Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 3
3.1.3.4 Product defects/returned product
Products not meeting the required specification, whether identified prior to dispatch or returned
by customers, can be a major source of loss of materials and waste, although some may be
recovered. This group also includes over-produced fresh products, e.g. in cases where order
fluctuations result in too much product being produced which cannot then all be sold in time
due to shelf-life considerations.
3.1.3.5 Inherent loss
Some process equipment, even with the most appropriate technique, can cause a loss of
materials and waste which is unavoidable by design. An example of inherent loss is the selfdesludging
centrifugal separator, where solids from the bowl, and inevitably some product, are
flushed to waste during desludging.
A similar situation exists where the product is purged through the equipment with water at the
end of production or at product change-over, e.g. in CIP systems. Inevitably the interface
between the product and the water will not be sharp and depending on what measures are taken
to minimise this, a greater or lesser quantity of a mixture of the two is produced.
3.1.3.6 Retained material
Retained material occurs when liquid products or ingredients cannot freely drain to the next
stage in the process. This can, e.g. be caused by dips in supposedly continuously falling
pipelines, which trap the product and prevent it from draining either way. Another example is
where the product rises in the pipelines and any trapped product will then not drain away, thus
leading to a loss of material. If the product cannot drain, then it must be purged with gas, water
or a pigging system.
Also, with very viscous products, e.g. yoghurt, adhesion to the pipeline and tank walls is a
significant source of retained material. Unless mechanically removed, e.g. by pigging,
prolonged pre-rinsing is likely to be required.
3.1.3.7 Heat deposited waste
Whenever liquid products are heated, there is a likelihood of deposition of the product onto the
heat-exchange surface. Deposits on the plates or tubes in heat-exchangers, and on batch kettles
may not rinse off and when removed with detergents is lost in the waste water. In many sectors,
these sources of loss are contained and recycled or recovered back into the process.
3.1.4 Energy
The FDM sector depends on energy for processing, storage, to maintain freshness and to ensure
food safety. Process heating uses approximately 29 % of the total energy used in the FDM
sector. Process cooling and refrigeration accounts for about 16 % of the total energy used.
In Germany, the FDM sector consumed about 54500 MWh/yr in 1998, representing 6.7 % of
the total German energy consumption making it the fifth largest energy consumer among all
industrial sectors. The energy was produced using 49 % gas, 23 % electricity, 21 % oil, and 7 %
coal. The energy consumption doubled in 30 years from 1950 to 1980. There was a slight
decrease in the 1980s and 1990s [2, Meyer, et al., 2000].
120 January 2006 RHC/EIPPCB/FDM_BREF_FINAL