Problem – Iron (Rust) & Manganese
Symptoms: Black, grey or orangish-red stains on fixtures, clothes and showerwalls. Buildup inside pipes and toilet tanks. Metallic taste and/or smell.
Causes:Many wells have significant amounts of iron and/or manganese because the underground rock and gravel formations contain large amounts of these elements. Manganese is one of the most abundant metals in the earth's crust and usually occurs in conjunction with iron.
Health Concerns: Drinking water with iron is not necessarily unhealthy, but is generally a nusiance and something that homeowners will not tolerate. At extremely high concentrations, manganese can be a health risk to the central nervous system.
Action Level: Any level over 0.3 mg/l (or ppm) of iron and causes stains and 0.05 mg/l of manganese which is where it form stains.
When treating for iron or manganese in your water, it is imperative that a good analysis of the water be performed. Not just for iron and manganese, but for a number of other contaminants, including hardness, pH, nitrate, tannin, sulfur, TDS and others. The inter-relationshipsof the different contaminats will help in chosing the best technology to solve your problem.
Iron and manganese are generally measured in parts per million (ppm) or milligrams per liter (mg/l). Essentially, these two measurements are the same. Iron is not considered hazardous to health. In fact, iron is essential for good health because it transports oxygen in your blood. In the India, most tap water probably supplies less than 5 percent of the dietary requirement for iron. Iron is considered a secondary or aesthetic contaminant. The present recommended limit for iron in water, 0.3 mg/l (ppm), is based on taste and appearance rather than on any detrimental health effect, while the limit for manganese is 0.05 mg/l. Private water supplies are not subject to the rules, but the guidelines can be used to evaluate water quality.
For instance, when the level of iron in water exceeds the 0.3 mg/l limit and/or manganese exceeds 0.05 mg/l, we experience red, brown, or yellow staining of laundry, glassware, dishes, and household fixtures such as bathtubs and sinks. The water may also have a metallic taste and an offensive odor. Water system piping and fixtures can also become restricted or clogged. As little as 0.3 ppm of iron and 0.05 ppm of manganese can cause staining , and the higher the concentration, the more severe the stains.
There are many types of iron which can occur in a water but it is generally divided into two main categories: (1) soluble or ferrous iron; and (2) insoluble or ferric iron.
Soluble iron, or “clear water” iron, is the type of iron found in groundwater and oxidizes to insoluble or red iron in the presence of oxygen either in the well or in your home. This type of iron is identified after you’ve poured a glass of cold clear water. If allowed to stand in the presence of air, reddish brown particles will appear in the glass and eventually settle to the bottom. When insoluble iron, or red water iron is poured into a glass, it appears rusty or has a red or yellow color. Insoluble iron can create serious taste and appearance problems for the water user.
Iron, which combines with different naturally occurring organic acids or tannins, may also exist as an organic complex. A combination of acid and iron, or organic iron, can be found anywhere; however, it is more common in shallow wells and surface water. Although this kind of iron can be colorless, it is usually yellow or brown.
Finally, when iron exists along with certain kinds of bacteria, problems can become even worse. The bacteria consume iron to survive and leave a reddish brown or yellow slime that can clog plumbing and cause an offensive odor. You may notice this slime or sludge in your toilet tank when you remove the lid.
Iron bacteria in wells do not cause health problems, but they can have the following unpleasant and possibly expensive effects:
There are many ways by which iron and manganese can be removed from the water and most operate on the principal of oxidizing the iron (oxidation) to convert it from a ferrous (dissolved or soluble) to a ferric or undissolved state. Once in the ferric state, iron can be filtered.
A backwashing filter, often called an iron filter, is the most widely used system for removing iron. The most common reasons for filter failure are a lack of flow in backwash or a lack of frequency of regenerations. Filtration using various means of oxidation is the most common method of iron removal. Depending on the media selected, other common processes such as ozone, aeration, chlorine or peroxide injection may be used to boost the oxidizing properties of the water being treated
The pH of the water plays an important role in how quickly ferrous or dissolved iron converts to a ferric or solid state. The higher the pH, the faster iron will convert to the ferric state that can then be filtered. This is good in all equipment selections with the exception of a water softener where the ferric iron plugs the exchange sites and fouls the resin. When using an iron filter a pH above 6.5 is an absolute necessicity, and in reality a pH above 7.0 is what is really needed. A pH of 8.0 to 8.5 greatly enhances the chance of a successful application.
If it is necessary to increase the pH level, chemical feed of sodium carbonate or soda ash is preferred over a filter filled with calcium carbonate or magnesium oxide, as the filter method may foul quickly. Low pH levels when using filters are the chief reason for unsatisfactory results.
Most Popular Media
What follows is a partial list of medias used in iron filtration. We have put them in an order of preference of how effective we feel each method is, from the least effective to the most effective. We do not attempt to address all medias, especially ones which are dubious in design or outdated.
Birm has the ability to remove iron and manganese and has no effect on hydrogen sulfide. Like manganese dioxide, birm also uses dissolved oxygen as a catalyst and may require some type of pre-oxidation in cases where the dissolved oxygen content is too low to affect a maximum iron removal result. Birm is .1 percent manganese dioxide and is fairly leightweight, which allows for proper backwashing. Green Water does not sell a Birm Filter as there are simply better methods which are more predictable and effective for removing iron. At .1 percent manganese dioxide, we feel that it simply is not effcetive for a long period of time.
