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topic 12873

Silica removal from water


A discussion started in 2002 but continuing through 2019

2002

Q. Dear Readers,

Can anybody tell me about silica removal process? I know two processes, soda lime and activated alumina ... but how much it is feasible, I don't know.

Please let me know how we can remove the silica from the water and what is the outlet limit of silica as per WHO.

Regards,

Brijesh Goel
- Mumbai, Maharashtra, India

----
Readers: Were you looking for Removal of Silica Stains instead? Then please see letter 12873a


2002

A. Silica can be removed from raw water easily with standard demineralization techniques. Normally silica is present in a weak acidic form. Ion exchange will remove this as long as the anion resin is the strong base type. Silica in deionized water can easily be reduced to 20-50 ppb. Reverse osmosis will also remove silica by 90-98%. Both of these techniques are non-specific for silica, meaning they also remove all other ionic components along with the silica. Normally these methods work well for most well or surface waters where silica is below 15-20 ppm. In some cases for very large flow rates you can remove silica with lime softening techniques. In lime softening the silica is co-precipitated along with magnesium present in the water (or added if necessary). High temperature softening greatly improves silica removal. For high silica waters as seen in Mexico, Hawaii or other sandy areas where levels are 50-60 ppm or higher, the ion exchange and RO options are more troublesome because you may exceed solubility limits for one, and also you are more likely to have significant levels or non-ionic colloidal silica. This will not ion exchange and may foul an RO membrane. Typically this must be removed with ultrafiltration.

Dan Cooper
- Roscoe, Illinois


thumbs up sign Nice answer. While I did not ask the question I learned a great deal from your post. Thank you.

John Holroyd
- Elkhorn, Wisconsin


thumbs up sign I'll have to agree. There were a couple of gems in that monograph.

John Tuohy
- Ireland



2003

Q. I'm doing my research in desalination esp. removal of silica from concentrated brines using lime. As per Dan Cooper, Mg helps in removal of silica; but in my research it proved wrong. Where the SiO2 conc. was 150-200 it proved negative. Can anyone explain why did this happen and is there anything where alkalinity comes into picture?

Bhaskar [last name deleted for privacy by Editor]
desalination - El Paso, Texas


2004

A. The optimum pH for silica adsorption onto Mg(OH)2 is around 10-11

Christian Tasser
- Irvine, California



2007

Q. Hi

I have come across the same problem to remove Silica (approximately 30 mg/L) in bore water to drinking water standard. The main concern is the use of membrane filters after chemical oxidation using Chlorine gas and pH and alkalinity adjustment using Calcite Filters. The water temperature is around 20 to 25 degree. The water has low hardness, less than 10 mg/L, low pH 4 to 5, and relatively high soluble iron, hydrogen sulfide and aluminium.

Can anyone suggest the most feasible and practical solution in my case? As in silica? Aluminium? Does calcite filters help in reducing aluminium concentrations?

By the way, I chose Chlorine gas out of potassium permanganate, ozone, and chlorine dioxide. Is there any comments or special considerations from anyone?

Thanks.

Max

Max Y [last name deleted for privacy by Editor]
Process Engineer - Australia


2007

A. Water Treatment of Silica can be quite interesting as many people generalize for text book simplicity perhaps.

Oxidised silicon atoms can and do exist in many different chemical and mineral forms, hence a process that works at one location may not be successful in another.

Silicate and silica particles of otherwise identical mineral forms can have different surface charge, according to their geo-history or immediate pre treatment. This characteristic of silicon is beneficial to the silicon chip! but adds complexity for water treatment design.

Understanding the chemical and or mineralogy involving silicon is a fundamental first step in selecting and designing the most appropriate solid-liquid separation technology for a silicate removal process, for any successful drinking water treatment.

Stewart Shipard
- Perth, Western Australia



To minimize your searching efforts and to offer multiple viewpoints, we've combined some threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.



2003

Q. I am experiencing problem with Silica rejection by RO membranes. RO projection software shows silica rejection at level of 99.3 %, but reality is different-close to 90 %. Does anybody have proven numbers(reality) on silica rejection by membranes like CPA3? I do appreciate any information

Jerry Simik
- Guelph, Ontario, Canada


2003

A. The problem may be the pH that you are operating at, particularly if you are using an acid feed to prevent hardness fouling. At lower than neutral pH values, there may be a significant amount of non-ionic, soluble silica that can pass through the membranes. Operation at a higher pH increases the degree of ionization of the silica and its rejection, but increases the vulnerability of your system to hardness fouling.

