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RO systems: Difference between revisions
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[[category: | [[category:Equipment and maintenance]] | ||
[[File:Buckeye-RO.jpg|thumb|right|Buckeye Hydro Premium RO system mounted to a utility sink. Photo by Dr. Adam Bittner]] | [[File:Buckeye-RO.jpg|thumb|right|Buckeye Hydro Premium RO system mounted to a utility sink. Photo by Dr. Adam Bittner]] | ||
A home RO water system is a convenient way to obtain pure water that can be adjusted to serve as the basis for any style of beer or wine. Reverse osmosis (RO) purification involves forcing [[water]] through a membrane using pressure, which removes minerals and other impurities.<ref>[https://www.dupont.com/water/technologies/reverse-osmosis-ro.html Reverse osmosis (RO).] DuPont website. Accessed October 2020.</ref> The pressure required for this process is usually applied via municipal water pressure or sometimes with a pump. RO is a type of crossflow filtration, having two output streams: one with the purified water and one that carries away the waste water containing a high concentration of minerals.<ref name=filmtec>[https://www.dupont.com/content/dam/dupont/amer/us/en/water-solutions/public/documents/en/45-D01504-en.pdf FilmTec™ reverse osmosis membranes technical manual.] Dupont website. Updated April 2020. Accessed October 2020.</ref> A good system typically removes at least 95% of the dissolved solids, and in some cases up to 100%.<ref>Kunze W. Hendel O, ed. [[Library|''Technology Brewing & Malting.'']] 6th ed. VBL Berlin; 2019.</ref><ref name=hob>Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=water/><ref name=hbtrog/> However, as little as 20% of the feed water may be captured as filtered water (i.e. for every 1 gallon collected, 4 gallons go down the drain), and this can be a concern in areas where water availability is limited and/or water disposal is problematic.<ref name=filmtec/><ref name=water/><ref name=bmp5>Eumann M, Schaeberle C. Water. In: Bamforth CW, ed. [[Library|''Brewing Materials and Processes: A Practical Approach to Beer Excellence.'']] Academic Press; 2016.</ref> | A home RO water system is a convenient way to obtain pure water that can be adjusted to serve as the basis for any style of beer or wine. Reverse osmosis (RO) purification involves forcing [[water]] through a membrane using pressure, which removes minerals and other impurities.<ref>[https://www.dupont.com/water/technologies/reverse-osmosis-ro.html Reverse osmosis (RO).] DuPont website. Accessed October 2020.</ref> The pressure required for this process is usually applied via municipal water pressure or sometimes with a pump. RO is a type of crossflow filtration, having two output streams: one with the purified water and one that carries away the waste water containing a high concentration of minerals.<ref name=filmtec>[https://www.dupont.com/content/dam/dupont/amer/us/en/water-solutions/public/documents/en/45-D01504-en.pdf FilmTec™ reverse osmosis membranes technical manual.] Dupont website. Updated April 2020. Accessed October 2020.</ref> A good system typically removes at least 95% of the dissolved solids, and in some cases up to 100%.<ref>Kunze W. Hendel O, ed. [[Library|''Technology Brewing & Malting.'']] 6th ed. VBL Berlin; 2019.</ref><ref name=hob>Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=water/><ref name=hbtrog/> However, as little as 20% of the feed water may be captured as filtered water (i.e. for every 1 gallon collected, 4 gallons go down the drain), and this can be a concern in areas where water availability is limited and/or water disposal is problematic.<ref name=filmtec/><ref name=water/><ref name=bmp5>Eumann M, Schaeberle C. Water. In: Bamforth CW, ed. [[Library|''Brewing Materials and Processes: A Practical Approach to Beer Excellence.'']] Academic Press; 2016.</ref> | ||
Terminology: | Terminology: | ||
'''Permeate''' - The purified water that passes through the RO membrane. | *'''Permeate''' - The purified water that passes through the RO membrane. | ||
'''Concentrate''' - The waste water that does not pass through the RO membrane. It contains relatively higher amounts of dissolved solids (e.g. salts). | *'''Concentrate''' - The waste water that does not pass through the RO membrane. It contains relatively higher amounts of dissolved solids (e.g. salts). | ||
'''Recovery rate''' - The percentage of permeate collected from the water entering the system. | *'''Recovery rate''' - The percentage of permeate collected from the water entering the system. | ||
'''Rejection rate''' - The percentage of dissolved solids removed by the filter. | *'''Rejection rate''' - The percentage of dissolved solids removed by the filter. | ||
'''Total dissolved solids (TDS)''' - The mineral content of the water, expressed as parts per million (ppm, which is effectively the same as mg/L). | *'''Total dissolved solids (TDS)''' - The mineral content of the water, expressed as parts per million (ppm, which is effectively the same as mg/L). | ||
