Abstract
Alternative energy sources have been extensively studied due to the environmental concerns caused by the employment of fossil fuels. Hydrogen is considered a very clean energy source, since its combustion releases mainly water as a reaction product and also it has the advantage of having the highest energy density when compared to any other fuel. Moreover, hydrogen may be produced biologically by fermentation from renewable sources, such as effluents and agroindustrial wastes. Based on this context, this work evaluated the hydrogen production by dark fermentation, using a microbial consortium obtained from a dairy wastewater treatment plant. The fermentative process occurred in batch with a reaction volume of 75 mL using lactose (20g/L) as substrate, which was procured from whey permeate. The response hydrogen conversion was evaluated from the process variables, temperature, which ranged from 27,9 to 42°C, and magnesium sulfate concentration, which varied from 0,31 to 1,44 g/L. The response surface, which was plotted from the results obtained in the Central Composite Design pointed out for best hydrogen yield for the temperature range from 30°C to 35°C and MgSO4 from 1.2 to 1.6 g/L. The maximum yield was 4.84 mol H2/mol lactose.The following organic acids, acetic, lactic, butyric and propionic were produced in the fermentation.