Lyle Kirman
consultant - Cleveland, Ohio


August 19, 2009

A. Check silica in reject water. If silica concentration is near or more than saturation of silica, then there are only two ways.
1.run your R.O AT LOWER RECOVERY ACCORDINGLY.
2. USE SILICA REMOVAL SPECIAL TECHNIQUES.

SHAHZAD MALIK
- lahore pakistan



December 27, 2008

Q. Silica value is coming very high in dm plant. in filter water silica value comes 7-10 ppm .
WBA INLET SHOWS 5-7 PPM, SBA OUTLET SHOWS 1-.7 PPM INSTEAD OF <.02 PPM. PROBLEM AROSE JUST A WEEK AGO. MY PLANT WAS RUNNING SMOOTHLY BEFORE THAT.

KINDLY TELL ME HOW TO REMOVE THIS SILICA FROM SBA?

GIRIDHAR CHATURVEDI
STUDENT - INDIA


January 15, 2009

thumbs up signThanks for the responses. I deal with water used in our boiler and domestic use.The silica levels are very high about 100 mg/l after being passed through a softening plant. Please keep on posting on this topic.

Eddah bonareri
- Kenya, Nairobi


January 15, 2009

A. Because of the range of particle size, silica removal has no "one size fits all" solution. Ultrafiltration (UF) offers complete removal down to .015 microns. Particles smaller than .015 microns can become lodged inside the membrane pores, occluding them and causing an earlier than expected loss of production.

Neil Oliver
- Elburn, Illinois



April 23, 2009

Q. Hi,
I'm designing a plant to bottle further treated municipal water but I'm not sure with the silica levels (10 mg/L) whether they are too high or ok. What are the WHO limits? what are the effects of having high levels of silica in bottled water?

Phylis Chauke
- Bulawayo, Zimbabwe


May 13, 2009

Q. Hi

Does silica contribute to water conductivity. Some sites say it does and some say it doesn't!
Kind Regards

Naeema Essop
- Vanderbijlpark, Gauteng, South Africa


October 6, 2009

Q. Dear Brijesh, I like your question, but let me ask something: if we have DI water but silica is 20 ppm, we want it 0.1 ppm, will RO work for it?

Regards

Abdul khurram
water care - Lahore Pakistan


December 14, 2009

A. Dear All...for all of you who work in Industries. There are mainly 2 forms of Silica the first one is Reactive Silica and the second one is Colloidal Silica.
Reactive silica is what it is called when silica and bisilicate are in equilibrium with each other.
Colloidal silica is basically a polymer with virtually no charge so Ion Exchange methods cannot remove the same.
The only way of removing these is by Ultrafiltration or Reverse Osmosis which can reduce both of the above >98%. The initial investment will be high but it will help those dealing in HP Boilers. Any questions please feel free to ask me about this.

Sunderam Nagar
- India



January 5, 2010

Q. I have a DI system which forks into different environmental chambers used for testing Glass PV Panels. I have noticed a lot of Silica build up on the samples in the chambers lately. How can I go about removing the Silica?

Can I install a polisher to remove excess Silica at the user (chamber) end of the system?

Tyler Barbaree
quality technician - tucson, Arizona


September 27, 2010

Q. Our spring water contains 68 ppm of Silica. Due to heavy rains the water tables are high and we encountered algae contamination. We add Chlorine Dioxide at the source killing most of yeast & moulds. total counts are low. One big problem is, we notice that the Chlorine Dioxide (0.4ppm) raises the pH to 7.6 and also reacts with silica forming a white precipitate (floc like) and I think this causes inefficiency in killing the algaes. I also use Ozone at bottling time. Still getting large growths of algae after about 20 days. Can anybody help?
A. Cid

albert cid
water provider - QLD, Australia


December 23, 2010

A. We developed a product to remove silica from geothermal brine. In Arizona this presents a problem of course; the cycling up of silica often limits the capacity to produce power. The product works by using a microbe that accepts silica through the cell wall, giving enough surface area and charge to physically remove the silica. Info was published in one of the Power Generation publications.

Scott Frazier
- Ozark, Missouri USA

----
Ed. note: Please get back to us with what magazine and what issue if you remember. Thanks.


