XXIst Symposium. Juice purification in sugar industry: recent methods and techniques. AVH


Reims, 27th of March 2014. Maison des Agriculteurs

The XXIst AVH Symposium was dedicated to Mr Jean Génotelle.

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Session I : Juice purification in beet sugar factories

President: Philippe REISER, CEDUS, Paris, France

9:00: – Evaluation of juice purification in sugar factories, Mohsen Ajdari Rad, Azar Ajdari Rad,  Südzucker, Obringheim, Germany, Gilles Schrevel, Raffinerie Tirlemontoise, Tienen, Belgium 

9:30 – Laboratory scale comparison of Dorr Carbonatation and Classical Liming purification. Methods, Greg McEntee, British Sugar, GB

9 :50  –   Calcium carbonate – polymorphism, size of aggregates, consequences in juice purification and application possibilities., Šárka E., Bubník Z., Kadlec P., Pour V.,  Technická 5, 166 28 Prague 6, Czech Republic 

10: 10 – Coffee Break, Posters and Exhibitors


Session II : specific impurities and consequences

President: Dr. Jan Maarten de BRUIJN, Südzucker, Obringheim, Allemagne

11:00 – Effect of invertase on beet juice purity, pH and sugar  loss, Franco Maniscalco, Nalco. EMEA, Business Development Consultant, Italy

11:30  –     Dextran : analysis, characterization and effect on juice filterability,  Maciej Wojtczak, University of Lodz, Poland

12:00 – Posters & Exhibitors

13:00 – Lunch


Session III : Equipment and separation techniques used in sugar and distillery factories

President: Dr. Martin BRUHNS, Retired from Pfeifer & Langen, Germany

15:00 –  De-sugaring and thickeners in the purification workshop, Gérard Choquenet, Stéphane Fossier, Choquenet, Chauny, France

15:30 – Membranes and Ion Exchange Resins: Adapted techniques to the diversity of cane sugar mills and refineries, François Rousset, Novasep, St Maurice de Beynost, France

16:00 – Benefit of combined treatments associating reverse osmosis and ion exchange for  recycling of distillery condensates in fermentation, M.-L. Lameloise, C. Fargues, M. Gavach, M. Bouix, AgroParisTech, Massy, France

16:30 – Preliminary Report on the use of High Performance Adsorbents in co-refining raw sugar in beet factories,  Ahmed Vawda, CarboUA, Beverly Hills, USA

17:00 – Conclusion

Simultaneous translation 


Paper # 1

Evaluation of juice purification in sugar factories

Mohsen Ajdari Rad, Azar Ajdari Rad and Gilles Schrevel

Südzucker Group

Improvement of beet quality, increased requirements of sugar quality (like reduction of ash and turbidity of sugar) and the demand for reduction of both energy and processing aids (like e.g. lime stone) consumption were important challenges over the past 20 years asking for further optimization of juice purification in beet sugar manufacture.  Numerous investigations were performed to optimize the different process steps of juice purification. More recently, the processing of poor/deteriorated beet quality came into focus due to prolonged beet processing campaigns as a result of the reform of the EU Sugar Regime.

Juice purification is an important step in sugar process technology. It has a significant impact on sugar quality and sugar yield. Despite the achieved substantial improvement of beet quality, still a relatively high content of non-sugar components (i.e. impurities) remains in the raw juice as produced from sugar beet. The presence of these non-sugars requires a rather complicated and costly purification process in order to enable the production of white sugar of the right quality, as well as to limit any unnecessary sugar loss to molasses. The task of juice purification is – above all – to increase the juice purity by neutralization, coagulation, degradation and separation of particular dissolved and colloidal non-sugar components in raw juice. After juice purification we aim at a thin juice with higher purity, low color and lime salts, and good thermostability. New analytic methods and instrumentation have helped to better understand the various physical and chemical reactions taking place during the different steps of juice purification and so how they can be affected.

