The SWS Unit is easy to install and run. Once the principle is understood it can be used successfully in a range of situations and for many purposes, but it is not a magic recipe for instant free clean water! The advice in this leaflet must be studied carefully, giving special attention to:
Choice of site, pump and pipe line.
Correct installation and thorough development.
These instructions should allow most sites to be worked but there is great advantage in having a small trained mobile team to establish units and teach other groups. This basic training can be given by SWS in Britain or overseas. It is possible for an experienced person to work alone but better to have a team of two or three, of which one has some experience of machines. Technical advice should be asked about difficult sites and also about projects where large volumes are needed.
GENERAL PRINCIPLES
The SWS Unit is not itself a filter but a device for making the sea or river bed serve as a natural sand filter. Dirt is held on the bed surface as water is drawn to the open bottom of the unit through an area of up to 10 m diameter. Water moving over the bed cleans it, helped by fish etc. that poke about and disturb the sediment. In the sea the action of waves and tides is effective. The bed itself becomes a biological filter that destroys bacteria and reduces the levels of ammonia, iron, BOD etc.
SITE REQUIREMENTS
A permeable bed is needed at least 60 cm deep, but preferably not less than 1 m, and under a minimum of 30 cm water. Different types of site, including those to which sand must be added, are described on pp 3 & 4. Beds of a wide range may be used - sand, gravel, broken coral, shell etc. The bulk of the grains should be between 0.5 and 5.0 mm (0.02 and 0.2 in) but a great advantage of this system is that during development, described below, excess fine sand is pumped out, leaving the larger grains in and around the unit so a precise sand specification is not needed. Uniformly fine sand, especially of wind-blown origin, is unsuitable on its own, but it can be graded up by adding course sand or gravel under and around the unit. If most grains are above c. 2 mm (0.1 in) it helps to add fine sand on the surface around the unit during development. “Fine sand” is material up to c. 1 mm and “course sand” from c. 2 to 5 mm, but these are not used as technical terms. A few stones up to c. 50 mm (2 in) do little harm but larger stones reduce the bed's efficiency and should be cleared around the unit.
INSTALLATION
Dig a hole with centre deep enough to take the unit, open end down, so that its top is up to 15 cm (6 in) buried when stabilised. (See Fig 7, App. 10.) Sand is filled in around the unit and more piled over to allow for settlement. If a hollow forms, more sand should be drawn over it.
A special tool is supplied with each unit, or set of units, for digging this hole. A 2 m pole is fastened to it and it is used like a rake.
In cold climates, most work can be done in waders but sometimes a skindiver is needed, especially in the sea. Men can work comfortably in warm water but special precautions must be taken in bilharzia areas.
DEVELOPMENT
Thorough development is the key to success and this section is most important.
When the Unit is buried and the suction line has filled with water, this is then connected to the pump intake. Tight joints with washers are essential, for the smallest air leak delays priming and lowers efficiency. Under-water leaks may admit raw water though if these are very small, they soon block. Develop with a temporary pump close to the water or work from a boat, especially if the permanent pump is to be submersible. It may help to stand on the unit, rocking it gently to settle it until the pump primes fully: the speed should then be reduced until it runs steadily. At first the water if full of silt and organic matter as it cleans the bed. Varying with the site, this water clears in anything from a few to many minutes. The pump is then stopped and restarted; after a very short interval the water becomes dirty but soon clears, when the pump is again stopped and restarted. Releasing the partial vacuum disturbs the sand in and around the unit, allowing more fine material to be sucked out and gradually pushing back the perimeter of clean coarse sand, so improving flow to the unit, which is one of the basic reasons for development. This process continues until water no longer becomes dirty after restarting and the pump is working to full capacity. The type of bed and the pump size determine whether this takes an hour or perhaps a whole day.
Where the bed has much black organic matter, development is best spread over several days to allow this to decay aerobically, after which it is easily sucked out.
The water should now be crystal clear, free of all suspended matter and organisms down to about 1 micron and sometimes below that. It is suitable for most purposes, including for village supplies where the water had previously been used raw. Where sea water is wanted for research or fresh water for town supply, it should be pumped to waste several hours daily for at least a week while the biological filter develops in the bed, the time needed varying with temperature and other factors. Where quality is critical, this should be monitored.
Where adverse site conditions impede progress the following procedures may be tried:-
Using a garden fork or similar tool, dig the bed well around the unit, letting the stream carry away much of the silt.
Instead of just stopping the pump, release the suction completely, letting the water flow back to the unit, before re-starting.
Interchange intake and take-off hoses and pump back for several minutes. Somebody should stand on the unit until normal pumping restarts.
Small amounts of sand (perhaps 10 ppm) may be drawn through for some days, especially when pumping is periodic, but this is sterile and settles at once in a reservoir or small baffle chamber.
If pump and pipe line are not limiting factors the rate of flow is largely determined by the site and large volume is often possible. For drinking water it is better to under-pump and a steady flow of not above 20 c.m./hour (4,500 gal) per unit is suggested. Although the system is designed for continuous working in both sea and river, it is equally efficient when pumped periodically, preferably daily, but the system has been shown to be clean and effective in a British river after being left for 3 months. When the pump is started again it is probably advisable to pump some water to waste; this need be for only a few minutes after a day's gap but perhaps for up to an hour after a week. Only local experience will show what is needed and in fact whether this is even necessary.
SITES WITH AMPLE SAND
1. Rivers and Streams
Conditions vary with climate, shape of ground, geology etc. so that the site must be chosen carefully. It must be stable and free from scour, which prevents the formation of a good filter bed and may even wash out the unit. The inside of a bend is often suitable. There should always be at least 30 cm water over it. In rivers which fluctuate widely the only permanent source is one covered at low water but as the water rises it may be necessary to take up the unit and replace it near the edge.
In rivers which stop flowing in the dry season and then disappear, the unit can sometimes be buried below the water table. Drawing the water by pumping instead of from an open hole has two big advantages: since the water is not exposed to sun and air there is less loss by evaporation and the source does not become polluted.
2. Water Catchment Dams
A bank of sand often forms where the stream enters and this should take a unit satisfactorily, but if the dry season level drops too far the unit must be taken up and reinstalled suitably. Wind and water movement should keep the bed surface clean but if it becomes blocked this is dealt with as advised under SITE CLEANING AND MAINTENANCE.
3. Sea Shore
The unit should have at least 30 cm water over it at spring low tide. In very permeable sand on a level beach a unit can sometimes be installed above LTM; it must be as deep as possible but unless water has free access to it at all times, flow may be limited at low tide. Salinity must be monitored during site selection if water is wanted for Aquaria, Marine Laboratories etc., for areas may be diluted by freshwater run-off or beach springs.
In contrast to rivers and dams, sea movements are daily and predictable, and a known factor in the suction head. Tidal pattern may vary widely: rise and fall may be from under 2 m to 15 m (6 to 50 ft) and the tide may recede anything from a few metres to over 500 metres.
SITES WITH LITTLE OR NO SAND
Soft mud areas cannot be used, but where the bed is of rock or clay it may be possible to apply the following general method. Excavate or blast a hole. The shape need not be regular but for top quality water the surface area should be about 2 s.m. per c.m./hour, with depth of at least 60 cm. Usually a much lower ratio is possible. The bottom should be filled with coarse gravel or small stones to a depth of 20 cm to prevent the unit from sealing itself on the bottom and also to provide good lateral access for water. The unit is then placed in position and water allowed to enter, after which the sand is poured in until it forms a hump over the hole. If 2 units are needed they should be well spaced in a long trench. This variation clearly needs more work than a standard site but it can be applied to such as the following:-
1. River
Sometimes it is possible to work on the actual river bottom, perhaps after putting in a coffer dam. Or a site may be prepared alongside the stream, to make an artificial ‘bay’ when complete. It is essential to avoid reaches with massive scour in the rainy season.
2. Storage Dams
These are sometimes lined to stop seepage and care must be taken not to cut through this lining. Two prepared holes may be needed, to draw water at various levels.
3. Foreshore
The inter-tidal zone is sometimes too compact for direct use but conditions vary so widely that only general suggestions can be made, and technical advice is needed, especially where large volumes are required.
On most shores the problem is to excavate holes near enough to LTM to allow continuous pumping. Where there is much beach run-off a long trench parallel to the shore line, plus the water in the trench, may allow at least an hour's pumping while the tide is off it. Perhaps a narrow trench dug seawards can give water access to the trench even at low tide.
Where only moderate volumes are needed the hole can be dimensioned to hold a reserve of say, two hours pumping over low tide. The simplest and cheapest solution is an excavation well up the beach which is pumped for a few hours while actually covered by the tide. This reduces suction head and run to a minimum. The formation of a hollow must be avoided where sea wrack etc. can be trapped and buried. Such work is seldom easy but it is well worth considering, especially on a shore where the tide recedes so far that LTM is beyond practical reach.