August 31, 2012

Q. I would like to know if there is a method of removing silica from boiler blowdown having a concentration of 150-200 ppm to below 5 ppm?

Scott, you mentioned microbes that remove silica. Can you post some technical information about this technology so that readers can view it.

Amin Manji
Consulting Company - Van, BC, Canada


December 9, 2011

A. Try electrocoagulation. We use it to remove a whole variety of suspended solids, emulsified oils, bugs, etc. Has been quite effective with silica. More cost effective than chemical flocculation. Capex is much higher than chemicals, but you make it up in opex.

Chuck Hanebuth
- Houston, Texas, USA


December 21, 2011

Q. I have a well, used for our house, that has high level's of silica (103 mg/L). What are my best AND least costly options? RO is an option but to centrally treat the water will cost over $15,000.

Any other good ideas for dealing with this?

Jeff O
- St. Helena, California, USA


December 28, 2011

Q. I am a student of one of the universities in A.P. I am trying to learn more information on removal of silicon from water.

B.Vijayalakshmi
- Andra Pradesh, India


Hi Vijayalakshmi,

So that we can keep moving forward, and not go around in circles, please ask for any desired clarifications about the many technologies already discussed, or post a more specific question. Thanks!

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


February 20, 2012

Q. What is the most efficient process to remove 180 ppm of silica (reactive or colloidal) to level of 5 ppm - is this by IE/RO/SBA or by EDI? Request your feedback..
Thank you. I appreciate it.

Ved

coimbatore vedavyasan
- Dubai, UAE


September 10, 2012

Q. Dear all

Kindly inform us to remove silica in high alkalinity water. Silica in bore well is 110 ppm, T. Alkalinity is 415 ppm, Total hardness is 150 ppm. We are consuming high ppm of lime and dolomite in the range of 950 ppm each to reduce the level up to 50 - 60 ppm. We are using FeCl3 as coagulant of 25 ppm and Poly electrolyte of 1 ppm.

We want to decrease the chemical consumption. PAC (Poly aluminium chloride) is not approved. Please reply at the earliest.

ARUNACHALAM NARAYANAN
- CHENNAI, TAMIL NADU & INDIA


October 10, 2012

Q. Hi folks,
I am a crude stabilization unit process engineer.
We use condensate as make-up water to electrical desalting vessel.
In order to get the salts out of the crude oil, it first has to be mixed with demineralized water (condensate in our case).
The condensate is pure water having almost zero conductivity. Lately we had a little silica (3.2 mg/L) show up in that make up stream. The reason for that is our carbon beds used for condensate filtering. So right now we are not able to eliminate the cause for such silica contamination but we need to figure out how bad can be the effect of silica-containing condensate to the desalting process as well as to downstream equipment: oil heat exchangers and reboilers.
I know that colloidal silica may strengthen oil-in-water emulsion, but what about dissolved silica?
Anybody know whether silica stays in water phase or it can be partially transferred to the oil phase during the mixing in desalter vessel? Oil coming out of desalter is almost free of water; however I would expect scaling formation in heaters/reboilers if there is still some retained in "dry" oil.
Thanks
Rustam

Rustam Kudaibergenov
oil - Tengiz, Kazakhstan


February 18, 2013

Q. Dear all... we need information on what technology to reduce silica content (silica content 490 ppm , TDS 900 mg/l ), because we need silica content not more than 10 ppm and electrical conductivity < 10 us/cm. This water is for for industrial battery charging.

Thanks for many information.

Subur W
engineering - Indonesia



July 4, 2014

Q. Silica present in water, tests say Silica (mg/L) 5.72

Is it okay OR does it needs to be treated?
If treatment required, please suggest treatment. Thanks.

Musa Shafi
- Lahore, Pakistan


July 2014

A. Hi Musa. I don't quickly see any WHO limits for silica, but how much more study would have to be done depends on your situation. If you are responsible for a public water supply, you'll need to learn the standards inside out.

Folks: Please detail your situation, and do your best to frame your questions in terms of the many very insightful answers already offered! When questions are presented as requests for clarification of suggestions that have been offered, they usually elicit enthusiastic response; but if earlier answers are just blown off, and questions are posed as "start over for me because I can't be bothered putting in any work to try to appreciate what you wrote", the thread often dies).

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


July 9, 2014

A. If this is tap water, then 5 mg/L of silica is a relatively low number. Values of 25-50 mg/L are not uncommon.

However, if this is DI water, then further treatment is needed for most uses.

