Two Factors Influencing Rice Straw Biogas Fermentation in High Concentrations Condition

In the straw biogas fermentation with high concentration, ratio of nitrogen and amount of seeding material have significant effect. Experiments show that gas production is very high in early time when the urea addition level is 2.5% or 3.0%, but the methane content of gas is less than 45%. when the urea proportion is 3.5%, the gas production curve is gently, the fermentation starting time is short (only 4 days), total gas production is higher with higher levels methane content. When the ratio of urea reaches 4%, gas production and methane concentrations are significantly reduced. When the amount of seeding material is between 30% and 50%, the more seeding material is, the better fermentation is. When the proportion of urea is 3.5%, seeding material ratio has little effect on the fermentation. In short, this experiment proved that the optimum ratio of urea is 3.5%, seeding material proportion is 30% for rice straw biogas fermentation with high concentration.