Exploring the production of bio-succinic acid from apple pomace using an environmental approach

Fermentation-derived bio-succinic acid (BioSA) is a valuable intermediate; it is used as a chemical building block, and has multiple industrial applications as an alternative to petroleum counterparts. The aim of this study was to develop a full-scale plant to produce BioSA from apple pomace, a low-cost solid waste from the cider- and juice-making industry, based on a biorefinery concept, and to determine its environmental profile using a cradle-to-factory-gate, scaled-up LCA approach. Foreground data used in this LCA were based on mass and energy flows, modelled in detail. The production process was divided into three stages: i) reconditioning and storage; ii) fermentation with Actinobacillus succinogenes; and iii) purification. The results indicate that the use of enzymes is responsible for the highest environmental burdens, due to their highly energy-intensive background production processes. When these were excluded from the analysis (following other studies available in the literature), the purification stage played an environmentally significant role, due to the extraction and distillation units involved. The electricity use and the requirements for organic solvents in these operations make up the largest environmental burdens. Thus, approaches with the highest potential for improvement must involve both operations. Alternatives for improvement are proposed that offer interesting potential reductions in the environmental profile, especially at the purification stage.