IL111523A - Apparatus for the production of drinking water - Google Patents

Description

APPARATUS FOR THE PRODUCTION OF DRINKING WATER The present invention relates to apparatus for the production of drinking water from a water source which is contaminated by pathogenic micro-organisms.

More particularly, the invention provides such an apparatus which operates by means of unconcentrated solar radiation, and which is suitable for use in undeveloped regions where no manufactured energy, e.g., electricity, is readily available.

Many parts of the world have large fresh water lakes, rivers or underground reservoirs which have been biologically contaminated due to natural causes or poor management. A safe supply of clean drinking water is a basic human requirement, but thirsty people will drink contaminated water if no other water is available. The resulting epidemics of cholera and dysentery, such as those recently seen in Rwanda and neighboring states flooded by refugees, require more resources for their control than would have been required to originally supply safe drinking water; aside from causing human suffering on a very large scale, such diseases claim thousands of lives.

Various methods are presently known for purifying contaminated fresh water in order to make it suitable for drinking, but most such methods are not suitable for use in the underdeveloped areas of the world which need them the most.

Water can be boiled before use, provided that fuel is available. This method, however, imposes a surprisingly onerous task on primitive peoples, and for this reason cannot be relied upon over the long term. Furthermore, boil-resistant bacteria have been discovered; thus, even - 2 - 111,523/2 after boiling, such water requires filtering to remove remaining impurities.

Other known large-scale purification methods include leverse osmosis, multi-stage flash distillation, and electrodialysis, all of which require electric power and are suitable mainly for desalinization of sea water. Solar distillation is a suitable process for producing drinking water from saline sources in underdeveloped areas, but there is no record of this process being effective for the removal of micro-organisms. Except for the solar stills, these plants are not suitable for small-scale local operation by unskilled personnel.

Apparatus for purifying water, arranged to cause decomposition of organic contaminants by exposing the water containing said contaminants to a beam of concentrated solar energy, has been disclosed by Inagaki, et al. in U.S. Patent 4.978.458, and by the present inventor in Israel Patent Application No. 98930. Such devices require the construction and maintenance of large lenses or reflectors and accurate tracking devices to follow the apparent movement of the sun. These devices are further limited by their inability to utilize the approximate 10% of solar radiation which arrives at ground level in diffuse form after being scattered by the Earth's atmosphere.

Williams, in U.S. Patent 4,008,136, describes and claims a process for the treatment of waste water containing organic materials, comprising adding to said waste water, in the presence of oxygen, a water-insoluble, polymer-based photosensitizer , and then photolyzing the resulting suspension with light having wavelengths between 320 nm and about 800 nm. Williams makes no claim to a method for producing drinking water, nor does he propose any apparatus for producing drinking water.

It is one of the object of the present invention to obviate the disadvantages of the prior art water purification methods, and to provide apparatus which can be operated in locations lacking electricity or fossil fuels.

A further object of the present invention is to provide a low-cost water purification apparatus which is inexpensive to manufacture and to operate.

The present invention achieves the above objectives by providing a water purification apparatus for use in combination with pre-filtered water containing pathogenic micro-organisms, comprising a first inlet for said water; a conduit leading the water from said first inlet into a lower port of a tilted, flat solar radiation collector, the collector being provided with water channels sealed between a lower reflecting surface and an upper light-transmitting cover, allowing exposure of said water to solar radiation including wavelengths in the visible part of the spectrum and thereby killing the micro-organisms contained therein, the collector being further provided with an upper port which serves as a water outlet; means arranged to feed a photosensitizer into the water passing through said channels; a storage tank arranged to receive water from said radiation collector water outlet, and filter means in fluid communication with said storage tank, arranged to remove remaining photosensitizer and remaining impurities from the irradiated water, thereby supplying water suitable for drinking.

In a preferred embodiment of the present invention, the apparatus is further provided with a filter connected to the inlet port for removing solids from water entering the collector. Consequently, the apparatus is able to accept fresh water from any source.

In a most preferred embodiment of the present invention, a water purification apparatus is provided which is arranged to feed photosensitizer into the water by means of a venturi tube formed in the conduit which leads the water from the first inlet into the tilted, flat solar radiation collector. The venturi tube can also be used to draw air into the water for oxygen enrichment.

It will be realized that the novel apparatus of the present invention is particularly suitable to many areas of the world where the only abundant types of energy are wind energy, solar energy, and human muscular power. As will be seen in the following description, the various embodiments of the apparatus of the present invention all make use of these three forms of energy.

The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.

With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice .

