GB2450486A

GB2450486A - Pasteurising solar still

Info

Publication number: GB2450486A
Application number: GB0712234A
Authority: GB
Inventors: Dominic Michaelis
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-25
Filing date: 2007-06-25
Publication date: 2008-12-31
Also published as: GB0712234D0

Abstract

A pasteurising solar still consists of a black tray 1 containing non potable water above which are located inclined transparent sheets which allow the sunlight to reach the water in the black trays and so increase the water temperature so that it evaporates, the inclined surfaces acting as condensers, the distilled water vapour condenses running down to receiving channels 3 which take the distilled water to sterilised containers 16. Further, temperature sensing means are provided 40 to monitor the temperature of the water. Once the water temperature has been above pasteurisation temperatures of 65{C or more for 20 minutes, the water may be removed from the vessel, preferably by siphon 35 to a pasteurised water container 37. The device is collapsible and portable.

Description

DESCRIPTION

Solar stills have been used for many years, principally as a mode of desalination, but also to purify non-potable water, on large and small scales.

Similarly, pasteurising water systems have been developed.

They are generally thought of as separate processes.

Some small scale pasteurising solar stills may have been built, but linked units for large scale production of both distilled and pasteurised water have not been attempted, with preheating water systems to make the process more efficient.

According to the present invention, there is provided a pasteurising solar still consisting of a fluid container vessel featuring horizontal lines to indicate water quantities contained, its base being fitted with a removable black tray, perforated and slightly lifted off the base itself to allow water circulation around it, the fluid container vessel being covered by a transparent element featuring one or many inclined facets, each such surface forming a condenser on which water vapour will condense, the condensate running into a distilled water channel, wherein valuable distilled water is collected, the top being provided with a hole through which non potable water can be introduced with a pipe or funnel through a closable opening, to the base of the tray, reaching desired quantities shown on the container lines, the said transparent cover allowing sunlight to penetrate through the water and the heat being absorbed by the black tray restoring it immediately to surrounding water, which heats up to pasteurising temperatures the quantities indicated by the lines, a separate hole allowing a variety of thermometers to be introduced, either liquid crystal strips, thermal temperature markers, classical thermometers or electronic probes, and water temperature readers, small double skin windows being provided where necessary to monitor internal workings difficult to see through condensation droplets, so that when the liquid reaches water pasteurising temperatures of 65 C or more and is held at that temperature for 20 minutes, it is then pasteurised and ready to be siphoned out by a clean siphon pump, and transferred to a sterilised container for pasteurised water, this pasteurised water benefiting also from exposure to sunlight which is known to be beneficial to water quality, the distilled water from condensation on the inclined surface or surfaces being recovered from the receiving channels and piped to a separate sterilised container, the removed pasteurised water replaced by non potable water, thus providing two qualities of water, one suitable for drinking purposes, the other requiring analysis to check on potability, but rid of most common bacteria, and, if not potable, suitable for other domestic uses, and much safer than the original polluted water introduced, distillation being necessary to make seawater potable, and leaving a potentially useful salt deposit, the pasteurising still fluid container vessel resting in an insulating container that increases its efficiency, and provides, in its base, a water levelling device so that the units are close to horizontal, a prerequisite for the distilled water channels to function efficiently, this basic system applicable to a single still, one application of this having a top formed from 1 pyramid, removable with a pinched grip at its crest, or from 4 pyramids, with a hole at its centre to remove it, to fill it or empty the fluid container vessel with a siphon pump, the water container designed then to have 4 upstands to collect internal trough distilled water, the system having the advantages of low height, and possibility of the top being reversed, to allow the pasteurising still to be packed within the depth of the fluid water container, the pasteurising still, sitting on a demountable table that forms the cover of the packed pasteurising still, the pasteurising still being so packed forming a carrying case, fitted with a handle, for ease of transportation, the cover able to contain the table legs and a flat plate solar collector with non return valves and with hinged reflecting flaps, the collector fitted to a southernly leg of the table linked in thermosyphon either to the fluid container vessel, to increase efficiency of the pasteurising still, or in a further development, to a secondary insulated fluid containing vessel, placed below the fluid container vessel, and linked to it by two openings, one with a pipe going down to its base to favour thermosyphoning, allowing the waters to mix and the overall water temperature to increase, providing a much larger volume of hot water, such that, at nightfall, after pasteurised water is no longer withdrawn, the distillation process can proceed through the night, the same insulated fluid containing vessel able to be withdrawn, and act on its own, with the solar collector, as a pasteurising device, these variations of a single pasteurising still able to be developed, with a different fluid container vessel, to multiple stills linked together by interconnecting pipes, forcing the non potable water now introduced at high level in the container vessel, so as to be seen entering and its inflow being interrupted, to follow a coming and going path so that no polluted water can go straight from one unit to another, but has to follow a circuit guaranteeing that water temperature taken at midpoint of the assembly, would allow, half the water contained in the assembled unit to be drawn off, or further down the array of lines if less is being removed, the last connecting tube being replaced by a delivery pipe, with a finely adjustable tap or valve, delivering large quantities of pasteurised water to an end container, the pipework from the distilled water channels also able to be interconnected to an inclined gathering pipe delivering all the distilled water from many units to a single distilled water container, the inlet water to the assembled units being preheated, for greater efficiency of both distillation and pasteurisation, in a black raised vessel,, provided with a reflective screen handled to follow the sun and located on a reflective base to increase solar radiation reaching the black vessel, the same vessel topped by a sand filter made up of a perforated vessel with a fine mesh cloth holding the sand, a fine sieve or cloth filter preventing particulate fragments from blocking the sand filter, water to be purified being piped or poured gently through the filter to keep the black raised vessel partly full, the pasteurising stills to which the system applies being formed of a basic container vessel with an inclined glass or plastic sheet in its simplest application, to more sophisticated pressings or moldings as illustrated, inflatable structures, and, on a much larger scale, under transparent or translucent green house structures, delivering distilled and pasteurised water for the benefit of a great number of people, in all these systems, the amount of distilled water, in sunny climates, being less than that of pasteurised water, which, if after analysis, can be considered potable, additionally to provision of distilled water, can help to solve potable water problems encountered worldwide.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: -Figure 1 shows a section through the basic solar pasteurising still.

