Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 3
In some seeds, e.g. rapeseed, the sulphur content may be high. Enzymatic and biological
processes may convert sulphur compounds into hydrogen sulphide. No emission data have been
reported yet during storage but significant hydrogen sulphide concentrations have been detected
in the exhaust air of extractors [65, Germany, 2002]. Air emission types during the manufacture
of crude vegetable oils are shown in Table 3.45.
Degumming Neutralisation Bleaching Deodorisation Hardening
Volatile
compounds
Odour Ffa
Volatile
compounds
Odours
Table 3.45: Summary of air emissions in the manufacturing of crude vegetable oils
[10, Environment Agency of England and Wales, 2000, 74, Greek Ministry for the Environment,
2001]
Odour is produced in all steps where heating is involved. It results from the volatile fatty acids,
organic nitrogen compounds and, in the case of rapeseed, hydrogen sulphide and organic
sulphur compounds.
3.3.4.4 Solid output
Depending on the type of vegetable, i.e. oilseed or oilfruit, the raw materials for vegetable oil
production can almost completely be converted into products, e.g. vegetable oil, protein rich
meal, fatty acids and lecithin, or by-products, e.g. for human food, animal feed and
pharmaceutical products.
Solid waste, e.g. leaves, wood, pieces of metal and stones, is generated in the raw material’s
primary treatment step (cleaning and hulling). This is separated during the cleaning of the raw
material by wind sifters, magnet separators and sieves. In oilseed production, this fraction is less
than 1 % of the processed seed. Metals are sent for recycling or disposal and the remainder,
such as stones and sand, is disposed of. Dust may be incinerated. In the pressing/centrifuging
step, used filter clothes from seed pressing are produced and are also disposed of [161, Verband
Deutscher Oelmuehlen, 2003].
In the case of chemical refining, soap stock is produced during the neutralisation of crude oil.
This consists mainly of NaOH saponified ffa, but also contains phosphatides, proteins and other
compounds. Normally, it is further processed in the refinery by splitting the soaps and regaining
the fatty acids (acid oil). In some countries, it is possible to mix the soap stock from the
chemical refining of vegetable oil with other ingredients for the production of low quality soaps
or for use in meal for animal feed.
The production of solid wastes from vegetable oil refining and processing is dependent on the
specific site. In bleaching operations, spent bleaching earth containing 20 – 40 % fat is
produced. This makes the waste prone to spontaneous combustion. In production installations,
which exclusively refine and modify edible oil, the spent bleaching earth is utilised by third
parties for energy production by co-fermentation to produce biogas or to make bricks [182,
Germany, 2003]. The spent catalyst is recycled to third parties for regeneration.
In mixed production installations, which produce crude oil and meal, and refine/modify the
edible oil, there are further opportunities for utilisation of components of the raw material and of
wastes. For example, utilisation of phospholipids in meal and utilisation of spent bleaching earth
in meal, both as animal feed. The precondition for the latter example is the absence of nickel
catalyst residues [161, Verband Deutscher Oelmuehlen, 2003].
RHC/EIPPCB/FDM_BREF_FINAL January 2006 181