PIPE SIZE AND SUCTION HEAD
Resistance (friction head) rises rapidly with both rate of flow and reduction in pipe size, as this table shows clearly. Bends, valves etc. add to this resistance (for details consult a textbook on Hydraulic Engineering). 40 mm (1–½ in) is unsuitable for over 5 c.m./hour (1,000 gal), while 50 mm (2 in) pipe can handle 18 c.m./hour (1,000 gal) if the pump is close to the water and not more than about 3 m (10 ft) above it. For any flow above 20 c.m. (4,500 gal) at least 75 mm (3 in) pipe is essential.
Failure to understand the importance of total suction head (i.e. friction head plus static head, or height of pump above water level) can be both expensive and disastrous. A pump can suck only from a limited depth, a maximum of c. 7 m (23 ft), and with most pumps the flow has already dropped severely before this is reached. This is reduced by 1 m for every 1000 m altitude (1 ft for 1000 ft). The suction line should therefore be dimensioned to have no noticeable resistance at maximum flow.
This is not so critical on the delivery side but the figures in this table apply equally and the higher cost of a larger pipe line is recovered in economy on pump size and power used. As diameter increases the carrying capacity of a pipe rises much more steeply than cost.
PIPE LINE
Flexible armoured hose is needed from the unit at least as far as the highest water level. It can be expected to last for at least 10 years. Semirigid PVC type can be used from the river edge and also for the delivery line. For river sites, local conditions will decide whether the line should be protected from vandalism, heating up etc. by burying or in some other way. In the sea it is better to bury the line up to 50 cm deep if the terrain allows, or else secure it to rocks and so reduce damage.
| Pipe Diam. | Gal. per hr. | Litres per hr. | Resistance per 100 ft. (30 M.) | ||
| inch | mm. | feet | m | ||
| 1–1/2 | 40 | 1,000 | 4,500 | 5 | 1.50 |
| 1,500 | 7,000 | 10 | 3.00 | ||
| 2,000 | 9,000 | 15 | 4.50 | ||
| 2 | 50 | 1,000 | 4,500 | 1 | 0.30 |
| 1,500 | 7,000 | 2 | 0.60 | ||
| 2,000 | 9,000 | 4 | 1.20 | ||
| 3,000 | 13,000 | 9 | 2.70 | ||
| 4,000 | 18,000 | 15 | 4.50 | ||
| 5,000 | 22,500 | 24 | 7.30 | ||
| 3 | 75 | Below 3,000 gal (13,000 l) negligible. | |||
| 3,000 | 13,000 | 1 | 0.30 | ||
| 4,000 | 18,000 | 2 | 0.60 | ||
| 5,000 | 22,500 | 3 | 0.90 | ||
PUMPS
Land-based pumps must be self-priming, i.e. be able to suck air from the suction line and pull water until there is a continuous column from unit to pump. The method of priming varies and instructions in the pump manual must be studied. However large the complex of units, each must be developed individually, using a petrol-driven pump of 3 to 4 h.p. able to pass 2.5 mm (0.1 in) solids. Machine pumps should not be considered for village supplies unless the power to run them, whether electricity or petrol, can be guaranteed. Once the system has been established a Patay hand-pump is recommended for regular use; this easily yields 4 c.m./hour (1,000 gal), it is strong and reliable, and its only running cost is a new diaphragm (under ₤2) every 400 hours running. Wind-powered pumps are not suitable for development but could perhaps be used for filling reservoirs etc. if a hand-pump is always kept in reserve. A simple reservoir holding 2 or 3 days supply makes the whole system most useful.
In the sea a shore-based pump should be used when the static head allows but it must be safely housed above HTM. In a marginal site a sunk pump chamber, thoroughly watertight, may reduce the static head by up to 1.5 m. Tidal pattern and beach shape sometimes make a submersible pump essential; the normal grille is replaced by a special fitting connected by flexible hose to the unit (s). The pump should be mounted firmly on a pile or similar support at a point just exposed at spring low tide for easy maintenance. Submersible pumps are powered only by electricity through heavy armoured cable. It may be undesirable to bring this down a beach to which the public has access but some types can be well protected by running the cable down the rising main, emerging by a special duct at the pump. A small submersible pump is now available that can be housed directly on top of the unit.
SITE CLEANING AND MAINTENANCE
In marine sites tidal and wave movements keep the surface clear and this is also true of most river units. If any blocking occurs this will be in the top 1 – 3 cm, usually 1 cm, and this is most likely in the still water of storage dams. If reduced flow, not due to pump or other factors, suggests that there is surface blocking the following progressively vigorous actions may be taken:-
Stop the pump and rake over an area of about 5 m radius around the unit, working to a depth of about 5 cm. Then pump to waste while redeveloping as long as needed.
Skim off about 3 cm sand and replace with new sand.
Fork over the area lightly and then back-wash by moving suction hose to pump outlet and drawing water through spare hose. Somebody should stand on the unit until the pipes are changed back and the redevelopment starts.
Remove unit and install and develop in nearby site.
3. and 4. will be needed seldom if at all. In a system with several groups of units, provision for back-washing can be made with little modification to the plumbing. If the suction lines are long this can be used to fill them with water and so reduce priming time when restarting.
A change in tidal pattern or badly sited breakwater may remove a metre or more of sand from the beach, though this is unlikely near or below LTM. If the unit becomes exposed it must be installed afresh.
The contours of a river bed may change, making it necessary to find a new site, though intimate knowledge of the river, with a careful preliminary survey, should allow the selection of stable reaches. Where scouring occurs it may be enough to replace the sand and develop again, but the trouble will probably recur and it is usually better to move the unit.
A firmly embedded unit can be quickly freed by changing over suction and delivery hoses at the pump and blowing back, after letting some air into the line to the unit.
IMPORTANT
For developing countries a small team should go around to assist in the installation of a system, especially where most villagers are illiterate, using a mobile petrol-driven pump for development before instructing in the use and maintenance of a hand pump. 5 litres (1 gal) petrol per site should be enough for this. If transport allows, it should be possible for a team to install an average of 1 unit per day.
A tool has been developed which has proved valuable in site survey and preparation. The diagram shows the general design, with dimensions and details. Attached to the delivery line of 3 to 4 h.p. pump, this tool will penetrate compacted gravel but, for very dense beds a pump of 5 to 7 h.p. may be needed. In normal strata its own weight is often enough but it must at times be used very strenuously.
Site exploration. The texture of the different layers can easily be sensed by feel, while the material being carried up the hole by the returning water can be collected by hand from time to time, roughly indicating the particle sizes. The stratification and depth of bed can be plotted much more quickly than in any other method known.
Site preparation
(a) Breaking up consolidated zones. Many river beds have remained untouched for long periods. Thorough probing can loosen the whole bed and wash out the silt and clay causing compaction, often leaving a bed suitable for direct use. In many cases the fluidising action allows hydraulic sorting, with larger stones sinking and the finer sand/gravel fraction moving upwards. In a stable reach this improvement of structure is permanent.
(b) Removing organic debris. Organic material buried in an anaerobic zone may take many years to break down. Thorough working over with the tool ‘boils out’ most of it, to be carried away by the stream, while accelerating the aerobic decay and greatly speeding development.
(c) Surface cleaning. If the tool is held at an angle near the bottom the surface is quickly cleared of debris to a depth of 15 cm or more, according to texture. This can also be used to clean the surface of an established SWS system in more or less still conditions.
Burying Units and lines. Thorough use of the jet tool eases excavation of a site and is also the quickest method of burying a suction line.
Removing SWS Units. If a Unit must be taken up and it is not convenient to blow it back, the tool can be used to jet all around it and ease its removal.
CAUTION: In a soft bed the probe can quickly make a hole up to 0.5 m deep in which the operator can easily step!
| A | Handle welded to 90° Elbow. Made from 25mm steel pipe. Cross-piece 300mm Upright 500mm |
| B | 90° Elbow threaded to take hose coupling and 37mm pipe. |
| C | 37mm steel pipe, about 75cm in length. Threaded to allow an additional extension to be used. |
| D | Details of end of Jet Probe made by welding three plates together to form point. |
| E | 50mm delivery line from pump. |
Fig 8. Suggested Construction of SWS Jet Probe
SYNOPSIS
The advantage of using the sea or river bed as a natural filter are emphasized and the progress of research in sub-sand abstraction over 10 years described, leading to the invention of the SWS unit. The method of construction is outlined and then the details of installation and development. The quality of the pre-filtered water produced by the unit is discussed, as well as the cost-effectiveness in various situations. Some important tropical applications are mentioned briefly and then the known uses of the unit for industrial countries, in both sea and fresh water, are listed.
INTRODUCTION
The SWS unit is a recent ‘spin-off’, the incidental product of a small team headed by an applied biologist who insisted that there must be a simpler and cheaper way of providing Marine Zoo animals with clean water than an orthodox filter circuit. The principale underlying the system will perhaps be best understood if its development is first described briefly.
