Enhancement of Pretreatment Feasibility of Lignocellulosic Substrates for Biogas Production with Alkaline Lake Water

To improve the biogas efficiency from lignocellulosic feedstock, an alkaline pretreatment method was investigated based on the sustainable use of a natural resource. A new aspect of this study is the use of water from Lake Van (Lake Van Water, LVW), the world's largest alkaline lake with a surface area of 3,755 km2, located in an agricultural area, instead of alkaline solutions made with chemicals in laboratories. Wheat straw is the main cultivated waste as lignocellulosic feedstock and was also selected for this experiment. The alkaline pretreatment was carried out on a pulverised straw (2 cm max) with the LVW and alkaline water (NaOH solution). The experimental pretreatments were carried out for 120 h at a temperature of 37 °C in a climate-controlled room. Batch tests for anaerobic digestion were conducted for 60 days under mesophilic conditions (37 °C) to assess biochemical methane potentials. The methane yield of both types of pretreated wheat straw gave higher values than untreated wheat straw. It was also indicated that the WS pretreated with the LVW had a higher methane yield than the WS pretreated with the NaOH solution. In this study, an economic feasibility evaluation was also conducted. The LVW was determined to be a better economic alternative to NaOH for the pretreatment of wheat straw, a model lignocellulosic biogas substrate.