Lyle Kirman
- Cleveland, Ohio USA



Lab says 10 ppm of silica in DM water -- are they wrong?

August 15, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear sir,
I am generating dm water of pH 6.4, conductivity 1.2 µs/cm.
Our lab in-charge says 10 ppm silica in DM water ... is that a right or wrong report, please tell me.
If silica in dm water, why?
All parameter is offline.

patel jayeshkumar
- gujarat, India


August 2014

A. Hi Jayeshkumar. We appended your inquiry to a long and detailed thread which offers some great explanation of silica in DM water. Still, if you don't trust your lab analysis, you'll have to have some other person or service re-do it -- you can't possibly rely on an internet vote to override an actual chemical analysis :-)

Best of luck.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


September 1, 2014

A. It is very possible that you have 10 mg/L of silica in your DI water. Silica is the first thing to leak off of an anion exchange resin and at pH values < 7 it is not ionized so it adds almost nothing to conductivity.

If you want to have less silica in your DI water, there are several possible ways to accomplish this. You could add a tank of mixed bed resin after your DI system, or you will need to regenerate the anion resin before the water reaches a conductivity set point. Regenerating the anion resin based upon a volume throughput rather than conductivity can accomplish this if your feed water analysis does not vary very much.

Lyle Kirman
consultant - Cleveland, Ohio



August 28, 2014

Q. Sir,
I am facing a problem in SBA supply by THERMAX PLANT. SiO2 of SBA is continuously increasing after regeneration system taken in line. What is the reason of SiO2 increasing? Maybe SBA EXHAUST but a doubt due to not possible that fresh SBA taken in. Chances of increasing SiO2 in SBA EXHAUST of SAC? Please give technical process if it's reason of SAC EXHAUST.

Thanks,

Dilip Singh Gohil
- Bharuch ,Gujarat India



April 14, 2015

Q. Sir,

in bore well water analysis (in ppm):
Mg : 910
Ca : 910
Cl : 5424
SiO2 : 85
Na : 1212
SO4 : 344
TDS : 9407

Designing RO of 12 M3/ Hr. My concern is whether there is any extra treatment required for SiO2 removal?

Himanshu Gohel
- Ahmedabad Gujarat India


April 15, 2015

A. Due to the high silica concentration, the RO recovery is very limited. There are anti-scalents that are reasonably effective for silica, but even with these, the silica in the RO concentrate will probably be limited to about 200 ppm. This is only about 60% recovery.

Lyle Kirman
consultant - Cleveland, Ohio


April 21, 2015

A. The best way to improve your RO recovery, is to go for Lime soda softening and bring down silica level to about 10-12 ppm. This will soften the water and simultaneously improve the system recovery.

Jayant Kumar Joshi
Consultant - New Delhi, India



July 7, 2015

Q. What could be the possible method to remove 50-70 ppb of colloidal silica to NIL ?

Piyush Garg
- Gurgaon, Haryana, India


September 23, 2015

A. Go with UF

Vaibhav M. K.
- Mumbai, India


October 18, 2015

A. At a concentration of < 1 mg/L, I doubt that it is colloidal silica. More likely it is reactive, soluble silica.

Your best approach depends upon what else is in the water and what quality you want the treated water to be. RO will probably remove >98% of this silica, but some type of adsorption might be a better choice.

Lyle Kirman
consultant - Cleveland, Ohio



October 18, 2015

Q. What is the tolerable levels of Silica in the rejects of RO? In other words, what is the solubility limits of Silica in RO rejects? Or What is the concentration limit of Silica in Rejects which will foul the RO membranes?

V Nirmalgandhi
Thirumalai Chemicals Ltd - Ranipet, Tamilnadu, India


October 27, 2015

A. A silica concentration of up to about 120 mg/L can be tolerated in most RO concentrates.

5 mg/L of silica in the permeate with only 28 mg/L in the feed is not very good rejection. You may need a tighter membrane. <1 mg/L should be possible.