Pre-filtered water, obtained by sub-sand abstraction, is ideal for projects using bulk sea water and it has many advantages over the open intake system still commonly used for fish farms, swimming pools etc. The most important are:
Suspended matter is removed down to 5 micron and mostly to 1 micron.
Oil spills and surface rubbish cannot enter the circuit.
The intake is never blocked by wrack, which is a big hazard after storms.
All larval stages of zooplankton are excluded, so that the pipeline cannot become colonised and blocked, to cause massive waste of time and efficiency.
An established system removes virtually all the bacteria that teem in inshore waters.
Evolution of SWS jet wells
In California I had seen several large Oceanaria which pumped large volumes of water continuously from sub-sand systems; when I became involved in the design of a project on the Lincolnshire coast, I specified such a system which the engineers said was quite impossible. However, I was certain there was a solution and accepted the challenge - which is how I became involved in this field. The Pacific coast intakes were elaborate and expensive - pipelines hunreds of metres out to sea and sub-sand complexes of perforated pipes installed by a diving team. Such were right beyond our DIY resources. Our first - and successful - efforts were literally wells sunk in the beach; using a sludge pump we pushed 3 concentric sections of porous sewage pipes down to about 2 m. Crystal-clear water seeped into the bottom which a suitable take-off and pipe line brought to our exhibits.
We found nobody to consult but had many helpful suggestions and were finally put on to the principal of jet wells, which allowed us to establish a source in as many minutes as the first well had taken days. These not only drew the water sub-sand; they also used the sand of the beach as a reservoir to be charged twice daily by the tides, which meant that on many shores the complex of points could be sited close to or even above H.T.M. We developed this work for some 9 years, finding our pre-filtered water increasingly requested by research laboratories, while our advice and services were being sought by several companies and Government Departments here and overseas, so we were probably slow to realise that we were in a line where few people seemed to have had any experience and where there was great potential.
Production of SWS unit for use in difficult sites
Our modified well points were ideal with the right site factors - in particular, topography of beach and the depth and grade of sand - but it was clear that only some sites could be used. In 1974 we were challenged by two difficult bits of coast in Western Scotland. Well points were impossible but, once again, we were reluctant to accept defeat - and the SWS unit was the answer. In effect we unwrapped the cylindrical slotted section of the well point and made it the false ceiling of a hollow box. This at once had three important effects:-
Instead of converging on 2 vertical cylinders of 5 cm. diameter and 60 cm length the water now had a perimeter of 180 cm (i.e. the sides of a box 30 × 60 cm) to give access to a flat slotted plate with the same surface area as the two well points combined.
Sand depth became comparatively unimportant and the unit could be used in rather shallow sites. In fact, sand may be under 1 m deep and in a marine situation the unit need not be actually below L.T.M. provided that water always has access to the base, which must always be below the level of the lowest spring tide. Further, since the water enters at the base the design effectively makes it traverse sand of twice the actual depth, for it must go down and then up. (In fact we find that much of the water travels more or less horizontally and may pass through several metres of sand.)
The particle size distribution of the sand also becomes less critical, for the process of development, discussed below, sorts out the sand, removing the fine material from inside and around the unit; further, the method of installation makes it easy to add either coarse or fine sand and so get a better mix.
Definition of SWS unit
At this stage it is essential to make two points clear:
This is not desalination, for the soluble salts which made up the sea water remain in solution; however, evidence is being found that sub-sand abstraction removes various metals including lead and zinc, probably because they are attached to rather large organic particles. This is being further investigated. Other incidental chemical effects are discussed below.
The SWS unit is not strictly a filter but a device to make the sea bed itself serve as an efficient natural filter. So the slotted septum, which is the heart of the system and the basis of the patent, is not in any sense a filter plate but a carefully designed screen that allows development of the surrounding ‘well’ and guards the entrance to the whole system.
SWS unit ideal for fresh water work
As soon as we had tested the prototype on the beach we realised that it was equally suitable for use in moving fresh water. I had served as a Forest Officer in the jungles of Ghana, where thousands of villages drew their water from perennial streams whose beds were lined with quartz and mica from the breakdown of granite; these made ideal sites.
Fig 9. SWS Filtration Unit
Construction and size
The SWS unit is an open-bottomed box in heavy fibreglass which can be seen in the exhibition. This material has been chosen because it is strong, inert and durable; it is also economic to fabricate by hand from simple moulds and the very expensive compression mould essential for forming the slotted septum could be avoided. The hollow section between this septum and the roof of the box is 10 cm deep; it has a series of distance pieces to give stability and stop collapse under vacuum, but these are so designed as to give free passage of water to the horizontal 50 or 75 mm take-off to the pump.
The septum has numerous slots 3 mm wide below tapering out to 6 mm above, so that any particles drawn into the slot go straight through and are evacuated; parallel-sided slots would become blocked. In theory sand grains one third of the slot diameter eventually bridge it and this is part of the process of development.
After much discussion, calculation and trial, the maximum unit size was fixed at 60 × 60 cm, with depth of 40 cm. The latter could perhaps be reduced and we plan to do more work on this point, but it is probably needed to give both stability and efficiency. The optimum cross section is decided by two entirely separate factors. First, the relation between perimeter and surface area is such that the latter increases much more rapidly than the former. It thus seemed that 60 × 60 cm was the largest that could be effective and that two units of this size run in parallel at 3 m centres would be more efficient than one unit of 85 × 85 cm (of the same combined intake area), though it must be admitted that this is largely theoretical. The second factor is a severely practical one. Most potential sites are unsuitable for mechanical handling and units must normally be installed by hand in moving water; the 60 × 60 cm unit weighs rather over 20 kg. and is the largest and heaviest that can safely be installed by one man. In fact we have now found that for many purposes, certainly for most village supply work, this is unnecessarily large and we are therefore producing one of 60 × 30 cm to take half the standard-size septum. It may well be that further experience will show it is better to use two of these small ones at 2 or 3 m centres than one large unit.
SWS unit installation
Tidal movements mean that establishment in the sea poses different problems, even though the general principle is the same. The following discussion is therefore based on freshwater work. The unit is placed in the river bed in not less than about 30 cm water. We have so far recommended that the top of the unit should be some 30 cm under the sand when stabilised but experience now suggests that it is probably enough to have it flush with the bottom. Careful attention must be paid to two aspects of site selection. First, the unit should be in the stream, yet not subject to heavy scour, for this can prevent both stabilisation and the formation of the surface filter mat described below. Second, the bed should consist of suitable material - sand, gravel or shell bank, if need be enriched with imported sand to produce a reasonable mix, though it is better to locate a site that can be used as it is. Working on spate streams in N. Nigeria, which are as opaque as a cup of cocoa, we found that the convex edge of a meandering reach was ideal whereas in the main stream the flow when in flood was too strong to allow us to work effectively. In fact we had clean water in under 15 minutes from starting the pump and the impact was such that the cry went around the astonished watching villagers that we were washing the water. In this trial we had interesting confirmation of what the unit could do, for the water had a faint opalescence quickly identified as a felspar breakdown particle of under 1 micron that the waterworks often found hard to remove.
Muddy river beds and estuaries are useless, apart from the fact that the water is brackish if tidal, and rocky gorges present major physical problems; otherwise, most rivers and streams can probably be used, if necessary by blasting or excavating suitable holes and filling with sand in which the unit is placed. Because such sites are artefacts, occasional working over and/or replacement of sand may be needed, followed by redevelopment, but this is only a morning's work.
How and where is the water filtered?
Before the basic and essential process of development is described -using this word technically as in well development - it is necessary to speak of the mechanism of filtration in such a system, for this is widely misunderstood. Water quality is, in fact, only partly dependent on the depth and quality of bed and it is interesting that such standard works as The Control of Water by P.A. Morley Parker treat at length both the size and depth of sand in gravity filter beds without coming to any firm conclusion, but emphasising that the two layers discussed below are the really important factors. This process is comparable with the system used - and clearly visible - in many exhibition aquaria for tanks of, say, 5,000 litres. The effluent flows into a plastic cistern full of fine gravel which is covered by a sheet of nylon wool or similar expendable medium; the latter does the physical filtration and is changed, perhaps daily, as required. The deep gravel bed develops into a biological filter which handles bacteria and organic matter; this takes days to build up and is left undisturbed for as long as possible, usually many months.
The river bed serves these two functions. The bottom surface is quickly sealed by a filter mat of find debris - known technically as the schmutzdecke -with finer interstices than any sand filter, and this usually removes particles down to 1 micron. This mat is 2–3 cm thick. The biological filter, which is truly a bacteriophagal layer, forms in the sub-surface zone, perhaps 10 cm deep. This is, of course, the principle on which the Metropolitan Water Board has been working for over a century with its slow gravity sand filter beds, but the precise working of this layer still seems not to be fully understood. Because we have worked much longer in marine sites we have more data from sea water; there is ample confirmation that inshore water with bacteria and yeasts too numerous to count shows virtually no colonies after proper culture, having been drawn subsand through an established system.
