Environmental impact of cellulase production from coffee husks by solid-state fermentation: A life-cycle assessment

Abstract

In this article, we present a study on the environmental impacts related to cellulase recovery from coffee husks (CH). The environmental impacts of the cellulase recovery process were determined using a comparative attributional life-cycle assessment (LCA) approach. The scenarios were developed according to a novel waste management system in which enzymes were produced during solid-state fermentation (SSF) using CH as a substrate. To date and to our best knowledge, this is the first LCA study applied to a complete SSF process (including downstream stages) at a representative scale. The novelty of this work was the assessment of the complete production process of this technology; namely, the fermentation, extraction, and purification of cellulase. Life-cycle inventory data were obtained from the EcoInvent v3.4 (SimaPro v8.5 software) database and from pertinent pilot-scale experiments. ReCiPe 2016 was used for calculating the environmental impacts. The results showed that most of the environmental impacts of SSF cellulase production were due to electricity consumption. A sensitivity analysis revealed that the lyophilisation step is the major contributor that effects all categories and this impact could be reduced by lowering electricity consumption during the downstream stages. In general, the results pointed out that improvements in the downstream process would help to reduce the SSF environmental impacts and costs.