Figure 2 shows a plan view of the basic solar pasteurising still.

Figure 3 shows views of the levelling tray Figure 4 shows an exploded view of a 4 pyramid solar pasteurising still.

Figure 5 shows the 4 pyramidal pasteurising solar still linked to a solar panel, and to an insulated water container, which, without the pasteurising solar still, can act as a field pasteurising unit.

Figure 6 shows the way whereby the pyramids can be reversed to allow the units to pack down into field carrying cases.

Figure 7 shows a section through a coming and going solar pasteurising still.

Figure 8 shows a plan view of a coming and going solar pasteurising still.

Figure 9 shows a section of a run of coming and going stills linked to filter feeder tank.

Figure 10 shows a plan of a run of coming and going stills linked to filter feeder tank.

Figure 11 shows an inflatable solar pasteurising still.

Figure 12 shows a tunnel greenhouse pasteurising solar still Referring to Figures 1 and 2, the basic pasteurising solar still comprises a non potable fluid water container vessel 1, provided with horizontal lines,2, around whose upper edge runs a distilled water collector channel,3, the base of which runs from a high point,4, down a slope,5, to a low point,6, where is fixed a spigot,7, prolonged by a tubular outlet to which is fixed a clear pipe,8, which runs between the water container and the insulating container tray, 10, leaving it through a gromet,9, preventing the tube from being ripped away from the spigot, and from there, it runs into a sterile bottle,16 An overflow pipe,1 1, prevents any excess water from being put in the still, and is screwed in place,12, but unscrewed to allow for component stacking. This applies to all pipework entering the water containers in connected stills in other figures, the water feeds,20, and connecting pipework,30 At the base of the water container, preferably of a reflective light colour, is a removable black tray,13, provided with holes, and small plots to raise it away from the container floor, so that water can flow freely underneath it, stiffened by its edge upstand, and the cruciform ridge stiffening the container base, which the black tray follows,14.

The inner fluid container vessel fits into an outer insulated container tray which is locked in position by four L shaped corner location upstands, 15. which, apart from its own insulating value, is lifted by 4 plots away from the base of the insulating container, and creates a cushion of stationary air which adds to the still efficiency; The whole assembly is covered by a pyramidal transparent cover,39, which can be removed and replaced by pinching 2 of 4 ridges,38, created at it's peak, and locates between the upper side of the insulating tray and the distilled water channel edge, insuring a perfect fit.

Referring again to figures 1 and 2, a funnel,33, is introduced into the conical guide to the hole, 31, the closing flap,32, being open, and non potable water, preferably preheated in a black vessel in the sun, is poured in gently to reach, in one example, line level two if a rapid cycle is required, or until line 4 if a longer cycle is envisaged. The funnel is then removed and the flap is closed. The double glazed window,34, will allow vision of the lines, and of the thermometers or probes to digital readers, or liquid cristal thermal sensors that are removed for reading and reintroduced, in to holes provided. The operator waits for the thermometer to show 65 C, at which point he notes the time, waits for 20 minutes, then opens the flap, introduces the siphon pump,35, and draws, as examples, either half the total content, if two lines have been filled, or 1/4 of the total content if filled to the fourth line, the temperature of remaining water being higher in the second case, which will have less effect on distilled water production. To obtain the greatest distilled water production, letting the water rise to higher temperatures may improve distilled water output, but it will depend on local climate and requirements for the correct balance to be achieved.

The pasteurised water is discharged into a jerry can or other large container,37.

Referring to Figure 3, the base of the insulating container tray is fitted with a water levelling device, 21, which also provides it with great stiffness. It consists of a cruciform 3 layer indentation in the base plate,22, with 4 circular water level readers at the 4 corners,23, a small amount of water being introduced for the initial levelling, and gradually more being added, to get greater precision when water just laps onto the third layer circles. Levelling is obviously easier if the pasteurising solar still is on a table,27, than when on the ground, a hole needing then to be dug to contain the distilled water bottle. The insulating tray has a water evacuation hole,24, to prevent any rainwater or dew accumulating there, and is provided with two large fitting holes, one for the overflow pipe,25 and one for fixing the distilled water pipe to the spigot,26, as well as the grommet hole,9, for the distilled water outlet pipe.

Figure 4 shows a different embodiment of the invention, in which the container tray is divided into 4 communicating lined chambers, with a peripheral and 4 central distilled water channels, all sloping from a high point,4, to a low point, 6, from where a spigot,7, takes the distilled water away, the inclined planes now taking the form of 4 low pyramids,42, provided with a central feed and siphoning hole,43, with its attached cap, the hole being located above the lines on the central upstands, to read water levels and allowing easy insertion of different thermometers to assess pasteurising temperature, to initiate timing.

Four smaller black trays,44, with holes, 45, and distance plots,46, provide the same service as the single black tray in figure 1. The assembly is inserted into the insulating tray,47, with the same levelling device at its base.

The 4 pyramid version is more compact, and the transparent cover reversed can be designed to fit into the container chambers, the insulating tray forming a cover, to constitute an easily transportable field unit,80, fitted with a handle,86, for ease of carrying, as shown in figure 6.

A marine version of the 4 pyramid pasteurising still, now becoming a desalinating/salt producing still, can be made by sealing all openings in the outer insulating tray, except for the watertight distilled water exit, the pipe going to a flexible removable container,48, fixed under the tray by a strap, the distilled water pipe leading to a watertight screw fitting, 49, that allows the container to be removed. Also, a black floating flexible sponge sheet placed over the seawater plane acts as evaporator and prevents the seawater from splashing into the distilled water channels. the still can float in calm waters, or be on board, when the container is laid alongside.