Efficiency of SWS unit as filter
The filter mat-layer forms quickly and clean water is usually obtained within 15 minutes though full development takes much longer than that. It seems certain that the build-up of the biological layer is temperature-related but this has not yet been fully quantified. From our work in tropical aquaria we know that the layer takes some 10 days at 21°C, but at around 10°C, the temperature of English streams in winter, it is presumably a matter of some weeks. This lack of precise data is not very important, for this bacterial control is of most relevance in the tropics where, with average temperatures of 23–25°C, the build-up is rapid. However, since the system being installed is for permanent use one can hardly complain that 2 or 3 weeks may be needed to develop it fully.
This lower layer also has a function that is of most importance when the water is needed for research work, fish farms etc. As soon as pumping starts, aerated water from the surface is drawn down through a bed which has previously been largely anaerobic. Breakdown products such as H2S are evacuated and as the zone is made aerobic it serves as an oxidising layer; ammonium compounds become first nitrites and then nitrates, in which form they are harmless and available to plants. However, for most applications the important layer is the schmutzdecke, for the basic requirement is freedom from suspended matter.
SWS unit site development
Well development is a process designed to increase and stabilise flow into the system; exactly the same principles apply to the SWS unit. When this is installed it is surrounded and partly filled by native sand which normally includes silt and broken-down organic material. When the pump primes, a stream of filthy water emerges, showing that the bed is being cleaned; the water quickly clears, usually in minutes unless the bed has a very high fraction of fine sand, in which case it may take several hours to concentrate the larger particles unless coarser material is introduced. As soon as the water is clean the pump is stopped and at once restarted, and this is repeated until stopping and restarting no longer makes the water dirty, even momentarily, or until the required volume has been reached.
Each time the pump stops the negative pressure is removed, allowing particles within and just around the unit to drop back or rearrange themselves thus freeing more dirt to be sucked out when pumping restarts. Gradually the unit is left filled and surrounded with coarser sand and, in effect, the perimeter of the source is expanded, easing water access to the unit so that the yield steadily increases, which is the purpose of initial development. (The second and chief purpose of development is to facilitate the growth of a biological filter. This takes from one to two weeks depending on the temperature.)
The time taken to complete this process varies with the site factors but we recommend that it should normally go on for a whole day. When deep tube wells are being developed the work may take many days with surging, i.e. racing and then easing the pump, blowing back with either air or water, all with the object of disturbing the aquifer and removing fine particles. Some or all of these techniques may be used when establishing a unit, for site factors vary widely and it is hardly possible to prescribe for all combinations. Minute amounts of clean sand from the bed may be drawn through for some time after development. These particles are sterile and large enough to settle immediately after the water passes through a baffle chamber or storage tank.
It must be emphasised that the SWS unit is not a recipe for Instant Clean Water in all situations; rather, it is a system based on a simple principle that must be applied intelligently. For this reason, we prefer to demonstrate our work in new areas, at the same time assessing the potential, and also hold training sessions to ensure that local teams know what it is about. Experience in Africa shows that after two days of working a range of sites, trainees should get a good grasp of the essentials.
Self-cleaning property
This system is intended for use in moving water, which makes it selfcleaning. In the sea, tidal movements do this work effectively, aided by the wealth of lower life on the sea bed. The stream in fresh water serves somewhat the same purpose and here also fish fry and other small fauna poke about in the accumulating debris, eating some and freeing some to be moved by the current. Around a fully developed unit, the drawing area is to some extent self-adjusting; there is evidence that water may enter the bottom surface on its way to the unit from as far away as 3 m, and one must assume that if one section blocks temporarily the water finds another route. In some stream beds, it is beneficial to use a garden fork to dig thoroughly for several square metres around the unit while development is taking place. This also gives an opportunity for removing large stones which hinder water access.
So far we have had no experience of using units in storage dams but we expect them to be effective there. Wind movement, especially in large dams, should give considerable disturbance while in many dams the suspended matter is fairly low except in or just after the rains. Even if decreasing flow indicates a gradual blocking of the surface, this is easily dealt with periodically; the surface is raked or forked over, for the blocking is usually in the top 3 to 5 cm, the unit is blown back by changing over intake and delivery lines on the pump, while somebody stands on it to keep it roughly in position, and then the unit is redeveloped. This whole sequence takes only an hour or two.
Cost effectiveness
The outstanding merit of the SWS unit system is its cost-effectiveness, both capital and current, and its simplicity. At present, the retail cost in U.K. is ₤160 for the larger unit, with an output of towards 40,000 l.p.h. The smaller unit will cost about ₤110. These units are almost indestructible and the pvc pipelines have a long life; assuming a total cost of ₤360 written off in 5 years, this is only 20p per day. Such a unit would have a yield of over 500,000 1 per day at lp per 5,000 litres for electricity and 5p for petrol. Water cost, therefore, is little more than that of pumping. Installation and development are simple and I have often taken less than one hour for a river unit. Sea work can be seriously complicated by tides and weather, for ideally the unit should be installed at spring low tide which is inevitably between about 5 and 7 o'clock morning and evening. Coastal work in Britain is therefore a summer task.
SWS unit for tropical village water supply
Before applications in industrial countries are listed it may be useful to comment briefly on the outlet that seems to have the greatest potential for good - the provision of clean domestic water for tropical villages. Obviously the unit can work only where there is permanent surface water, which is true of millions of villages in the forest zones of the tropical world. An established system excludes bacteria as well as cleaning the water, and by separating the women from the stream cuts the chain of infection of several diseases. The unit has no moving parts and uses no chemicals, so that maintenance is minimal; this is a great advantage in lands where at the first sign of breakdown a filter system tends to be put permanently on bypass. Further, the system is selfmonitoring, for the output is clean only when the unit remains fully sunk and sealed; as soon as it is displaced the dirty water is obvious.
Although field trials are not yet complete it appears that the SWS method of abstraction excludes the larval forms of bilharzia, one of the world's most debilitating scourges. In their c. 36 hours of active life - after emerging from the snail and while waiting to find a mammalian host - the cercariae stay in the top 3 or 4 cm of water, far out of reach of the unit draw-down. If these results are confirmed the unit could bring great benefit to the increasing areas of the tropics infested with bilharzia.
In countries such as Nigeria where petrol is obtainable the cost per head per annum for 50 litres water per day is 1 litre petrol, or 20p at U.K. prices.
Many developing lands can neither obtain nor afford petrol for water pumping. For these we have located and tested an efficient hand pump (made by Patay Pumps) which costs under ₤30 in U.K. and easily delivers 4,000 1.p.h. Maintenance costs are one new diaphragm (₤2) per 400 hours.
Application in industrial countries
It is ironical that the low cost and simplicity of this system also seem to be its main drawbacks! Engineers have agreed about its effectiveness but said they would rather put in plant doing the same job for several times as much money simply because they needed the work. On the other hand some academics have had great difficulty in accepting that something so unsophisticated could work, and only actual demonstration of the unit in action has convinced those prepared to see it.
The following applications for the SWS unit in industrial countries have been identified:
MARINE
Research and fish-farms. The need is for clean water free from bacteria, zooplankton and algae.
Marine Zoos. The clarity of the pre-filtered water is an important benefit.
Cleaning shellfish prior to sale. Removing E. coli and other harmful bacteria by sub-sand abstraction is much cheaper than elaborate methods of sterilisation often advised, and equally effective. Oysters etc. must stay long enough in clean flowing water to evacuate all gut contents.
Water for electrolytic chlorine. This method of providing chlorine has the major advantage that no chlorine need be stored. Particle-free water, with no obstruction of pipe line or intake, is a big advantage.
Desalination intake. In addition to an unbroken supply this system gives freedom from organisms and needs no further filtration.
Coastal swimming pools. Ready access to clean water at all times instead of batch-filling off the tide should encourage managers to change water more frequently and so obviate the serious complications of combined chlorine caused by the presence of organic nitrogen.
The cost-effectiveness of marine sub-sand systems is shown by one complex installed recently in N.W. Scotland for an experimental fish farm; the total cost was rather under what had been spent annually on keeping the open intake operational.
FRESH WATER
Fish farms. With increasing pressure on supplies there is great need to use all water to the full. SWS units can clean the water and send it round once again. They are also ideal for bringing in water free from unwanted eggs and fry, fish parasites, etc.
Town water supplies. Although a large complex of units would be needed to handle a town supply the system is worth considering and costing in suitable areas. Water is brought in silt-free and needing minimum treatment, thus saving labour and chemicals. An SWS unit is very suitable for supplying good quality water to outlying communities.