[[File:RO-filtration.png]] | [[File:RO-filtration.png|alt=RO filtration diagram]] | ||
==Quality RO systems== | ==Quality RO systems== | ||
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|[https://www.buckeyehydro.com/premium-ro-systems/ Buckeye Hydro Premium RO System]<br/><br/> | |[https://www.buckeyehydro.com/premium-ro-systems/ Buckeye Hydro Premium RO System]<br/><br/> | ||
[[File:Star-6-16.png|left]] Editor's pick | [[File:Star-6-16.png|left|alt=star]] Editor's pick | ||
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# Sediment filter, 1 micron, multi-layer | # Sediment filter, 1 micron, multi-layer | ||
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====Carbon post-filter==== | ====Carbon post-filter==== | ||
A carbon post-filter is often suggested to help to improve the taste of drinking water.<ref name=hbtguide/><ref>Woodard J. [https://www.freshwatersystems.com/blogs/blog/stages-of-reverse-osmosis-systems Stages of reverse osmosis systems.] Fresh Water Systems website. October 2017. Accessed October 2020.</ref> However, a high-quality carbon block pre-filter combined with a low-flux RO membrane along with proper maintenance should allow the system to effectively remove basically all of the offensive volatile organic compounds. Therefore a carbon post-filter will be generally unnecessary on a quality system, even for drinking water. However, in-line GAC post-filters can easily be added or removed | A carbon post-filter is often suggested to help to improve the taste of drinking water.<ref name=hbtguide/><ref>Woodard J. [https://www.freshwatersystems.com/blogs/blog/stages-of-reverse-osmosis-systems Stages of reverse osmosis systems.] Fresh Water Systems website. October 2017. Accessed October 2020.</ref> However, a high-quality carbon block pre-filter combined with a low-flux RO membrane along with proper maintenance should allow the system to effectively remove basically all of the offensive volatile organic compounds. Therefore a carbon post-filter will be generally unnecessary on a quality system, even for drinking water. However, in-line GAC post-filters can easily be added or removed based on your particular water and RO system performance. GAC is acceptable as a post-filter (vs carbon block) because high performance isn't needed at this stage, and also the contact time in a post-filter is significantly longer compared to a pre-filter, which increases the effectiveness. | ||
===Filter housings=== | ===Filter housings=== | ||
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===TDS meter=== | ===TDS meter=== | ||
A Total Dissolved Solids meter (which actually measures water conductivity and | A Total Dissolved Solids meter (which actually measures water conductivity and estimates TDS) is an essential tool for monitoring RO membrane performance. Some systems offer inline TDS monitoring for convenience, but using a handheld meter is probably a better option. See [[TDS testing]] for meter recommendations and testing instructions; they are fairly inexpensive and easy to use. | ||
<gallery mode="nolines" widths=300px heights=300px> | <gallery mode="nolines" widths=300px heights=300px> | ||
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A flush valve temporarily allows a higher flow of water through the system to flush minerals and organic contaminants (including microbes) away from the RO membrane. Periodic flushing significantly increases the longevity of the RO membrane and can improve system performance (see the maintenance section below). The RO membrane is the most expensive component of the system and therefore a manual or automatic flush valve is a good option to reduce operational cost. A flush valve can still be installed even if you already purchased a system without one. | A flush valve temporarily allows a higher flow of water through the system to flush minerals and organic contaminants (including microbes) away from the RO membrane. Periodic flushing significantly increases the longevity of the RO membrane and can improve system performance (see the maintenance section below). The RO membrane is the most expensive component of the system and therefore a manual or automatic flush valve is a good option to reduce operational cost. A flush valve can still be installed even if you already purchased a system without one. | ||
A flush valve is an optional component since an RO system will function adequately without it. In fact, most home RO systems on the market do not have a flush valve. The sellers obviously prefer that you buy expensive replacement RO membranes more frequently rather than perform preventative maintenance to extend the membrane life | A flush valve is an optional component since an RO system will function adequately without it. In fact, most home RO systems on the market do not have a flush valve. The sellers obviously prefer that you buy expensive replacement RO membranes more frequently rather than perform preventative maintenance to extend the membrane life. | ||
