FIELD OF INVENTION
[001] This invention relates to a system and a method for water purification, and more particularly but not exclusively to a system and a method using reverse osmosis for purifying water,
BACKGROUND OF INVENTION
[002] Water pollution has become a major global problem. The water bodies such as rivers, lakes, ground water and so on get contaminated due to the discharge of pollutants from industries and other setups to such water bodies. The water from the water bodies is utilized for irrigation and domestic purposes. However, for drinking purposes, the water has to be purified since the water from the water bodies may be contaminated with physical, chemical and microbiological impurities and may also have a high total dissolved solids (TDS) level.
[003] At present, numerous water filters or purifiers are being used for purifying the water. The water filters or purifiers are designed for specific types of contaminants. Some of the basic water filters or purifiers are distiller, reverse osmosis filter, activated carbon water filter, UV water purifiers and purifiers based on halogen disinfection technologies. Of the available water filters, reverse osmosis filter is capable of providing drinking water with reduced total dissolved solids (TDS) level and hence is
most recommended to make the water pure and palatable, where the water tastes brackish or saline and has high levels of hardness and TDS.
[004] Further, reverse osmosis filters or purifiers uses reverse osmosis to purify the water. In reverse osmosis, which is a membrane based filtration method, large molecules and ions in solutions are removed by applying pressure to the solution when the solution is on one side of the membrane. In other words, reverse osmosis is a process of forcing a solvent from a region of high solute concentration through a semi permeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.
[005] Reverse osmosis based water filters or purifiers available in the market achieve about 90% reduction in total dissolved solids (TDS) level of input water. The reverse osmosis water filters or purifiers during the process of reducing the total dissolved solids (TDS) level reject about 75% of input water and produce only 25% of purified water. The volume of reject water increases with increase in total dissolved solids (TDS) level of input water. Since the water wastage is high, existing reverse osmosis water filters or purifiers are considered to be environment unfriendly.
[006] Further, the existing home Reverse Osmosis water purifiers are generally and largely installed in areas where the TDS range of input water is more than 350ppm and upto 2000ppm. Further, if the TDS level of input water is less than 350ppm, then taste of purified water in most cases
becomes bitter. Therefore, it is recommended to check the TDS level of input water before installation of the Reverse Osmosis water purifier. In case where the TDS level of input water exceeds 2000ppm, then a suitable membrane filter generally referred to as 'brackish water Reverse Osmosis membrane filter' meant for very high levels of TDS is used.
[007] Therefore, there is a need for a system which uses reverse osmosis for water purification without otherwise wasting the water and which can eliminate or minimize the problem of bitter taste if Reverse Osmosis purifier is used in very low TDS water.
OBJECT OF INVENTION
[008] The principal object of this invention is to provide a reverse osmosis system to reduce wastage of water during water purification.
[009] Another object of the invention is to provide a reverse osmosis system that avoids bitterness in the purified water, if Reverse Osmosis purifier is used in low TDS water.
[0010] A further object of the invention is to provide a method for reducing wastage of water and avoiding bitterness in the purified water during purification of water by reverse osmosis.
[0011] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be
understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF FIGURES
[0012] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0013] FIG. 1 depicts a reverse osmosis system according to embodiments as disclosed herein;
[0014] FIG. 2 is a graph between time and total dissolved solids (TDS) level according to an embodiment disclosed herein;
[0015] FIG. 3 is a graph between time and total dissolved solids (TDS) level according to an embodiment disclosed herein;
[0016] FIG. 4 is a graph between time and total dissolved solids (TDS) level according to an embodiment disclosed herein;
[0017] FIG. 5 is a graph between time and total dissolved solids (TDS) level according to an embodiment disclosed herein; and
[0018] FIG. 6 is a graph showing recovery and reject percentage.
