The global energy demand keeps rising at a dramatic speed since the beginning of the industrial revolution in the late 18 th century. In contrast, easy accessible fossil fuel reservoirs are rapidly decreasing, which leads to increasing the energy prices. Therefore, one of the major challenges for industrialized countries is to ensure the energy supply for the future. Combustion of fossil energy carriers like petrol, natural gas and coal leads to the release of CO 2 , cause environmental problems which are projected to manifest in problematic climate changes. Biological conversion of biomass (energy crops, agricultural wastes) and various organic wastes such as organic fraction of the municipal solid waste (OFMSW) has a great potential for continuous production of renewable energy. Bioga i a potentially important energy source that ca be used for the productio of heat, electricity and fuel. It can be produced at wastewater treatment plants, landfills, food and other industrial operations throughout the world. There is a great potential in agricultural operations where animal wastes often land applied or otherwise disposed without any conversion to energy. In this study, the biomethane potential (BMP) of whole wheat plant (WWP), as an agricultural waste, was investigated in batch fermentation reactors during the anaerobic digestion (AD) process working at mesophilic temperature. Two different pretreatment methods using sodium hydroxide as well as sulfuric acid were investigated to improve the BMP of WWP. Different temperatures of pretreatment (0, 25, 50, 75, and 100 ?C) were used for the alkaline pretreatment using NaOH (8% w/w) during 60 min. Also, the acidic pretreatment using H 2 SO 4 (1% v/v) was performed at 121 ?C for different time duration of 10, 30, 60 and 120 min. Clear positive effects of the pretreatments on the yield of methane production were observed. The best improvement was achieved when 8% NaOH for 60 min at 75 °C was used for the pretreatment, which resulted in 54.5% improvement in the yield of methane production. In addition, treatment with 1% sulfuric acid for 120 min at 120 °C resulted in 15.5% improvement in the methane production yield compared to that of the untreated material. Furthermore, the BMP of untreated starch and cellulose was compared with that of untreated WWP in batch fermentation reactors under the same conditions. The NREL test was applied to evaluate the effect of different pretreatments on the composition of WWP. The highest content of glucose of total solids (TS) were measured after pretreatments with NaOH at 75 °C and 25 °C counting up to 63% and 57%, respectively. In order to qualitatively investigate the effect of pretreatment on the structure and surface properties of WWP, fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were applied for the best results of each pretreatment and also untreated WWP. The results showed that the NaOH pretreatment have a greater effect on improving the BMP of whole wheat plant in contrast to dilute sulfuric acid pretreatment and also, it was observed that the WWP could be efficiently converted to methane under the AD process at mesophilic temperature in batch fermentation reactors. Keywords: Biomethane potential, anaerobic digestion, biogas, biomass, whole wheat plant, alkaline pretreatment, acidic pretreatment.
