Claims:We claim:
1. A water purification device (10) comprising
? a filter (12) connected to a raw water feed line (14);
? at least one Reverse Osmosis (RO) membrane (16) connected between outlet of said filter (12) and an inlet of a storage tank (18); characterized in said water purification device (100)
? a total dissolved solids (TDS) sensor (20) placed at the outlet of said filter (12);
? a bypass path (22) connected to the outlet of said filter (12) and said storage tank (18); and
? said bypass path (22) is opened based on the output of said TDS sensor (20).

2. The water purification device (100) of claim 1, wherein a valve (24) in said bypass path (22) is opened to supply water directly from the filter (12) to said storage tank (18), if the TDS level in the water at the outlet of the filter (12) is less than or equal to a threshold value.

3. The water purification device (100) of claim 2, wherein said valve (24) in said bypass path (22) is closed to supply water from the filter (12) through said RO membrane (16) to said storage tank (18), if the TDS level in the water at the outlet of the filter (12) is more than a threshold value.

4. The water purification device (100) of claim 1, further comprises a controller to control the opening or closing said valve based on the output of said TDS sensor.

5. A water purification method comprises
? filtering raw water supplied from a feed line by a filter (12);
? measuring level of total dissolved solids (TDS) present in the filtered water supplied by the filter (12); and
? supplying the filtered water to storage tank (18) directly or through at least one Reverse Osmosis (RO) membrane (16) to said storage tank (18) based on the level of total dissolved solids (TDS) present in the filtered water.

6. The method of claim 5, wherein the measuring step comprises determining the TDS level of water at the outlet of the filter (12).

7. The method of claim 5, wherein the measuring step comprises determining the TDS level of water at the storage tank (18).

8. The method of claim 5, wherein the supplying step comprises opening a valve (24) provided in a bypass path (22) to provide water directly from the outlet of said filter (12) to said storage tank (18), if the level of TDS is less than or equal to a threshold value.

