Contribution of Membrane Technology in Concentration of Thin Sugar Juice

Beet sugar industry is a major Energy consumer. Sugar from the beet slices is extracted by leaching process using hot water in the diffuser at about 70°C. After extraction the thin juice sugar is concentrated to 70% Brix. Evaporation is one of the conventional processes for concentration thin juice sugar from 15% to 70% Brix; Evaporation is the most energy intensive process in the sugar industry. Contribution of Reverse osmosis in preconcentration of row thin juice sugar from 15% to 21% Brix leads to reduce energy consumable in evaporation process, and reuse the water of permeate stream again in the diffuser.

In this work, the thin juice sugar was concentrated by reverse osmosis in spiral pilot plant with 5m² of filtration area before the multiple-effect evaporators as a pre-concentrator to reduce the load on the multiple-effect evaporator or to increase the capacity of the evaporation step and produce high quality sugar. Five temperatures 30, 40, 50, 60, 70°C were evaluated. Also, the performance of the reverse osmosis unit was investigated at different driving forces. High flux and high rejection were obtained at the highest temperature (70°C). Energy required for concentration thin juice sugar was reduced by 12% by contribution of one stage of membrane separation process as a pre-concentrator before evaporation. Also, saving in fresh water consumable was achieved.