In a further embodiment of the invention, referring to figures 5 and 6, the pasteurising still can form the upper part of a table, resting on 4 L shaped angle egs, shorter than the pasteurising still, so that they can stack, in pairs,81, within the cover of the packed unit formed by the table top,82, in it basic form, with the potential for this cover to also hold a solar collector panel, 83, provided with a transparent front panel, a finned tube, and insulation, with in and out fluid ways, 84, leading, one to a lower manifold, the other collecting from a top manifold, to allow a thermosyphon to be established when the panel is connected with spiral tubes to the openings in the fluid container itself, to increase the pasteurising still efficiency, or, in a further development, is connected to a non potable insulated water container,89, held on the 4 legs under the fluid container, the solar panel's flow and return valves fitted with non-return flaps to prevent reverse thermosyphon from taking place, so that the water in the lower container, connected to the solar panel, will reach higher temperatures than those in the still, adding to its efficiency, but, continuing the thermosyphon procedure after sunset, when no pasteurised water is being drawn, allowing the still to continue its operation through the night, benefiting from the colder external night temperatures. The solar panel,83, is flexibly fitted to a southernly leg of the still to allow it to pivot and to be inclined for its greatest efficiency, two thin hinged reflective panels,85, spreading out, held by cables, to increase the panel's efficiency. The non potable water, 89, on its 4 legs, linked to the solar collector, can operate without the pasteurising still above it, using the connection holes to the still, one for filling, the other for thermometer introduction, provided with a low level tap to empty the content when pasteurised, and serves as a pasteurising unit, easily packed and transported as a field unit,80. The coming and going pasteurising still also allows for the prismatic cover to be reversed, a demountable cross u channel assembly joining at a central annulus being necessary to recover distilled water from inward slopes.

It can similarly be packed, and covered to form a transportable field unit.

In a further embodiment of the invention, referring to Figures 7 and 8, a number of pasteurising solar stills can be connected in line, fed from a solar preheated main non potable water tank, with inlet and outlet valves, such that large quantities of pasteurised water can be drawn at a time, or with correct settings, a constant flow can be established.

However, for this to be possible, a different layout is necessary to force the non-potable water to take a coming and going route, to prevent any drops of non-potable water from taking a short cut between units, and arriving at the outlet without having been pasteurised. To achieve this, a number Qf ridges, 90, rise up from the floor of the fluid container vessel,1, the initial feed water being dropped in from a valved high level pipe, 91, so that it can be seen through the double glazed window when flowing and when stopped by the inlet valve 92, the connecting pipe, 93, not connected in the first element of a series, the water being introduced at a point located at the closed end of the first upstand, the water then flowing up and down the six channels so formed, in this example, before leaving the first still by the connecting pipe,93, linking it to further units, until the last unit, which is fitted with a valved outlet,94. The end unit is fitted with an overflow pipe,95, to help monitor correct water content, whether stationary, or flowing.

The temperature gauges and openings,99, 101, are, as examples, fitted in the middle of the run, if half the water is to be withdrawn, two thirds of the way down if two thirds of the water is to be withdrawn, or three quarters of the way down if one quarter of the way down if a quarter is to be withdrawn, so that in one mode, up to a half of the water content, having reached the pasteurising temperature, and having been kept for 20 minutes at that temperature, it can be safely drawn off, up to the line desired, or in the flowing mode, so that water flowing past a temperature gauge at the correct location and temperature, the amount taken out is no more than the content of water in the container after the temperature gauge before reaching the valved outlet, 94, the total water content being known, and the flow allowing, as examples, half, a third or a quarter of that quantity to run through, measured by a flow meter, bearing in mind that taking out more than half would significantly cool the water and would have an adverse effect on the distillation process, which may, if it is the priority, require that only 1/3 or 1/4 is removed every 20 minutes, the first mode being easier to establish, the second one needing expert handling.

The ridged unit can be used as the basic unit, with a hole for filling and siphoning.

The distilling takes place as in the basic still, with surround channels, the distilled water outlets being connected to a sloping collector pipe,97, taking all the distilled water to a single sterile container,98.

Referring to Figures 9 and 10, an assembly for a series of pasteurising solar stills is illustrated, showing a black feeder tank,50, raised on a round table, the top surface of which is painted with reflective paint or coated with aluminium foil, but not to be so reflective as to cause damage to the eye,51, so that its valved oulet, 52, is above the fluid entry pipe,91, surrounded by a mobile reflector screen,53, painted silver or coated with aluminium foil increasing the solar radiation reaching the feeder tank, preferably not made of shiny mirror like surfaces to avoid damage to the eyes, preheating the water to increase system performance, the tank topped by a sand filter, 54, consisting of a container with base perforations, and funnel water receiver,55, lined with a fine mesh cloth,56, holding the sand, below a top fine sieve,57, eliminating particles that could block the sand filter, non potable water being piped or poured into to its top, filling the main tank with the amount desired to be pasteurised and distilled.

The preheated water is released by a valve,58, and reaches the fluid entry pipe,91, also valved,92, to reach the desired water input, or rate of flow. The water then follows the coming and going channels as described above.

Referring to figure 10, an inflatable, easily packed for transportation, pasteurising solar still is shown, consisting of inflatable base ribs,61, and riser ribs,62, forming the main structure, with transparent sheets fixed between these ribs,63, one panel being removable, by strip velcro or zip edges, to allow for cleaning of smaller units from outside, or entering larger units, one rib fitted with an inflatable funnel with a closure cap,64 allowing non potable water to be delivered to the base non potable water p001,65, and thermal probes to be introduced to read the pool temperature, seen through a double skinned window,69, the said funnel also serving to introduce the suction pipe of a siphon pump, to remove pasteurised water, which can otherwise be let out of the pool by a tap,60, into a calibrated tank, 160, the inner wall edges of the base water pool being provided with lined markers around their inner edges to allow levelling, and to read quantities of water contained, the evaporation from the container condensing on the panels, 63, and running down to an inclined recovery channel,68, from where the collected distilled water runs into a sterile tank,163, located alongside the non potable water container structure of the pasteurising solar still, which rests on a foldable insulating base,66, providing protection to the black ground sheet,67, the still raised off the ground on a levelled table or earth mound,161, the ground sheet converting the incident solar radiation into thermal energy, thereby heating the water contained by the non potable water container created by the base ribs connected to the ground sheet.

As with the 4 pyramid pasteurising still, a marine version is fitted with an anti-splash black flexible sponge material sheet over the seawater plane, and the distilled water is collected in a separate attached flexible bag, to be removed as required, the unit either floating in calm waters, or kept on board.

Referring to Figure 10, the same principle is applied to a larger structure, such as a greenhouse, in which the outer skin is made of transparent or solar energy transmissive material, the ground of which 70, is either built of insulated concrete, or is covered by a strong dark* groundsheet built up or formed at its edges to form the non potable water container, and featuring lines indicating the depth of water contained, provided with a window for temperature sensors,77, located as in the pasteurised still runs, covered with linear staggered structures, 72, insuring that water introduced by an inlet pipe,73, follows a coming and going route, before exiting through an outlet pipe,74, both inlet and outlet controlled by valves, adjusted according to the mode of withdrawing water, either by finite quantities being withdrawn, according to the level readings, or by establishing a regular flow such that pasteurisation is achieved.

