Environmental performance of orange citrus waste as raw material for pectin and essential oil production

Abstract

This study evaluated the potential environmental impact of the integrated extraction process of byproducts from orange processing, i.e., essential oil and pectin. A cradle-to-gate attributional Life Cycle Assessment was performed, considering 1 kg of pectin as the functional unit, following the ISO 14040/44 standards. The product system includes from the raw material (orange) to the stages to obtain the essential oil and pectin. The impact assessment considered eight categories from the ReCiPe Midpoint (H) v.1.02 method, using SimaPro® software as a supporting tool for modeling the product system. In addition, mathematical modeling was developed using Scilab 6.0.1 software seeking to discuss performance trade-offs versus environmental impact and process improvements. The impact assessment found that pectin production is the main hotspot, most attributed to the hydrolysis operating unit. Electricity, hydrochloric acid, and water consumption contributed most to negative environmental impacts. From the perspective of process modeling, the conventional temperature (373 K), the reduction of pH (pH=1.5), and the greater volume of water in the tank corresponded to the best effects in terms of yield, which is not necessarily related to the best environmental performance. The sensitivity analysis showed the best scenarios regarding environmental impacts correlating temperature with the energy source (SA1) and the pH with the acid used for the extraction (SA2). The analysis revealed that natural gas is the best alternative as an energy source, reducing emissions in six of the eight impact categories compared to the standard scenario. Citric acid increases emissions in all impact categories assessed due to the greater amount needed to achieve the simulated optimal extraction pH (1.5). The conventional scenario (hydrochloric acid) becomes the best alternative in this condition. These results bring a combined approach to life cycle sustainability with process modeling, identifying opportunities to improve the environmental performance of products based on citrus residues, contributing to the achievement of the 12th and 13th Sustainable Development Goals, and providing strategies to implement the Circular Economy in the citrus chain.