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Teil 3 Seite 4-53
This is why agricultural reuse is considered by several sectors such as the starch, the
fruit and vegetable and the sugar sectors as an environmental friendly valorisation of or-
ganic liquids and biosolids.
For example, in the starch industry, this technique is used for the potato fruit juice, proc-
ess water, potato washing water, wheat solubles and the sludge from the waste water
treatment plant of the factory.
Legislation
The use of organic liquids and biosolids for reuse as fertiliser, is ruled by EC, national
laws and local legislation. EC legislation for biowaste is in force/under preparation (sew-
age sludge directive, biowaste directive, ÖkolandbauVO).
These rules set the conditions regarding for example :
- pollutants,
- the way and the seasons in which fertilising is authorised,
- the amount of fertiliser to be spread on the soil according to the crop and the
level of nutrition supply of the soil as well as potential leaching into groundwater
- soil quality.
These elements are the monitoring basis used by national authorities.
Methods and equipment
Techniques, dosage and periods are strongly dependant on the environment, agricul-
tural context and climate and can therefore be significantly different from one site to an-
other.
There are, however, a number of variables which influence agricultural reuse, including:
legal requirements, quality of the materials, climate, soil type and quality, crops to be
grown, slope, water table, water quality, proximity to a watercourse, amongst others.
Depending on the size of facilities, quantities of organic matters spread vary a lot from
one site to another.
Depending on the nutrient balance of the spread liquids and biosolids, farmers may need
to use a complementary fertiliser.
Techniques
Agricultural reuse can be carried out directly from mobile containers or by a network of
hydrant pipes, connected to mobile spreading devices such as mobile sprayer arms or
irrigation nozzles.
In fact, organic liquids for agricultural reuse can be transported to the fields either by
pumping through pipelines to different hydrants or transported by trucks. From the edge of
the field, a sprayer or injection machine is fed with the organic liquid fertiliser. Spraying is
done by mobile sprayer arms with nozzles that are moved by a turbine effect. Organic