One-step multi enzyme pretreatment and biohydrogen production from Chlorella sp. biomass

Abstract

One-step multi-enzyme (OSME) pretreatment of Chlorella sp. biomass were statistically optimized. Enzyme dosages of 380 units/g-VS Termamyl SC, 229.45 units/g-VS Dextrozyme GA, and 34.13 filter paper units/g-VS Cellic CTec 2, and a hydrolysis time of 90 min were the optimal conditions yielding a RSY of 167.61 mg/g-VS, equivalent to 49.29% carbohydrate solubilization. An OSME pretreated biomass was used as substrate for biohydrogen production that was optimized under feed/inoculum ratio of 3.0 and initial pH of 6.5. A hydrogen yield of 43.16 mL-H2/g-VS was obtained under optimal conditions, which was 39.63% greater than that observed with non-treated biomass. Addition of nutrients in the form of a basic anaerobic medium with or without a nitrogen source, tended to decrease the efficiency of hydrogen production from the hydrolyzed biomass. This work demonstrated OSME hydrolysis as an alternative to the sequential hydrolysis processes for efficient conversion of microalgae biomass to fermentable sugars and biohydrogen.