Untitled

Nowadays, treatment of vinasse from the alcohol fermentation is a major cost centre which decides the economic viability of this traditional industry. Increasingly stringent environment norms in France have put enormous pressure on manufacturers of alcohol from traditional feedstock like beet molasses. Nowadays, the most industrial treatment is the vinasse valorisation as fertiliser in the field after concentration. Nevertheless, the final solids are limited because of the sulphate potassium crystallisation and precipitation in evaporator tubes, storage tanks and fertiliser sprayers. The paper gives some figures of beet molasses vinasse composition, details the most widely used treatment schemes and presents the first results obtained with an electrodialysis treatment to reduce the potassium concentration in view to prevent the crystallisation and even increase the final dissolved solids of the concentrated vinasse.

These first results are encouraging. They proved that the reduction of potassium concentration in vinasse using electrodialysis is performant and that it is not necessary to operate a previous clarification step. Nevertheless, these results must be completed by bigger pilot tests (at least with 1 m2 membrane area) and longer tests to check the cleaning recovery. In the same way, experiments have to be carried out to measure the real potassium sulphate solubility in concentrated vinasse, because it is known [9] that it depends on the vinasse composition which is linked to many factors (molasses composition, must preparation, distillation scheme). Furthermore, at an industrial scale, the brine is not changed after each experiment but regularly drained and diluted with fresh tap water. The recovery mode of the potassium sulphate 10.0 8.0 6.0 4.0 2.0 0.0 time (min) Fig. 3. Potassium concentration evolution during the electrodialysis of light beet molasses vinasse.