Evaporated water from the container condenses as distilled water on the cooler greenhouse surfaces, including the ends, and runs down to be collected by inclined gutters,76, that take the distilled water to the distilled water outlet,75, both outlets running into tanks or underground sumps from which the waters are pumped to surface tanks.

The water condensing on the top portion of the greenhouse, which is too flat to allow the condensed water to run, falls and is recovered by a transparent or translucent inclined part upwardly concave cylinder,78, the recovered water running into a downpipe,79, which discharges into the main distilled water pipe,171. The interior of the greenhouse is accessible through a door, 170, which allows periodic cleaning and general system maintenance. As in the runs of solar pasteurising stills, the inlet non potable water comes from a dark coloured tank,50, surrounded by a mobile reflective screen,53, resting on a reflective floor, increasing radiation on the tank to preheat the incoming water, covered by a sand filter,54.

This arrangement allows to provide pasteurised and distilled water to larger groups of population and small and large villages.

In all these systems, hygiene is crucial, all condensing distilled water carrying surfaces, and accompanying pipework need to be periodically cleaned and disinfected.

The pasteurising systems need to be similarly cleaned and disinfected periodically. I0

Claims

1 A pasteurising solar still consisting of a fluid container vessel featuring horizontal lines to indicate water quantities contained, its base being fitted with a removable black tray, perforated and slightly lifted off the base itself to allow water circulation around it, the fluid container vessel being covered by a transparent element featuring one or many inclined facets, each such surface forming a condenser on which water vapour will condense, the condensate running into a distilled water channel, wherein valuable distilled water is collected, the top being provided with a hole through which non potable water can be introduced with a pipe or funnel through a closable opening, to the base of the tray, reaching desired quantities shown on the container lines, the said transparent cover allowing sunlight to penetrate through the water and the heat being absorbed by theblack tray restoring it immediately to surrounding water, which heats up to pasteurising temperatures the quantities indicated by the lines, a separate hole allowing a variety of thermometers to be introduced, either liquid crystal strips, thermal temperature markers, classical thermometers or electronic probes, and water temperature readers, small double skin windows being provided where necessary to monitor internal workings difficult to see through condensation droplets, so that when the liquid reaches water pasteurising temperatures of 65 C or more and is held at that temperature for 20 minutes, it is then pasteurised and ready to be siphoned out by a clean siphon pump, and transferred to a sterilised container for pasteurised water, this pasteurised water benefiting also from exposure to sunlight which is known to be beneficial to water quality, the distilled water from condensation on the inclined surface or surfaces being recovered from the receiving channels and piped to a separate sterilised container, the removed pasteurised water replaced by non potable water, thus providing two qualities of water, one suitable for drinking purposes, the other requiring analysis to check on potability, but rid of most common bacteria, and, if not potable, suitable for other domestic uses, and much safer than the original polluted water introduced, distillation being necessary to make seawater potable, and leaving a potentially useful salt deposit, the pasteurising still fluid container vessel resting in an insulating container that increases its efficiency, and provides, in its base, a water levelling device so that the units are close to horizontal, a prerequisite for the distilled water channels to function efficiently, this basic system applicable to a single still, one application of this having a top formed from 1 pyramid, removable with a pinched grip at its crest, or from 4 pyramids, with a hole at its centre to remove it, to fill it or empty the fluid container vessel with a siphon pump, the water container designed then to have 4 upstands to collect internal trough distilled water, the system having the advantages of low height, and possibility of the top being reversed, to allow the pasteurising still to be packed within the depth of the fluid water container, the pasteurising still, sitting on a demountable table ii that forms the cover of the packed pasteurising still, the pasteurising still being so packed forming a carrying case, fitted with a handle, for ease of transportation, the cover able to contain the table legs and a flat plate solar collector with non return valves and with hinged reflecting flaps, the collector fitted to a southernly leg of the table linked in thermosyphon either to the fluid container vessel, to increase efficiency of the pasteurising still, or in a further development, to a secondary insulated fluid containing vessel, placed below the fluid container vessel, and linked to it by two openings, one with a pipe going down to its base to favour thermosyphoning, allowing the waters to mix and the overall water temperature to increase, providing a much larger volume of hot water, such that, at nightfall, after pasteurised water is no longer withdrawn, the distillation process can proceed through the night, the same insulated fluid containing vessel able to be withdrawn, and act on its own, with the solar collector, as a pasteurising device, these variations of a single pasteurising still able to be developed, with a different fluid container vessel, to multiple stills linked together by interconnecting pipes, forcing the non potable water now introduced at high level in the container vessel, so as to be seen entering and its inflow being interrupted, to follow a coming and going path so that no polluted water can go straight from one unit to another, but has to follow a circuit guaranteeing that water temperature taken at midpoint of the assembly, would allow, half the water contained in the assembled unit to be drawn off, or further down the array of lines if less is being removed, the last connecting tube being replaced by a delivery pipe, with a finely adjustable tap or valve, delivering large quantities of pasteurised water to an end container, the pipework from the distilled water channels also able to be interconnected to an inclined gathering pipe delivering all the distilled water from many units to a single distilled water container, the inlet water to the assembled units being preheated, for greater efficiency of both distillation and pasteurisation, in a black raised vessel,, provided with a reflective screen handled to follow the sun and located on a reflective base to increase solar radiation reaching the black vessel, the same vessel topped by a sand filter made up of a perlorated vessel with a fine mesh cloth holding the sand, a fine sieve or cloth filter preventing particulate fragments from blocking the sand filter, water to be purified being piped or poured gently through the filter to keep the black raised vessel partly full, the pasteurising stills to which the system applies being formed of a basic container vessel with an inclined glass or plastic sheet in its simplest application, to more sophisticated pressings or moldings as illustrated, inflatable structures, and, on a much larger scale, under transparent or translucent greenhouse structures, delivering distilled and pasteurised water for the benefit of a great number of people, in all these systems, the amount of distilled water, in sunny climates, being less than that of pasteurised water, which, if after analysis, can be considered potable, additionally to provision of distilled water, can help to solve potable water problems encountered worldwide. (2