The classical juice purification uses milk of lime in the pre-liming and main liming and subsequently CO2 in the 1st carbonation and 2nd carbonation in order to achieve the before-mentioned chemical and physical reactions. The precipitated and insoluble non-sugars are removed by filtration and/or decantation.

Some examples of developments over the past 20 years by the R&D departments of the Südzucker Group related to the optimization of the juice purification system will be illustrated:

  • Raw juice viscosimetry
  • Raw juice pre-alkalisation
  • Optimal pH-value of flocculation in the pre-limer
  • Optimal course of pH in the pre-limer
  • Optimal temperature/retention time in the pre-limer and main limer
  • Optimal pH-value of 1st carbonation
  • Lime milk optimisation system (LIMOS-system) to reduce lime stone consumption
  • Lime salts analyser (Lisa)
  • Optimisation of decalcification SZ/RT-Juice purification system with separation of the colloid fraction after the pre-limer

The achieved optimization of the juice purification system has enabled the sugar factories to significantly reduce processing costs whilst increasing sugar quality and yield.


Paper # 2

Laboratory scale comparison of Dorr Carbonatation and Classical Liming purification Methods,

Greg McEntee, British Sugar, GB

All British Sugar factories use a Dorr type lime/carbonic acid treatment for juice purification. This is a simultaneous liming and carbonatation process, followed by settlement clarification for slurry separation. In recent years, processing difficulties at some factories relating to poor weather beet deterioration have led us to question whether a classical liming system, would better suit our beet quality, campaign length and local weather patterns.

Throughout campaign 2013/14 we have sampled diffusion juices from all British Sugar factories, covering different growing areas and soil types, different slicing strategy and different diffuser types. We have simulated Dorr carbonatation and classical liming processes in a batch, laboratory scale experiment aiming to determine the benefits and drawbacks of a classical liming system over our existing Dorr system and to investigate the difference in the diffusion juices produced at our factory sites.

Our observations and findings will be discussed in this presentation.


Paper # 3

Calcium carbonate – polymorphism, size of aggregates, consequences in juice purification and application possibilities

E. Šárka, Z. Bubník, P. Kadlec, V. Pour

ICT Prague, Department of Carbohydrates and Cereals. 

Although sugar technologists and researchers seek to reduce or entirely exclude lime usage in sugar technology, e.g. by membrane application or by separation of preliming precipitate, classical juice purification including lime addition and carbonation gas supply, continues to be a part of sugar technology, where a significant by-product is carbonation sludge.
A contemporary low lime addition in sugar technology causes the percentage of CaCO3 + MgCO3 to be only around 75 % DM in filtration cake and CaCO3 is therefore the major component.

Generally, calcium carbonate exists in various solid forms that are divided into two classes: well-known anhydrous forms: calcite, aragonite and vaterite, and hydrated forms: monohydrated calcium carbonate, hexahydrated calcium carbonate, and amorphous carbonate.

The crystallization of calcium carbonate is connected with the solubility product which is influenced by existing salts in technical sugar solutions and by formation of sugar-calcium complexes as well.

The carbonation precipitate exists in form of agglomerates. Their size, which can be measured by image analysis, laser diffraction, sedimentation techniques or using scanning electron microscope, is very important to have good filterability of the 1st and 2nd carbonation juices. In order to obtain clear 1st carbonation juice when clarifiers are used the right dosing of flocculating agents is very important. The filterability of the 2nd carbonation juice can be negatively influenced by presence of particles < 5 μm as a result of damaged beet

Agglomerate damage may occur during any of the technological stages of juice purification for various reasons, chemical, mechanical, or a combination of both, e.g. chemical dissolution in a prelimer, chemical and mechanical changes during the 1st carbonation, and mechanical damage prior to filter press filtration.

Carbonation sludge (mainly in dried form) has been used or proposed for future applications such as: fertilizer; filler for adhesives, polymer matrices, paper and paperboards; raw material for recalcining to substitute limestone; a part of feeding mixtures; raw material in the building industry for cement and breeze-block production etc.

