3. Notes on the analysis and evaluation of environmental impacts
Contents - Previous - Next
Limit values for air pollution are laid down in Germany by the guidelines of the Technische Anleitung zur Reinhaltung der Luft (TA-Luft - Technical Instructions on Air Quality Control), and comply with the Bundes-Immissionsschutzgesetz [BImSchG - Federal Immission Control Act]. Further reference material is to be found in the Richtlinien des Vereins Deutscher Ingenieure [Guidelines of the Association of German Engineers VDI] for maximum immission concentrations [MIK] which are concerned with the establishment of limit values for certain air contaminants.
Under the terms of TA-Luft, the dust emission for organic substances in industrial plants may not exceed 50 mg/m3 air at a mass flow of 0.5 kg/h. The waste air from extraction today may not contain more than 150 mg hexane/m3.
Where noise levels are over 70 dB(A), noise-reducing measures such as hearing protection (ear muffs etc.) or silencing devices on machines must be provided. For comparison: leaves rustling in the wind produce a noise level of 25 - 35 dB(A) and normal conversation ranges from 40 - 60 dB(A). Years of exposure to around 85 dB(A) or more during most of a person's time in work is deemed damaging to the hearing at the workplace. It is, in fact, just as harmful to be exposed constantly to a uniformly low noise level as to a correspondingly higher one for a short time.
In Germany, the Technische Anleitung zur Lärmbekämpfung [TA-Lärm - Technical Instructions on Noise Abatement] establishes principles for noise protection and approximate emission values. The following approximate atmospheric immission values27) apply to:
27) Immissions are the effect of air-borne contaminants, vibrations, radiation and noise on humans, animals, plants and property (e.g. buildings).
- areas containing mainly commercial premises: daytime 65 dB(A), night 50 dB(A),
- areas containing mainly residential accommodation: daytime 55 dB(A), night 40 dB(A).
It should be borne in mind that noise immissions inside buildings can have more damaging consequences because of building materials and methods used, in which case the values should be assumed to be correspondingly lower.
In crude oil refining, a wastewater quantity of 10 to 25 m3/t initial product must be assumed (see Table 3, details from Germany's 4. AbwVwV). The following are the principal constituents of the wastewater:
- sodium sulphate or sodium chloride
- calcium phosphate
- fatty acids (in part as calcium soap)
- mono-, di- and triglycerides
A refinery's wastewater output can be reduced by up to 90% if the vapour cooling water is managed in a circuit - a system however, which results in higher COD concentrations in the circuit water. The minimum requirements for the final discharge of refinery wastewater must take account of this circumstance. However, despite the higher COD concentration where the cooling water is managed in a circuit, there is an overall general reduction in pollutant load. Biological wastewater treatment cannot yet be described as the most modern state-of-the-art process in view of the land required, the higher energy consumption and the problem of sludge disposal.
In Germany, the 4. Allgemeine Verwaltungsvorschrift [4. AbwVwV - 4th General Administrative Regulation] establishing minimum requirements for the discharge of wastewater from oil-seed processing and fat and edible oil refining applies with regard to wastewater control.
Table 4 indicates the minimum requirements imposed on the wastewater. In works with biological wastewater treatment, a 5-day biological oxygen demand (BOD5) of 25 mg/l and a chemical oxygen demand (COD) of 100 mg/l is prescribed28).
28) BOD5 stands for the biological oxygen demand which is required by microorganisms in a five day period for the processing of organic substances in industrial water. In the case of COD, the quantity of oxygen produced by an oxidant to oxidize organic substances in wastewater is calculated.
Table 4 - Minimum requirements of the 4.AbwVwV
|Parameters||Quantity of contaminated water||Settleable solids||COD||Extractable substances|
|Type of sample||random sample||2h||24 h||2 h||24 h|
|Crude oil refining for edible oil production||10||0.3||250||230||50||40|
|10 - 25||0.3||200||170||30||20|
|Analysis process||DEV H 2.2
|Appendix to 2. AbwVwV of 10.01.80 (3)||DEV H 17/18-1|
|Analysis of measured values||Single value or mean value (4)||Single value or mean value|
*) Within 2 or 24 hours
(1) Initial product
In crude oil refining for the production of edible oil and edible fat, the following initial products are used:
- crude oil, produced in the oil extraction process
- reject and reprocess batches passing through the refining process once again.
(2) German standard process for water testing.
(3) If the value specified for settleable solids are exceeded in a single sample, 0.3 ml/l can be used to obtain the arithmetical mean if the dry mass of the filterable substances (DEV H 2.1) does not exceed 30 mg/l.