Lyle Kirman
consultant - Cleveland, Ohio



Colloidal silica in boiler water

October 10, 2016

Q. Sir...I am facing a big problem with new High Pressure Boiler cleaning. Silica is reaching out of control in super heated steam having value 3.2 to 4.0 PPM, but boiler feed water parameter is TDS-2, pH-8.6, P.Alkalinity-01, M.Alkalinity-02, Total hardness-00 and SILICA IS 00 PPM. Why does steam carry silica and where does it come from if FEED WATER SILICA is zero?

chirag singh
- ambala, haryana,india


March 16, 2017

A. Hi Chirag,

you gave a clue to the answer in your heading.."Colloidal" silica.
Firstly, silica adds very little to conductivity of water.. Many times I have seen water with TDS of <5bppm (measured with conductivity meter) have a Silica level of >>10ppm (measured with spectrophotometer, molybdo-vanadate method).

Colloidal silica will show up very little even in the chemical test, as it is a polymer and quite unreactive. Once it goes into your boiler, it is hydrolysed under high temperature and high pH of the boiler water and appears as if by magic, as suddenly it is monomeric and able to react with the test method.

As for silica's presence in the steam, above about 27BARg, silica is able to evaporate and travel as a gas/vapour with the steam... boiler water carryover is not necessary for this 'silica carryover' to occur, as the silica has become volatile at this temperature..
The silica will condense at the first big pressure drop, which is invariably, across your turbine, leaving silica deposits and consequent loss of balance, vibration, and eventual catastrophe!
I face these issues a lot in Papua New Guinea, which has hard, high silica water in most areas. RO is replacing Demin in many plants, but is not the "magic bullet" that the boiler owners were told it would be..
I try to convince them to base exchange soften before RO, so that we can fine tune the RO for silica rejection by increasing pH of RO feed...(increasing pH of RO feed without softening first will rapidly scale membrane with Calcium).

Andy Webster
Boiler Water Treatment Chemist - Brisbane QLD Australia



March 20, 2017

Q. How to remove 120 ppm silica( to get 60 % ro recovery with single stage;

Also, how to reduce COD? In my RO feed the COD is 700 ppm, so my membrane fouls instantly.

Please give a solution,

Regards,

mahendra singh
- panipat, HARYANA, INDIA



June 23, 2017

Q. Hi there,

I tested town water this week and I received the following information from the lab.

Silicon 53g/m3
Reactive silica 88g/m3 as SiO2
Total Dissolved Silica 114g/m3 as SiO2 (silicon x 2.14 by calculation)

I understand that Total Silica = reactive silica + unreactive silica, so does the lab result give me unreactive silica?

Which of these silica forms can I remove by microfilter?

Thanks all.

Ming Yii
- New Zealand



November 14, 2017

Q. Sir, my plant is ion exchange and anion silica is 0.456 mg/Lit.
But the anion resin [is] in one vessel [and is a mix of] 2 types [of] resin, FFIP & 850. Please give me solution.

Lucky Kagankar
- Maharashtra india


November 2017

A. Hello Lucky. I'm not sure if I even understood the question, but in order to try to remove silica you have mixed two anion exchange resins in the one vessel for better performance than you got from either resin alone?

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


November 18, 2017

A. Silica leakage is lower if you regenerate the DI system counter-currently and regenerate the anion exchanger before exhaustion as determined by conductivity and also more frequently.

Lyle Kirman
Consultant - Cleveland Heights



March 26, 2018

ACRONYMS:

CBD = continuous blowdown
IBD = intermittent blowdown

Q. Dear, in our boiler the silica contains 0.53. In our boiler drum, saturated steam contains 0.01 silica but in super heated steam silica increases up to 0.52 ppm. We are continuously open cbd and every hour ibd for 20 sec. in DM water with silica 0.02 ppm. Can you provide us some suggestion to reduce the silica concentration in final steam?

Dibya Ranjan sahoo
BEC Ltd. - India,bhilai



September 10, 2018

Q. I want to know whether we can reduce reactive silica of 2 ppm in RO2 treated water by doing distillation.

I mean by distillation method can we reduce reactive silica from 2 ppm to below 0.02 ppm.

Basavaraj Kubsad
buyer - Bangalore - Karnataka, India



Full House Water Filtration of Silica

August 21, 2019

Q. Are there now any whole house water filtration systems that reliably
remove silica so that deposits do not occur on bathroom fixtures,
bathroom and kitchen faucets, stainless steel sinks, counter tops, glassware, etc.
I am not talking about silica seen with the naked eye floating in water.
But this "invisible" silica leaves white deposits on surfaces.
This is not lime scale because products for removal of lime scale have no effect. Also, I have read the forum on how to remove the deposits once made. But I want to know about preventing the deposits to begin with.