In this presentation several examples of calcium carbonate crystals will be shown; the reaction scheme of calcium carbonate origin will be depicted; the analytical method to determine composition of carbonation mud in the precipitate, in scales or in produced sugar will be surveyed. Additionally, practical skills in juice purification and application possibilities of carbonation sludge will be presented.


Paper # 4

Effect of invertase on beet juice purity pH and sugar Losses

Franco Maniscalco. Nalco EMEA

Since many years we have been focusing on the loss of sugar in diffusion due to the free Invertase entering the system with fresh cossettes, whereas, vice versa, the bacterial activity plays a marginal role.

As far as we found out, such a phenomenon reached dramatic levels in the South Mediterranean countries, but which also affects the middle area, sharing the same extreme climatic conditions.

For sure, the exposition to unfavourable conditions, such as excessively hot weather or frost & thawing, parasite’s attacks, injuries during transport/storage, plays a significant role.

This paper concerns a factory located in the South Mediterranean area that have been still suffering a significant loss of sugar in the extraction process due to inversion. The failure of an intensive, as well as extended biocide-program (up to 2500 ppm of formaldehyde), led us to be focused on the enzymatic activity rather than on the microbial growth.

Two extraction units are operating: In the first, a BMA tower, the increase of Invert Sugar in the Raw juice, reaches up to 4% Brix. In the second, a RT, the phenomenon is less obvious.


Paper # 5

Dextran: analysis, characterization and effect on juice filterability

Maciej Wojtczak, Aneta Antczak-Chrobot

Lodz University of Technology, Institute of Chemical Technology of Food, Łódź, Poland

Since sugar market regime results in longer campaigns, the problem of processing deteriorated beets is still an important topical problem. Deterioration of beets is mainly a result of storage of defrosted beets. Frost damaged beets are very susceptible to microbiological infections. The growth of microbiological infections in frost-damaged beets leads to several changes in the chemical composition of the beets. These changes concern mainly the hydrolysis of sucrose by microorganisms and the production of various metabolites.

The most harmful result of deterioration of beets is the appearance of dextran. Dextran is one of the most significant impurities negatively influencing sugar production. Dextrans are synthesized by dextransucrase by the transfer of D-glucosyl unit from sucrose to acceptor molecules. This polymerization results in the formation of different molecular mass dextrans. Microbiological dextran is not a pure chemical substance but it consists of a mixture of polymeric chains of glucose of different degree of polymerisation. Thus, we find in dextran some fractions of different molecular mass. Usually, we divided dextran into 3 groups: high molecular weight dextran, that is, above 1000 kDa, medium molecular weight, that is, from 100 to 1000 kDa, and low molecular weight, that is, below 100 kDa.

To date many methods were investigated for dextran determination such as: alcohol haze method, Robert`s copper method, chromatographic method (ion, gel), immunological method, Mean Infra Red Spectroscopy or Nuclear Magnetic Resonance (NMR).

The presence of dextran in the raw juice leads to a disruption of normal processing operations, particularly first and second carbonatation filtration. The blockage of filters is mainly caused by increasing of juice viscosity and decreasing the average size of a particle of calcium carbonate precipitated during carbonatation. The negative impact of dextran on the process can be eliminated by the use of dextranase or addition of precipitated calcium carbonate (PCC). The effect of dextran on the juice purification process depends not only on its content but also on its average molecular weight.


Paper # 6

De-sugaring and thickeners in the purification workshop

Stéphane FOSSIER  & Gérard CHOQUENET

Choquenet, Chauny, France

The company CHOQUENET SAS, founded in 1925 specializes since than in filtration of heterogeneous mixtures in many areas and among others that of beet sugar juices. On the other hand, given its geographical location CHOQUENET society has always been present in the sugar industry and was able to develop and improve its products.

