Sugarcane juice clarification by distillery fermenter gases

In India and elsewhere many sugar factories employ the double sulphitation process of clarification for the production of plantation white sugar for direct consumption. Volatility in sulphur prices, growing demand for sulphur-free good quality sugar and health and environmental concerns prompted efforts to reduce or even eliminate the use of sulphur dioxide during the clarification process. With the objective to develop a greener techno-economic process which, besides eliminating sulphur, would also provide an opportunity to utilize CO2 from distillery fermenters for producing sulphur less plantation white sugar, laboratory trials have been conducted with the juice from two factories in the tropical region of India and juice available in sub-tropical region at the National Sugar Institute, Kanpur. Experiments were conducted using different doses of milk of lime in the range 1.2-2.4% v/v at 65 and 70 degrees C and saturating the juices with CO2 gas up to a pH of 8.2 to 8.4. The final pH was adjusted to 7.0-7.2 with phosphoric acid. The treated juice was heated to 100-102 degrees C and allowed to settle. The juices were analyzed before and after treatment for pH, colour, turbidity, brix, pol, reducing sugar and CaO content. Clear juice obtained by the proposed 'Single Carbonation and Decantation Process' was compared with clear juice obtained by the conventional double sulphitation process. The quality of the clear juice obtained by the proposed process was comparable or even better than the clear juice by the double sulphitation process as reflected by various quality parameters, and there were no adverse effects on sucrose or reducing sugar content. Preliminary trials indicate that the juice clarification process using fermenter gases from the distillery may be applied in place of the double sulphitation process in sugar factories with attached distilleries aiming at producing sulphur-free plantation white sugar as well as addressing environmental concerns.