Gompertz, Logistic and Richards. The experimental results indicated that the treatment with 20% cow manure and at 45?C yielded the maximum cumulative gas production equal to 0.4268 m3/ (kg VS), while containing 72% methane. The mass reduction of available volatile compounds in this treatment was 81%. In general, the treatments mixed with higher proportions of cow manure reached their maximum level of daily gas productions in shorter periods of time. The results of mathematical modeling of the process indicated that Gompertz and Logistic models better fitted the experimental data with an R2 of over 94%.