I have a house near Yosemite in California. It is a rental property and thus needs a low maintenance solution to the following problem - Single property residential well with the following specs on a recent water test:
Iron-11.6ppm, Manganese-0.326ppm, Arsenic-358ppb, Lead-50.4ppb, pH-7.3, Total sulfide-2ppm, iron bacteria present. Water is clear.
My thought is to oxidize and filter the Iron and Arsenic, hopefully co-precipitating both to a large extent.
I am considering a well pellet chlorinator followed by a Filox filter and a POU RO, but am wondering if I should add aeration to the Filox filter - 1 or 2 tank (don't know current DO or have a ready way to measure it). I am also wondering if the pellet chlorinator will be a problem since the water will only be used maybe one weekend a month or every other month - ie. the well will not have any chlorine on start-up. Liquid chlorine injection would solve that problem, but I understand that it is not that stable if it left sitting open for months before use. Some have suggested hydrogen peroxide may be more stable, but I have read you have to be 'careful' with H2O2 and Filox. H2O2 is obviously more expensive too...
I am looking for the most cost-effective way to reduce the Arsenic&Iron to manageable levels on POE basis. I am hoping one of the experts here can say if I am going in the right direction or if there might be a better solution. Thanks so much in advance.
One other interesting product I am considering for the above application is the sanitizer plus zeolite softener that has a built-in chlorine generator. Don't know if anyone has used these, but they seem to have it all...
The Water Rite built-in chlorine generation got me thinking about whether it would be possible to generate the chlorine at the well on demand. It turns out there is a system called i-chlor which does exactly that...Has anyone tried this one?
Saw your post and have a solution possibility you might look into. A dissolved oxygen generator would address iron,manganese and oxidize any arsenic 3 to arsenic 5. Softening is a unknown since I don't see hardness listed. Since it is a well, post filtration bacterial prevention would be recommended. The unit I am talking of is made in Minnesota I believe. Would look online and if you can't find you can contact me privately. I have a customer near you closer to Nevada who has a problem well like this.
Interesting idea, thanks. The product is called Water D.O.G. and looks like it would work particularly well with the Filox for everything but the iron bacteria. Iron bacteria are aerobic and I worry that increasing the dissolved oxygen might cause them to proliferate and plug the downstream filter.
This all has me thinking that a chlorine generator ahead of the filter might be the way to go. I've since learned that it might be best NOT to chlorinate the well itself though since it might actually increase the disolved arsenic.
"Iron bacteria are aerobic and I worry that increasing the dissolved oxygen might cause them to proliferate and plug the downstream filter."
I think you may be somewhat off the path here.
Generally speaking IRB's require very little, or miniscule amounts of oxygen to survive. They can easily live in water with oxygen measured in Ppb's.
Some of them have the ability to substitute Nitrate for Oxygen, others convert different sources of nutrients into food which requires very little, if any, oxygen at all.
However, they do like oxygen because it makes life easier for them.
These bacteria have actually been classified as anaerobic by many sources.
It would be important to know which kind of IRB you may have present.
Gallionella, Sheathed IRBs,Crenothrix, Sphaerotilus, Siderocapsa, Heterotrophic, Enteric, or even Pseudomads can be considered associated with IRB. Even though some may be considered iron oxydizing using Redox and other substates for growth.
I would recommend a BART (Biological Activity Reaction Test) as supplied by LaMotte (for example only) sample be pulled and cultured. Then you will know exactly what kind of bacterias you are dealing with in this situation.
There is no doubt that chlorination and proper contact time will eliminate any of the above mentioned critters.
A rule of thumb when co-precipitating iron with arsenic is that you'll need roughly 20 times the amount of Fe vs As. If you're oxidizing all that iron from ferrous to ferric, then you should have plenty to get the As below EPA's limit of 10 ppb. Don't forget to consider the need for adequate contact time. With that much precipitate, a good backwashing filter is definitely called for. On-site generation of chlorine seems like a good idea, though if there's much in the way of natural organic matter you may also have to address disinfection byproducts. In addition to dissolved oxygen, may want to look into ozone generated on site to see how user-friendly that would be.
I also noted you mentioned you did not perform a DO test. I use two methods - Chemetrics DO test kit and the solution offered below. I have tried them both and the 'old fashioned' way works remarkably well.
Rex Johnson
Dissolved Oxygen Test: Richard Chase: 8/20/2009 10:34:05 AM
Rex, this simple ORP test may help you out. It's a good low cost age old proven method.
At room temperature, mix 1 pint water with 1 ounce of potassium permanganate.
Take two drops of the resulting mixture and add to 1 quart of subject water, mix well.
Let stand for 15 minutes.
If pink color remains, media will work without additional oxidants.
If pink color disappears, then additional oxidant is required.
You make some excellent points. I've got Siderocapsa iron bacteria. My main point/question was whether increasing the dissolved oxygen would kill the bacteria like chlorine would and I didn't think it would.
