The utilization of clean and renewable fuels as a replacement for some of the consumed fossil fuels has been considered in recent decades. There are numerous ways to produce these energies, including using waste product. In recent years, scholars in this sector have become interested in sugarcane bagasse, which is the most preva‎lent agricultural industrial waste in both Iran and the rest of the globe. In this research, with the aim of improving the digestibility of sugarcane bagasse and increasing its deligninization rate through pre-processing, one molar sodium hydroxide solution was used as an alkaline agent in combination with autoclave. Sodium hydroxide solution and sugarcane bagasse were blended using ultrasonic for three periods of 0, 15, and 30 minutes in order to eva‎luate the effects of the ultrasound. The Van Soest method was used to quantify changes in the levels of lignin, hemicellulose, and cellulose. The deligninization rate was then estimated based on the results. Through the compare of means, statistical analysis and also the comparison of energy consumption of the optimal level, the duration of ultrasound treatment was selected. Then, in experiments involving anaerobic digestion, various treatment combinations chosen for sugarcane bagasse preparation were applied. Following the preparation of different compounds, sugarcane bagasse was combined with chicken manure and activated sewage in discontinuous digesters at a mesonilic temperature of 37±1 degrees Celsius. There were seven levels of the mixture, with varying carbon to nitrogen ratios ranging from 15 to 55. In order to eva‎luate and study the effect of carbon-nitrogen ratio on the anaerobic digestion process, the amount of biogas produced and its biomethane content were investigated. The results indicate that the pre - treatments used in the present study had a substantial impact on the deligninization rate, and the combined alkaline-ultrasonic pretreatment technique can be regarded as an effective approach for deligninization of sugarcane bagasse. Among the treatments, the highest de-lignin rate was observed with the amount of 96.77 ± 2.13 using 45 minutes of autoclave and 30 minutes of ultrasound treatment. The results of PCA analysis demonstrated a favorable correlation between the applied treatments and the delignin rate and cellulose content while their correlation to lignin and hemicellulose content was adverse. The 45-minute autoclave treatment with a 15-minute ultrasonic treatment was chosen as the optimum method for sugarcane bagasse preprocessing based on the findings of the statistical analysis. The results of the anaerobic digestion test showed that the ratio of carbon to nitrogen in the range of 25 to 35 can be considered as the optimal range. The maximum concentration of biogas was 93.27 ml/g of volatile solids, and the lowest concentration of biogas was associated with the combination of 45 carbon to nitrogen. Three conventional Gompertz, transfer, and logistic models were used to semi-empirically model the test data of cumulative biomethane production. The results of cumulative biomethane modeling showed that the Gompertz model had the best fit to the experimental data. This is when the transfer model showed the weakest fit.

اسماعيل مهريار , مرتضي صادقي

محمد حسن , حميد زيلوئي

مهرنوش جعفري , عليرضا علافچيان