Greensand is one of the oldest but proven oxidation technologies. Potassium permanganate, itself an oxidizer, is used to regenerate the greensand. Potassium permanganate produces manganese dioxide on the surface of the mineral and, once the water comes in contact with it, any iron is immediately oxidized. The iron can be filtered and then cleaned away in the backwash cycle. Greensand is also effective with low levels of H2S or hydrogen sulfide and manganese. Again, Green Water chooses not to recommend a Greensand system and dislikes the use of potassium permanganate.
KDF-85 is a redox media, which requires dissolved oxygen to be effective. It consists of two metals - 85 percent copper and 15 percent zinc. These two dissimilar metals create a small electrical field in the bed that will not allow bacterial growth in the media. This property earns redox the distinction of being effective on bacterial iron without the use of chlorine injection, and being rated as bacteriostatic. While it is effective on the removal of iron and hydrogen sulfide, and is able to reduce chlorine and heavy metals such as lead and mercury, redox is not effective with manganese. The biggest drawback for this media is its weight. Being almost twice as heavy as other medias, it requires more than twice the backwash rate of other minerals.
Manganese Dioxide - Filox, Adox, Pyrolox
Manganese dioxide, often called Adox, Filox or Pyrolox, is a naturally mined ore with the ability to remove iron, manganese and hydrogen sulfide. The hydrogen sulfide capability exceeds that of either greensand or Birm and requires no chemicals to regenerate. It does, however, require adequate amounts of dissolved oxygen in the water as a catalyst. If the dissolved oxygen level is not sufficient it may require some type of pre-oxidation to achieve its maximum ability, such as injection of chlorine with a chemical feed pump.
The biggest drawback to Filox or any manganese dioxide-based media is that it is heavy and requires a strong backwash to properly remove the the oxidized iron, which wastes a lot of water as well
Many companies promote the injection, pumping or drawing of air to serve as an oxidizer instead of chlorine and some even use air compressors to inject air. We have found that compressors are not the mose effective way to do this, as frequently too much air is in the water. If there is too little, the iron is not oxidized and if there is too much your water fizzes like an Alka-Setlzer.
Ozone is a powerful oxidizer and when used properly can be effective on large amounts of iron. Similar to aeration, ozone is injected into water via a contact vessel as a pre-treatment to filtration. A properly sized Ozone Generator and proper system design is the key to success. Due to ozone’s expense it is usually applied on iron levels higher than normal filtration is known to handle effectively. Each system is custom designed for the application. Ozone costs more than other methods but has a very minimal operating cost.
Water softeners exchange ions. When used in iron removal, the softener uses a cation resin to exchange iron for sodium, in addition to the calcium and magnesium exchanged for sodium in the softening process. Softeners are commonly used in removing low levels of ferrous iron, like 1-3 ppm, though it is not uncommon to remove 10 or more ppm depending on water conditions and control settings.
The last thing a water softener needs is for the ferrous iron to oxidize and convert to a ferric state. Since pH plays a big part in how quickly this conversion takes place, it is important to note that softeners perform better on low pH, which will also prolong bed life.
In the ferric state, iron will coat the resin, plugging the exchange sites and fouling the resin. Iron fouling will eventually happen in any iron application and requires replacement of the media. High saltings, longer backwashes, frequent regenerations and the use of iron cleaners are keys to longer bed life. However, even after taking these steps to prevent the bed from fouling, the resin will eventually succumb to the iron and require replacement.
Filter & Water Softener Combo
Most water which contains iron, also contains higher levels of hardness and for those applications, Green Water offers the filter and softener combo. It couples the Water Softener and Filter into one package. It "infuses" the water with oxygen from the air (naturally) and is extremely effective in removing iron and manganese in concentrations under 10 mg/l.
Using 5 percent to 10 percent chlorine as an oxidizer is also widely used. Chlorination requires a contact tank which should have a 15-20 minute supply of water at peak flow. For instance, if the peak flow is 10 gallons per minute, then a 150-200 gallon contact tank would be needed. Many chlorination systems are undersized in respect to the contact tank, and meet with mixed results. After the injection of the chlorine and flow into the contact tank, a backwashing carbon filter is utilized to remove the precipitated iron and chlorine residual. Chlorine works well with iron IF the contact or retention tank is sized properly and the user knows how to clean the injection point fitting and check valve, as chlorine will frequently chrystalize at that injection point and stop working. Chlorine is a method that works for low levels of iron, but not something we recommend.
The use of hydrogen peroxide in water treatment is best for the eradication of iron or rust, sulfur, which is hydrogen sulfide odor, and manganese. It can truly be called an Eradicator because it TOTALLY removes iron, sulfur and manganese.An OXYgREEN Hydrogen Peroxide System is THE MOST EFFECTIVE METHOD for removing iron, rust, sulfur, hydrogen sulfide and manganese and the rotten-egg odor from your water supply. Hydrogen Peroxide is not a hazardous chemical - to the contrary, hydrogen peroxide or H2O2, is composed of the elements of water: Hydrogen and Oxygen.
There is nothing foreign or chemical added to the water supply. Unlike chlorine, hydrogen peroxide requires no contact time and the reaction or oxidation of iron, rust, sulfur, manganese and hydrogen sulfide is immediate. The OXYgREEN Hydrogen Peroxide System is the answer to practically any iron, rust, sulfur, hydrogen sulfide and manganese problem. With hydrogen peroxide or H2O2 as it is called, you can always predict for a certainity that it will always work, even with iron bacteria.
The distinctive smell of rotten-eggs is caused by hydrogen sulfide or sulfur or sulfate-reducing bacteria or both, and is very difficult to remove. The OXIgREEN System eradicates it – PERIOD! As little as .5 PPM of Sulfur causes this obnoxious odor and as little as .3 PPM of iron or rust causes stains.