In sugar factories, our equipments are mainly concentrated in the purification workshop, just after diffusion and allow either to clarify the carbonated juice or to recover the residual sugar in the scum or dehydrate these scum at maximum.

The purification workshop is indeed a key factory workshop and it determines the quality of the final sugar.

For this, we have developed and improved our equipment in partnership with our customers in sugar factories with the following main purposes:

  • Improving of the quality of the juice outlet in our devices first and second filtration.
  • The increase of filtration rates in the first and second filtration by the specific form of our candle type filters and minimizing of head losses.
  • Increasing of the concentration of sludge on our EXOFALC to reduce limestone consumption, decrease the recycling and therefore to increase the tonnage of the plant.

Finally, we made innovations on our press filter, which remains the most effective device for solid liquid separation, in order to increase performance. Cycle durations have been optimized and therefore the volume of filter according to the tonnage of beet which is also improved.


Paper # 7

Membranes and Ion Exchange Resins: Adapted techniques to the diversity of cane sugar mills and refineries

François Rousset

Novasep, Saint Maurice de Beynost, France

Modern separation technologies, based on membranes cross-flow filtration and ion-exchange resins, provide efficient purification processes in the sugar industry.

Basic principles for purification of sugar solutions using membranes, ion-exchange and industrial chromatography will be summarized in this presentation.

Main proven industrial applications will be reviewed, including softening and demineralization of sugar juice by ion-exchange, decolorization of refinery liquors by ion-exchange, and fractionation of beet molasses by ion-exclusion chromatography.

Raw sugar juice purification systems have been developed at laboratory and pilot scale, with limited industrial applications so far. Raw juice clarification by membranes cross-flow filtration has been tested both in beet and cane sugar production, but despite encouraging results they have not been adopted at large production scale. The complete extent of their benefits over existing physico-chemical purification technologies still need to be better established.

Production of high grade industrial liquid sugar directly from cane raw sugar seems to be an attractive application under current economical conditions, to avoid the costs associated to conventional refining and production of liquid sugar from refined sugar.


Paper # 8

Benefit of combined treatments associating reverse osmosis and ion exchange for  recycling of distillery condensates in fermentation

M.L. Lameloisea, C. Farguesa, M. Gavacha, M. Bouixb

aAgroParisTech, INRA, UMR 1145 Ingénierie Procédés Aliments, F-91300 Massy

bAgroParisTech, INRA, UMR Génie et Microbiologie des Procédés Alimentaires, F-78850 Thiverval Grignon

Water consumption and effluent production accompany ethanol production. In France, the thermal concentration of beet vinasse is largely developed. The removal of inhibiting compounds present in the condensate would allow for reusing these condensates as fermentation water, which provides a significant economy of water. The presentation provides an update on the work carried on for several years in AgroParisTech on intensive purification processes and eco-compatible: adsorption (Ads), ion exchange (IE), reverse osmosis (RO) and demonstrates the benefit of associating RI and IE.

Potential inhibitors in the condensates are aliphatic acids (including acetic acid: 1-2 g / L), alcohols, aromatic compounds, and furan derivatives. The work focused on the elimination of “target” molecules: C1-C6 acids, 2,3-butanediol, furfural and phenyl-2-ethanol from model solutions and real condensates.

Weak anionic resins have a high acid-binding capacity. Resins A21 or FPA 51 (Dow) showed a total capacity of 1.08 eq / LR acids in a condensate containing 15 mEq /LR of acetic acid. However, as the neutral compounds are not retained, the anionic resin must be supplemented by an adsorbent resin. The Optipore SD2 resin (Dow) has proved very effective for the phenyl-2-ethanol and furfural.

