The Application of Membrane Separation Processes as Environmental Friendly Methods in the Beet Sugar Production

Abstract

The sugar industry is one of the key segments of the food industry. This industry is also well known as one of the most energy-intensive in the field of food and chemical industry. In 1999, the total quantity of produced sugar was summarized. It was reported that the production reached 16 700 000 tones, while the total value of the produced sugar was 8924 million EUR. A significant quantity of thermal energy was consumed for the evaporation and beet pulp drying, as well as electrical energy needed for the pumps and for driving the centrifuges. According to CEFS, specific energy consumption was 31.49 kWh/100 kg beet in 1998 (IPPC, 2003). In a Greek study, a figure of 280 kWh/t is given for the electrical part of the energy consumption in sugar manufacturing (IPPC, 2003). While the overall water used is about 15 m3/t sugar beet processed, the consumption of fresh water is 0.25 – 0.4 m3/t sugar beet processed, or even less in modern sugar factories. Water consumption depends on the activities of each installation, e.g. more water is consumed in an installation that extracts and refines sugar beet compared to the one that does only one of these activities (IPPC, 2003). For example, the consumption of water in Austria was reported at a level of 1.5 m3/t of sugar beet processed, which is equivalent to 9 m3/t of produced sugar (IPPC, 2003). The transport water has high organic contamination due to the soil and sugar from damaged beets. Its COD is 5000 – 20000 mg/L. Waste water with high BOD levels is produced in large volumes (IPPC, 2003). Despite the fact that the sugar industry is one of the causes of the environmental pollution, not enough has been done on its improvement. The technology applied in almost all European sugar factories is based on the traditional principles and methods. The major steps in the traditional sugar beet processing are (Poel Van der et al., 1998): i) Pre treatment – Washing and slicing of the sugar-beets into cosettes are the initial operations;