9. The method of claim 8, wherein the supplying step comprises closing said valve (24) provided in said bypass path (22) for providing water from the outlet of said filter (12) to said storage tank (18) through said RO membrane (16), if the level of TDS is more than the threshold value.
, Description:Field of the invention:
[0001] The invention relates to a device and a method for water purification.
Background of the invention:
[0002] Water purifiers comprising filters such as ultra-filters and Reverse-Osmosis (RO) membranes are already known in the art.
[0003] Sometimes, it is not necessary to re-filter the water filtered by the ultra-filter by RO membrane; because, the amount of total dissolved solids (TDS) or the hardness level of water coming from the feed line may be less, which can be very well purified by the ultra-filter. When the filtered water from the ultra-filter is again passed to the RO membrane, more amount of good water gets filtered out and wasted at the outlet of the RO membrane. Further, the load on the RO membrane is increased, as a result, the life of the RO membrane is reduced.
[0004] Hence there is a need for a system which can selectively use the existing filters such as ultra-filter and RO membrane and yet increasing the safety of drinking water.
[0005] WO2009050737 discloses one such water purification device. It comprises water collection tank with a built in water condition assessing TDS sensor.
Brief description of the invention:
[0006] The invention discloses a device and a method for a water purification. The water purification device comprises a filter connected to a raw water feed line. At least one Reverse Osmosis (RO) membrane is connected between outlet of the filter and an inlet of a storage tank. A total dissolved solids (TDS) sensor is placed at the outlet of the filter. A bypass path is connected to the outlet of said filter and the storage tank. The bypass path is opened based on the output of the TDS sensor.
[0007] A valve in the bypass path is opened to supply water directly from the filter to the storage tank, if the TDS level in the water at the outlet of the filter is less than or equal to a threshold value. The valve in the bypass path is closed to supply water from the filter through said RO membrane to the storage tank, if the TDS level in the water at the outlet of the filter is more than a threshold value. A controller controls the opening or closing of the valve based on the output of the TDS sensor.
[0008] The water purification method involves filtering raw water supplied from a feed line by a filter. The level of total dissolved solids (TDS) present in the filtered water supplied by the filter is measured. In one example, the TDS level of water at the outlet of the filter is measured. In another example, the TDS level of water at the storage tank is measured. In a third example, the TDS level of water at inlet to the filter is measured. The filtered water is supplied to the storage tank directly or through at least one Reverse Osmosis (RO) membrane to the storage tank based on the level of TDS present in the filtered water.
Brief description of the accompanying drawings:
[0009] An embodiment of the invention is described with reference to the following accompanying drawings,
[00010] Fig. 1 shows a schematic block diagram of a water purification device in accordance with an embodiment of the invention; and
[00011] Fig. 2 illustrates a flow chart of a water purification method in accordance with an embodiment of the invention.
Detailed description of the embodiments:
[00012] Fig. 1 shows a schematic block diagram of a water purification device in accordance with an embodiment of the invention. The water purification device 10 comprises a raw water feed line 14 through which water is supplied. The raw water can be supplied through a pump or a pipe. There could be various other arrangements by which water can be supplied to the water purification device 10. Examples of the water purification device 10 can include, but not limited to, a domestic water filter, an industrial water filter, etc.
[00013] The input water can be initially filtered through a pre-filter, carbon filter, etc. to remove certain impurities and odor. After the initial filtering, the water is supplied to a filter 12. The filter can be an ultra-filter or a nano-filter 12. For example, the ultra-filter can filter impurities of particle size of very small range.
[00014] A total dissolved solids (TDS) sensor 20 is placed at the outlet of the filter 12. The TDS sensor 20 measures the amount of dissolved solids in the water, including anions, cations, minerals, salts, etc. The TDS may include metals such lead, copper, etc and non-metals. High TDS results in degradation of the taste of the water. For example, high TDS water may be salty, bitter, and may smell bad. High TDS may indicate high hardness of water also.
[00015] According to the Bureau of Indian Standards (IS: 10500) guidelines, 500 mg/L is the desirable limit and 2000 mg/L is the permissible limit for the drinking water. Drinking water with TDS in excess of 2000 mg/L should be rejected.
Presence of TDS beyond 500 mg/L in drinking water decreases palatability and may cause gastrointestinal irritation. Therefore, the amount of TDS should be controlled during water filtration.
[00016] A RO filter/ RO membrane 16 is connected between the outlet of the filter 12 and an inlet of a storage tank 18. That is, RO filter 15 is connected to the output line of the filter 12 after the TDS sensor 20.
[00017] The connection from the filter 12, RO filter 16 and the storage tank 18 constitute the regular water flow path. Through this path, the water purified by the filter 12 is supplied to the RO membrane/filter 16. The filtered water from RO filter 16 is then supplied to the storage tank 18. Water is then dispensed for drinking from the storage tank 18 for drinking or other purposes.
[00018] However a bypass path 22 is provided connecting the outlet of the filter 12 and the storage tank 18. The bypass path 22 is opened based on the output of the TDS sensor 20.
[00019] In an embodiment of the invention, the bypass path 22 has a valve 24. This valve 24 is opened to supply directly from the filter 12 to the storage tank18, if the TDS level in the water at the outlet of the filter 12 is less than or equal to a threshold value (e.g. 1000 mg/L). This threshold value can be defined by the user.
[00020] When the water from the filter 12 contains TDS of acceptable limit, it is directly supplied to the storage tank 18. At this time, the RO path is switched OFF thereby saving power. This avoids the need for again filtering the water with RO membrane/ filter 16. As a result, wastage of water at the RO filter 16 is reduced considerably. Also the load on the RO membrane 16 is minimized, thereby increasing the life of the RO membrane 16.
[00021] If the TDS level in the water at the outlet of the filter 12 is more than a threshold value (e.g. 1000mg/L), then the valve 24 is closed. When the valve 24 is closed, the water is supplied to the RO membrane 16 and gets filtered further. When the water is filtered by RO membrane 16, the TDS level gets further reduced below the threshold value and supplied to the storage tank 18. Thereby, the TDS level is maintained within the acceptable range by a simple arrangement.
[00022] A controller such as a microcontroller or a programmable logic controller is provided in the water purification device 10, and connected to the TDS sensor 20. Based on the output of the TDS sensor 20, the controller regulates the opening/closing of the valve 24.
[00023] In another embodiment of the invention, the TDS sensor 20 is inside the tank. Based on the output of the TDS sensor 20, the bypass path 22 is opened/closed by the valve 24.
[00024] Fig. 2 illustrates a flow chart of a water purification method in accordance with an embodiment of the invention. The method involves filtering the raw water supplied from a feed line 14 by a filter 12 such as an ultra-filter 12 at step S1. Then, the TDS level in filtered water supplied by the filter 12 is measured with the help of a TDS sensor 20 at step S2. Based on the measured level of TDS present in the filtered water, the filtered water from the filter 12 is either directly supplied to the storage tank 18 at step S3 or supplied through RO membrane 16 to the storage tank 18 at step S4.
[00025] For instance, if the TDS level is less than or equal to the threshold value (which is acceptable as per the safety standards), then a valve 24 in the bypass path 22 is opened to provide water directly from the outlet of the filter 12 to the storage tank 18 with RO circuit switched OFF. Thereby, there power saving is achieved. Thereby, the wastage of water at the RO membrane 16 is prevented. Further the load on the RO membrane 16 is reduced, leading to increase in the life of the RO membrane 16.
[00026] Further, if the level of TDS at the outlet of the filter 12 is more than the threshold value, the valve 24 in the bypass path 22 is closed. As a result, the water is supplied to the RO membrane 16 for further purification. After purification at the RO membrane 16, water is supplied to the storage tank 18. Hence, TDS level in the water is reduced.
[00027] The invention makes use of simple and inexpensive arrangements, yet improves the safety of the drinking water.
[00028] Alternately, the TDS sensor 20 can be placed in the storage tank 18 or at the inlet line 14. Based on the output of the sensor 20, the valve 24 in the bypass path 22 can be either closed or opened.
[00029] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.