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Thread: Arsenic removal

  1. #1
    Like an engineer alternety's Avatar
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    Default Arsenic removal

    I would appreciate it if some of the experts could recommend approaches to cleaning up my well water. Here is the analysis. I do not have Arsenic speciation numbers. PH - 8.3 Alkalinity - 180 mg CaCO3/L Chloride - 39 mg/L Hardness - 49 mg CaCO3/L Calcium Hardness - 31 mg CaCO3/L Sulfate - 29 mg/L TDS - 280 mg/L Nitrate + Nitrite - 0.5 mg NO3 -N/L Copper - 0.014 mg/L Iron - 0.02 mg/L Manganese - 0.004 mg/L Zinc - 0.005 mg/L Sodium - 88 Potassium - 1.3 Calcium hardness - 12 mg Ca/L Magnesium hardness - 4.6 mg Mg/L Arsenic - 0.017 It will be a whole house filter. Maximum flow rate of about 10 gpm (rated flow rate of particulate filter preceding the equipment under discussion here). Assume about 6 people in the household.

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    In the Trades Akpsdvan's Avatar
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    Whole house for the arsenic?
    Ready to drop 5-6K? for a unit that will do the job?

    0.017 mg/l? is that not 17ppb?

    Research research and then research and more research

    So if you take it out of your water , then what about the food that has arsenic? Look it up..

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    The numbers for Arsenic are directly from the report. It did not have units. I have always assumed 0.017 is in mg/L and that would be 17 ppb. I have done a very significant amount of research over a fairly long period of time. I have accumulated a lot of knowledge, but I am looking for some experts who balance the parameters in their head from long experience. And have seen the pluses and minuses of different approaches. People that have done this a lot. Experience counts.
    Last edited by alternety; 04-29-2010 at 03:45 PM.

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    In the Trades Akpsdvan's Avatar
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    Arsenic removal on the small scale or home has only really been going on now for about 10 years.. before that it was on the large 100gpm range and above.

    I keep asking what is driving this train? I am not saying that some thing should not be done, but who is this truely going to help? you ? me? or the makers and there are only 2-3 of truest worthy arsenic media right now.

    And then there is the government that is saying that we should all be taking care of this in the water, but not one thing about what is in the food from the store.

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    Perhaps you could share the two or three trustworthy media. And maybe some matching equipment. Within the house the water will only be used in a separate drinking water system. For that I coupd use a POU filter seeding just that water circuit. However, I want to use filtered water for watering the food garden and some sensitive indoor plants to avoid building up the arsenic concentration on those beds. Hence "whole house" size filter. I could use both. I am after a system that can measure when the material needs to be replaced/regenerated based on gallons processed and initial concentration levels and chemistry. I would like something that can use regeneration, but disposable media would be acceptable. I have been surprised at the lack of response. Arsenic is not all that uncommon. I live in an area that has levels like mine or higher in many wells. And it is largely untreated. I have been analyzing all the wells on the island and immediate area as part of an effort to define the subterranean water resources. The results of this would be used as input to a new subarea (zoning, development rules, etc.) for our area. I would like to have a solution if I identify specific wells with problems. I would like to come up with a design that I could then use as an example for getting other people in the area to protect themselves with the knowledge I am propagating. Given the mostly rural nature of the area, I expect there will be a need for POU and a higher volume treatment approaching POE. Hence the system I want to build. There will be different levels of concern and money availability. So a broad solution with separable or sizable parts would be a good model. I have read many many studies and tests, etc. I have seen lots of techniques and materials. What I have not found is any specific comparisons of commercially available equipment; or even a good source of the necessary equipment and info for a good DIY effort. A community DIY project would be an interesting project to attempt if I felt comfortable with a couple of designs. Can someone please help out on this?

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    That's all folks! Gary Slusser's Avatar
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    There are different types of arsenic and they require different types of treatment. You haven't said what type you have. Then the type of equipment is based on what else and how much of it is in the water and if there are any pretreatment requirements, and how much water is going to be used.

    IOWs equipment is not 'standardized' so you can use like Consumer Reports to compare from one area to another. That's due to the complexity of water from one location to another and the different 'minerals' used to do the same job, and the way CR does its testing is a joke anyway because they don't test all equipment/products of the same type, they select those they want to test or those the manufacturers provide them for testing.