2 A pasteurising solar still, as claimed in claim 1, consisting, in its basic model, of an upper part made of 4 transparent pyramids, the lower outer edges of which are located over distiiled water channels, to be of a light colour to prevent evaporation of distilled water, the edges being formed with a drip created by a change of angle over the channel, such that no distilled water can run to the outside lip of the insulating tray, as it reaches its edge which fits neatly over the top of the lined fluid container vessel and its upper channels. In the centre of the four pyramids is a capped hole, so that the top can be removed for periodic cleaning, and that water can be introduced into the fluid container vessel, which is divided into four interconnected chambers, so that water introduced or removed applies to the whole vessel, the divisions being formed by the distilled water channel upstands interrupted in the centre to allow funnels, thermometers and siphons to be introduced, a small ridge being formed at the end of each upstand to prevent any non potable water entering the distilled channels, each one sloping away from the centre to join the peripheral distilled water channel, which runs from a high point to a low point, where a spigot allows the distilled water to enter a tube, taking it through the insulating outer molding through a grommeted hole to prevent it from being torn away, and thence to a sterile distilled water container. The base of the light coloured lined fluid container vessel is provided with 4 thin black trays with small downstands to raise the trays away from the base and openings to allow water to circulate freely around them, the centre of the 4 trays having curved lips, forming a circle to locate the siphon pump, and thermometers, the assembly sitting in an outer insulated tray, which increases rates of distillation and pasteurisation, and has at its base, location studs to make sure the fluid container vessel is centred in the insulating tray, upstands to keep a layer of insulating air between the outer and inner units, and a levelling device, formed of 4 corner lined conical sided circles, linked diagonally by lined V formed linear recesses, such that water can be levelled between the 4 circles to insure that the assembly is level, and that the distiiled water channels will run properly, and that the lines show meaningful quantities, the outer insulating tray also being provided with a drainage hole. In the basic model, temperatures are read by introducing thermometers through the hole or having sensors shown through the hole, and when the water has been at 65 C for 20 minutes, pasteurised water can be withdrawn, and new water introduced, bearing in mind that it reasonable amounts are withdrawn, it will have little effect on distillation rates. In a variation to the basic model, a small tap can be fitted at the bottom of the fluid container vessel, to avoid siphoning, and simplify the process.

The reversed top will fit into the fluid container unit, and if a table is not provided, a simple cover can be devised to form a cover, and crossed straps will hold it in place and can provide a carrying handle. J3

A marine version of the 4 pyramid pasteurising still, now becoming a desalinating/salt producing still, can be made by sealing all openings in the outer insulating tray, except for the watertight distilled water exit, the pipe going to a removable container,48, fixed under the tray by a strap, the distilled water pipe leading to a watertight screw fitting, 49, that allows the container to be removed. Also, a black floating flexible sponge sheet placed over the seawater plane acts as evaporator and prevents the seawater from splashing into the distilled water channels. It can float in calm waters, or be on board, when the plastic bag is laid alongside.

3 A pasteurising solar still, as claimed in claim 1, in which a number of pasteurising solar stills can be connected in line, fed from a solar preheated main non potable water tank, with inlet and outlet valves, such that large quantities of pasteurised water can be drawn at a time or with correct settings, a constant flow can be established. However, for this to be possible, a different layout is necessary to force the non-potable water to take a coming and going route, to prevent any drops of non-potable water from taking a short cut between units, and arriving at the outlet without having been pasteurised. To achieve this, a number of ridges rise up from the floor of the fluid container vessel, the initial feed water being dropped in from a valved high level pipe, so that it can be seen through the double glazed window when flowing and when stopped by the inlet valve, the connecting pipe not connected in the first element of a series, the water being introduced at a point located at the closed end of the first upstand, the water then flowing up and down the many channels so formed, before leaving the first still by the connecting pipe, linking it to further units, until the last unit, which is fitted with a valved outlet. The end unit is fitted with an overflow pipe to help monitor correct water content, whether stationary, or flowing.

The temperature gauges and openings are always fitted in the middle of the run, if half the water is to be withdrawn, two thirds of the way down if two thirds of the water is to be withdrawn, or three quarters of the way down if one quarter of the way down if a quarter is to be withdrawn, so that in one mode, up to a half of the water content, having reached the pasteurising temperature, and having been kept for 20 minutes at that temperature, can be safely drawn off, up to the line desired, or in the flowing mode, so that water flowing past a temperature gauge at the correct location and temperature, the amount taken out is no more than the content of water in the container after the temperature gauge before reaching the valved outlet, the total water content being known, and the flow allowing half, a third or a quarter of that quantity to run through, measured by a flow meter, bearing in mind that taking out more than half would significantly cool the water and would have an adverse effect on the distillation process, which may, if it is the priority, require that only 1/3 or 1/4 is removed every 20 minutes, the first mode being easier to establish, the second one needing expert handling, the ridged unit being able to be used as the basic unit, with a hole for filling and siphoning.

The distilling takes place as in the basic still, with surround channels, the distilled water outlets being connected to a sloping collector pipe taking all the distilled water to a single sterile container.

4 A pasteurising solar still, as claimed linked to a thermosyphon solar collector, fitted with a non return valve to avoid reverse thermosyphon, to increase the temperature of the water, and greatly increase the production of pasteurised and distiiled water.

A pasteurising solar still as claimed in claim 1, supported by four L shaped legs, below which is slung an insulated water container, linked to a solar collector, such that it heats the water in the pasteurising solar still, but also allows, after sunset, when pasteurised water is no longer extracted, for the distillation process to continue throughout the night, benefiting from cooler air on the condensing surfaces.

The insulating water container with the solar collector can be used to produce pasteurised water only, where distilled water is not required.

6 A pasteu rising solar still, as claimed in claim 1, where the pasteurisation / distillation unit can be packed with the transparent top reversed, and a table top supporting it, containing on is underside 4 stacking L shaped legs and the solar collector and hinged reflectors, these being packed to form the top cover, constituting a compact carrying case, with a handle fitted for ease of transportation.

7 A pasteurising solar still, as described in Claim 1, where water to be distilled and pasteurised is made to follow a coming and going movement to prevent any drop of polluted water from travelling unchecked between linked units.

