DESC:FIELD OF INVENTION
[001] This invention generally relates to a reverse osmosis system, and more particularly but not exclusively to a method of manufacturing spiral wound reverse osmosis membrane for use in home reverse osmosis systems.
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. The water from these water bodies is utilized for irrigation and domestic purposes. However, for drinking purposes, the water has to be purified since the water from these water bodies may be contaminated with physical, chemical and microbiological impurities and may also have a high total dissolved solids (TDS) level. As people nowadays are aware of the benefits of purified water, there exists a huge demand for equipment capable of removing the contaminants from the drinking water. One of the equipment that is commonly used for purifying water in areas where the TDS range of input water is more than 500ppm and upto 2000ppm is Home Reverse Osmosis systems (HRO systems).Further, if the TDS level of input water is less than 500ppm, then taste of purified water becomes bitter. In case where the TDS level of input water exceeds 2000ppm, a suitable membrane filter generally referred to as Reverse Osmosis membrane filter’ is used.
[003] HRO systems are convenient to use and provide a good quality of drinking water. As a result, there exists a huge demand for HRO systems. The reverse osmosis membrane that is used in HRO systems is selected primarily based on the quality of water source. Further, the reverse osmosis membranes used in HRO systems are enclosed in a cartridge and are usually spiral wound. Spiral wound reverse osmosis membranes used in home reverse osmosis systems are designed to treat water with high levels of dissolved solids.
[004] In spiral wound configuration, long sheets of the reverse osmosis membrane are ingeniously sandwiched together and rolled up around a hollow central tube (core) in a spiral fashion. The conventional cartridges that are used in HRO systems include a spiral wound reverse osmosis membrane having a size of around 10 inch.
[005] To spirally wound the reverse osmosis membrane for use in cartridges for HRO systems, the core is prepared by sticking the double sided tape in the core body and sticking the transparent tape in the end of the cores (step 106). Further, the conventional process of manufacturing spiral wound reverse osmosis membrane (100) includes providing a 40 inch wide flat reverse osmosis sheet (master sheet)(step 102) and slitting the 40 inch wide flat reverse osmosis sheet into three sub sheets of 12inch each by a slitting unit (step 104). A permeate carrier and feed spacer is provided with each of the sub sheets(step 108) Each of the sections is rolled up around the corresponding core using a rolling machine and labeled (Step 110). Further, each of the rolls is trimmed into the standard size of 10inch using a trimming unit in order to obtain a spiral wound reverse osmosis membrane (step 112). A brine seal is fixed with the spiral wound reverse osmosis membrane and subjected to scanning, testing, preservation drying and packaging (step 114). Although, the conventional process of manufacturing the spiral wound reverse osmosis membrane provides the suitable reverse osmosis membrane for use in cartridge in HRO systems, it should be noted that the conventional process of manufacturing the spiral wound reverse osmosis membrane results in high amount of reverse osmosis membrane sheet wastage. Further, as the demand for HRO system increases, significant importance is given to the cost associated with the process of manufacturing the HRO systems. The process of wastage of reverse osmosis membrane sheet associated with the conventional process results in increased cost of manufacturing the HRO systems. For example, in conventional practice, the 40 inch flat reverse osmosis sheet is slitted into three numbers of 12inch sheets. The slitting process generates 4inch reverse osmosis sheet as process wastage (40inch – (12inch X 3) = 4). Further, each of inch reverse osmosis sheet is rolled and then trimmed into 10 inch reverse osmosis sheet, which is a standard size for 75gpd(Gallons Per Day) . The process of trimming generates 1 inch wastage in each side of each of the rolled reverse osmosis membrane thereby resulting in a total wastage of 6 inch for the 40 inch flat reverse osmosis sheet ((12inch -10inch) X 3 = 6 inch). Therefore, the conventional process of manufacturing the spiral wound reverse osmosis membrane results in the total wastage of 10 inch for the 40 inch reverse osmosis sheet.
[006] Further, the conventional process of manufacturing the spiral wound reverse osmosis membrane leads to the reduced yield of spiral wound reverse osmosis membrane. As a result, the conventional process is partially inefficient in satisfying the increasing demand of the HRO systems. For example, for a flat sheet reverse osmosis membrane of 100 meter length, the conventional process provides the total yield of 124 numbers of spiral wound reverse osmosis membrane. Furthermore, significant importance is given to the small size HRO system, thereby small size of the spiral wound reverse osmosis membrane which at the same time achieving the optimum performance as the conventional systems is desired.

[007] Therefore, there is a need for an improved method of manufacturing a spiral wound reverse osmosis membrane that could reduce the process wastage of reverse osmosis membrane sheets. Further, there is a need for a method of manufacturing a spiral wound reverse osmosis membrane that could increase the yield of reverse osmosis membrane thereby satisfying the increasing demand for HRO systems. Further, there is a need for a method of manufacturing a spiral wound reverse osmosis membrane for use in HRO systems that could obviate the above mentioned drawbacks with respect to conventional methods and at the same time provides the optimum performance in HRO systems.