Fine-spray irrigation. The need for a separate filter system is obviated.
Vegetable washing. This is now becoming general and very large volumes of water are used. Trials are now being conducted in Norfolk on methods of processing water rich in organic debris so that it can be used at least once more.
George S. Cansdale, B.A., B.Sc., F.L.S.
Technical Consultant, Sea Water Supplies Ltd.
SOME USEFUL CONVERSION FACTOR*
| Multiply | By | To Obtain | ||
| cubic | centimetres | (cm3) | 0.00948 | ft3 (cubic feet) |
| " | " | cm3 | 0.061 | in3 (cubic inches) |
| " | " | cm3 | 10-6 | m3 (cubic metres) |
| " | " | cm3 | 0.001 | litres |
| cubic | feet | (ft3) | 0.028 | m3 (cubic metres) |
| " | " | ft3 | 6.24 | gallons (imperial) |
| " | " | ft3 | 28.32 | litres |
| cubic feet of water | 62.37 | pounds (weight) of water (lbs) | ||
| cubic litres of water | 1.0 | kilograms weight of water | ||
| cubic feet per minute | 471.9 | cm3/sec (cubic centimeters per second) | ||
| cubic | metres | (m3) | 106 | cm3 (cubic centimetres) |
| " | " | m3 | 35.3 | ft3 (cubic feet) |
| " | " | m3 | 220 | gallons (imperial) |
| " | " | m3 | 1,000 | litres |
| imperial | gallons | 1.2 | U.S. gallons | |
| " | " | 0.162 | ft3 (cubic feet) | |
| " | " | 0.00454 | m3 (cubic metres) | |
| " | " | 4.54 | litres | |
| litres | 1,000 | cm3 (cubic centimetres) | ||
| " | 0.0353 | ft3 (cubic feet) | ||
| " | 0.22 | gallons (imperial) | ||
| hectares | 10,000 | square metres | ||
| " | 2.471 | acres | ||
| " | 0.01 | square kilometres | ||
| " | 11,960 | square yards | ||
| square miles | 640 | acres | ||
| square kilometres | 0.3861 | square miles | ||
| square metres | 10.76 | square feet | ||
| horsepower | 745.7 | watts | ||
* From “How to Use Natural Energy” 161 Clarence Street, Kingston-Upon-Thames, Surrey KTl lQT, U.K.
PUBLICATIONS OF THE
SOUTH CHINA SEA FISHERIES DEVELOPMENT AND COORDINATING PROGRAMME
WORKING PAPERS
| SCS/74/WP/1 | Rabanal, H.R. The potentials of aquaculture development in the Indo-Pacific Region. Manila, South China Sea Fisheries Programme, 1974. 34p. |
| SCS/74/WP/2 | Crutchfield, J.A., D.A. Lawson and G.K. Moore. Malaysia - Legal and institutional aspects of fisheries development. Manila, South China Sea Fisheries Programme, 1974. 27p. |
| SCS/74/WP/3 | Marr, J.C. Republic of Vietnam - Legal and institutional aspects of fisheries development. Manila, South China Sea Fisheries Programme, 1974. 20p. |
| SCS/74/WP/4 | Larsson, S.O.R., G.C.A. Van Noort and E.O. Oswald. Malaysia - A report on artisanal fisheries of Peninsular Malaysia with particular reference to Kuala Besut. Manila, South China Sea Fisheries Programme, 1975. 58p. |
| SCS/75/WP/5 | Rabanal, H.R. Irian Jaya, Indonesia - Survey of possibilities and recommendations for development of brackishwater fish production. Manila, South China Sea Fisheries Programme, 1975. 27p. |
| SCS/75/WP/6 | Tussing, A.R. Fishery development perspectives. Sub-Region V: South China Sea. Manila, South China Sea Fisheries Programme, 1975. (IPFC/74/Sym/7). 23p. |
| SCS/75/WP/7 | Murdoch, W.R. and M.A. Myers. Republic of Singapore - An assessment of the Jurong Fishing Harbour complex and expansion site on the east bank of the Jurong River. Manila, South China Sea Fisheries Programme 1975. 46p. |
| SCS/75/WP/8 | Peterson, C.L., K.J. Rosenberg and A.C. Simpson. Regional - Trip reports of chartered purse seine vessels Royal Venture and Southward Ho covering voyages I and II. Dec. 1–13, 1974 and Jan. 5 - Feb. 3, 1975. Manila, South China Sea Fisheries Programme, 1975. 37p. |
| SCS/75/WP/9 | Oswald, E.O. and R.E.K.D. Lee. Regional - A proposal for a live bait pole-and-line tuna fishing survey in the South China Sea and adjacent waters. Manila, South China Sea Fisheries Programme, 1975. 38p. |
| SCS/75/WP/10 | Rosenberg, K.J. and A.C. Simpson. Regional - Trip reports of chartered purse seine vessels Royal Venture and Southward Ho covering voyage 3. 9 February to 26 March 1975. Manila, South China Sea Fisheries Programme 1975. 28p. |
| SCS/75/WP/11 | Peterson, C.L. Regional - Resource survey of larger pelagic fish. Manil South China Sea Fisheries Programme, 1975. 32p. |
NOTE: Copies of these papers can be obtained by writing to the Programme in Manila, Philippines.
| SCS/75/WP/12 | Rosenberg, K.J., A.C. Simpson and C.M. Renwick. Regional - Trip reports of chartered purse seine vessels Royal Venture and Southward Ho covering voyage 4. 9 April to 24 May 1975. Manila, South China Sea Fisheries Programme, 1975. 36p. |
| SCS/75/WP/13 | Baum, G.A. Kuala Besut II. - A supplementary report on selected socio- economic aspects and problems in a fisherman's community on the East Coast of Peninsular Malaysia. Manila, South China Sea Fisheries Programme, 1975. 43p. |
| SCS/75/WP/14 | Cuerden, C. Library services for the South China Sea Fisheries Programme and its participating countries. Manila, South China Sea Fisheries Programme, 1975. 48p. |
| SCS/75/WP/15 | Lawson, R.M. Malaysia - An interim report on socio-economic aspects of the development of artisanal fisheries on the East Coast of Malaysia. Manila, South China Sea Fisheries Programme, 1975. 29p. |
| SCS/75/WP/16 | Jamandre, T.J. and H.R. Rabanal. Engineering aspects of brackish water aquaculture in the South China Sea region. Manila, South China Sea Fisheries Programme, 1975. 96p. |
| SCS/75/WP/17 | Murdoch, W.R. Malaysia - Assessment of the viability and potential of the joint venture, Majuikan Mideast Sdn Bhd, Kuching, Sarawak, as requested by Lembaga Majuikan, Malaysia. Manila, South China Sea Fisheries Programme, 1975. 16p. (Restricted) |
| SCS/75/WP/18 | Cleaver, W.D. Malaysia - A preliminary design and general arrangement for an offshore purse seine vessel for the East Coast of West Malaysia. Manila, South China Sea Fisheries Programme, 1975. 35p. |
| SCS/75/WP/19 | Pischedda, J.L. Republic of the Philippines - Legal and institutional aspects in the development of the fishing industry. Preliminary observations and identification of the main obstacles. Manila, South China Sea Fisheries Programme, 1975. 35p. |
| SCS/75/WP/20 | Simpson, A.C. Regional - Acoustic surveys of pelagic resources. Report No. 1. Gulf of Thailand, July 1975. Manila, South China Sea Fisheries Programme, 1975. 28p. |
| SCS/75/WP/21 | Cintas, D. and C.M. Renwick. Regional - Report of aerial survey for schooling pelagic fish. 1. Philippine waters, 12–29 June 1975. Manila, South China Sea Fisheries Programme, 1975. 28p. |
| SCS/76/WP/22 | Baum, G.A. and J.A. Maynard. Tobuan/Sual, Pangasinan Province Central Luzon - A socio-economic study on a rural fishing population in Central Luzon in connection with the Municipal Fisheries Pilot Programme. Manila, South China Sea Fisheries Programme, 1976. 44p. |
| SCS/76/WP/23 | Baum, G.A. Panigayan, Lampinigan, Baluk-Baluk and Manangal, Basilan Province. A socio-economic study on four fishermen's communities affiliated to the Basilan Fishing Association (BFA/Isabela in connection with the Municipal Fisheries Pilot Programme). Manila, South China Sea Fisheries Programme, 1976. 62p. |
| SCS/76/WP/24 | Barica, J. Nutrient-dynamics in eutrophic inland waters used for aquaculture in some countries bordering the South China Sea, with particular reference to mass fish mortalities: Proposal for monitoring programmes, Philippines, Thailand and Hong Kong. Manila, South China Sea Fisheries Programme, 1976. 43p. |
| SCS/76/WP/25 | Rosenberg, K.J., A.C. Simpson and J.A. Maynard. Regional - Trip reports of chartered purse seine vessels Royal Venture and Southward Ho covering voyages 5 and 6, 13 June to 10 September 1975. Manila, South China Sea Fisheries Programme, 1976. 52p. |
| SCS/76/WP/26 | Moore, G.K. Malaysia - Legal and institutional aspects of fisheries development. (2nd working paper). Manila, South China Sea Fisheries Programme, 1976. 38p. |