8 A pasteurising solar still, as claimed in Claim 1, provided at the base of the insulating container tray with a water levelling device, which also provides it with great stiffness consisting of a diagonal cruciform 3 layer indentation in the base plate with 4 circular water level readers at the 4 corners, a small amount of water being introduced for the initial levelling, and gradually more being added, to get greater precision when water just laps onto the upper layer circles.

9 A pasteurising solar still, as claimed in Claim 1, taking the form of an inflatable pasteurising still, easily packed for transportation, consisting of inflatable base ribs and riser ribs, forming the main structure, with transparent sheets fixed between these ribs, one panel being removable, by strip velcro or zip edges, to allow for cleaning of smaller units from outside, or entering larger units, one rib fitted with an inflatable funnel with a closure cap allowing non potable water to be delivered to the base non potable water pool, and thermal probes to be introduced to read the pool temperature, seen through a double skinned window, the said funnel also serving to introduce the suction pipe of a siphon pump, to remove pasteurised water, which can otherwise be let out of the pool by a tap, into a calibrated tank, the inner wall edges of the pool being lined around their inner edges to allow levelling, and to read quantities of water contained, the evaporation from the container condensing on the panels, and running down to an inclined recovery channel, from where the collected distilled water runs into a sterile tank, located alongside the non potable water pool structure of the pasteurising solar still, which rests on a foldable insulating base, providing protection to the black ground sheet, the pasteurising still raised off the ground by a table or an earth mound, the ground sheet converting the incident solar radiation into thermal energy, thereby heating the water contained by the non potable water pool created by the base ribs, connected to the ground sheet.

A marine version is fitted with an anti-splash black flexible sponge material sheet over the seawater plane, and the distilled water is collected in a separate attached flexible bag, to be removed as required, the unit either floating in calm waters, or kept on board.

A pasteurising solar still, as claimed in Claims 1, 2, 6 and 7, where the insulating container is sealed permanently, the joint between the transparent cover and the insulating container being sealed with a removable flexible strip, fitted with black sponge material acting as the solar energy evaporator, and preventing seawater from splashing onto the condensing walls and distilled water ducts. It can be floated in gentle seas, or placed on board, or in an onboard pool reducing sea movements.

11 A pasteu rising solar still, as claimed in claim 1, the same principle being applied to a larger structure, such as a greenhouse, in which the outer skin is made of transparent or solar energy transmissive material, the ground of which is either built of insulated concrete, or is covered by a strong dark groundsheet built up or formed at its edges to form the non potable water container, and featuring lines indicating the depth of water contained, provided with a window for temperature sensors located as in the pasteurised still runs, covered with linear staggered structures, insuring that water introduced by an inlet pipe follows a coming and going route, before exiting through an outlet pipe, both inlet and outlet controlled by valves, adjusted according to the mode of withdrawing water, either by finite quantities being withdrawn, according to the level readings, or by establishing a regular flow such that pasteurisation is achieved.

Evaporated water from the container condenses as distilled water on the cooler greenhouse surfaces, including the ends, and runs down to be collected by inclined gutters that take the distilled water to the distilled water outlet, both outlets running into tanks or underground sumps from which the waters are pumped to surface tanks.

The water condensing on the top portion of the greenhouse, which is too flat to allow the condensed water to run, falls and is recovered by a transparent or translucent inclined part upwardly concave cylinder, the recovered water running into a downpipe, which discharges into the main distilled water pipe.

The interior of the greenhouse is accessible through a door, which allows periodic cleaning and general system maintenance.

As in the runs of solar pasteurising stills, the inlet non potable water comes from a dark coloured tank, surrounded by a mobile reflective screen, resting on a reflective floor, increasing radiation on the tank to preheat the incoming water, covered by a sand filter.

This arrangement allows to provide pasteurised and distilled water to larger groups of population and small and large villages 12 A pasteurising still as described in claims 1, 2,3,4, in all of which systems, hygiene is crucial, aH condensing distilled water carrying surfaces, and accompanying pipework needing to be periodically cleaned and disinfected, the pasteurising systems needing to be similarly cleaned and disinfected periodically.

13 A pasteurising solar still, substantially as described herein with reference to figures 1-12 of the accompanying drawings /7 Amendments to the claims have been filed as follows:

