Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 3
Most processes involve some type of grading, trimming and size reduction. Sometimes density
graders containing brines of different strength are used. Discharge of significant quantities of
brine can adversely affect any biological WWTP. Washing of the produce after these operations
creates waste water containing soluble starch, sugars and acids. The use of water fluming to
convey both the product and waste material causes additional leaching of these substances.
Waste water from citrus fruit processing also contains pectic substances that can interfere with
the sedimentation of SS.
All lines, equipment and process areas that are not in designated dry areas require wet cleaning,
which generates waste water contaminated with raw material, product and cleaning chemicals.
There are generally fewer requirements for aggressive chemicals in this sector than in others,
unless oil or fat is used in processing.
3.3.3.3 Solid output
Large amounts of solid wastes are produced. These are organic materials, including fruit and
vegetables discarded during selection, and those from processes such as peeling or coring.
These typically have a high nutritional value and can be used as animal feed. Undesired
materials discarded from the first processing steps include soil and extraneous plant material,
spoiled food stocks, and some trimmings, peels, pits, seeds and pulp.
When caustic agents are used for peeling fruit and soft vegetables, a highly alkaline or salty
solid waste is produced. High moisture content solid wastes can be generated by wet cleaning
and re-use operations in which the dissolved solids or SS are concentrated and separated from
the waste water.
Up to 50 % of fruit and typically 10 to 30 % of raw vegetable materials are wasted during
processing. Part of the waste goes to the waste water and significant amounts of solid wastes are
also generated. Some reported figures are shown in Table 3.28.
Raw material
processed
Solid waste
produced per
tonne of
product
(kg)
Maize 40
Peas 40
Potatoes 40
Strawberries 60
Apples 90
All
vegetables
130
Peaches 180
Broccoli 200
Carrots 200
Frozen
peaches*
*Product
200
Table 3.28: Solid waste produced during fruit and vegetable processing
[140, World Bank (IBRD), et al., 1998]
The reported types and amount of wastes produced in processing and preservation of fruit and
vegetables are shown in Figure 3.8.
RHC/EIPPCB/FDM_BREF_FINAL January 2006 169