| SCS/76/WP/27 | Wheeland, H.A. Malaysia - Preliminary observations and recommendations concerning the fisheries statistics programme of Peninsular Malaysia. Manila, South China Sea Fisheries Programme, 1976. 22p. |
| SCS/76/WP/28 | Maynard, J.A. Regional - Report of aerial survey for schooling pelagic fish. II. Thailand - 20 November to 1 December 1975. Manila South China Sea Fisheries Programme, 1976. 20p. |
| SCS/76/WP/29 | Baum, G.A. and J.A. Maynard. Salay, Misamis Oriental Province - A socio-economic study on the fishing population of the seven coastal barrios of Salay Municipality in connection with the Municipal Fisheries Pilot Programme. Manila, South China Sea Fisheries Programme, 1976. 47p. (Country - Philippines) |
| SCS/76/WP/30 | Murdoch, W.R. Hong Kong - A preliminary feasibility study to prosecute offshore pelagic stocks from Hong Kong. Manila, South China Sea Fisheries Programme, 1976. 27p. |
| SCS/76/WP/31 | Johnson, R.F. Preliminary report on aquatic pollution in the South China Sea Region. Manila, South China Sea Fisheries Programme, 1976. 34p. |
| SCS/76/WP/32 | Wheeland, H.A. Preliminary observations and recommendations concerning the fisheries statistics programme of Singapore. Manila, South China Sea Fisheries Programme. 1976. 21p. |
| SCS/76/WP/33 | Baum, G.A. and J.A. Maynard. Coron/Tagumpay - Busuanga Island/Calamianes Group (Palawan Province). A socio-economic study on two rural fishing populations in northern Palawan in connection with the Municipal Fisheries Pilot Programme. Manila, South China Sea Fisheries Programme, 1976. 112p. |
| SCS/76/WP/34 | Jones, R. Mesh regulations in the demersal fisheries of the South China Sea area. Regional. Manila, South China Sea Fisheries Programme, 1976. 79p. |
| SCS/76/WP/35 | Simpson, A.C. and S. Chikuni. Progress report on fishing for tuna in Philippine waters by FAO chartered purse seiners. Manila, South China Sea Fisheries Programme, 1976. 38p. |
| SCS/76/WP/36 | Bonga, O.B. Vessel specifications and drawings for two 10 m multi- purpose fishing vessels for the small-scale fisheries project - Kuala Besut. Manila, South China Sea Fisheries Programme, 1976. 36p. |
| SCS/76/WP/37 | Shang, Y.C. Economics of various management techniques for pond culture of finfish. Manila, South China Sea Fisheries Programme, 1976. 36p. |
| SCS/76/WP/38 | Johnson, H.N. Malaysia - A preliminary study of investment opportunities for the development of small-scale fisheries on east coast of Peninsular Malaysia. Manila, South China Sea Fisheries Programme, 1976. 21p. |
| SCS/76/WP/39 | Shang, Y.C. Follow-up programmes on economics of aquaculture in the South China Sea Region. Manila, South China Sea Fisheries Programme, 1976. 19p. |
| SCS/76/WP/40 | Cook, H.L. Problems in shrimp culture in the South China Sea Region. Manila, South China Sea Fisheries Programme, 1976. 50p. |
| SCS/76/WP/41 | Johnson, H., J. Dibbs and R. Nasoetion. Indonesia - A preliminary assessment for small-scale fisheries development in Riau, North Sumatra and West Kalimantan Provinces. Manila, South China Sea Fisheries Programme, 1976. 51p. |
| SCS/76/WP/42 | Baum, G.A. and J.A. Maynard. Bayawan Municipality, Negros Oriental Province/Negros. A socio-economic study on the rural fishing population of Bayawan Muncipality in connection with the Municipal Fisheries Pilot Programme. Manila, South China Sea Fisheries Programme, 1976. 33p. (country - Philippines) |
| SCS/76/WP/43 | Maynard, J.A. Philippines - Report on aerial survey for schooling pelagic fish in waters of the South China Sea and Sulu Sea adjacent to Palawan Island, 9–12 March 1976. Manila, South China Sea Fisheries Programme, 1976. 17p. |
| SCS/76/WP/44 | Chakraborty, D. Fisheries statistics in the Philippines - A plan for a new and expanded data collection programme. Manila, South China Sea Fisheries Programme, 1976. 70p. |
| SCS/76/WP/45 | Marr, J.C., G. Campleman and W.R. Murdoch. Thailand - An analysis of the present and recommendations for future fishery development and management policies, programmes and institutional arrangements. Manila, South China Sea Fisheries Programme, 1976. 185p. (Restricted) |
| SCS/76/WP/46 | Cleaver, W. and O.B. Bonga. Thailand - Preliminary design, general arrangement and lines plans for two pelagic purse-seine/midwater trawl research vessel, 27.5 m and 24 m lengths. Manila, South China Sea Fisheries Programme, 1976. |
| SCS/76/WP/47 | Cleaver, W. Hong Kong - A preliminary design, general arrangement and specifications for a combination pelagic/demersal research vessel. Manila, South China Sea Fisheries Programme, 1976. |
| SCS/76/WP/48 | Simpson, A.C. and W.R. Murdoch. Regional - Trip reports of chartered pur seine vessel Royal Venture - Trips Nos. 7 & 8. 1 October to February 1976. Area - Moro Gulf. Manila, South China Sea Fisheries Programme, 1976. 17p. |
| SCS/76/WP/49 | Simpson, A.C. Regional - Trip reports of chartered vessel Southward Ho - Trips 7 & 8. 11 September 1975 to March 1976. Areas - Malaysia and Thailand. Manila, South China Sea Fisheries Programme, 1976. 33p. |
| SCS/76/WP/50 | Simpson, A.C. Regional - Trip reports of chartered purse seine vessel Royal Venture and Southward Ho - Trip No. 9. Manila, South China Sea Fisheries Programme, 1976. 22p. |
| SCS/76/WP/51 | Simpson, A.C. Regional - Trip reports of chartered purse vessel Southward Ho - Trips Nos 10 and 11. 15 April to 8 August 1976. Area - East, North and West Coasts Luzon Island, Bohol Sea, Sulu Sea, Moro Gulf. Manila, South China Sea Fisheries Programme, 1976. 20p. |
| SCS/76/WP/52 | Simpson, A.C. Wheeland, H.A. Statistics for fisheries development. Regional. Manila, South China Sea Fisheries Programme, 1976. 11p. |
| SCS/76/WP/53 | Christy, L.C. Republic of the Philippines - Legal and institutional aspects of fisheries development. Manila, South China Sea Fisheries Programme., 1976. 65p. (Restricted) |
| SCS/76/WP/54 | Maynard, J.A. Philippine - Province of Tawi-Tawi project identification and semi-detailed feasibility study relative to improving the status of small-scale fishermen and creating an integrated fishing industry in the Province of Tawi-Tawi. Manila, South China Sea Fisheries Programme, 1976. 110p. |
| SCS/77/WP/55 | Oswald, E.O & J. A Maynard. Thailand - Proposed small-scale fisheries pilot project for Ban Ao Makam Pom, Rayong Province. Manila, South China Sea Fisheries Programme, 1977. |
| SCS/77/WP/56 | Murdoch, W.R. & P.S. Walczak. Regional - Trip reports of chartered purse seine vessel, Southward Ho covering voyage 12. Area - waters of the Sulu Sea. Manila, South China Sea Fisheries Programme, 1977. 11p. |
| SCS/77/WP/57 | Murdoch, W.R. Regional - Trip reports of chartered purse seine vessels Southward Ho and Royal Venture covering voyage 13. Area - Mainly Moro Gulf, Philippines. Manila, South China Sea Fisheries Programme, 1977. 18p. |
| SCS/77/WP/58 | Simpson, A.C., W. R. Murdoch. Regional - Trip reports of chartered purse seine vessel Southward Ho covering voyages Nos. 14 and 15. Area - Moro Gulf. Manila, South China Sea Fisheries Programme, 1977. 15p. |
| SCS/77/WP/59 | Murdoch, W.R. & P.S. Walczak. Regional - Trip reports of chartered purse seine vessel Southward Ho covering voyages Nos. 16 and 17. Area - Waters of the Moro Gulf. Manila, South China Sea Fisheries Programme, 1977. 23p. |
| SCS/77/WP/60 | Doty, M.S. Seaweed resources and their culture in the countries of the South China Sea Region. Manila, South China Sea Fisheries Programme, 1977. 19p. |
| SCS/77/WP/61 | Rabanal, H.R. et al. Shellfisheries of Thailand: Background and proposal for development. Manila, South China Sea Fisheries Programme, 1977. 14p. |
| SCS/77/WP/62 | Chakraborty, D. Observations and recommendations concerning the fisheries statistics programme of Hong Kong. Manila, South China Sea Fisheries Programme, 1977. 14p. |
| SCS/77/WP/63 | Murdoch, W.R. Observations and recommendations concerning the inland fisheries statistics programme of Thailand. Manila, South China Sea Fisheries Programme, 1977. 15p. |