(4) Analysis of the precipitated sample.
The values given in Table 5 should apply for the discharge of acid solutions from soap fractionation.
Table 5 - Limit values for the discharge of acid solutions from soap fractionation
|Quantity||0.3 m3/t oil|
|pH value||6.0 - 9.0|
|Settleable solids which can precipitate in 30 mins.||10 mg/l|
Generally speaking, oil processing is linked to a laboratory in which checks are constantly carried out using a standardised measuring procedure. COD, BOD, special waste requiring disposal, dissolved solids and the oils and fats should be constantly tested for content. Regular temperature checks should also be carried out in situ.
In addition, the World Bank gives the following information relating to the wastewater in question here:
- In principle cooling water should not be discharged; if it cannot be recycled in the circuit, it should only be discharged if the temperature of the water into which it is released does not rise by more than 3°C,
- The pH of the wastewater and liquid waste should be kept constant between 6.0 and 9.0,
- The BOD value of the wastewater should be less than 100 mg/l,
- The COD value of the wastewater should be less than 1000 mg/l,
- The dissolved solid content of the water should be less than 500 mg/l,
- Additional preservation and storage facilities and areas should be kept available in case of accidents resulting in leaks of solvents, lyes and acids. Equipment should also be kept to hand to deal with any such accident situations.
Types of waste defined in § 2 of the German Abfallgesetz [Waste Avoidance and Waste Management Act] are determined for oil- and fat- producing facilities in the ordinance on the determination of waste and residues Verordnung zur Bestimmung von Abfällen und Reststoffen. Waste types are further qualified by waste codes in accordance with the information bulletin entitled "Abfallarten der Landesarbeitsgemeinschaft Abfall" [LAGA - Waste types of the state working group on waste]. Waste groups 52 (acids, lyes, concentrates) and 55 (organic solvents, dyes, varnishes, adhesives, fillers and resins) are relevant.
Soil contamination problems in the production of vegetable oils and fats only occur in connection with improper disposal of waste and wastewater (see also sections 3.3 and 3.4).
3.6 Choice of site
The following is to be borne in mind when choosing a site:
- The plant or plant complex should not be sited near ecologically sensitive habitats (marshlands, protected areas, national parks etc.).
- Local resource protection agencies or authorities should be involved at an early stage in the selection of the site or alternatives.
- Because of the odour nuisance, the plant should not be sited in the immediate vicinity of residential areas. Generally speaking, plants should be sited on high ground above the local topography; the sites should not constitute areas through which air passes and the prevailing wind currents must not affect populated areas. Local climatic and meteorological studies can be used to obtain useful information.
- The plant or plant complex should be built close to surface water (preferably flowing water), and this water must have the maximum dissolving and absorption capacity for wastewater.
- At the site it should be possible to recycle wastewater - following minimal treatment - for agricultural and industrial purposes.
- The plant should only be built in a municipality if the production wastewater can be treated in the municipal sewage system.
Processing facilities for fruit are sited in the actual growing areas as the crop has to be processed immediately after harvesting. Economic processing capacities in industrial countries start at 15 to 20 t feedstock per day.
Oil-seeds and nuts are transported in some cases over long distances to the processing industries. Processing capacities for pressing plants start at around 200 t/day, and those of solvent extraction plants at around 100 t/day. In highly industrialised countries, however, capacities of 1000 to 2000 t/day are commonplace. Refineries can operate economically from 50 t/day but plants in industrialised countries have processing capacities of 100 to 300 t/day. The question to be answered when deciding on the capacities to be installed is whether it would be preferable (for reasons of environmental protection and employment) to have small, decentralised plants rather than one large plant. Wastewater and waste air treatment systems and likewise waste disposal can also be organised decentrally as can the operation of a test laboratory.
Decentralised processing can obviate the need - as sometimes happens in view of the amount of traffic to and from large plants - to rethink local transport routes and traffic plans, and can avoid the associated noise, air pollution and traffic jams, as well as the risks to pedestrians from heavy goods traffic transporting raw materials or products to or from the plant. A transport sector and traffic study should be produced for route selection and for the analysis of problems and possible remedies.
4. Interaction with other sectors
Oil-cake or meal are by-products of crude oil production and are frequently processed further in the same plant to make animal feed (see environmental brief Livestock Farming).
As soap and fatty acids are produced in the refining process, a soap factory can be built alongside the plant. This eliminates problems with the sale of fatty acids or the fractionation of the soapstock (acid solutions). Likewise, the production of edible oil or edible fat in the refinery can be linked to the production of baking or cooking fat, shortenings or margarine.
