Performance targets defined by retro-techno-economic analysis for the use of soybean protein as saccharification additive in an integrated biorefinery

Mariana G Brondi,Felipe F Furlan,Andrew M Elias,Roberto C Giordano,Cristiane S Farinas

doi:10.1038/s41598-020-64316-6

Mariana G Brondi, Felipe F Furlan + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-64316-6

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Abstract

The use of additives in the enzymatic saccharification of lignocellulosic biomass can have positive effects, decreasing the unproductive adsorption of cellulases on lignin and reducing the loss of enzyme activity. Soybean protein stands out as a potential lignin-blocking additive, but the economic impact of its use has not previously been investigated. Here, a systematic evaluation was performed of the process conditions, together with a techno-economic analysis, for the use of soybean protein in the saccharification of hydrothermally pretreated sugarcane bagasse in the context of an integrated 1G-2G ethanol biorefinery. Statistical experimental design methodology was firstly applied as a tool to select the process variable solids loading at 15% (w/w) and soybean protein concentration at 12% (w/w), followed by determination of enzyme dosage at 10 FPU/g and hydrolysis time of 24 h. The saccharification of sugarcane bagasse under these conditions enabled an increase of 26% in the amount of glucose released, compared to the control without additive. The retro-techno-economic analysis (RTEA) technique showed that to make the biorefinery economically feasible, some performance targets should be reached experimentally such as increasing biomass conversion to ideally 80% and reducing enzyme loading to 5.6 FPU/g in the presence of low-cost soybean protein.

Highlights

The use of additives in the enzymatic saccharification of lignocellulosic biomass can have positive effects, decreasing the unproductive adsorption of cellulases on lignin and reducing the loss of enzyme activity
For this set of experiments, the enzyme dosage was fixed at 5 FPU/g solids, in order to avoid a high loading of enzymes masking the effect of soybean protein during the hydrolysis reaction
A systematic study employing techno-economic analysis was performed to evaluate the effects of operational conditions during sugarcane bagasse enzymatic hydrolysis reactions with soybean protein as an additive

Summary

Introduction

The use of additives in the enzymatic saccharification of lignocellulosic biomass can have positive effects, decreasing the unproductive adsorption of cellulases on lignin and reducing the loss of enzyme activity. A systematic evaluation was performed of the process conditions, together with a techno-economic analysis, for the use of soybean protein in the saccharification of hydrothermally pretreated sugarcane bagasse in the context of an integrated 1G-2G ethanol biorefinery. The retro-techno-economic analysis (RTEA) technique showed that to make the biorefinery economically feasible, some performance targets should be reached experimentally such as increasing biomass conversion to ideally 80% and reducing enzyme loading to 5.6 FPU/g in the presence of low-cost soybean protein. Soybean protein had a greater effect in enhancing the reaction yield, with these positive results being attributed to the mitigation of nonproductive adsorption[11,21,23] Given these positive findings concerning the use of soybean protein to improve the saccharification yield, it is crucial to evaluate the techno-economic impact of its addition in the 2G ethanol production process, in the biorefinery context. There is still a need to provide targets to be pursued by the R&D teams to improve the performance of the technology in order to make the integrated biorefinery economically feasible

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