Integrierte Vermeidung und Verminderung der Umweltverschmutzung
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Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Integrierte Vermeidung und Verminderung der Umweltverschmutzung Integrierte Vermeidung und Verminderung der Umweltverschmutzung

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10.12.2012 Aufrufe

Chapter 2 2.2.18.7 Cold stabilisation Cold stabilisation involves rapid cooling of the wine to near freezing temperatures to precipitate tartrate crystals which are undesirable in the bottled wine, whether present in the cork or in the bottom of the bottle. Tartrate precipitates in the tanks and is removed with an alkaline cleaning solution of 10 % caustic soda. 2.2.18.8 Bottling Before bottling, wine is passed through a filtration system to remove remaining solid and insoluble turbid compounds. Bottling involves the microbial stabilisation of the wine and preserves the wine from important changes in taste and chemical composition. 2.2.19 Soft drinks Soft drinks can be categorised into two main types, i.e. carbonated and still. Soft drinks include spring waters, fruit and juice based drinks such as cordials, squashes and barley waters; flavoured drinks such as ginger beer; tonic waters and lemonades, as well as infusions such as tea and coffee. Ingredients typically found in most soft drinks include water, sweetener, acid and flavourings. Optional ingredients include fruit, carbon dioxide, preservatives and colour. Water is the main ingredient of all soft drinks and, as such, the quality of the water, in terms of its microbiological loading and other parameters which affect the final sensory qualities of the drink, are of paramount importance. Most soft drinks are sweetened with natural sweeteners such as sugar and sugar syrups, and/or intense sweeteners such as saccharin and aspartame. Flavourings used in manufacture are often derived from highly concentrated liquid mixtures of plant extracts such as fruit, flowers, seeds, leaves, bark and root. Alternatively, they may be synthetic. All sparkling soft drinks require the addition of carbon dioxide. This may be sourced as a coproduct from the petroleum, beer and whisky industries, or produced on site. The preservation of soft drinks can be achieved by a number of techniques including heating, chemical preservation and filtration. These methods, in combination with low pH, prevent microbiological spoilage. The basic processes for the manufacture of soft drinks involve the mixing of ingredients in the syrup room, followed by the addition of water that has been subjected to various water treatments. The mixture may be heat processed or chemically preserved at this stage. The product is carbonated if required. Alternatively, after the syrup and water are combined, the product may be filled into packaging and in-pack heat processed. Syrups may require filtration or homogenisation and may be pasteurised. Most packaging is cleaned prior to filling, either by rinsing with water, possibly containing rinsing aids, or by air blasting. 2.2.20 Citric acid Citric acid, a tricarboxylic acid, exists widely in nature and is produced in almost all living cells as an intermediate substance in the metabolic cycle. Most plant and animal tissues, as well as human serum, contain citric acid in a significant quantity. The most economical method to produce citric acid is fermentation, which employs a strain of Aspergillus niger as an inoculum, to convert sugar to citric acid. The fermentation feedstock or substrate is a carbohydrate, usually molasses, crystalline sugar, glucose from wheat, maize or potato starch, or isomerose. There are two types of fermentation processes, i.e. submerged and surface fermentation. Submerged fermentation is preferred to surface fermentation. Submerged fermentation consists of three main phases, i.e. fermentation, recovery, and purification of citric acid. The flowchart for this process is presented in Figure 2.22. 110 January 2006 RHC/EIPPCB/FDM_BREF_FINAL

Chapter 2 In citric acid fermentation, the substrate is prepared in a tank and then sterilised. The inoculum is produced under controlled aseptic conditions. The inoculum and the substrate are transferred aseptically to the production fermenter. The fermentation process requires 3 to 14 days. Finally, the biological solids called mycelium are removed by filtration. In the recovery of citric acid, the dissolved citric acid is separated from residual sugars, proteins and other soluble impurities by the addition of lime precipitating calcium citrate. Then, the slurry containing calcium citrate is filtered. The filtrate is washed to remove soluble impurities. The waste water generated is discharged. Sulphuric acid is added and this converts the calcium citrate to calcium sulphate and citric acid. Finally, the precipitated calcium sulphate or gypsum is filtered from the slurry and the remaining citric acid solution is further treated. Ultimately, the citric acid solution is purified by ion exchange and carbon adsorption. The citric acid solution is evaporated and crystallised from the solution (first crystallisation). The citric acid crystals are centrifuged. Later, citric acid is dissolved in water and crystallised again from the solution (second crystallisation). The crystals are centrifuged yet again and are dried, milled and sieved. The resultant citric acid is then packaged. Figure 2.22: Citric acid fermentation process [151, Austrian contribution, 2002] RHC/EIPPCB/FDM_BREF_FINAL January 2006 111

Chapter 2<br />

In citric acid fermentation, the substrate is prepared in a tank and then sterilised. The inoculum<br />

is produced <strong>und</strong>er controlled aseptic conditions. The inoculum and the substrate are transferred<br />

aseptically to the production fermenter. The fermentation process requires 3 to 14 days. Finally,<br />

the biological solids called mycelium are removed by filtration.<br />

In the recovery of citric acid, the dissolved citric acid is separated from residual sugars, proteins<br />

and other soluble impurities by the addition of lime precipitating calcium citrate. Then, the<br />

slurry containing calcium citrate is filtered. The filtrate is washed to remove soluble impurities.<br />

The waste water generated is discharged. Sulphuric acid is added and this converts the calcium<br />

citrate to calcium sulphate and citric acid. Finally, the precipitated calcium sulphate or gypsum<br />

is filtered from the slurry and the remaining citric acid solution is further treated.<br />

Ultimately, the citric acid solution is purified by ion exchange and carbon adsorption. The citric<br />

acid solution is evaporated and crystallised from the solution (first crystallisation). The citric<br />

acid crystals are centrifuged. Later, citric acid is dissolved in water and crystallised again from<br />

the solution (second crystallisation). The crystals are centrifuged yet again and are dried, milled<br />

and sieved. The resultant citric acid is then packaged.<br />

Figure 2.22: Citric acid fermentation process<br />

[151, Austrian contribution, 2002]<br />

RHC/EIPPCB/FDM_BREF_FINAL January 2006 111

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