DETAILED DESCRIPTION OF INVENTION
[0019] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0020] The embodiments herein achieve purification of water without substantial water wastage and minimizing the bitter taste to the purified water by using the system as described herein below. Referring now to the drawings, and more particularly to FIGS. 1 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0021] FIG. 1 depicts a reverse osmosis system 100 according to an embodiment as disclosed. The system 100 includes a diverter valve 101 having an inlet 10li, an outlet 10lo and an stopcock 101s, a lower pressure switch 102 having an inlet 102i and an outlet 102o, a sediment cartridge 103 having an inlet 103i and an outlet 103o, a plurality of solenoid valves
104, a plurality of total dissolved solids (TDS) probe 105, a 106, an antiscalant reservoir 107 having an inlet 107i and an outlet 107o. The antiscalant reservoir 107 further includes an antiscalant media 107a. The system 100 further includes a pre carbon block 108 having an inlet 108i and an outlet 108o, a reverse osmosis membrane filter 109 having an inlet 109i and two outlets 109a and 109b, a post carbon filter 110 having an inlet 100i and an outlet 110o, a storage tank 111 having an inlet 111i and an outlet 111o, a reject flow mechanism 112, and a plurality of non return valves 113. The system 100 further includes an electronic control device (not shown) for regulating the functioning of various electro-mechanical components included in the system 100.
[0022] The inlet 10li of the diverter valve 101 is connected to a water source such as a tap. The diverter valve 101 is in fluid communication with the low pressure switch 102 via inlet 102i thereby facilitating a flow of water from the tap into the low pressure switch 102. The outlet 102o of the low pressure switch 102 is in fluid communication with the inlet 103i of the sediment cartridge 103. The sediment cartridge 103 is configured to remove suspended particles such as dirt, dust, mud and sand from the water. Further, the sediment cartridge 103 is configured to allow a passage of water via the outlet 103o into the booster pump 106 which in turn pumps the water to the antiscalant reservoir 107 through the inlet 107i. The antiscalant reservoir 107 further includes an antiscalant
medium 107a which reduces the hardness of the water. In an embodiment, the antiscaling medium is sodium hexa metaphosphate spheres suspended in the antiscaling reservoir 107.
[0023] Further, the antiscalant reservoir 107 is configured to allow a passage of water to the inlet 108i of the pre carbon block 108 through the outlet 107o. The pre carbon block 108 acts as a pre filter to the reverse osmosis membrane filter 109. The pre carbon block 108 is configured to remove or reduces excess chlorine, odour, color and organic impurities in the water.
[0024] The reverse osmosis membrane filter 109 facilitates the reduction of total dissolved solids (TDS) level by reverse osmosis in the water which comes from the outlet 108o of the pre carbon block 108 through the inlet 109i. Further, the post carbon block 110 is configured to receive the purified water from the outlet 109a through the inlet 100i. The post carbon block 110 is configured to further remove any traces of odour and organic impurities and further is configured to impart freshness to the water. Fresh and purified water is allowed to pass through the outlet 110o of the post carbon filter 110 to the inlet 111i of the storage tank 111.
[0025] Further, the outlet 109b of the reverse osmosis membrane filter 109 is configured to allow a passage of reject water or brine produced by the reverse osmosis membrane filter 109 to the reject flow restrictor mechanism 112. The reject flow restrictor mechanism 112 is configured to
allow, based on the total dissolved solids (TDS) level of the water and other parameters such as capacity of reverse osmosis membrane filter 109, both a flushing of the reject water or brine out of the system 100 and a re¬circulation of the reject water or brine inside the system 100.
[0026] Further, one of the total dissolved solids (TDS) level probe 105 is provided in between the outlet 102o of the low pressure switch 102 and the inlet 103i of the sediment cartridge 103 and the other probe 105 is provided between the outlet 108o of the pre carbon block 108 and the inlet 109i of the reverse osmosis membrane filter 109. One of the non return valves 113 is provided between reject flow restrictor mechanism 112 and the booster pump 106. One of the solenoid valves 104 is placed between the outlet 103o of the sediment cartridge 103 and the booster pump 106.
[0027] It should be noted that the aforementioned configuration of system 100 is provided for the ease of understanding of the embodiments of the invention. However, certain embodiments may have a different configuration of the components of the system 100 and certain other embodiments may exclude certain components of the system 100. For example, instead of the antiscalant reservoir 107, a liquid antiscalant may be added to the stream of water flowing inside the system 100 by a dosing device (not shown) which can be attached in-line along the water circulation path. Further, the locations of solenoid valves 104, total dissolved solids (TDS) level probe 105, and non-return valve 113 may also
be altered. Therefore, such embodiments and any modification by addition or exclusion of certain components of the system 100 without otherwise deterring the intended function of the system 100 as is apparent from this description and drawings are also within the scope of this invention.