    You should not limit flow or require a prefilter in front of a regenerated or backwashed filter. You size that filter based on peak demand flow rate of the house, not a prefilter.

    IMO you need to find someone willing to work with you and trust them and not dictate this'er that because as you say, experience counts and you have none and how you'd like to do it may not be possible. I suggest someone local.
    Gary Slusser Retired (= out of business)
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    Let me try just a simple question. What is/are a reliable brand of a system using a disposable media (that gets both arsenic types) and can be calibrated based on well analysis to alert when media needs to be changed?

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    In the Trades Akpsdvan's Avatar
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    The only media that I would have any faith in if that is what you are asking would be from Adedge.
    I know that there was a unit for full building removal done up years ago and to the best that I know it is still on the first round of media.
    The media holds onto the Arsenic and will not release it.
    One could use a meter after the filter to count the gallons used for removal of arsenic.

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    Yes, that is the sort of thing. There are commercial systems that do that; including water-adjusted metering. I would like DIY, but knowing a reliable equipment brand would be helpful. My wife is not into things that need operating attention and maintenance. When I die, she does not want to be stuck with stuff no one but me can fix.

    I don't recollect the material offhand while sitting here, but there is at least one material that tolerates a fairly wide range of ph, locks both flavors of arsenic, and can be disposed of as normal waste. It can be reactivated, but it is a real annoying process, best left to proper facilities. It is, of course, very expensive. There are a number of systems sold as services. Many that I have seen of the service variety, use a dual tank system to protect from breakthrough, and regular arsenic tests. They seem to send some of the materials to a re-activation facility so it is a bit friendlier to landfills.

    My ratio of iron to arsenic is sufficient that oxidation may be able to precipitate it. That is certainly an alternative I am looking at. I am not sure how much of the iron may be bound by other water contents such as a clay. I need to experiment. I have an ozone generator around someplace.

    My primary issue is to fix my water. An additional goal is to find a couple of core components that could be propagated with volume discounts as a community effort.

    There is lots of alternatives. In addition to a technique, the problem I have is in choosing a reliable vendor/manufacturer. Techniques are relatively easy to find and understand. There are bunches of government and academic comparisons of media. Some real interesting techniques developed at some universities, but with no disclosure of sufficient information to build a system. There is one system that uses electrical currents to migrate the arsenic to a collection material. Very inexpensive in terms of construction. Their proof of concept system cost them less than a couple of hundred dollars to build. But they won't disclose any real implementation details. Low maintenance requirement and very little operating cost. Their target is the third world; but lots of these types of people seem to forget that there are people here without a lot of money as well.

    What is lacking is publications of independent evaluations of specific equipment and vendors.

  10. #10
    In the Trades Akpsdvan's Avatar
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    Use the word adedge in the search. Find out what it has to say.

    From what I am seeing of your test that you have posted there is not enough iron to shake a stick at.

    The Arsenic may go up and it may go down.. thus the best would be quater checking with a simple test , and there is one.. I would bet the size of the system needed on that test, but would use the test as a way of "Is it time for a change of media?"

    Also look up Water Quality Assocation.

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    I have examined the Adedge media performance specs. It does indeed seem to be an excellent material. From other sources, real world results with Adedge media has issues with high (> 8) Ph ranges like my water. It is marginally OK. If I do a POU treatment for drinking water, one of their cartridges should last for a very long time for any specific faucet. A whole house filter with extensive irrigation requirements is rather another issue.

    I have worked with a local engineering company to evaluate my problem. We did some tests with my water. The most relevant was the addition of some chlorine and ferric chloride to my raw water. This approach removed all of the arsenic.

    I would like to create a POE system that can deal with a large total volume of water to deal with significant plant irrigation. I am concerned with long term arsenic accumulation in garden beds producing edible materials.

    So what I am looking for is a system that handles about 3 gpm, injects (based on water volume) chlorine and ferric chloride (or a suitable alternative), and filters the flock using a back-washable filter. Capable of a large total volume of processed water. Backwash capabilities from the back-end (filtered water) system can be 10-15 gpm.

    I need a reliable system to inject these materials based on water flow volume, and a suitable back-washable filter stack/controller. I would like to remove residual chlorine.

    Can you suggest a suitable set of hardware for this scenario? Controls, metering system, filter bed. A low cost source would be a real help. The system should be one I can maintain (e.g., no contracts or unavailable materials).

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