Process design and economic evaluation of integrated, multi‐product biorefineries for the co‐production of bio‐energy, succinic acid, and polyhydroxybutyrate (PHB) from sugarcane bagasse and trash lignocelluloses

Abstract

This study investigates whether a biorefinery, annexed to an existing sugar mill and co‐producing succinic acid, polyhydroxybutyrate (PHB), and electricity from sugarcane bagasse and trash lignocelluloses, will be a viable investment opportunity for existing sugarcane mills. Four scenarios were simulated in Aspen Plus® and were included in the economic analysis. Scenario A involved the production of PHB and electricity; Scenario B the production of PHB, succinic acid, and electricity; Scenario C the production of succinic acid and electricity; and Scenario D involved the production of electricity only. The most favorable configuration was found for Scenario B where PHB was produced from 25% of the fermentable glucose stream, and succinic acid from the hemicellulose hydrolysate together with 75% of the glucose, resulting in an internal rate of return (IRR) of 24.1% with a net present value of US$477.2 million. Alternatively, Scenario D could be selected if low capital (130.1 million US$) and operational costs (US$13.2 million) are desired, although weak returns (IRR 10.3% and net present value of US$6.08 million) were observed for an electricity price of 0.08 US$ kWh−1. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd

Revitalizing the sugarcane industry by adding value to A‐molasses in biorefineries

“…21 Moreover, genetically modified E. coli has been successfully used for the commercial production of SA from commodity sugars. [20][21][22]36 Escherichia coli strain KJ122-KJSUC-24T 16 cells were growth on 10% (v/v) of the dilute A-molasses in a two-stage seed train 7,21 with no cells recycle. 36 A simple mineral salt medium (AM1) sterilized at 120 °C 16 supplied the nutrients required for the growth of the micro-organism, which was modeled in Aspen RStoic reactor at 37 °C.…”

“…The fermentation broth was filtered to remove E. coli cells and solid impurities as waste. 7 Then the broth was treated with tri-n-octylamine (TOA) diluted with 1-octanol in three successive stages of reactive extraction process to extract the SA into an organic phase, leaving an aqueous waste stream. 34 Subsequently, the product was recovered from the organic phase in a back extraction step using a mixture of trimethyl-amine and water, which was recycled back to the process through distillation.…”

“…2 These are used as cheap feedstocks instead of processed sugar to reduce production cost. 6,7 However, lignocellulose feedstocks (bagasse, trash, and leaves) contain structural carbohydrates, which require energy-intensive and expensive pre-treatment and hydrolysis steps for their conversion to fermentable sugars and in the long run, making them too expensive to use. 7 On the other hand, C-molasses contains high amounts of non-sucrose impurities, 8 which may not be suitable for sucrose-based non-fermentation products and may also affect the purity of products.…”

“…6,7 However, lignocellulose feedstocks (bagasse, trash, and leaves) contain structural carbohydrates, which require energy-intensive and expensive pre-treatment and hydrolysis steps for their conversion to fermentable sugars and in the long run, making them too expensive to use. 7 On the other hand, C-molasses contains high amounts of non-sucrose impurities, 8 which may not be suitable for sucrose-based non-fermentation products and may also affect the purity of products. 9 Moreover, Brazilian and other sugarcane biorefineries have demonstrated that using clarified juice and intermediate (A and B) molasses for co-production of sugar and ethanol 10,11 have superior economics compared to using C-molasses.…”

“…Efe et al 28 found that sucrose raw material had the highest contribution (29%) to the yearly operational cost of SA production and suggested the need for alternative raw materials such as molasses in the future, with suitable downstream processes to yield the required market purity. Nieder-Heitmann et al 7 reported high pre-treatment and hydrolysis costs as the main challenge with the use of lignocelluloses as cheap raw material for SA production, aside the low product concentrations typical of xylose-based feedstocks. 29 The techno-economic studies of scFOS production from pure crystalline sucrose in stand-alone plants focused on the types of enzyme systems and fermentations used rather than the raw material.…”