[0028] In one embodiment, the specification of booster pump 106 is 24VDC; 0.55amps with maximum pressure 120psi. Further, the reject flow restrictor mechanism 112 has a flow restrictor having 800CC capacity. The reverse osmosis membrane filter 109 is 75GPD and an AC-DC adaptor is selected so as to have an input of 140-300V; 50hz and an output of 24V with 1.5A.
[0029] The method for purification of water using the system 100 is explained herein below. The method includes providing water to the inlet lOli of the diverter valve 101. The water is diverted inside the diverter valve 101 and is passed to the low pressure switch 102. The water is checked for the total dissolved solid (TDS) levels by the total dissolved solid (TDS) probe 105 and then sent to the sediment cartridge 103.
[0030] Suspended particles in the water such as dust, dirt, mud and sand are removed inside the sediment cartridge 103. The resultant water is sent from the sediment cartridge 103 to the booster pump 106. The booster pump 106 pumps the water received from the sediment cartridge 103 to the antiscalant reservoir 107. The water thus received by the antiscalant reservoir 107 is treated with the antiscalant medium 107a to reduce the
hardness of the water. The water is then sent to the pre carbon block 108. In the pre carbon block 108, excess chlorine, odour, color and organic impurities in the water is reduced or removed thereby reducing the load on the reverse osmosis membrane filter 109. Thereafter, the water is checked for the total dissolved solid (TDS) levels by the total dissolved solid (TDS) probe 105 and then sent to the reverse osmosis membrane filter 109. In the reverse osmosis membrane filter 109, certain volume of water is purified and the purified water is sent to the storage tank 111 via the outlet 109a. Further, the reject water is sent to the reject flow restrictor mechanism 112. The reject water from the reject flow restrictor mechanism 112 is again re¬circulated inside the system 100. The recirculation is done by providing the stream of reject water or brine from the reject flow restrictor mechanism 112 to mix with the stream of water coming out of the sediment cartridge 103. Since the reject water or brine would have already gone through the sedimentation process in the sediment cartridge 103 during the previous cycle, the reject water or brine is not provided inside the sediment cartridge 103 again. The aforementioned process is referred to as a filtration cycle.
[0031] The filtration cycle will depend upon the total dissolved solid (TDS) level of the influent tap water as well as the saturated total dissolved solid (TDS) level just before the reverse osmosis membrane filter 109. The recirculation of reject or brine water results in gradual increase in concentration of total dissolved solid (TDS) level and should be flushed out
before the concentration level of the total dissolved solid (TDS) reaches the tolerance level of the reverse osmosis membrane filter 109. The flushing of reject water or brine is carried out in two different steps. In the first step, the water is discharged, indicated by arrow P, from a pre membrane filter spot for a set period of time. The pre membrane filter spot is a location between the outlet 108o of the pre carbon filter 108 and the inlet 109i of the reverse osmosis membrane filter. In the second step of flushing water is discharged from the post membrane filter spot, indicated by arrow F, for a set period of time.
[0032] Further, after the flushing time, the system 100 again resumes the filtration cycle as explained below. The process is carried on until the storage tank 111 is full upon which the electronic device triggers the system 100 to stop the operation. Alternatively, the total dissolved solid (TDS) level probe 105 located in the system 100 along with the electronic device can initiate the automatic selection of filtration and flushing cycle. A flush time is determined based on the volume of brine that needs to be flushed out of the system so that the total dissolved solid (TDS) level in the water again drops down to the initial level which existed at the start of the filtration cycle. Further, the flush time is selected based on the delivery of the pump and volume of reject water or brine flowing within the system 100.
[0033] As is evident from the above description, with the system 100 and the method disclosed herein, the objectives as was set forth initially will be achieved.
[0034] Experiments were conducted for water having various total dissolved solids (TDS) level. Table. 1 provides values obtained at input TDS of 280 ppm for production of 7500ml of water. Corresponding graph is provided in FIG. 2 of the drawings.
(Table Removed)
Table. 1 [0035] Table. 2 provides values obtained at input TDS of 570 ppm for production of 7500ml of water. Corresponding graph is provided in FIG. 3 of the drawings.
(Table Removed)
Table. 2
[0036] Table.3 provides values obtained at input TDS of 753 ppm for production of 7500ml of water. Corresponding graph is provided in FIG. 4 of the drawings.