The previous forum questions/answers, while interesting, relate mainly to treatment of large water treatment systems or for industrial use. Please address whether there are reasonably priced ways to reliably filter out silica for an individual house, other than reverse osmosis. RO would be too costly for the whole house application which I am interested in. I saw "ultrafiltration" mentioned for commercial applications. What about whole house? Any other solutions? Thank you.

Shirley Tyler
Home Owner - Underwood, Washington, USA


August 26, 2019

A. Hi Shirley,
I'm afraid this isn't going to be the news you want to hear.

Yes, it can be done. Ion-exchange across a resin bed would work. Read further up the thread for discussion of 'DI systems' using this technology.

Quick notes on what it is and how it works:
You'd have a contractor set up a system that includes a pump, a prefilter, one or more ion-exchange canisters full of resin, a postfilter, a holding tank, various pressure monitoring gauges, pipes, hoses, and a conductivity sensor that will indicate when the system is not able to process your incoming water any more due to the resin being saturated or 'spent'. When the resin is spent, you call the service provider (I can guarantee you will not be trying to self-pack your media canisters) and have them swap out the canister(s) for fresh.

A canister return/regenerate contract can cost thousands per year. You *could* self-pack instead, but then you have to be willing to do the work of the VERY messy cleanout, and know what to do with the used resin beads (pro tip: start by not spilling any on the floor, or you'll be channeling a toddler trying to walk on ice for the first time, but as a normal sized human with further to fall), which might actually have accumulated enough metals out of the water by this point to be considered a RCRA waste, but you won't know that without lab work, which is another expense of getting set up. It's just a LOT of things to do and keep track of! That's why the water purification companies whose marketing is aimed at the retail/residential market can get away with charging what they do for basically taking on all the headaches themselves!

If you read earlier discussion in this thread, one of the things you might notice is that with water purification there is an efficiency of scale (oh no did I just make a bad mineral deposits pun? oh yes I did!). That's why you mostly see these systems pop up in industrial settings (that, and seriously no one in their right mind would want to shower in deionized water. Speaking from experience here; do not recommend. But that's another conversation entirely). Your operating cost per gallon of water produced on a homeowner sized system is going to be higher than what we pull off out here in the industrial settings, where we have large purchase contracts for consumables (resin) that we get on bulk pricing, and run in facilities that already have means to legally dispose of this type of waste, and skilled labor to operate it. As a residential consumer, you don't get to take advantage of all these efficiencies, and will, unfortunately, pay top dollar.

If it helps get a sense of cost to install, I've been involved in building a couple of these systems sized to provide rinse water to a lab-sized plating line. The cost of materials for our 3-canister, 2-filter system on a 3hP recirculating pump was about $5000. JUST the materials/components. NOT including labor or resin matrix.

You should call up one of the many companies that specializes in this sort of thing, explain your predicament, and get some quotes to help you decide how much it is worth to you annually not to have mineral deposits on glassware and fixtures. Get ready for some sticker shock. There is no cheap whole-house solution to your problem. It's going to be a big initial investment. Think of the cost of setting up a photovoltaic system capable of running your whole house. Personally, I think the return on the solar panels, being cost savings on electricity over time, is a better one than not having streaky dishes, but that's just the opinion of someone who drinks my wine out of coffee mugs anyway so the dog doesn't knock them over...

All that being said, it's quite likely that a couple strategic under-counter softening systems (found at large home improvement stores) to at least take care of a couple lines, like the one into the dishwasher, will be more cost effective. And you can usually install them yourself! Make sure you check that the softener is rated for Silica removal.

Good luck... and oh yeah... don't shower in deionized water :)

rachel_mackintosh
Rachel Mackintosh
Plating Solutions Control Specialist / Industrial Metals Waste Treatment - Brattleboro, Vermont


August 29, 2019

Q. Thank you for taking the time to so thoroughly explain what a DI system is, how it works and the costs involved in installation, use, upkeep, etc. It is much more involved and costly than I had hoped.
And I assume a reverse osmosis system for the whole house would be no better?
Thank you again,
Shirley

Shirley Tyler [returning]
- Underwood, Minnesota, USA


September 8, 2019

A. You could certainly get a quote. Big RO systems like that are ubiquitous on ships -this is the experience I've had with them, working the commercial fishing fleet in the Bering sea, and where I discovered how atrocious they are for showering. Get ready for itchy cracked skin and dandruff like you've never imagined in your worst nightmares!