Filling installations are often linked to refineries as edible oil and edible fat are now sold almost exclusively in a packaged form. The linking of filling installations to refineries is advantageous as the oils and fats are packed immediately and so have no chance of becoming rancid, and plant wastewater produced during the filling process can be treated and disposed of with the wastewater from the refinery (see environmental brief Wastewater Disposal).
Steam is required to produce and refine vegetable oils in small and large plants, thus oil mills or refineries often operate their own steam production plant. National provisions for large furnace installations must be observed in this regard (in Germany: the TA-Luft).
5. Summary assessment of environmental relevance
5.1 Crude oil extraction
In the extraction of vegetable oils from fruit and seeds, the cleaning, crushing and conditioning operations generate dust which it must be possible to remove with centrifugal cyclones. Dust is also produced when meal and press cake are made and it must be possible to remove it in the same way.
As this dust is of vegetable origin, it can be biologically degraded without the need to take any technical environmental protection measures (small plants), or it can be used as fertiliser (castor-oil seed meal). Production plants should not, however, be sited close to populated areas. The same is true of the larger quantities produced by large-scale plants in which the dust, after extraction, must be collected and dumped in a well-organised manner.
When oil-bearing fruits are extracted and boiled, large quantities of waste-water are produced which can be degraded biologically, albeit at the expense of a high oxygen consumption. For this reason, mechanical pre-cleaning is necessary - an operation in which sediments are precipitated and removed from time to time.
All oil mill wastewater should be fed through oil separators as larger quantities of wastewater containing vegetable oil cause the formation of a thin film of oil on bodies of water which interferes with the oxygen supply. Wastewater with an excessively high oil content must also pass through a biological treatment plant in which organic substances can be degraded by constant aeration (oxygen supply).
Extraction processes produce wastewater which can contain solvents. Measures must therefore be taken to ensure that the maximum solvent discharge into the environment is not exceeded.
5.2 Crude oil refining
Large quantities of falling water are produced in the refining of crude vegetable oils and fats and these are passed through oil separators for disposal. The water is fed back into the refinery after passing through a recooler. Excess falling water can be discharged into the surrounding water once it has passed through a biological treatment plant in which organic substances are degraded.
When soapstock is separated into fatty acids, acid solutions are produced which can no longer be used in the circuit. Before their discharge into treatment plants or water, they must be specially treated (neutralised) as they are acidic and contain - in addition to fat and mucilaginous substances - sulphate ions, which must not exceed certain values as they lead to salination of the wastewater and can destroy concrete drainage pipes.
A 100% reduction in wastewater and pollutant discharges into surface water is considered to be feasible if one of the following measures is taken:
· discharge by other irrigation systems
· drainage into settling tanks
· drainage into municipal and urban sewage treatment systems.
In oil and fat production, the environmental pollutants formed and released in waste air or wastewater depend largely on compliance with technical tests and countermeasures for environmental safety purposes. Constant supervision of normal plant operation is essential to ensure that limit values are observed in terms of pollutant removal. Personnel is to be appropriately instructed in the framework of continuous training and upgrading. Training and preparation campaigns aimed at women are recommended for environmental protection jobs.
In view of the potentially serious negative implications for the environment and health in large plants in particular, the appointment of safety, environmental protection and works officers should also be demanded and the women concerned should be involved in the selection process.
Abwassertechnische Vereinigung (ATV) (Ed.): Lehr- und Handbuch der Abwassertechnik, Bd. I - VI, Ernst Verlag, Berlin, various years.
Abwassertechnische Vereinigung (ATV) (Ed.): Arbeitsblatt A 115, Hinweise für das Einleiten von Abwasser in eine öffentliche Abwasseranlage, draft of 22.03.1990.
Adam, W.A.: Waschmittel und Gewässerschutz, FSA 77, 1975.
40. Anhang zur Allgemeinen Rahmen-Verwaltungsvorschrift über Mindestanforderungen an das Einleiten von Abwasser in Gewässer, GMBI. (joint ministerial circular) 1989, Nr.25, page 517 ff.
Baily's Industrial Oil and Fat Products, Vol.2, 1982.
Brammer, H.: Industrielle Verarbeiter von Speisefetten im Lichte von Umweltfragen, FSA 75, 1973.
Brauch, V.: Einsatz von physikalisch-chemischen Reinigungsmitteln in der Fettindustrie, FSA 84, 1982.