Although the interest of the reverse osmosis has been highlighted with membranes of the “sea water” type, the search for high flow at moderate pressure led to test membranes more permeable like CPA2 (or CPA3) and ESPA2 (Hydranautics) and BW30 (Dow). Two strategies ESPA2 / 10 and BW30 bars / 25 bars lead to optimal flow 30 L h-1 m-2. Both membranes reject 100% of targeted neutral molecules. The release of acetic, propanoic and butanoic acids is differentiated: 59, 80, 98% (ESPA2) and 85 92% 100 (BW30) and led us to prefer BW30. On this basis, and a condensate containing 1.5 g / L of acetic acid, the concentration in the permeate would be 371 and 452 ppm respectively for recovery of 75% and 88%. Additional anion exchange step is required to completely remove the acid.

Fermentation assays (3 chemostats in series) by S. Cerevisiae have been made, with monitoring the growth and physiological condition of the cells and the production of ethanol. RI used alone, lets acidic compounds cross which affects cell viability; ethanol production declines significantly when acetic acid exceeds 460 ppm. The IE retains acids but it leaves phenyl- 2-ethanol in solution, and this molecule is finally revealed more toxic than acid for yeast which dies with the increase of alcohol concentration. The combination RI + IE allows recovering of 88 % of water at a concentration of  target inhibitor molecules lower than the quantization threshold. The treated condensate has good recyclability in fermentation, with ethanol concentration of 80 g / L, productivity 4.23 g / L / h (equivalent to tap water) and physiological state of yeast equivalent to the control sample. This result confirms the appropriateness of the choice of target molecules and the need for their total elimination for safe recycling of condensate. The results need to be confirmed in terms of higher ethanol concentration measured in the distilleries.


Paper # 9

Preliminary Report on the use of High Performance Adsorbents in co-refining raw sugar in beet factories.

Vawda, A.S,  Sarir, E.M,  Donado, C.A.

CarboUA, Beverly Hills, USA

In the last few years, the co-processing of raw sugar has been allowed in the EU and also conducted extensively elsewhere. Due to the fact that a beet sugar factory has a lower color reducing ability, the amount of raw sugar added is limited. The reason for this is due to the fact that cane and beet contains different type of colorants. The challenge is to control the percentage of raw added while still delivering a high quality of white sugar.

The standard procedure for blending raw sugar has been conducted as shown below:

  • Co-refining at the  beet end (with raw juice) goes to pre-limer
  • Co-refining at the beet end (with 2nd carbonatation juice) goes to juice before second filtration
  • Co-refining at the sugar end (melter with thick juice)

Several factories have reported mixed successes, mainly because of the expensive way to suppress the color from the cane sugar. (i.e. excess washing in the centrifugals with consequent high recycle and energy costs). Whereas the color transfer factor in cane refineries is between 5 – 10%, the color transfer at beet factories tends to be 1 – 2%. This paper focuses on the removal of the colorants that are preferentially transferred to the surface of the crystal, thereby allowing the beet factory to increase the percentage of raws blended into the process without the typical problems associated with this practice.


With the contribution of:

Centre d’études et de documentation du sucre. CEDUS23 Avenue d’Iéna, 75116 Paris – www.lesucre.com 

BMA .. Am  Alten Bahnhof 5 . 38122 Braunschweig Germany – www.bma-de.com

ITECA SOCADEI SAS -445 Rue Denis Papin – Europôle de l’Arbois – CS 30478 – F – 13592 Aix-en-Provence CEDEX 3  – www.iteca.fr

proMtec Theisen GmbH, Pforzheimer Straße 162 – 76275 Ettlingen, Germany – www.pro-m-tec.de

Bilfinger Water Technologies SAS – Zone Industrielle F-86530 Availles-en-Châtellerault – www.water.bilfinger.com

Buckman Wondelgemkaai 159 – 9000 Gand, Belgique. www.buckman.com

CarboUA Beverly Hills, USA. www.carboua.com

Maguin 2 Rue Pierre Semart – F-02800 Charmes, France. 

Comessa 101 Rue du Rhin-Napoléon – F-67100 Strasbourg. www.comessa.fr

GreenEurope Rue de Sterpigny 7, Be-6673 Gouvy. www.greeneurope.be




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