Integrierte Vermeidung und Verminderung der Umweltverschmutzung

3.3.4.6 Chemicals used
Chapter 3
Ideally, the extraction solvent should only dissolve glycerides and leave undesirable
components such as colouring matter, gums, and phospholipids. The solvents must not contain
toxic components, and should be recoverable with minimum loss, be safe in handling, and be
readily removable from the extracted material. For these reasons, aliphatic hydrocarbons,
especially hexane, are used almost exclusively. Technical hexane with a boiling point range of
55 – 70 °C has proved to be the optimum solvent. Hexane can be readily removed from the oil
at temperatures below 100 °C under vacuum and can be stripped from the meal with steam. The
solubility of hexane in the condensed water is only 0.1 %.
Alcohols like ethanol, isopropanol, methanol, butanol, and furfural are especially suited to the
extraction of relatively wet materials. The extraction of oilseed with alcohols leads to relatively
high concentrations of phosphatides, glycolipids, carbohydrates, and similar constituents in the
crude oil, although the glycerides can, in principle, be concentrated by cooling or extraction of
the alcoholic solutions. Alcohols are generally not used as primary extraction solvents.
However, they are occasionally used as secondary extraction solvents to remove gossypol from
cottonseed meal, thioglycosides from rapeseed meal, sugars from soybean meal (to produce
protein concentrates), and alkaloids from bitter lupine meal. A new technology is oil
supercritical propane or carbon dioxide extraction, where extraction takes place under high
pressure. This process is reserved for special products of high intrinsic value because of the high
equipment costs involved [87, Ullmann, 2001].
Chemicals are used in the chemical neutralisation of crude oil. 1 – 6 kg/t oil
NaOH and 0.1 - 2 kg/t oil is used depending on the function of the type of oil and the ffa content
of the pre-degummed or not, crude oil. If phosphoric acid is used, 0.1 – 2.0 kg/t oil is consumed.
Alternatively, citric acid may also be used, its consumption is 0.1 – 1.0 kg/t oil. Sulphuric acid
used in soap-stock splitting amounts to 100 – 250 kg H2SO4/t soap [109, CIAA-FEDIOL, 2002].
3.3.5 Dairy products
3.3.5.1 Water
3.3.5.1.1 Water consumption
Water consumption is mainly associated with cleaning operations. The factors affecting water
consumption in European dairies are [160, European Dairy Association, 2002]:
• availability of surface and groundwater for cooling
• time and amount of water used for rinsing
• characteristics of CIP programmes
• maintenance, e.g. reparation of leaks.
A reasonably efficient consumption of water is reported to be around 1 – 5 l/kg milk [134,
AWARENET, 2002], however, it is reported that a water consumption of 0.8 – 1.0 l/kg milk can
be achieved by using advanced equipment and a good operation [74, Greek Ministry for the
Environment, 2001]. According to a German survey, 132 dairies used, on average in
1999, 2.06 l/kg of milk [39, Verband der Deutschen Milchwirtschaft (German Dairy
Association), 2001]. Table 3.49 shows water consumption in European dairies. Table 3.50
shows water consumption for some Nordic dairies.
RHC/EIPPCB/FDM_BREF_FINAL January 2006 185