Introduction
Delivery of raw material
Raw material at the factory
Processing
Handling and storage of fish meal
Factory and equipment design
Factory management
Maintenance
The process of making fish meal from fish and fish offal generates odours and this note gives advice on reduction of these odours. The advice covers the handling and storage of fish and fish offal, process control, handling and storage of the product, and design and maintenance of equipment.
Fish converted to meal and oil is an important indirect source of human food; the industry produces high grade feed for animals and edible oil for human consumption. The raw materials, which cannot be used for human consumption, are fish and offal from processing factories, surplus fish and fish caught specifically for fish meal and oil production. A description of the manufacture, storage, composition and use of fish meal is given in Advisory Note 49.
The substances in the vapour from fish handling and processing operations, including fish meal manufacture, are normally much diluted and not harmful but they can be odorous even when present in low concentrations. Thus, while the public may be conscious of an odour from a fish meal factory on occasions, it could be unaware of possibly harmful air pollution caused by industrial processes that produce little or no odour.
It is not yet possible to prevent odour completely but, by the adoption of the best practicable means presently available, it can be considerably reduced. Although much of the advice is being followed already, some of it applies particularly to the design of new buildings and equipment.
Special odour reducing equipment, which is normally included in plant for fish meal manufacture, is referred to but is not described in detail. The advice given here is also intended to serve as a basis for discussion between local authorities and industry when existing factories are being modified or when new installations are being planned. This note has been endorsed by the Department of the Environment whose recommendations have been taken into account and has been prepared in consultation with the Association of Fish Meal Manufacturers.
The staler the raw material the more odorous it becomes during handling and processing; regular and frequent deliveries from processors' premises in suitable containers and vehicles are, therefore, essential to avoid causing offence at the collecting points, on the journey or at the fish meal factory. Whole fish caught specifically for fish meal manufacture should also be landed and conveyed as quickly as possible from quayside to factory before they spoil and become odorous.
Recommendations
Offal should be delivered to the factory on the day it is produced, preferably within 12 hours. Whole fish should be landed before they are stale and be delivered to the factory from the quayside as soon as possible after landing, preferably within 12 hours.
Regulations that limit drivers' hours should be taken into account when planning long distance deliveries, in order to avoid delay in transit.
Where possible, suppliers of raw material and carriers should agree on a collection schedule that prevents accumulation of material. Whenever there is an unexpected increase in supply the carrier should treat removal as a matter of urgency and take away the oldest material first. Suppliers should endeavour not to allow offal to accumulate.
Whenever a carrier cannot make a collection promptly, he should notify the supplier and the fish meal manufacturer so that alternative arrangements can be made.
Special arrangements may have to be made when material becomes available at a time when the fish meal factory is closed; a decision has to be made about whether it is better kept at the collection or delivery point, and transport and reception arrangements made if required.
The most suitable containers or vehicles for carrying raw material are robust, easy to clean, resistant to corrosion, leakproof, covered to prevent spillage in transit and easily emptied.
Containers should not be overfilled; otherwise there is a risk of spillage during handling.
The inside of each container or vehicle should be cleaned at the end of a day's work and the outside should be cleaned if necessary after every journey.
Where the carrier agrees to supply containers for the producer to fill, he should ensure there are always sufficient numbers of them at the collecting point.
The carrier should continually review the adequacy of his vehicle fleet and, when planning any replacement, consider the purchase of a purpose built vehicle.
The driver should be instructed to take care that his load docs not create offence and to deal immediately with any spillage or leakage.
The problem of odorous raw material becomes more acute at the fish meal factory where large quantities are handled and stored. Processing capacity should be matched as closely as possible to input of raw material to avoid long periods of storage; generally the more odorous material should be handled first. Stoppage of the plant with raw material on hand, for example at a weekend, can cause an odour problem when the plant is restarted. Enclosed storage areas confine odours and prevent the attraction of vermin and birds.
Recommendations
Raw material should be processed as soon as possible and preferably within 24 hours of arrival. Any build up of raw material during a glut should be cleared as soon as possible, if necessary to other outlets when the factory cannot cope.
Storage capacity should be sufficient to cope with normally anticipated supplies of raw material. When the storage area is full, no more material should be accepted. If it cannot be avoided, raw material should not be stored anywhere on the premises outside the storage area.
