Claire Fargues

Interest of electrodialysis to reduce potassium level in vinasses. Preliminary experiments

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.

Complete Decalcification of Saline Effluent by Associating a Carboxylic Resin with a Chelating Resin

Saline effluent from the glucose industry can be reused as resin regenerants after treatment by a bipolar membrane electrodialysis process preceded by chromatographic decalcification. Ca2+/Na+ isotherms measured on two weak acidic resins showed that the chelating resin has a higher selectivity for calcium. The decalcification process was optimized by combining rough decalcification on a carboxylic resin, followed by a finishing step on a chelating one. This chromatographic system led to the expensive chelating resin being spared and to the treatment of 60% more volume of effluent than with the carboxylic resin alone.

Structural characterization of flocs in relation to their settling performances

This paper reports on the use of particle size analysis and settling tests for characterizing the structure of metal coagulation floes and further identifying optimum conditions for their settling and dewatering. A velocity-size variation law was established for model floes created from colloidal clay particles suspensions with different initial clay concentrations using two coagulants [aluminium sulphate, A1 2 (SO 4 ) 3 and ferric chloride, FeCl 3 ]. It allowed deduction of the volume fractal characteristic D 3 of each clay floe family and their settling performances. Floes also appeared to be made from three basic units, the size of which was estimated from particle size analyses performed at different stages of the coagulation/flocculation. All the D 3 values obtained were high, about 2.5, nearly independent of the initial clay concentration. In contrast, the floe and the basic unit sizes decreased with the clay concentration increase. More concentrated suspensions led to lower settling rates. Ferric floes appeared to be made from larger basic units than aluminium ones and to be less dense and less compact with lower settling rates. They were therefore thought to contain more water.

Sugar cane stillage: a potential source of natural antioxidants.

Biorefinery of sugar cane is the first economic activity of Reunion Island. Some sugar cane manufactured products (juice, syrup, molasses) have antioxidant activities and are sources of both phenolic compounds and Maillard Reaction Products (MRP). The study aimed to highlight the global antioxidant activity of sugar cane stillage and understand its identity. Chromatographic fractionation on Sephadex LH-20 resin allowed the recovery of a MRP-rich fraction, responsible for 58 to 66% of the global antioxidant activity according to the nature of the sugar cane stillage (DPPH test), and a phenolic compounds-rich fraction for 37 to 59% of the activity. A good correlation was recorded between the antioxidant activity of the sugar cane stillage and its content in total reducing compounds amount (Folin-Ciocalteu assay), among them 2.8 to 3.9 g/L of phenolic compounds (in 5-caffeoylquinic acid equivalent). Preliminary experiments by HPLC-DAD-MS allowed to identify several free phenolic acids and gave clues to identify esters of quinic acids.