Revalorization of industrial by-products from frozen concentrated orange juice for a circular economy

Brazil is the major producer and exporter of orange juice in the world. Orange peel (OP) derived from juice processing, the main industrial by-product, is generally intended for animal feed without further revalorization. The frozen concentrated orange juice (FCOJ) productive chain presents high energy requirements. A possible route to revalue OP and to generate renewable energy is the anaerobic digestion (AD) technology, for which a previous assessment of the theoretical electricity generation from biogas combustion indicated that 0.017 MWh per ton of OP could be obtained. Aiming to support a clean and renewable energy transition for the citrus industry, a thorough literature search regarding OP revalorization routes was made to investigate the potential energy recovery from AD technology for the Brazilian's FCOJ scenario. The results indicated that the AD of the total OP amount derived from industry could be enough to supply from 71 to 111% of the total energy consumption in the FCOJ chain (from the initial step, i.e., permanent orange fields and their fertilization technologies-organic or conventional systems-until the industrial energy requirements). Despite the agricultural system (organic or conventional), a positive energy replacement can be achieved through the adoption of AD. Finally, the study concluded that FCOJ industry presents an opportunity to obtain energy savings. Moreover, for the Brazilian FCOJ production, OP revalorization could mitigate 9.74 tCO(2eq)/year of GHG. A decarbonization strategy and a healthy circular economy for the Brazilian citrus industry could flourish from AD adoption as an alternative route for OP disposal.