All storage areas should be enclosed and ventilated to the odour reduction equipment. Entrances and exits should be open for as short a time as possible and be closed when not in use.
Raw material should pass through the storage area on the first in, first out principle, unless particularly objectionable material has to be given priority.
Storage areas and containers should be cleaned at least once a week.
Storage areas and containers should be designed for rapid and efficient movement of raw material; there should be no dead spots where material can accumulate.
Storage areas should be kept as cool as possible.
Liquor that drains from the raw material should be processed wherever possible. If it cannot be processed, arrangements for disposal and treatment should be considered.
Any raw material or effluent spilt outside the storage area during delivery should be cleared away immediately and the contaminated surface cleaned.
Vehicles used to move raw material within the factory should be cleaned at least daily.
Reception and storage areas should be designed to handle the whole range of raw material, should be easily cleanable and be constructed from materials that are not corroded by either the raw material or the cleaning agents.
Raw material should be handled as little as possible, with the minimum number of transfers from one point to another. Conveyors should be short in length, totally enclosed without dead spaces and be easily cleanable.
The raw material is heated and kept hot throughout the process; hot fish readily gives off odour. Much of the odour is produced in the dryer but vapour from cookers, presses and screens also makes a significant contribution.
Even when odour reduction equipment is being used, poor housekeeping and leaky ducting can make it largely ineffective.
Recommendations
Loose solids carried over from processing equipment should if necessary be trapped in the effluent duct and returned to the process.
All odorous vapour should be contained or be ducted directly to the odour reduction equipment.
Each section of the processing plant should have sufficient capacity to cope with fluctuations in supply.
The amount of air that has to be treated by the odour reduction equipment should be kept as small as possible.
Suitable arrangements should be made for the disposal of liquid effluent from the odour reduction equipment.
Processing plant should be housed in a purpose built factory. Where this is not possible, the existing building should be modified as far as practicable to minimize the escape of odour.
Fish meal when cooled has little odour but if particles of the product become dispersed and then spoil, there is further risk of offence.
Recommendations
The finished product handling area should be divided from the rest of the factory. Product handling and storage areas should be dry and weatherproof; water from elsewhere in the factory should not seep through. Any spillage of finished product should be cleaned up immediately.
Depending on the handling system, including grinders and conveyors for dried material, it may be necessary to treat, filter or recycle air rather than discharge it to atmosphere.
Vehicles taking fish meal in bulk should be loaded in an enclosed area to avoid spillage and dispersion, or the vehicles themselves should be enclosed and filled direct.
Few existing fish meal factories were designed for effective odour control, and modification to satisfy all the recommendations listed below would require substantial capital investment. When new premises are being planned, efficient processing and adequate odour control should be integrated in the design.
Recommendations
New premises should be designed and located with the express purpose of avoiding offence in the neighbourhood. Good planning by the local authority is important.
The site should have an adequate supply of water, have good facilities for disposal of liquid effluent, and be within easy reach of sources of raw material.
If existing buildings have to be modified, expert advice should be taken in an attempt to improve the premises as a whole.
Equipment should be designed so that there is little possibility of odour escaping, and so that escapes are easily rectified.
All areas should have enough enclosed, odourproof drainage to cope with the amount of effluent anticipated.
Residual oil and solids should be collected in traps and tanks that are easily cleaned.
All structures should be kept clean and in good repair.
Floors should be hard wearing, easily cleaned and resistant to corrosion. They should have a slope of 1 in 100 towards the drains and be coved at junctions with walls.
Yards and roads on the site should have an impervious surface, be properly drained and be kept in good repair.
Walls should be free of ledges, windowsills and other projections and be finished to a height of 2 metres with a hard impervious material.
Ceilings should be smooth and nonabsorbent; they should be cleaned regularly and kept in good repair.
Material should flow through the system in a logical manner and with as few transfers as possible. Conveyors and pipes should be kept as short as possible and mounted clear of the building structure to allow easy cleaning and maintenance.
Equipment should not be overloaded; otherwise it may fail and allow odour to escape.
The outer surfaces of equipment should be smooth, durable, leakproof and easy to clean. Seals and gaskets should be leakproof.
