Evaluating the feasibility of commercial arabinoxylan production in the context of a wheat biorefinery principally producing ethanol: Part 2. Process simulation and economic analysis

This study investigated the economic feasibility of co-producing an arabinoxylan (AX) product with ethanol from wheat, in order to establish whether, under plausible scenarios, it was realistic that a commercial source of wheat AX could be established. The possibility of recovering wheat bran via pearling was also investigated, both as an opportunity to have bran bypass the main ethanol production process and enter the distillers dried grain with solubles (DDGS) co-product in a dry state, or as a means of obtaining bran for AX extraction. Process flowsheets describing three scenarios were created using SuperPro Designer: conventional wheat-to-bioethanol production with DDGS as the principal co-product; bioethanol production with co-production of AX using conventional hammer milling and sieving to recover the bran for AX extraction; and the use of pearling technology to recover bran for AX extraction. Full economic analysis of each of the three scenarios, considering all capital and operating costs, was undertaken, basing comparisons on a constant return on investment in order to estimate the production costs of AX.

Sending bran removed via pearling directly to DDGS was not economic; the reduced ethanol yield and increased electricity costs more than offset the savings in drying costs. Simulation of the integrated processes indicated that an AX product of 80% purity could be co-produced with ethanol at a cost of around 3.7–4.5£/kg. This is within the range of comparable viscosity-enhancing ingredients used in the food industry, but is towards the top end of the range. In order to establish a market, AX would therefore need to offer some additional functionality. AX production from bran obtained via pearling was more expensive that from bran obtained via hammer milling and sieving; however, whether the functionality of the AX differs needs to be established. The research indicates that creating a market for AX is feasible in terms of production costs if the AX is co-produced with ethanol. On this basis, further research is justified to investigate the functionality of AX from different sources, to optimise the AX extraction process and to establish the potential of AX as a food or pharmaceutical ingredient.