(Table Removed)
Table. 3
[0037] Table.4 provides values obtained at input TDS of 800 ppm for production of 7500ml of water. Corresponding graph is provided in
FIG. 5 of the drawings.
(Table Removed)
Table. 4 17/25
[0038] Table. 5 indicate the recovery and reject ratio. Corresponding graph is provided in FIG. 6 of the drawings.
(Table Removed)
Table. 5
[0039] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

We Claim:
1. A system for purifying water using reverse osmosis, said system
comprising:
a reverse osmosis membrane filter having an inlet adapted to receive water with a first total dissolved solids level and at least one outlet adapted to allow passage of water with a second total dissolved solids level; and
a reject flow restrictor mechanism configured to be in fluid communication with said outlet of said reverse osmosis membrane filter, wherein
said first total dissolved solids level is lower
than said second total dissolved solids level; and
said reject flow restrictor is configured to
allow a re-circulation of water with said second total
dissolved solids level into said system.
2. The system as claimed in claim 1, wherein said system further
comprises
a sediment cartridge for removing suspended particles from
water;
a reservoir provided with a means to reduce hardness of the water, said reservoir adapted to receive water from said sediment cartridge;
a pre carbon block for removing at least organic impurities from the water received from said reservoir; and
a post carbon block for allowing a passage of water from said reverse osmosis membrane filter to a storage tank.
3. The system as claimed in claim 2, wherein a first total dissolved solids probe is provided for determining a total dissolved solids level of the water in the sediment cartridge.
4. The system as claimed in claim 2, wherein a second total dissolved solids probe is provided for determining said first total dissolved solids level.
5. The system as claimed in claim 1, wherein said system comprises a dosing device adapted to inject a liquid antiscalant into the water.
6. The system as claimed in claim 2, wherein said system further comprises a pump provided to pressurize the water which flows into said reservoir.
7. The system as claimed in claim 2, wherein said means to reduce hardness is sodium hexa metaphosphate spheres antiscalant medium.
8. The system as claimed in claim 1, wherein
said reject flow restrictor is further configured to allow flushing of water with a third total dissolved solids level for a predetermined time; and
said third total dissolved solids level is equal to said first total dissolved solids level and said third dissolved solids level is lower than said second total dissolved solids level.
9. A method for purifying water using reverse osmosis, said method
comprising:
passing water with a first total dissolved solids level into a
reverse osmosis membrane filter;
filtering the water with said first total dissolved solids level
by reverse osmosis to attain a second total dissolved solids
level; and
passing the water with said second total dissolved solids
level to a reject flow restrictor,
wherein
said reject flow restrictor is configured to allow a re¬circulation of water with said second total dissolved solids level to the reverse osmosis membrane filter for a predetermined duration;
said first total dissolved solids level is lower than said second total dissolved solids level.
10. The method as claimed in claim 9, wherein the water passed into
the reverse osmosis membrane filter is free of at least suspended
particles and organic impurities.
11. The method as claimed in claim 9, wherein said method further
comprises
flushing of water with a third total dissolved solids level from the reject flow restrictor for a predetermined time, wherein
said third total dissolved solids level is equal to said first total dissolved solids level and said third dissolved solids level is lower than said second total dissolved solids level.
12. The method as claimed in claim 11, wherein said flushing of water
includes a first stage flushing and a second stage flushing.
13. The method as claimed in claim 12, wherein
said first stage flushing includes discharging of water with a third total dissolved solids level from a pre membrane filter spot for said predetermined time; and
said pre membrane filter spot is located before said reverse osmosis membrane filter.
14. The method as claimed in claim 12, wherein
said second stage flushing includes discharging of water with a second total dissolved solids level from a post membrane filter spot for said predetermined time; and
said post membrane filter spot is located after said reverse osmosis membrane filter.
15. The method as claimed in claim 9, wherein re-circulation of water
with said second total dissolved solids level includes mixing of
water with water having said first total dissolved solids levels.
16. A method for purifying water using reverse osmosis, said method comprising:
providing water from a water source;
removing suspended particles from the water;
reducing hardness of the water;
removing at least organic impurities, excess chlorine, odor
and color from the water; and
reducing total dissolved solids level in the water;
re-circulating water with increased total dissolved solids
level, wherein said re-circulation includes mixing of water with increased total dissolved solids level with the water at said step of reducing hardness of said water.