Clarification of Sugarcane Juice by Ozonation and Anodic Electrooxidation: Effects of Process Variables and Energy Consumption

Abstract

Most of the white sugar production is based on the clarification of sugarcane juice through sulfitation. In this work, alternative clarification technologies, namely ozonation and the electrochemical advanced oxidation process using the DSA® anode, are compared for the first time. In the first case, the effects of temperature and ozone concentration in the gas bubbled into raw sugarcane juice were investigated; for the electrochemical process, the effects of applied electric potential and temperature were considered. Central composite experimental designs were used to study the effects of these process variables on ICUMSA color removal, remaining sucrose content, rheology of the juice and energy consumption. For ozonation, the highest ICUMSA color removals at the end of 60 min were 75% (55 °C; 22.9 mg O3 L−1), 71.4% (33.7 °C; 14.5 mg O3 L−1), and 57.6% (55 °C; 14.5 mg O3 L−1), with energy consumptions of 532, 442 and 642 kWh m−3 order−1, respectively. In contrast, the highest ICUMSA color removal achieved by anodic electrooxidation was around 35%, at 33.8 °C and 18 V or 40 °C and 28 V, with 199 and 587 kWh m−3 order−1, respectively. In both cases, no losses of sucrose or appreciable variation in juice viscosity were observed. Considering equivalent clarification performances, the electrochemical process was shown to be more energy-efficient. Conversely, given the best performances achieved in each case, the clarification technologies studied did not reveal significant differences regarding energy consumption, sounding promising for industrial application, while further detailed process design and economic evaluation are needed.