| SCS/77/WP/64 | Hansen, K.A., P. Lovseth and A.C. Simpson. Acoustic surveys of pelagic resources. Report No. 2. Hong Kong, Nov. 1976. Manila, South China Sea Fisheries Programme, 1977. 24p. |
| SCS/77/WP/65 | Christy, L.C. Republic of the Philippines - Legal and institutional aspects of fisheries development. Manila, South China Sea Fisheries Programme, 1977. 55p. |
| SCS/77/WP/66 | Murdoch, W.R. et al. A proposal for a small-scale fisheries pilot project in the Pulau Tujuh (Seven Islands) area, Riau Archipelago District, Riau Province, Indonesia. Manila, South China Sea Fisheries Programme, 1977. 69p. |
| SCS/77/WP/67 | Moore, G. Malaysia - A new fisheries bill. Manila, South China Sea Fisheries Programme, 1977. 56p. |
| SCS/77/WP/68 | Gedney, R.H. Water supply of the fishery development Centre in freshwater aquaculture at Sukabumi, West Java, Indonesia. Manila South China Sea Fisheries Programme, 1977. 20p. |
| SCS/78/WP/69 | Chan, W.L. et al. Cage culture of marine fish in East Coast Peninsular Malaysia. Manila, South China Sea Fisheries Programme, 1978. 66p. |
| SCS/78/WP/70 | Lee, R.E.K.D. Results of small scale live-bait pole-and- line fishing explorations for tuna in the Philippines. Manila, South China Sea Fisheries Programme, 1978. |
| SCS/78/WP/71 | Moore, G. Legal and institutional aspects of fisheries management and development - A new licensing system (Thailand). South China Sea Fisheries Programme, 1978. (Restricted) |
| SCS/78/WP/72 | Angeles, H. G. Preliminary fish seed resources survey along the coast of Peninsular Malaysia. Manila, South China Sea Fisheries Programme, 1978. |
| SCS/78/WP/73 | De la Cruz, Y. T. Malaysia - Small-Scale fishermen credit and subsidy programmes - Implementing guideline recommendations (with particular reference to the Kuala Besut Fishermen's Association). Manila, South China Sea Fisheries Programme, 1978. 50p. |
| SCS/78/WP/74 | Chikuni, S. Report on fishing for tuna in Philippine waters by FAO chartered purse seiners. Manila, South China Sea Fisheries Programme, 1978. |
| SCS/78/WP/75 | Fyson, J. E. Fishing vessel design proposals for small scale artisanal fisheries in the Philippines. Manila, South China Sea Fisheries Programme, 1978. |
| SCS/78/WP/76 | Lau F. and Cheng Chor Luk. Recent innovations in the cage culture activity at Kuala Besut small scale fisheries pilot project, Malaysia. Manila, South China Sea Fisheries Programme, 1978. |
| SCS/78/WP/77 | Wheeland, H. A. Proposal for further development of fishery statistics programmes in developing countries with particular reference to the South China Sea region. Manila, South China Sea Fisheries Programme, 1978. |
COORDINATING COMMITTEE REPORTS
| SCSP: | 74/1 | REP | Report of the Ad Hoc Coordinating Committee Meeting of the South China Sea Fisheries Development and Coordinating Programme. Manila, 18–19 June 1974. 27p. |
| SCSP: | 74/2 | REP | Report of the first session of the Coordinating Committee of the South China Sea Fisheries Development and Coordinating Programme. Jakarta, Indonesia, 6 November 1974. Rome, FAO, 1974. 22p. |
| SCSP: | 76/3 | REP | Report of the second session of the Coordinating committee of the South China Sea Fisheries Development and Coordinating Programme. Manila, 9 April 1976. 16p. |
| SCSP: | 77/4 | REP | Report of the third session of the Coordinating Committee of the South China Sea Fisheries Development and Coordinating Programme. Manila, 24–25 February 1977. 19p. |
| SCSP: | 77/5 | REP | Report of the fourth session of the Coordinating Committee of the South China Sea Fisheries Development and Coordinating Programme. Manila, 11–12 October 1977. 21p. |
| SCSP: | 78/6 | REP | Report of the fifth session of the Coordinating Committee of the South China Sea Fisheries Development and Coordinating Programme. Manila, 11 March 1978. 16p. |
WORKSHOP REPORTS
| SCS/GEN/74/1 | Report of the workshop on planning and coordinating of resources survey and evaluation in the South China Sea. 28 August to 4 September 1974. Manila, South China Sea Fisheries Programme, 1974. 197p. |
| SCS/GEN/76/2 | Report of the workshop on the fishery resources of the Malacca Strait. Part I. Jakarta, 29 March to 2 April 1976. Manila, South China Sea Fisheries Programme, 1976. 89p. |
| SCS/GEN/76/3 | Report of workshop on legal and institutional aspects of fishery resources management and development. 5–8 April 1976. Manila, South China Sea Fisheries Programme, 1976. 95p. |
| SCS/GEN/76/4 | Report on the training workshop for field enumerators of the Bureau of Fisheries and Aquatic Resources - Philippines. 22–31 March 1976 by D. Chakraborty and H. Wheeland. Manila, South China Sea Fisheries Programme, 1976. 32p. |
| SCS/GEN/76/5 | UNDP/FAO Training course on the management of small-scale fishery enterprises. Kuala Trengganu, Malaysia. 25 August to 26 September 1975. Rome, FAO, 1976. 14p. |
| SCS/GEN/76/6 | Report of the workshop on the fishery resources of the Malacca Strait - Part II. Jakarta, 29 March to 2 April 1976. South China Sea Fisheries Programme, 1976. 85p. |
| SCS/GEN/76/7 | Report of the BFAR/SCSP workshop on the fishery resources of the Visayan and Sibuyan area. Tigbauan, Iloilo, Philippines. 18–22 October 1976. Manila, South China Sea Fisheries Programme, 1976. 26p. |
| SCS/GEN/76/8 | Philippines - Report seminar on the fisheries statistics survey of the Bureau of Fisheries and Aquatic Resources. 23 July 1976. DNR/BFAR/SCSP/, Manila, 1976. 17p. |
| SCS/GEN/76/9 | Report of the consultative group meeting on small-scale fisheries development in the South China Sea region. 13–15 December 1976. Manila, South China Sea Fisheries Programme, 1976. 140p. |
| SCS/GEN/77/10 | Report on the training workshop on fisheries statistics, Malaysia, 12–21 October 1976. Manila, South China Sea Fisheries Programme, 1977. 27p. |
| SCS/GEN/77/11 | Report on the BFAR/SCSP workshop on fishery resources of the Sulu Sea and Moro Gulf areas. 25–29 April 1977, Cagayan de Oro. Manila, 1977. 58p. |
| SCS/GEN/77/12 | Report of the workshop on the demersal resources, Sunda Shelf. Part I. Nov. 7–11, 1977. Penang, Malaysia, Manila, South China Sea Fisheries Programme, 1978. 58p. |
| SCS/GEN/77/13 | Report of the workshop on the demersal resources, Sunda Shelf. Part II. Nov. 7–11, 1977. Penang, Malaysia. Manila, South China Sea Fisheries Programme, 1978. 120p. |
| SCS/GEN/77/14 | Joint SCSP/SEAFDEC workshop on aquaculture engineering (with emphasis on small-scale aquaculture projects) Vol. 1- General Report. Manila, South China Sea Fisheries Programme, 1978. v.p. |
| SCS/GEN/77/15 | Joint SCSP/SEAFDEC workshop on aquaculture engineering (with emphasis on small-scale aquaculture projects) vol. 2- Technical Report. Manila, South China Sea Fisheries Programme, 1978. 463p. |
| SCS/GEN/77/16 | A layout of standard tables of fishery statistics in the Philippines. Manila, South China Sea Fisheries Programme, 1978. 162p. |
| SCS/GEN/78/17 | Report of the workshop on the biology and resources of mackerels (Rastrelliger spp.) and round scads (Decapterus spp.) in the South China Sea. Part I. Manila, South China Sea Fisheries Programme, 1978. 70p. |
| SCS/GEN/78/18 | Report of the workshop on management of resources of the Sunda Shelf, Malacca Strait and related areas. Manila, South China Sea Fisheries Programme, 1978. 14p. |
| SCS/GEN/78/19 | Report of the BFAR/SCSP workshop on the fishery resources of the Pacific Coast of the Philippines. 18–22 September 1978. Manila, South China Sea Fisheries Programme, 1978. (In preparation) |
SCS MANUALS
| SCS Manuals No. 1 | Handbook on field identification of fishes, crustaceans, molluscs, shells, and important aquatic plants. Manila, South China Sea Fisheries Programme, 1978. 60p. |
PERIODIC PROGRESS REPORTS