rachel_mackintosh
Rachel Mackintosh
Plating Solutions Control Specialist / Industrial Metals Waste Treatment - Brattleboro, Vermont


September 2019

thumbs up sign  Thanks for the entertainment included in your postings, Rachel :-)

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


September 9, 2019

Q. Many thanks to Rachel and all others who have provided information helpful to homeowners. I am not educated in the 'hard' sciences so most of the information provided in this thread for water experts over the many years is above me. Here are additional questions and comments that I have for my situation:

1) One gentleman from Australia wrote in 2007, 'Oxidized silica atoms can and do exist in many chemical and mineral forms, hence a process that works in one location might not work in another' Despite this, is it still true that, as was stated by another person, that silica, whether in colloidal or reactive (soluble) form, can be effectively removed to very low levels by reverse osmosis?
2) One person with a home well said that it would cost $15,000 for whole house reverse osmosis. More than I can spend.
3a) We are in a rural community served by a county spring, treated only with minimal levels of chlorine. The county utility says our water is not hard (calcium levels aren't high). They said silica is at only about 20 parts.
Do you think under sink RO systems would be effective/realistic? A quick perusal of sales of these suggests that using them for all water obtained at our bathroom and kitchen sinks would be quite affordable. Our main shower is travertine and the silica deposits aren't noticeable there like they are on the dark granite around the sinks. I would have to research to see if our water pressure would provide adequate flow for the proposed uses and how much waste water would be produced.
3b) I wash glassware and flatware by hand. The other items are cleaned in the dishwasher and don't have noticeable etching or deposits like glassware does so I'm not concerned about treating water for the dishwasher.
3c) Would the 'waste' water be safe for grass and plants?
4) Is it healthier to drink our minimally treated spring water which always passes the utility's required testing or to drink RO water from which minerals are removed?
Thanks for taking the time to respond.
Shirley

Shirley Tyler
- Underwood, Washington, USA


September 10, 2019

A. Quick questions, quick answers as I shove a cold cheeseburger in my face, here goes!!!
1) "is it still true that, as was stated by another person, that silica, whether in colloidal or reactive (soluble) form, can be effectively removed to very low levels by reverse osmosis?"
Yes. Reverse osmosis will remove both dissolved and suspended solids.
2) "One person with a home well said that it would cost $15,000 for whole house reverse osmosis. " That number doesn't surprise me one bit!
3a) "They said silica is at only about 20 parts.
Do you think under sink RO systems would be effective/realistic?" A bit bulky to take up a lot of under counters space but realistic if required. What about just a water softener?
3b) "I wash glassware and flatware by hand. The other items are cleaned in the dishwasher and don't have noticeable etching or deposits like glassware does"
Automatic dishwasher chemicals include a serious dose of surfactants to help rinse clean. This makes sense. There are barware sanitizer/clean rinse washes specifically to prevent streaking on glass when used as a final rinse; you might try this for stemware.
3c) "Would the 'waste' water be safe for grass and plants?" If you're talking about the concentrated water from the other side of the membrane, I wouldn't put it on any plantings I care about, although a controlled application of Silica is indeed very good for a plant's immune system- this could be scorch-level concentrated, including with other stuff like Sodium, though so no.
4)" Is it healthier to drink our minimally treated spring water which always passes the utility's required testing or to drink RO water from which minerals are removed?"
Don't drink the RO water. Nor shower in it, or use it in a fish tank. If you use it to water your houseplants, you must add CalMag to about 100ppm or the plants will soon show signs of multiple nutrient deficiency as the purified water leaches nutrients from the soil and roots. Besides having a flat, awful taste, you actually are better off with a certain level of minerals in your drinking water. All living things have evolved to require a bit of mineral content in the water they use, such as is found in nature. And spring water tastes so much better anyway (unless one is unfortunate enough to share an aquifer with my parents who have a wicked sulfur problem and the well water smells like eggy toots until it's been run through their whole-house permanganate water softener...).

Why not try out some clean-rinse additives (cascade platinum, jet-dri, etc, but read the packaging to see if they are safe for skin contact or ONLY in the dishwasher) in your dish/mopping up water and see if the situation improves before committing to anything pricey?

Good luck!

rachel_mackintosh
Rachel Mackintosh
Plating Solutions Control Specialist / Industrial Metals Waste Treatment - Brattleboro, Vermont

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