The microalgae Scenedesmus sp. is a potential source for biohydrogen production

Biohydrogen production is among the most promising solutions to energy scarcity as a 
renewable source to replace fossil fuel. Most of hydrogen nowadays is produced by chemical 
means.  Biohydrogen could be produced from vast arrays of substrates. In this study, the 
biohydrogen was produced from the Scenedesmus sp. microalgae by dark fermentation. The algal 
cultures were pretreated before digestion with the seeding material to investigate the best 
performance for hydrogen production. The seeding material was sludge from wastewater treatment 
plant. The pretreatments included microwave digestion, ultrasonic, hydrochloric acid pretreatment 
and a combination between acid pretreatment and microwave digestion. For the control, 
experiments without pretreatment were performed. Pretreated and not pretreated Scenedesmus sp. 
cultures were digested in batch experiment under mesophilic conditions with different pH-values to 
produce hydrogen. The quality and quantity of gas were monitored during the experiment by 
eudiometer for measuring the quantity of gas produced and infrared gas analyzer to know the 
composition of produced gas. The quantity and quality of gas volume produced differed between the 
various pretreatments. The highest H2 concentration produced at pH 5.0 glucose fermentation of 
ca. 130 mlN was attributed to ultrasonic pretreatment while the lowest (< 97 mlN) was recorded by 
microwave and hydrochloric acid digestion. At pH 6.0 fermentation by the algal strain, the highest 
H2 yield of ca. 118 mlN was produced by microwave digestion at 70 °C for 15 min. The effect of 
Scenedesmus sp. pretreatments on organic acid yields as well as diluted organic carbon (DOC) and 
total nitrogen bound (TNb) as indirect measures for biohydrogen production was discussed