SUMMARY
[008] In one embodiment the present invention provides a method of manufacturing a spiral wound reverse osmosis membrane that could reduce the process wastage of reverse osmosis membrane sheets comprising providing a fourty inch reverse osmosis membrane sheet into a slitting unit, wherein said slitting unit being configured to slit the reverse osmosis membrane sheet into four sub-sheets of ten inch each. Further stacking the sub- sheet of ten inch along with a permeate carrier and feed spacer of ten inch, wherein said permeate spacer is provided between two sub-sheets. Furthermore, rolling said stacked sub-sheet of ten inch around a core. Further trimming the rolled stacked sub-sheet to form a spiral wound reverse osmosis membrane of nine inch. In addition sealing both ends of the spiral wound reverse osmosis membrane.
OBJECT OF INVENTION
[009] The principal object of this invention is to provide a method of manufacturing a spiral wound reverse osmosis membrane that could reduce the wastage of reverse osmosis membrane sheets.
[0010] Another object of the invention is to provide a method of manufacturing a spiral wound reverse osmosis membrane that could increase the yield of reverse osmosis membrane thereby satisfying the increasing demand for HRO systems.
[0011] A further object of the invention is to provide a method of manufacturing a small size spiral wound reverse osmosis membrane, thereby HRO system that could achieve optimum performance.
[0012] 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
[0013] 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:
[0014] FIG. 1 is a flowchart depicting a conventional process of manufacturing spiral wound reverse osmosis membrane; and
[0015] FIG. 2is a flowchart depicting a process of manufacturing spiral wound reverse osmosis membrane according to an embodiment disclosed herein.

DETAILED DESCRIPTION OF INVENTION
[0016] 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.
[0017] The embodiments herein achieve a method of manufacturing a spiral wound reverse osmosis membrane that could reduce the wastage of reverse osmosis membrane sheets. Further, the embodiments herein achieve a method of manufacturing a spiral wound reverse osmosis membrane that could increase the yield of reverse osmosis membrane thereby satisfying the increasing demand for HRO systems. Furthermore, the embodiments herein achieve a method of manufacturing a small sized spiral wound reverse osmosis membrane having optimum performance. Referring now to the drawings, and more particularly to FIGS. 1 to 2, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0018] FIG. 2is a flow chart depicting a method 200 of manufacturing a spiral wound reverse osmosis membrane that could reduce the process wastage of reverse osmosis membrane sheets. In the specification at various instances the terms “ reverse osmosis membrane sheet and master sheet” are related to a single element i.e. a reverse osmosis membrane sheet. The method 200 includes providing a standard 40inch width flat reverse osmosis membrane sheet (master sheet) (step 202) to a slitting unit. The master sheet transferred to the slitting unit and slitted into four equal number of sub sheets, each having a width of 10 inch (step 204). In an embodiment, the master sheet is slitted in to four sub sheets by altering the slitting unit. The conventional slitting unit includes four cutting blades and designed to slit three number of sub sheets each having a 12inch width. Whereas, the slitting unit in the present invention is modified by changing the slitting width from 12inch to 10inch. Further, at least one cutting blade is eliminated to the conventional slitting unit and thereby slitting 4 equal sub sheet of 10 inch. Thereby the present invention eliminates 4 inch process wastage which occurs in the conventional process. However, it is also within the scope of the invention that the standard 40inch master sheet could be slitted into four sub sheets each having 10inch width by any other mechanism without otherwise deterring the intended function of the method 200 as can be deduced from this description. The slitting process according to the present invention eliminates the 4inch process wastage that is provided in the convention process.
[0019] In an embodiment, a core for the reverse osmosis system is prepared by sticking a doubled sided tape to a tube defined by core and by sticking a transparent tape at end of the core (step 206). Further, each sub sheet of ten inch is stacked along with a feed spacer & the permeate carrier of ten inch, such that said feed spacer & permeate carrier is provided between two sub-sheets. The feed spacer is a netting material placed between the sub sheets to promote turbulence in the feed or concentrate stream (step 208).The permeate carrier is a non-woven netting material placed between the sub sheets to carry the permeate (the purified water) from the membrane sub sheets. Furthermore, the stacked sub sheets are rolled around the core using a rolling unit. The conventional rolling unit is modified in order to compensate decrease in the size of sub sheets and to achieve optimum performance of the spiral wound reverse osmosis membrane. The conventional rolling unit is programmed to provide a glue line at 10inch width and an end seal at 95inch length. In one embodiment, the rolling unit according to the present invention is programmed to provide a glue line at 9inch width and an end seal at 105inch length. In one embodiment the rolling unit may be configured to accommodate any width and length of sub-sheet.
[0020] The increase in length of the sub sheets provides active surface area of reverse osmosis membrane that could achieve the optimum performance. The thickness of the feed spacer is optimized to meet the dimensional requirements of the standard Home RO element. Further, the tension is adjusted to suit the increased diameter due to the increase in layout length. The stacked sub-sheet roll is labeled as per user requirements.
