Abstract
Waste biomass from forestry and wood processing industries is a source to obtain fine chemicals, and its processing is a good example of circular economy, but it generates secondary environmental impacts. The main objective of this study was to analyse the environmental performances of laboratory scale processes for polyphenols extraction from spruce bark by means of life cycle assessment (LCA) and to simulate and evaluate the scale-up possibilities of the most favourable alternative. The assessed extraction processes were: a classic Soxhlet extraction using ethanol as solvent (SE), a high-temperature extraction in 1% NaOH solution (NaOH-SLE) and an ultrasound assisted extraction process (UAE). The functional unit was 1 mg of extracted polyphenols, measured as gallic acid equivalents (mg GAE)/g spruce bark. The life cycle inventory has included specific laboratory scale operations and extraction processes (infrastructure and transport processes were not considered). Life cycle impact assessment was performed with ReCipe 2016 at midpoint. For all extraction processes, the environmental profiles were dominated by the electricity use for heating and this has generated the highest impacts in most of the impact categories, followed by the production and use of ethanol as solvent. For the ultrasound assisted extraction, a scale-up scenario has proven that by raising capacity to a 30 L extraction vessel and by changing the heating source to a biomass-fired boiler, environmental impacts may be greatly diminished. The paper discusses also the uncertainty of lab-scale generated data for LCA. A sensitivity analysis has proven that for this case, the energy efficiency of different lab-scale equipment induce acceptable degrees of uncertainty for the LCA results.
Highlights
Method must be simple, fast, economic, with large applicability and with low environmental impacts
The general environmental profiles for the extraction processes are presented in Table 3, where one may observe that the highest impacts in all categories are generated by the NaOH extraction, followed by the Soxhlet extraction and the ultrasound assisted extraction (UAE) extraction
The analysis was carried out by using the LCA methodology which has considered the specific processes for extractions, for which relevant LCA data was measured and collected and which was related to the functional unit of the study (1 mg of extracted polyphenols measured as gallic acid equivalents (GAE))
Summary
Method must be simple, fast, economic, with large applicability and with low environmental impacts. Recently, new research approaches have been tested in the field of fine chemicals and green synthesis to consider waste treatment[13], emerging technologies[14], novel materials[15] and innovative processes and scaleup[16], multi-criteria comparison of complex systems[17], to name just few methodological challenges related to biorefinery processes In this field, LCA has been mainly used to evaluate full-scale bioenergy production (mainly bio-ethanol18, biogas[19,20], jet fuel21) and to a lesser extent the production of chemicals like p olysaccharides[5] or tannins[22]. In the field of small-scale solvent extraction processes, LCA was primarily used to investigate the environmental impacts of bio-fuel production processes, especially by using algae systems[23,24,25], and for bio-active compounds production, like: p harmaceuticals[26], carotenoids 27
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