'''Manual:''' As the name implies, a manual flush valve must be opened and closed by hand whenever you need to flush the system. It's easy—just turn the valve 90°, but you need to remember to use it. | '''Manual:''' As the name implies, a manual flush valve must be opened and closed by hand whenever you need to flush the system. It's easy—just turn the valve 90°, but you need to remember to use it. | ||
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# Pressurized storage tank | # Pressurized storage tank | ||
Collection in an open (unpressurized) vessel simply requires placing the end of the permeate tubing into whatever vessel you want to fill with water, such as plastic water jugs. You will need to manually turn off water flow to the RO system when the vessel is full. The obvious major downside to this method is that the vessel will overflow if it runs for too long. A simple solution to avoid problems in that case is to place the collection vessel in a sink, in a tub, on the ground near a drain, or outside (weather permitting). | Collection in an open (unpressurized) vessel simply requires placing the end of the permeate tubing into whatever vessel you want to fill with water, such as plastic water jugs. You will need to manually turn off water flow to the RO system when the vessel is full. The obvious major downside to this method is that the vessel will overflow if it runs for too long. A simple solution to avoid problems in that case is to place the collection vessel in a sink, in a tub, on the ground near a drain, or outside (weather permitting). Once you know the production speed of your system, you can set a timer to remind you to turn off the system when the vessel is full. | ||
If you prefer to have the system shut-off automatically when the vessel is full, you can use a dedicated vessel with a float valve installed. The float valve will shut off the permeate flow when the water fills to the level set by the valve (similar to how a toilet tank works). In this setup, an automatic shut off valve (ASOV) is also needed to shut off the flow of water from the feed water supply line; otherwise water would continue to flow down the drain after filling stops.<ref name=bhfaq/><ref name=screwy/> Additionally, a check valve is needed to prevent backflow through the RO membrane.<ref name=buckeye>[https://www.buckeyehydro.com/content/3_Stage_RO_System.pdf Understanding and operating your new reverse osmosis system (premium series RO system instructions).] Buckeye Hydro website. Accessed October 2020.</ref> Keep in mind that tanks and plumbing in contact with the filtered water should be plastic (or lined with plastic) because the purified water is corrosive to metal.<ref name=water/><ref>[https://www.homebrewtalk.com/threads/letting-ro-water-sit.686123/ Letting RO water sit.] HomeBrewTalk website. October 2020. Accessed October 30, 2020.</ref> If metal must be used for the collection vessel, [[stainless steel]] is preferred.<ref>[https://www.homebrewtalk.com/threads/ro-systems-cost-effective.670740/ RO systems cost effective?] HomeBrewTalk website. 2019–2020. Accessed October 2020.</ref> | If you prefer to have the system shut-off automatically when the vessel is full, you can use a dedicated vessel with a float valve installed. The float valve will shut off the permeate flow when the water fills to the level set by the valve (similar to how a toilet tank works). In this setup, an automatic shut off valve (ASOV) is also needed to shut off the flow of water from the feed water supply line; otherwise water would continue to flow down the drain after filling stops.<ref name=bhfaq/><ref name=screwy/> Additionally, a check valve is needed to prevent backflow through the RO membrane.<ref name=buckeye>[https://www.buckeyehydro.com/content/3_Stage_RO_System.pdf Understanding and operating your new reverse osmosis system (premium series RO system instructions).] Buckeye Hydro website. Accessed October 2020.</ref> Keep in mind that tanks and plumbing in contact with the filtered water should be plastic (or lined with plastic) because the purified water is corrosive to metal.<ref name=water/><ref>[https://www.homebrewtalk.com/threads/letting-ro-water-sit.686123/ Letting RO water sit.] HomeBrewTalk website. October 2020. Accessed October 30, 2020.</ref> If metal must be used for the collection vessel, [[stainless steel]] is preferred.<ref>[https://www.homebrewtalk.com/threads/ro-systems-cost-effective.670740/ RO systems cost effective?] HomeBrewTalk website. 2019–2020. Accessed October 2020.</ref> | ||
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==Maintenance== | ==Maintenance== | ||
Regular maintenance will lower the operation cost, extend the life of the system, and ensure | Regular maintenance will lower the operation cost, extend the life of the system, and ensure production of high-quality water. | ||
Summary: | Summary: | ||