[0021] Furthermore, the stacked sub-sheet roll is trimmed in to smaller spiral wound reverse osmosis membrane for use in cartridge in HRO systems (step 212). In an embodiment, the stacked sub-sheet roll of size 10inch is trimmed for 0.5inch from each side thereby making a 9inch spiral wound reverse osmosis membrane. According to the present invention, the wastage that occurs during the trimming process of reverse osmosis
membrane is 1inch for each stacked sub-sheet roll and 4 inch for the 40inch standard master sheet. Thereby saving 2 inch of master sheet. In conventional system, the wastage that occurs during the trimming process of reverse osmosis membrane is 2 inch for each stacked sub-sheet roll and 6 inch for the 40 inch standard master sheet. Thus the present invention saves 2 inch of master sheet in the trimming process. Although, the size of spiral wound reverse osmosis membrane obtained from the process as described in the present invention is less than the size of spiral wound reverse osmosis membrane obtained from the conventional process, it should be noted that the increase in layout length from 95inch to 102inch compensates the surface area of reverse osmosis membrane thereby providing optimum performance. Also, the diameter of the spiral wound reverse osmosis membrane increases from 1.8 inch to 1.9 inch, which constitutes for optimum performance of the reverse osmosis membrane. In an embodiment, the performance of the spiral wound reverse osmosis membrane obtained from the process as disclosed in the present invention is determined as 200 ml/min average flow and above 90% TDS rejection.
[0022] In one embodiment a brine seal is fixed to the ends of the trimmed spiral reverse osmosis membrane. Further, a bar code is affixed to the trimmed spiral wound reverse osmosis membrane. The bar code affixed on the trimmed spiral wound reverse osmosis membrane assists in traceability of the membrane. Further, the trimmed spiral wound reverse osmosis membrane is scanned (Step 214). The scanned spiral wound reverse osmosis membrane is then transferred to a testing section in order to identify flow and conductivity reduction (Step 216). Furthermore, the trimmed spiral wound reverse osmosis membrane which satisfies the optimum requirements is transferred to the preservation and drying station (step 218). In preserving and drying station, the spiral wound reverse osmosis membrane is preserved and dried as per the specification. Furthermore, the dried spiral wound reverse osmosis membrane is packed and dispatched (step 220) to respective requirements. In an embodiment, the packaging is performed by wiping off all excess glycerin and removing all debris from the spiral wound reverse osmosis membrane.
[0023] It should be noted that the aforementioned steps for manufacturing spiral wound reverse osmosis membrane are provided for the ease of understanding of the embodiments of the invention. However, various steps provided in the above method may be performed in the order presented, in a different order, or simultaneously. Further, in some embodiments, one or more steps listed in the above method may be omitted. Therefore, such embodiments and any modification that is apparent from this description and drawings are also within the scope of this invention.
[0024] As is evident from the above description, with the method 200 disclosed herein, the objectives as was set forth initially will be achieved. For example, the method of manufacturing spiral wound reverse osmosis membrane as disclosed in the above description discloses the process of slitting the 40inch wide master sheet into four number of sub sheets each having 10inch width. The slitting process as disclosed in the present invention eliminates the 4inch process wastage unlike the convention slitting process. In an embodiment, it is observed that the present invention results in 154 spiral wound reverse osmosis membrane for 100meter standard 40inch reverse osmosis sheet whereas the conventional process results in 124 spiral wound reverse osmosis membrane for 100meter standard 40inch reverse osmosis sheet. Thus the present invention improves the output yield ratio by 24%.
[0025] Also, the trimming process as disclosed in the present invention provides 4 inch reverse osmosis membrane as process wastage for a standard 40inch master sheet thereby saving 2 inch reverse osmosis membrane when compared to conventional trimming process that provides 6inch reverse osmosis membrane as process wastage. Thus the present invention results in saving 6 inch of master sheet in total which results in 60 % reduction in the process wastage.
[0026] 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.

,CLAIMS:We claim:
1. A method for manufacturing a reverse osmosis membrane for HRO systems, said method comprising:
providing a forty inch reverse osmosis membrane sheet into a slitting unit, wherein said slitting unit being configured to slit the reverse osmosis membrane sheet into four sub- sheets of ten inch each;
stacking the sub-sheet of ten inch along with a permeate carrier and feed spacer of ten inch, wherein said permeate carrier is provided between two sub-sheets;
rolling said stacked sub-sheet of ten inch around a core;
trimming the rolled stacked sub-sheet to form a spiral wound reverse osmosis membrane of nine inch; and
sealing both ends of the spiral wound reverse osmosis membrane.
2. The method as claimed in claim 1, wherein said ends of the spiral wound reverse osmosis membrane are sealed using a brine seal
3. The method as claimed in claim 1, wherein said method further comprises of attaching a bar code to the trimmed spiral wound reverse osmosis membrane.
4. The method as claimed in claim 1, wherein the core is prepared by sticking a doubled sided tape to a tube defined by core and by sticking a transparent tape at end of the core.
5. The method as claimed in claim 1, wherein the stacked sub-sheet is rolled around the core by a rolling unit.
6. The rolling unit as claimed in claim 6, wherein the rolling unit is programmed to provide a glue line at nine inch width and an end seal at hundred and five inch length.

Date: 7th August 2013 Signature:
Vikram Pratap Singh Thakur