In the drawings: Fig. 1 is a schematic view of a preferred embodiment of the water purification apparatus according to the present invention; Fig. 2 is a schematic, partial view of a second embodiment of said apparatus; Fig. 3 is a schematic plan view of a solar radiation collector used in the apparatus of the invention; Fig. 4 is a schematic view of an embodiment of the apparatus provided with solar cells; Fig. 5 is a detailed view of part of an apparatus using a venturi tube to feed photosensitizer and air into the water to be purified; Fig. 6 is a sectional detailed view of part of a solar radiation collector used in the present invention; Fig. 7 is a side view of part of a water purification apparatus wherein means are provided to increase the absorbed solar radiation; Fig. 8 is a perspective view of a further embodiment of a solar radiation collector used in the apparatus of the present invention; Fig. 9 is a perspective view of a solar radiation collector provided with a transferable reflective surface; and Table 1 gives test results, using an apparatus built according to the embodiment of Figs. 1 and 7.

Fig. 1 shows a water purification apparatus 10 for use in combination with incoming prefiltered fresh water 12, which water contains micro-organisms. The term "fresh water" as used herein refers to water containing no more salt than is acceptable for drinking.

A water feed tank 14 is supported at a height above that of the other components of apparatus 10. The top of tank 14 may be opened and serves as a first inlet 16 for water to be purified. The feed tank 14 is filled manually, using, for example, a ladder 17 and buckets; such a method is feasible for the limited quantities of drinking water to be produced. Material for photosensitizer 36 can be simply added manually in a batch process through said opening. A simple, hand-turned propeller 15 can be provided in the tank for mixing the water and photosensitizer.

Conduit 18 leads water 12 from feed tank 14 into a lower port 20 of a tilted, flat solar radiation collector 22. The collector 22 is provided with water channels 24, seen in Fig. 3, which are sealed between lower reflecting surface 26 and an upper light-transmitting cover 28. While the water 12 flows through channels 24, it is thus exposed to solar radiation including wavelengths in the visible part of the spectrum, which kills micro-organisms contained therein. Collector 22 is also provided with an upper port 30, which serves as a water outlet leading into a storage tank 32.

Filter means 52, in fluid communication with storage tank 32, are arranged to remove remaining photosensitizer 36 and any remaining impurities from the irradiated water, thus supplying drinking water.

Advantageously, the water purification apparatus 10 is further provided with an inlet filter 54, suitably comprising activated carbon, which is connected to the first inlet 16 for removing solids from water entering the solar collector. Apparatus 10 is consequently able to accept fresh water from any source.

Referring now to Fig. 2, there is seen part of a water purification apparatus 56, which is similar to apparatus 10. However, a manually operated pump 58 is arranged to feed water through filter 54. The pump 58 shown is hand-operated; a foot-operated pump (not shown) can alternatively be used.

Means 34 are arranged to feed a photosensitizer 36 into the water to be purified, before the water enters the water tank 14'. In the embodiment of Fig. 2, means 34 comprise a small tank 38 having a gravity drip tube 40 and a flow valve 41.

Fig. 3 illustrates a detail of the water purification apparatus 10. Solar radiation collector 22 has water channels 24, which are configured to form a long, serpentine flow path between the lower port 20 and upper port 30.

As an example of exposure time and related output, if the combined channel length is 25 meters and flow velocity is 5 meters per minute, exposure time is 5 minutes. If the channel flow path has a cross-sectional area of 8 cm2, the apparatus will produce 4 liters of water per minute. Six hours of operation will thus supply 1440 liters of drinking water per day, an amount sufficient for about 700 people.

In Fig. 4 there is seen a water purification apparatus 60, which is similar to apparatus 10, but which is further provided with an array of solar cells 62 arranged to power pump 64 driven by electric motor 66. Apparatus 60 has an important advantage: the quantity of water pumped into radiation collector 22 is approximately proportional to the intensity of solar radiation acting to purify the water. For example, during a cloudy period, the solar cell array will cease supplying electricity to motor 66; consequently, pumping will cease, unpurified water will remain in the collector 22, and only irradiated water, produced after solar radiation is again available, will be pumped into storage tank 32.' In the embodiment of Fig. 4, means are provided to feed air into the water, optional for use with water found not to have enough oxygen. As electricity produced by the cells 62 is available, these means comprise an electrically-powered air blower 68. A small metering pump 70 feeds photosensitizer 36 into the water to be purified.

Storage tank 32, holding purified water, is shown as provided with a float valve 72, which is arranged to operate switching means 74 when the tank is full. Switching means 74 cut and restore current supplied to motor 66, thus preventing overflow of the tank.

Referring now to Fig. 5, there is shown a detail of a further embodiment of a water purification apparatus 76. In this embodiment, the means provided to feed photosensitizer 36 into the water entering radiation collector 22 comprise a venturi tube 78 formed in conduit 18 leading water into lower port 20. Venturi tube 78 has two important features. First, it allows feeding of photosensitizer 36 into the water without requiring any electric power. Second, the quantity of photosensitizer 36 drawn into the water is roughly proportional to the water flow rate through tube 78, thus ensuring that the desired mixing ratio is maintained.