1 A pasteurising solar still comprising a fluid containing vessel, a transparent or translucent roof having an inclined side or sides forming a condenser and a distilled water channel below it or around the periphery of the base of the roof recovering the distilled water; wherein means for measuring the temperature of the fluid at an appropriate point or points are provided, to in.;ure that the said fluid can be kept at 65 C or Iiore for a minimum period of 15 minutes to insure pasteurisation, a means for removing part of or all the pasteurised fluid from the fluid containing vessel, particularly a siphon or a tap, are provided; and wherein the pasteutising solar still is collapsible for transport; in particular a pasteurising solar still consisting of a fluid container vessel featuring horizontal lines to indicate water quantities contained, its base being fitted with a removable black tray, perforated and slightly lifted off the base itself to allow water circulation around it, the fluid container vessel being covered by a transparent element featuring one or many inclined facets, each such surface forming a condenser on which water vapour will condense, the condensate running into a distilled water channel, wherein valuable distilled water is collected, the top being provided with a hole through which non potable water can be introduced with a pipe or funnel through a closable opening, to the base of the tray, reaching desired quantities shown on the container lines, the said transparent cover allowing sunlight to penetrate through the water and the heat being absorbed by the black tray restoring it immediately to surrounding water, which heats up to pasteurising temperatures the quantities indicated by the lines, a separate hole allowing a variety of thermometers to be introduced, either liquid crystal strips, thermal temperature markers, classical thermometers or electronic probes, and water temperature readers, small double skin windows being provided where necessary to monitor internal workings difficult to see through condensation droplets, so that when the liquid reaches water pasteurising temperatures of 65 C or more and is held at that temperature for 20 minutes, it is then pasteurised and ready to be siphoned out by a clean siphon pump, and transferred to a sterilised container for pasteurised water, this pasteunsed water benefiting also from exposure to sunlight which is known to be beneficial to water quality, the distilled water from condensation on the inclined surface or surfaces being recovered from the receiving channels and piped to a separate sterilised container, the removed pasteurised water replaced by non potable water, thus providing two qualities of water, one suitable for drinking purposes, the other requiring analysis to check on potability, but rid of most common bacteria, and, if not potable, suitable for other domestic uses, and much safer than the original polluted water introduced, distillation being necessary to make seawater potable, and leaving a potentially useful salt deposit, the pasteurising still fluid container vessel resting in an insulating container that increases its efficiency, and provides, in its base, a water levelling device so that the units are close to horizontal, a prerequisite for the distilled water channels to function* efficiently, this basic system applicable to a single still, one application of this having a top formed from I pyramid, removable with a pinched grip at its crest, or from 4 pyramids, with a hole at its centre to remove it, to fill it or empty the fluid container vessel with a siphon pump, the water container designed then to have 4 upstands to collect internal trough distilled water, the system having the advantages of low height, and possibility of the top being reversed, to allow.the pasteun sing still to be packed within the depth of the fluid water container, the pasteurising still, sitting on a demountable table that forms the cover of the packed pasteurising still, the pasteurising still being so packed forming a carrying case, fitted with a handle, for ease of transportation, the cover able to contain the table legs and a flat plate solar collector with non return valves and with hinged reflecting flaps, the collector fitted to a southernly leg of the table linked in thermosyphon either to the fluid container vessel, to increase efficiency of the pasteurising still, or in a further development, to a secondary insulated fluid containing vessel, placed below the fluid container vessel, and linked to it by two openings, one with a pipe going down to its base to favour thermosyphoning, allowing the waters to mix and the overall water temperature to increase, providing a much larger volume of hot water, such that, at nightfall, after pasteurised water is no longer withdrawn, the distillation process can proceed through the night, the same insulated fluid containing vessel able to be withdrawn, and act on its own, with the solar collector, as a pasteurising device, these variations of a single pasteurising still able to be developed, with a different fluid container vessel, to multiple stills linked together by interconnecting pipes, forcing the non potable water now introduced at high level in the container vessel, so as to be seen entering and its inflow being interrupted, to follow a coming and going path so that no polluted water can go straight from one unit to another, but has to follow a circuit guaranteeing that water temperature taken at midpoint of the assembly, would allow, half the water contained in the assembled unit to be drawn off, or further down the array of lines if less is being removed, the last connecting tube being replaced by a delivery pipe, with a finely adjustable tap or valve, delivering large quantities of pasteunsed water to an end container, the pipework from the distilled water channels also able to be interconnected to an inclined gathering pipe delivering all the distilled water from many units to a single distilled water container, the inlet water to the assembled units being preheated, for greater efficiency of both distillation and pasteurisation1 in a black raised vessel,, provided with a reflective screen handled to follow the sun and located on a reflective base to increase solar radiation reaching the black vessel, the same vessel topped by a sand filter made up of a perforated vessel with a fine mesh cloth holding the sand, a fine sieve or cloth filter preventing particulate fragments from blocking the sand filter, water to be purified being piped or poured gently through the filter to keep the black raised vessel partly full, the pasteunsing stills to which the system applies b&ng formed of a basic container vessel with an inclined glass or plastic sheet in its simplest application, to more sophisticated pressings or moldings as illustrated, inflatable structures, and, on a much larger scale, under transparent or translucent greenhouse structures, delivering distilled and pasteurised water for the benefit of a great number of people, in all these systems, the amount of di stilled water, in sunny climates, being less than that of pasteurised water, which, if after analysis, can be considered potable, additionally to provision of distilled water, can help to solve potable water problems encountered 2 A pasteurising solar still, as claimed in claim I, consisting, in its basic model, of an upper part made of 4 transparent pyramids, the lower outer edges of which are located over distiiled water channels, to be of a light colour to prevent evaporation of distilled water, the edges being formed with a drip created by a change of angle over the channel, such that no distilled water can run to the outside lip of the insulating tray, as it reaches its edge which fits neatly over the top of the lined fluid container vessel and its upper channels. In the centre of (1 the four pyramids is a capped hole, so that the top can be removed for periodic cleaning, and that water can be introduced into the fluid container vessel, which is divided into four interconnected chambers, so that water introduced or removed applies tothe whole vessel, the divisions being formed by the distilled water channel upstands inten-upted in the centre to allow funnels, thermometers and siphons to be introduced, a small ridge being formed at the end of each upstand to prevent any non potable water entering the distilled channels, each one sloping away from the centre to join the peripheral distilled water channel, which runs from a high point to a low point, where a spigot allows the distilled water to enter a tube, taking it through the insulating outer molding through a grommeted hole to prevent it from being torn away, and thence to a sterile distilled water container. The base of the light coloured lined fluid container vessel is provided with 4 thin black trays with small downstands to raise the trays away from the base and openings to allow water to circulate freely around them, the centre of the 4 trays having curved lips, forming a circle to locate the siphon pump, and thermometers, the assembly sitting in an outer insulated tray, which increases rates of distillation and pasteurisation, and has at its base, location stud.s to make sure the fluid container vessel is centred in the insulating tray, upstands to keep a layer of insulating air between the outer and inner units, and a levelling device, formed of 4 corner lined conical sided circles, linked diagonally by lined V formed linear recesses, such that water can be levelled between the 4 circles to insure that the assembly is level, and that the distiiled water channels will run properly, and that the lines show meaningful quantities, the outer insulating tray also being provided with a drainage hole. In the basic model, temperatures are read by introducing thermometers through the hole or having sensors shown through the hole, and when the water has been at 65 C for 20 minutes, pasteurised water can be withdrawn, and new water introduced, bearing in mind that it reasonable amounts are withdrawn, it will have little effect on distillation rates. In a variation to the basic model, a small tap can be fitted at the bottom of the fluid container vessel, to avoid siphoning, and simplify the process.

The reversed top will fit into the fluid container unit, and if a table is not provided, a simple cover can be devised to form a cover, and crossed straps will hold it in place and can provide a carrying handle.