| SCS/PR/74/1 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 July to 31 December 1974. Manila, South China Sea Fisheries Programme, 1974. 19p. |
| SCS/PR/75/2 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 January to 30 June 1975. Manila, South China Sea Fisheries Programme, 1975. 40p. |
| SCS/PR/75/3 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 July to 31 December 1975. Manila, South China Sea Fisheries Programme, 1975. 38p. |
| SCS/PR/76/4 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 January to 31 December 1976. Manila, South China Sea Fisheries Programme, 1976. 47p. |
| SCS/PR/77/5 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme, 1 January to 30 June 1977. Manila, South China Sea Fisheries Programme, 1977. 37p. |
| SCS/PR/77/6 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 January to 30 June 1977. Manila, South China Sea Fisheries Programme, 1977. 19p. |
| SCS/PR/78/7 | Woodland, A.G. Project progress report of the South China Sea Fisheries Development and Coordinating Programme. 1 January to 30 June 1978. Manila, South China Sea Fisheries Programme, 1978. 12p. |
FISHERIES TECHNICAL PAPERS
| SCS/DEV/73/1 | Woodland, A.G. et al. The South China Sea Fisheries: A proposal for accelerated development. Rome, FAO, 1974. 162p. |
| SCS/DEV/73/2 | Yamamoto, T. Review of marine fishery statistical systems in countries bordering the South China Sea, and proposals for their improvement. Rome, FAO, 1973. 46p. (Cover title: The South China Sea Fisheries Statistical Systems) |
| SCS/DEV/73/3 | Aoyama, T. The demersal fish stocks and fisheries of the South China Sea. Rome, FAO, 1973. 80p. (Cover title: The South China Sea Fisheries Demersal Resources) |
| SCS/DEV/73/4 | Kume, S. Tuna resources in the South China Sea. Rome, FAO, 1973. 18p. |
| SCS/DEV/73/5 | Ling, S. Status, potential and development of coastal aquaculture in the countries bordering the South China Sea. Rome, FAO, 1973. 51p. (Cover title: The South China Sea Fisheries Aquaculture Development) |
| SCS/DEV/73/6 | Menasveta, D. et al. Pelagic fishery resources of the South China Sea and prospects for their development. Rome, FAO, 1973. (Cover title: The South China Sea Fisheries Pelagic Resources) |
| SCS/DEV/73/7 | Mistakidis, M.N. The crustacean resources and related fisheries in the countries bordering the South China Sea. (Cover title: The South China Sea Fisheries Crustacean Resources) |
| SCS/DEV/73/8 | Ruckes, E. Fish utilization, marketing and trade in countries bordering the South China Sea - status and programme proposals. Rome, FAO, 1973. 33p. (Cover title: The South China Sea Fisheries Marketing and Trade) |
| SCS/DEV/73/9 | Doucet, F.J. et al. Institutional and legal aspects affecting fishery development in selected countries bordering the South China Sea. Rome, FAO, 1973. 32p. (Cover title: The South China Sea Fisheries Institutional Legal Aspects) |
FAO species identification sheets for fishery purposes. Eastern Indian Ocean (Fishing area 57) and Western Central Pacific (Fishing area 71) Rome, FAO, 1974. 4 vols.
ADB/FAO MARKET STUDIES
| SCS/DEV/76/11 | Development potential of selected fishery products in the regional member countries of the Asian Development Bank. Manila, South China Sea Fisheries Programme, 1976. 107p. |
| SCS/DEV/76/11 (Appendix 1) | Fishery country profiles. Manila, South China Sea Fisheries Programme, 1976. 173p. |
| SCS/DEV/76/12 | The international market for shrimp. Manila, South China Sea Fisheries Programme, 1976. 105p. |
| SCS/DEV/76/13 | The international market for tuna. Manila, South China Sea Fisheries Programme, 1976. 69p. |
| SCS/DEV/76/14 | The international market for crab. Manila, South China Sea Fisheries Programme, 1976. 49p. |
| SCS/DEV/76/15 | The international market for lobster. Manila, South China Sea Fisheries Programme, 1976. 46p. |
| SCS/DEV/76/16 | The international market for cephalopods. Manila, South China Sea Fisheries Programme, 1976. 95p. |
| SCS/DEV/76/17 | The European canned fish market: Prospects for Rastrelliger spp. Manila, South China Sea Fisheries Programme, 1976. 56p. |
TECHNICAL REPORTS CONTRIBUTED TO SYMPOSIA/MEETINGS, ETC.
Rabanal, H.R. 1975 FAO activities in inland fisheries and aquaculture with particular reference to Asia and the Far East. Manila, South China Sea Fisheries Programme. 17p. (Contributed to the First Fisheries Research Congress, Philippine Council for Agriculture and Resources Research, 7–10 March 1975, Legaspi City, Philippines)
Rabanal, H.R. 1975 Preliminary report on the Macrobrachium fishery in the Indo-Pacific region. Manila, South China Sea Fisheries Programme. 20p. (Contributed to the International Conference on Prawn Farming, Vung Tau, Vietnam, 31 March - 4 April 1975)
Rabanal, H.R. 1975 Distribution and occurrence of milkfish Chanos chanos (Forskal). Manila, South China Sea Fisheries Programme, 1975. 18p. (Contributed to the National Bangus Symposium. Manila, 25–26 July 1975)
Rabanal, H.R. 1976 Mangrove and their utilization for aquaculture. Manila South China Sea Fisheries Programme. 20p. (Contributed to the National Workshop on Mangrove Ecology held in Phuket, Thailand, 10–16 January 1976)
Rabanal, H.R. 1976 Report of project identification mission to Bangladesh on inland fisheries and aquaculture. Manila, Asian Development Bank. 56p.
Rabanal, H.R. 1976 Aquaculture 1976: Focus Southeast Asia. Manila, South China Sea Fisheries Programme. 12p. (Talk delivered at the National Convention of the Federation of Fish Producers of the Philippines, Iloilo City, 26 August 1976)
Simpson, A.C. 1976 Some proposals for research related to the understanding of mangrove ecology and the utilization of mangrove areas. Manila, South China Sea Fisheries Programme. 10p. (Contributed to the National Workshop on Mangrove Ecology held in Phuket, Thailand, 10–16 January 1976)
Cook, H.L. 1976 Some aspects of shrimp culture research with particular reference to Philippine species. Manila, South China Sea Fisheries Programme. 7p. (Contributed to the Philippine Council for Agriculture and Resources Research (PCARR) Fisheries Workshop, Subic, Zambales, Philippines, 15–17 January 1976)
Rabanal, H.R. 1976 The resources in inland waters: their utilization and management. Manila, South China Sea Fisheries Programme. 21p. (Talk delivered before the Phi Sigma Biological Society as a contribution to the Deogracias V. Villadolid Memorial lecture series. Manila, Philippines, 26 November 1976)
Rabanal, H.R. 1977 Aquaculture in the Philippines. Manila, South China Sea Programme. 15p. (Talk delivered before the United States Peace Corps Volunteers, Los Baños, Laguna, Philippines - 11 January 1977)
Rabanal, H.R. 1977 Aquaculture in Southeast Asia. Manila, South China Sea Fisheries Programme. 10p. (Paper contributed to the Fifth FAO/SIDA Work shop on Aquatic Pollution in relation to Protection of Living Resources. Manila, Philippines, 17–27 February 1977)
Simpson, A.C. 1977 Fisheries research and development in the Philippines: Some recommendations with special reference to resource management. Manila, South China Sea Fisheries Programme. 16p.
Rabanal, H.R. 1977 Aquaculture management. Manila, South China Sea Fisheries Programme. 12p. (Contribution to the BFAR/FAO-UNDP Training of Regional Trainors in Aquaculture. Lucena, Quezon, Philippines, 19 September to 27 October 1977)
Rabanal, H.R. 1977 Recent trends in aquaculture. Manila, South China Sea Fisheries Programme. 13p. (Paper contributed to the Seminar/ Workshop for Fishery Schools' Administrators, conducted by the Bureau of Fisheries and Aquatic Resources. Manila, Philippines, 24–28 October 1977)
Rabanal, H.R. 1977 Forest conservation and aquaculture development of mangroves. Manila, South China Sea Fisheries Programme. 15p. (Paper contributed to the International Workshop on Mangrove and Estuarine Area Development for the Indo-Pacific Region. 14–19 November 1977, Manila, Philippines)