In the embodiment of Fig. 5, the venturi tube 78 is put to further use. As seen in the drawing, air is also drawn into the water by means of the venturi tube 78, thus achieving the required oxygen enrichment of the water to be purified.

Fig. 6 depicts a detail of a further, similar water purification apparatus 80. Solar radiation collector 82 is provided with an upper cover 84 made of a material which is substantially transparent to solar radiation in the ultraviolet range of the spectrum, such as quartz or fused silica glass. Ultraviolet radiation is particularly effective in neutralizing micro-organisms, hence it is advantageous that the cover 84 has a high transmission factor for this wavelength range. Cover 84 is clamped by retainer channel 85a onto a flexible seal element 85b.

Shown in Fig. 7 are details of a water purification apparatus 86, wherein means 87 are provided to increase the absorbed solar radiation in the flat plate collector 88 in early morning and late afternoon. Collector 88 is mounted on a hinge rod 90, which allows the user to swing the collector 88 towards the east in the morning and towards the west in the afternoon. The water inlet tube 92 and outlet tube 93 are flexible, and are suitably made of reinforced rubber or plastic.

Fig. 8 depicts a further embodiment of a solar radiation collector 46, as used in apparatus 10. Upper surface 48 is transparent, made of PMMA. The lower face 50 has a mirror-like reflective surface facing upwards, and sealed channels 50 are provided for water flow. The collector 46 can be cleaned by flushing- Referring now to Fig. 9, there is seen part of a further embodiment of a water purification apparatus 94, wherein means 96 are provided to increase the absorbed solar radiation in the flat plate radiation collector 98 in the early morning and late afternoon. The collector 98 is provided with two pairs of rails 100, 102. Either pair is able to hold a reflective surface 104, shown assembled in the western pair of rails 100 so as to reflect morning solar radiation into collector 98. At mid-day, the surface 104 is manually transferred to the eastern pair of rails 102, and will thus reflect afternoon radiation into collector 98. Thus, the embodiment of Fig. 8 has the further advantage of providing more intense radiation to sterilize the water. As the collector itself is not moved, the water inlet and outlet tubes 106 and 108 are rigid.

Table 1 gives test results, using an apparatus as described with reference to Figs. 1 and 7. Test conditions were as follows: Test date: 13 October Photosensitizer : 18 ml 1% MBH added to 350 liters water Air addition: none Collector tilt: adjusted as needed, to face the sun TABLE I Time E coli cfu/100 ml Irradiation Water Flow In Out W/m2 1 min 11.50 2,500,000 65 724 2 12.30 2,110,000 25 742 2 13.10 2,340,000 11 628 2 13.50 1,770,000 3 552 1.8 It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrated embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (11)

WHAT IS CLAIMED IS:

1. A water purification apparatus for use in combination with pre-filtered water containing pathogenic micro-organisms, comprising: a first inlet for said water; a conduit leading the water from said first inlet into a lower port of a tilted, flat solar radiation collector, the collector being provided with water channels sealed between a lower reflecting surface and an upper light-transmitting cover, allowing exposure of said water to solar radiation including wavelengths in the visible part of the spectrum and thereby killing the micro-organisms contained therein, the collector being further provided with an upper port which serves as a water outlet; means arranged to feed a photosensitizer into the water passing through said channels; a storage tank arranged to receive water from said radiation collector water outlet, and filter means in fluid communication with said storage tank, arranged to remove remaining photosensitizer and remaining impurities from the irradiated water, thereby supplying water suitable for drinking.

2. The water purification apparatus as claimed in claim 1, further comprising a filter connected to said first inlet, for removing solids from water entering the collector.

3. The water purification apparatus as claimed in claim 2, further comprising a pump arranged to feed water into said filter.

4. The water purification apparatus as claimed in claim 1, wherein said water channels are configured to form a long, serpentine flow path between said lower port and said upper port.

5. The water purification apparatus as claimed in claim 3, further comprising an array of solar cells arranged to power said pump.

6. The water purification apparatus as claimed in claim 1 , wherein said means arranged to feed photosensitizer into the water before said water enters the radiation collector comprise a venturi tube formed in said conduit.

7. The water purification apparatus as claimed in claim 1, further comprising means arranged to feed air into the water before said water enters the radiation collector.

8. The water purification apparatus as claimed in claim 7, wherein said means arranged to feed air into the water before said water enters the radiation collector comprise a venturi tube formed in said conduit.

9. The water purification apparatus as claimed in claim 7 , wherein said means arranged to feed air into the water comprise an air blower and an array of solar cells for powering said blower.

10. The water purification apparatus as claimed in claim 1, wherein said solar radiation collector is provided with an upper cover which is substantially transparent to solar radiation in the ultraviolet range of the spectrum.

11. The water purification apparatus as claimed in claim 1, wherein means are provided to increase the absorbed solar radiation in the flat plate collector in the early morning and the late afternoon. for the Applicant: WOLFF, BREGMAN AND GOLLER