3 A pasteurising solar still, as claimed in claim I, in which a number of pasteurising solar stills can be connected in line, fed from a solar preheated main non potable water tank, with inlet and outlet valves, such that large quantities of pasteurised water can be drawn at a time, or with correct settings, a constant flow can be established. However, for this to be possible, a different layout is necessary to force the non-potable water to take a coming and going route, to prevent any drops of non-potable water from taking a short cut between units, and 2o arriving at the outlet without having been pasteurised. To achieve this, a number of ridges rise up from the floor of the fluid container vessel, the initial feed water being dropped in from a valved high level pipe, so that it can be seen through the double glazed window when flowing and when stopped by the inlet valve, the connecting pipe not connected in the first element of a series, the water being introduced at a point located at the closed end of the first upstand, the water then flowing up and down the many channels so formed, before leaving the first still by the connecting pipe, linking it to further units, until the last unit, which is fitted with a valved outlet. The end unit is fitted with an overflow pipe to help monitor correct water content, whether stationary, or flowing.

The temperature gauges and openings are always fitted in the middle of the run, if half the water is to be withdrawn, two thirds of the way down if two thirds of the water is to be withdrawn, or three quarters of the way down if one quarter of the way down if a quarter is to be withdrawn, so that in one mode, up to a half of the water content, having reached the pasteurising temperature, and having been kept for 20 minutes at that temperature, can be safely drawn off, up to the line desired, or in the flowing mode, so that water flowing past a temperature gauge at the correct location and temperature, the amount taken out is no more than the content of water in the container after the temperature gauge before reaching the valved outlet, the total water content being known, and the flow allowing half, a third or a quarter of that quantity to run through, measured by a flow meter, bearing in mind that taking out more than half would significantly cool the water and would have an adverse effect on the distillation process, which may, if it is the priority, require that only 1/3 or 1/4 is removed every 20 minutes, the first mode being easier to establish, the second one needing expert handling, the ridged unit being able to be used as the basic unit, with a hole for filling and siphoning The distilling takes place as in the basic still, with surround channels, the distilled water outlets being connected to a sloping collector pipe taking all the distilled water to a single sterile container.

3 A pasteuri sing solar still, as claimed linked to a thermosyphon solar collector, fitted with a non return valve to avoid reverse thermosyphon, to increase the temperature of the water, and greatly increase the production of pasteurised and distiiled water.

4 A pasteurising solar still as claimed in claim 1, supported by four L shaped legs, below which is slung an insulated water container, linked to a solar collector, such that it heats the water in the pasteurising solar still, but also allows, after sunset, when pasteurised water is no longer extracted, for the distillation process to continue throughout the night, benefiting from cooler air on the condensing surfaces.

A pasteurising solar still, as claimed in claim 1, where the pasteurisation I distillation unit can be packed with the transparent top reversed, and a table top supporting it, containing on is underside 4 stacking L shaped legs and the solar collector and hinged reflectors, these

V

being packed to form the top cover, constituting a compact carrying case, with a handle fitted for ease of transportation.

6 A pasteurising solar still, as described in Claim I, where water to be distilled and pasteurised is made to follow a coming and going movement to prevent any drop of polluted water from travelling unchecked between linked units.

7 A pasteunsing solar still, as claimed in Claim 1, provided at the base of the insulating container tray with a water levelling device, which also provides it with great stiffness consisting of a diagonal cruciform 3 layer indentation in the base plate with 4 circular water level readers at the 4 corners, a small amount of water being introduced for the initial levelling, and gradually more being added, to get greater precision when water just laps onto the upper layer circles.

8 A pasteuri sing solar still, as claimed in Claim 1, taking the form of an inflatable pasteurising still, easily packed for transportation, consisting of inflatable base ribs and riser ribs, forming the main structure, with transparent sheets fixed between these ribs, one panel being removable, by strip velcro or zip edges, to allow for cleaning of smaller units from outside, or entering larger units, one rib fitted with an inflatable funnel with a closure cap allowing non potable water to be delivered to the base non potable water pool, and thermal probes to be introduced to read the pooi temperature, seen through a double skinned window, the said funnel also serving to introduce the suction pipe of a siphon pump, to remove pasteunsed water, which can otherwise be let out of the pool by a tap, into a calibrated tank, the inner wall edges of the pool being lined around their inner edges to allow levelling, and to read quantities of water contained, the evaporation from the container condensing on the panels, and running down to an inclined recovery channel, from where the collected distilled water runs into a sterile tank, located alongside the non potable water pool structure of the pasteurising solar still, which rests on a foldable insulating base, providing protection to the black ground sheet, the pasteunsing still raised off the ground by a table or an earth mound, the ground sheet converting the incident solar radiation into thermal energy, thereby heating the water contained by the non potable water pool created by the base ribs, connected to the ground sheet.

9 A pasteurising solar still, as claimed in Claims 1, 2, 6 and 7, where the insulating container is sealed permanently, the joint between the transparent cover and the insulating container being sealed with a removable flexible strip, fitted with black sponge material acting as the solar energy evaporator, and preventing seawater from slashing onto the condensing walls and distilled water ducts. It can be floated in gentle seas, or placed on board, or in an onboard pool reducing sea movements.

A pasteunsing solar still, as claimed in claim 1, the same principle being applied to a larger structure, such as a greenhouse, in which the outer skin is made of transparent or solar energy transmissive material, the ground of which is either built of insulated concrete, or is covered by a strong dark groundsheet built up or formed at its edges to form the non potable water container, and featuring lines indicating the depth of water contained, provided with a window for temperature sensors located as in the pasteurised still runs, covered with linear staggered structures, insuring that water introduced by an inlet pipe follows a coming and going route, before exiting through an outlet pipe, both inlet and outlet controlled by valves, adjusted according to the mode of withdrawing water, either by finite quantities being withdrawn, according to the level readings, or by establishing a regular flow such that pasteurisation is achieved.

Evaporated water from the container condenses as distilled water on the cooler greenhouse surfaces, including the ends, and runs down to be collected by inclined gutters that take the distilled water to the distilled water outlet, both outlets running into tanks or underground suinps from which the waters are pumped to surface tanks.

This arrangement allows to provide pasteunsed and distilled water to larger groups of population and small and large villages 11 A pasteurising still as described in claims 1, 2,3,4, in all of which systems, hygiene is crucial, all condensing distilled water carrying surfaces, and accompanying pipework needing to be periodically cleaned and disinfected, the pasteunsing systems needing to be similarly cleaned and disinfected periodically.

12 A pasteurising solar still, substantially as described herein with reference to figures 1- 12 of the accompanying drawings