Screening and optimization of pretreatments in the preparation of sugarcane bagasse feedstock for biohydrogen production and process optimization

This work evaluated the effects of individual alkaline, sodium carbonate (Na2CO3 denoted as; NaC), sodium sulfide (Na2SO3 denoted as; NaS) and combination of NaC + NaS pretreatment for the saccharification of sugarcane bagasse (SCB). The effects of different pretreatments on chemical composition and structural complexity of SCB in relation with its saccharification were investigated. For enzymatic hydrolysis of pretreated SCB we have utilized the produced crude enzymes by Streptomyces sp. MDS to make the process more cost effective. A enzyme dose of 30 filter paperase (FPU) produced a maximum reducing sugar (RS) 592 mg/g with 80.2% hydrolysis yield from NaC + NaS pretreated SCB under optimized conditions. The resulted enzymatic hydrolysates of each pretreated SCB were applied for hydrogen production using Clostridium beijerinckii KCTC1785. NaC + NaS pretreated SCB hydrolysates exhibited maximum H2 production relative to other pretreatment methods. Effects of temperature, initial pH of culture media and increasing NaC + NaS pretreated SCB enzymatic hydrolysates concentration (2.5-15 g/L) on bioH2 production were investigated. Under the optimized conditions, the cumulative H2 production, H2 production rate, and H2 yield were 1485 mL/L, 61.87 mL/L/h and 1.24 mmol H2/mol of RS (0.733 mmol H2/g of SCB), respectively. The efficient conversion of the SCB hydrolysate to H2 without detoxification proves the viability of process for cost-effective hydrogen production.