Evaluation of different pretreatments on organic matter solubilization and hydrogen fermentation of mixed microalgae consortia

This study investigated the effects of pretreatment methods (such as autoclave, ultrasonication and electrolysis) of mixed microalgae consortia (predominantly composed of Scenedesmus followed by Chlorella species) from natural ecological niche. In addition, the cultivated biomass (wet) was subsequently utilized for fermentative H₂ production in mesophilic regime. The results showed that peak hydrogen production rate (HPR) and hydrogen yield (HY) were achieved from electrolysis pretreated algal consortia as 236 ± 14 mL/L-d and 37.7 ± 0.4 mL/g (volatile solids) VS_added, whereas the untreated algal consortia resulted in the turnout as 64 ± 5 mL/L-d and 9.5 ± 0.0 mL/g VS_added, respectively. The significant increment observed in HPR and HY values were nearly 4 times higher. The solubilization of organic matter during the pretreatment showed positive correlation with the H₂ production. The energy generation rate and yield of the corresponding pretreatment methods were as follows, 1.44, 1.79 and 2.65 kJ/L-d for autoclave, ultra-sonication and electrolysis, the corresponding yields also fell in the range of 0.32, 0.41 and 0.43 kJ/g VS_added, respectively.