Mark,
Any idea how much contact time would be enough? I was guessing 20-30 minutes with chlorine or just using a static mixer with hydrogen peroxide. I had heard ozone was tough to titrate...anyone have good experience with ozone?
Rex,
Thanks, I knew about the permangenate test but have not been able to find a small quantity of permangenate. It does not seem to be as commonly used anymore.
what is the best residential shower filter and would it remove iron and high aresenic? what is best technology for the shower filter to
#1 to noticeably improve my skin/hair because of ph or lead removal and 32 get rid as many of the bad chemicals like clorine , and any others like the ones mentioned. thanks. Jerseyville Il 62052 Kathy diehl
what is the best residential shower filter and would it remove iron and high aresenic? what is best technology for the shower filter to
#1 to noticeably improve my skin/hair because of ph or lead removal and 32 get rid as many of the bad chemicals like clorine , and any others like the ones mentioned. thanks. Jerseyville Il 62052 Kathy diehl
I would recommend the filox system with the water-right unit. I am very familiar with their products. The iron is quite high so you will probably need to follow it with a fine mesh water softener. The iron will probably be ferric if it gets past the softener so the fine mesh would be a better choice. DO would not be an issue due to the design of the system I am thinking of. I would use the chlorinator system to help keep the beds clean. The water right system will not constantly inject chlorine, only during regeneration and a brine tank will need to be installed on the filox to convert the chloride to chlorine. They do have the ability for a chemical injection system to be added and regulated through the valve which would be paced on flow due to the metered valve function. I would try without this first. The filox is very heavy and will require a good flow rate to properly back wash. I agree with the 20/1 ratio on arsenic reduction with the reduction of iron with an oxidizing system. I also would recommend some sort of redundancy with an arsenic specific media as an added precaution. This could either be POE or POU, If the filox fails without redundancy you would not have back up protection.
I would not go down the road of a self chlorinator on the well for the chlorine can eat up pump ends and it will oxidize all that iron in the well. You may want to investigate well rehabilitation and knock down the iron bacteria coming from the well.
You can always contact me privately and I can help you further. I am trying to be careful to help you with your problem and staying within board rules.
The co-precipitation of iron and arsenic requires 1 mg/L of iron for every 20 ug/L of arsenic. This is a 50:1 ratio. Therefore a 0.326 mg/L concentration of arsenic will require approximately 16.3 mg/L of available iron. This application will require the addition of an iron salt in order to reduce the arsenic to below MCL.
It would probably be advisable to pilot study what ever technology you chose before investing in the full scale system. It is very apparent that you will need more than just a strong oxidant and manganese oxide filtration media to successfully treat this raw to the point where it will meet the EPA's drinking water standards.
Sorry for the late post but I get busy and sometimes it's a week or so between checking the blog. Consider this: At 358 PPB As and 50 PPB Pb this is fairly toxic water. Several very good suggestions have been made for treatment, which are testament to the fact that we in this industry are problem solvers. But I would caution that there is a potentially serious liability here. This job may be "a lawsuit waiting to happen." You are going to need redundancy. You are going to need regular monitoring. You should probably have a written contract with the resident that he/she will not drink the water, even after treatment. Even so, you should probably add an under-the-sink RO. Your legal exposure is great, and I would be very leery of this project.
Dave is exactly correct. You need to have a redundancy system in this applicaton. I also agree that there should be a contract with the customer that they agree to not drink this water even after treatment.
In handeling both of these contaminants at once (although not at this level of As) the beauty is that As has a great affinity for Fe, and the two of them bond to each other very very well.
I would not go with a well chlorinator, instead I would make sure that I had this customer on a semi annual well chlorination schedule to shock the well every 6 months with a product called well sanitizer to keep the Iron Bacteria under control.
I would then use a product like the Iron Curtain or Iron Guard to provide the aeration in one contact tank, and then the filtration through multi medias in the second tank. A key here is enough dissolved oxygen and contact time. I would also suggest replenishing the head of oxygen every 6 hours or even sooner if whole house application especially if any lawn irrigation is occuring. Contact time is key.
I would make sure the well pump is strong enoough for propwer backwashing flow rates. I would then use a large (roughly 24-36") aeration tank followed by 3 12 x 54 filter tanks, with no raw water by-pass pistons for backwashing. This will give you a max flow rate of about 25gpm when all 3 are online, and usually only 2 will be online at a time.
I would confirm with the costomer that you are removing the Iron first, and then re analyzing the As. Once installed retest the As to see what levels you still have. Any remaining levels should be treated with an As system provided by some of the industry As filter companies so that they have the responsibility and ownership of the As filtration and exhausted media disposal.
Then install an RO system approved for As (typically one with a booster pump) and install this to a dedicated source faucet and fridge if ice and water.
So, I installed the Filox system described by Carl a few months ago and it worked pretty well for 2 months or so. Soon after my last visit though, renters started complaining about iron and iron bacteria in the house again. I’m going back up to check on it in a couple of weeks, but wanted to see if anyone has any ideas what the problem could be. Thanks.
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