All equipment should be easily accessible for cleaning and maintenance.
Equipment should be vented at a controlled rate through ducts connected to the odour reduction equipment.
Equipment should be fitted with instruments that assist in monitoring the process; accuracy of instruments should be systematically checked.
Hot vessels and pipes should be insulated to keep the surface temperature low; the insulation should have an impervious coating.
Condensers and odour reduction equipment should be designed to cope with all likely operating conditions.
Equipment that generates a large amount of dust should be enclosed and fitted with a dust control system.
There should be two separate transport cleaning areas, one for vehicles and containers used for raw material, and one for vehicles used for carrying fish meal.
There should be ample cleaning facilities and cleaning material available.
There should be changing rooms with hot and cold water for the use of factory personnel.
Constant vigilance on the part of management staff at all levels is essential if odour control measures are to be effective. Complacency and lack of concern lead to lax supervision and unsympathetic handling of complaints from the neighbourhood.
Recommendations
Management staff should always be available during factory working hours and should be on call outside working hours.
Untrained staff should not be left on duty without proper supervision.
All factory personnel should be made aware of the function of odour reduction equipment.
Managers should check frequently that agreed factory procedures are being followed.
Managers should be responsible for ensuring that delivery of raw material does not exceed storage capacity. They should have authority either to alter the processing schedule to cope with the excess or to stop further deliveries, arranging where necessary for diversion to another factory or for storage at the producer's premises.
Where necessary, factory personnel should be provided with clean protective clothing and footwear for use only in the factory.
Management should deal sympathetically with complaints and be prepared to take immediate remedial action where practicable. It may be useful to liaise with the local authority.
The measures described above, including use of odour reduction equipment and good housekeeping under supervision, will do much to reduce odour from a fish meal factory. Continuous preventive maintenance is also essential, however, if the risk of causing offence is to be kept as low as possible.
Recommendations
Trained personnel should be allotted well defined routines for cleaning and inspection and should carry out a comprehensive programme of preventive maintenance. Good housekeeping is one of the cheapest and most effective means of reducing odour.
Spare parts for essential equipment, especially the odour reduction equipment, should be kept on site to permit speedy repairs.
All equipment should be checked regularly and parts replaced before they fail. The escape of odour through faulty seals, corroded ducting and the like should be prevented. The surfaces of all structures and processing equipment should be cleaned periodically with cold water, detergent and sterilizer; in some cases fixed cleaning jets can be used for washing.
All vehicles and containers should be kept in good repair.
All drainage areas and collecting tanks should be cleaned daily.
All yards and roads on site should be cleaned at least daily and more frequently if required.
All solid waste that cannot be processed should be stored in sealed containers and removed daily.
Routine instrument readings and observations of factors affecting odour should be recorded systematically.
If you have any queries, write, phone or visit
|
The Director |
The Officer in Charge |
|
Torry Research Station |
Humber Laboratory |
|
135 Abbey Road |
Wassand Street |
|
ABERDEEN |
HULL |
|
AB9 8DG |
HU3 4AR |
|
Phone: 0224 877071 |
Phone: 04827879 |
|
Department of the Environment |
Warren Spring Laboratory |
|
Queen Anne's Chambers |
PO Box 20 |
|
28 Broadway |
Gunnels Wood Road |
|
LONDON |
STEVENAGE |
|
SW1H 9JU |
Hertfordshire SG1 2BX |
61 Gaping of fillets, by R. M. LOVE.
62 The freezing time of fish, by F. J. NICHOLSON.
63 Fishing ports in the UK, by J. J. WATERMAN.
64 Fish silage, by I. TATTERSON and M. L. WINDSOR.
65 Fishworking machinery, by S. MAIR.
66 Handling and processing mackerel, by J. N. KEAY.
67 The haddock, by J. J. WATERMAN.
68 Icemaking plant, by J. GRAHAM.
69 Cook-freeze fish products, by J. N. KEAY.
70 Advice for the fish industry; who does what, by J. J.
WATERMAN.
71 Processing cod: the influence of season and fishing ground,
by R. M. LOVE.
Earlier notes in the series, most of which are still available, are summarized in 60 Key to Advisory Notes 1-59, by J. J. WATERMAN.
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