Brunner K.H.: Kontinuierliche Alkaliraffination und on-line Verlustanzeige, FSA 88, 1986.
Conze, E.: Abwasserschlämme in der Speisefettraffination und ihre Entstehung, Möglichkeiten zur umweltfreundlichen Beseitigung, FSA 84, 1982.
Deutsches Einheitsverfahren zur Wasseruntersuchung: Verlagsgesellschaft Deutscher Chemiker, Weinheim a.d. Bergstraße, loose-leaf collection, last issue on 26.03.92.
Dieckelmann, A., Hirsch A. et al.: Abluftverbrennung und Abluftnutzung aus öl-chemischer Produktion, FSA 85, 1983.
Jennewein, H.: Über Wasserreinigung in Ölmühlen, FSA 75, 1973.
Jongenelen C. H. and Veldhoen: Fermentation von Abwässern in einem Säulenfermentator, FSA 82, 1982.
Kaufmann H.P. et al.: Technologie der Fette, Verlag Aschendorff, Münster, 1968.
Krause, A.: Abluftprobleme in der Fettindustrie und in verwandten Gebieten, FSA 80, 1978.
Krause, A.: Pflanzliche und tierische Fette und ihre Wirkung auf Mikroorganismen in biologischen Kläranlagen, FSA 85, 1982.
Lehr- und Handbuch der Abwassertechnik, 3. Auflage (Ernst u. Sohn), Bd. 5, 1985.
Liebe, H.G., Münch, E.W.: Neues Verfahren zur Reduzierung geruchsintensiver Emissionen, FSA 88, 1986.
Air Quality Guidelines for Europe, WHO regional publications European series: No.23/1987).
Mahatta, T.L.: Technology and Refining of Oils and Fats (Production and Processing of Oils and Fats). Delhi: Small Business Publ. without year of publication, 360 pages (SBP Chemical Engineering Series. 49).
Morger, M.: Abwasseraufbereitung in Betrieben der Speisen-, Fett- und Molkereiprodukteindustrie in werkseigenen Kläranlagen, FSA 88, 1986.
Niemitz, W.: Abwasser und Abfall. Schwerpunkte der Umweltprobleme industrieller Produktionen, FSA 75, 1973.
Nösler, H.G.: Umweltschutz zwischen Wunsch und Wirklichkeit, FSA 86, 1984.
Organisch verschmutzte Industrieabwässer in Nahrungsmittel-, Genußmittel und Getränkeindustrie, 1984.
Pardun, H.: 50 Jahre Technologie pflanzlicher Öle und Fette, FSA 85, 1983.
Schmidt-Holthausen, H.J.: Verfahren zur Abwasser-Aufbereitung in der Speisefett- und Fettverarbeitenden Industrie, FSA 81, 1979.
Segers, J.C.: Möglichkeiten und Beschränkungen bei Verringerung der Umweltbelastung infolge der Raffination von Ölen und Fetten, FSA 87, 1985.
Segers, J.C.: Superdegamming. A new degamming process and its effect on the effluent problems of edible oil refining, FSA 84, 1982.
TA-Luft, Technische Anleitung zur Reinhaltung der Luft of 27.02.1986, GMBI. (joint ministerial circular) p.95, rep. p.202.
TA-Lärm, Technische Anleitung zum Schutz gegen Lärm of 16.07.1968, appendix to volume no.137 of 26.07.1968.
Umweltbundesamt - German Federal Environmental Agency (Ed.): Handbuch Abscheidung gasförmiger Luftverunreinigungen, Erich Schmidt Verlag, Berlin 1981.
VDI (Verein Deutscher Ingenieure): VDI-Handbuch Reinhaltung der Luft, Beuth Verlag, Berlin and Cologne, Feb. 1992.
VDI (Verein Deutscher Ingenieure): VDI-Richtlinien zur Geräuschmessung, Schallschutz, Schwingungstechnik: 2560, 2564, 2567, 2570, 2571, 2711, 2714, 2720, 3727, 3749, 3731, 3742.
Verordnung über die Herkunftsbereiche von Abwasser of 03.07.1987, BGBl. (Federal Law Gazette) I, p.1529.
World Bank: Environmental Assessment Sourcebook, Volume II Sectoral Guidelines, Environment Department, Technical Paper Number 140, Washington D.C., 1991.
World Bank: Environmental Guidelines, Environmental Department, Washington D.C., August 1988.
Zockoll, C.: Sicherheitstechnische Fragen beim Silobetrieb, FSA 81, 1979.
Contents - Previous - Next