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So far, a large number of pretreatment methods have garnered significant attention aimed only at optimizing the reducing sugar and bioethanol yields. This study however, carried out pretreatment of sugarcane bagasse (SCB) using hydrothermal, organosolv, alkaline and alkaline peroxide pretreatment methods comparing their process performance. An evaluation of the energy consumption parameter during pretreatment showed lowest energy use (0.619 kWh/kg) during 5% alkaline peroxide pretreatment. The energy efficiency (0.162 kg bioethanol/kWh) was thus highest whereas the waste generation was lowest (38.895 kg waste/kg bioethanol) during alkaline peroxide pretreatment process. The solid biomass was utilized for enzymatic saccharification and bioethanol fermentation using SSF. Maximum enzyme efficiency and bioethanol yields achieved were 85.02% and 0.101 kg bioethanol/kg biomass respectively. Process performance evaluation can be projected to open up a new avenue for practical implementations of life cycle analysis (LCA) and techno-economic assessment aiding the circular bio-economy approach. [Display omitted] • Chemical pretreatment technologies investigated for process performance evaluation. • Energy efficiency and waste generation used to evaluate process performance. • 0.162 kg bioethanol/kWh- energy efficiency during alkaline peroxide pretreatment. • Also, lowest waste generation (38.895 kg waste/kg bioethanol) was recorded. • NaOH and H 2 O 2 at 5% (w/w) chemical concentration was most effective pretreatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ethanol productivity was improved by a combined AP pretreatment and SSSF process. [•] 64.9% of lignin was removed by AP pretreatment. [•] Ethanol yield was significantly increased from 12.8% to 63.1%. [•] SSSF generated fewer inhibitors than SSF. [Copyright &y& Elsevier]

Abstract: Bamboo is an alternative feedstock for the production of fine chemicals, such as fuel ethanol and lactic acid, because bamboo has a large amount of sugars. An effective pretreatment method for enzyme saccharification is required for the efficient production of these materials. Enzyme saccharification (48h) using a 35atm and 5min steam exploded bamboo produced 426 and 488mg/(g initial dry sample) of glucose and reducing sugar, respectively. In addition, pretreatments using 20atm and 5min steam explosion or mechanical milling for 5min followed by 10wt.% sodium hydroxide treatment at 121°C for 60min were attempted in order to enhance the digestibility of the holocellulose component. Both of these pretreatment methods had a large positive effect on the production of sugars by subsequent enzymatic hydrolysis. In particular, the maximum value of glucose production was obtained by the 20atm steam explosion and 10wt.% sodium hydroxide treatment. This produced 456mg/(g initial dry sample) of glucose and 460mg/(g initial dry sample) of reducing sugar. In comparison, the mechanical milling and 10wt.% sodium hydroxide treatment produced 383 and 485mg/(g initial dry sample) of glucose and reducing sugar, respectively. From these results, it was concluded that the pretreatment with 20atm steam explosion and 10wt.% sodium hydroxide treatment was the most effective pretreatment method for the production of glucose from bamboo by enzyme saccharification. However, since this pretreatment method requires the severe conditions of both high pressure and temperature steam explosion and high concentration sodium hydroxide, an alkaline peroxide pretreatment without a steam explosion and high concentration sodium hydroxide was also attempted. A comparatively large amounts of glucose and reducing sugar production, i.e. 399 and 568mg/(g initial dry sample), respectively, were obtained in 1%(v/v) hydrogen peroxide and 1wt.% sodium hydroxide treatment at 90°C for 60min. Therefore, it was concluded that alkaline peroxide pretreatment is an effective and environmentally friendly method for the enzyme saccharification of bamboo. [Copyright &y& Elsevier]