Iron removal is a common treatment for commercial industrial and drinking applications. Iron and Manganese in their oxidized forms can contribute to suspended solids in water. Found as dissolved ions in many underground water sources, Iron and Manganese become insoluble solids after oxidation when in contact with Oxygen present in surface waters.
Australian groundwater can contain soluble Iron and oxidised Iron as hydroxides and oxides. Bore water can contain high levels of soluble iron which is oxidised and forms particles when in contact with the dissolved oxygen in water.
In general terms and when present in low to medium concentration levels in drinking water, Iron does not represent a risk to health or environment. However it brings unpleasant metallic taste and colour to the water flow.
In commercial and industrial environments Iron has a much bigger impact: Iron will deposit on surfaces and cause corrosion, overheating problems, clogs and blockages. Iron deposits on the heat transfer surfaces are typically hard, dense and porous and accelerate corrosion while generate an insulating effect that prevents heat transfer and causes the temperature of metals to increase.
Dissolved Iron removal involves converting it into non-dissolved particles that can be removed by standard filtration methods. Treated water can have an Iron content as little as 0.01 ppm, which qualifies for membrane filtration systems such as reverse osmosis, nanofiltration or ultrafiltration.
Dissolved Iron cannot be filtered easily so the common practice consists of transforming it into the undissolved form and then remove the particle flocks by filtration.
Hence, removal of Iron from water is divided in two separate stages:
The oxidation stage can also be carried out by:
Aeration requires a significant footprint but is easy with low running costs other than the initial investment. It also helps removing aggressive CO2 and with Hydrogen Sulfide removal.
Oxidation by means of chemical dosing is faster than aeration and very effective regardless of the iron content in water, however operational costs will be higher and chemical handling will be a part of the process.
Manganese, along with Iron and turbidity, is a common quality issues in Australian groundwater. The recommended limits of 0.3 mg/l for Fe and 0.05 mg/l for Mn in drinking water are the approximate concentrations above which both cause problems like metallic taste and odour, laundry stains, and blockages.
Manganese is usually present in lower concentrations than Iron but will also need to be removed.
Manganese can be found dissolved as Mn2+ or insoluble as Mn3+ or Mn4+.
Same as Iron, dissolved Manganese cannot be filtered easily and will require a first oxidation stage followed by sediment filtration.
Fe and Mn can be oxidised using aeration, chlorine dosing or any other oxidation agent but reaction times are, in general, high (5 to 30 min). These reaction times can be accelerated by means of a catalytic media like Greensand or DMI-65, with which Fe and Mn are oxidised and precipitated by contact with the catalytic media.
Watercore engineers, designs and manufactures water treatment systems based on catalytic filtration that removes not only Iron (Fe) and manganese (Mn), but also hydrogen sulfide (H2S). The filter design will consider flow rates, Iron content and final use.
| Data Sheet | Fe & Mn reduction by media filtration |
|---|---|
Feed Flow | 5 – 200 m3/h |
Raw Water Turbidity | If turbidity > 1 NTU it is recommended to use a pre-filtration |
Filtration Media | DMI-65 |
Filtration Rate | 8 – 12 m/h (m3/h per m2). Fe concentration and presence of Mn will determine final filtration rate design |
Working Pressure | 2 bar – 8 bar |
Filter Diameter | 0.3 – 3 m |
Filter Height | 1.1 – 3 m |
Vessel Materials | FRP filament winding |
Backwash options | Manual Automatic (Timer) Automatic (diff Pressure) |
| Model | Filtration Flow (m3/h) | Backwash Flow (m3/h) | Tank Dimensions D x H (inches) | Pipe Size |
|---|---|---|---|---|
| HR-SF22 | 0.4 (10 m3/day) | 0.9 (22 m3/day) | 8×44 | 3/4″ |
| HR-SF30 | 0.6 (15 m3/day) | 1.2 (30 m3/day) | 9×48 | 3/4″ |
| HR-SF36 | 0.7 (18 m3/day) | 1.5 (36 m3/day) | 10×54 | 3/4″ |
| HR-SF44 | 0.9 (22 m3/day) | 1.8 (44 m3/day) | 12×52 | 1″ |
| HR-SF65 | 1.3 (32 m3/day) | 2.6 (65 m3/day) | 13×54 | 1″ |
| HR-SF75 | 1.6 (38 m3/day) | 3.2 (75 m3/day) | 14×65 | 1-1/2″ |
| HR-SF88 | 1.8 (44 m3/day) | 3.6 (88 m3/day) | 16×65 | 1-1/2″ |
| HR-SF115 | 2.4 (57 m3/day) | 4.75 (115 m3/day) | 18×65 | 1-1/2″ |
| HR-SF145 | 3 (72 m3/day) | 6 (145 m3/day) | 21×62 | 1-1/2″ |
| HR-SF200 | 4.1 (100 m3/day) | 8.2 (200 m3/day) | 24×72 | 1-1/2″ |
| HR-SF256 | 5.3 (128 m3/day) | 10.7 (256 m3/day) | 30×72 | 2″ |
| HR-SF400 | 8.2 (200 m3/day) | 16.5 (400 m3/day) | 36×72 | 2″ |
| HR-SF580 | 12 (290 m3/day) | 15 (377 m3/day) | 42×72 | 2″ |
| HR-SF630 | 13.1 (315 m3/day) | 17 (400 m3/day) | 48×72 | 2″ |
| HR-SF1000 | 21 (500m3/day) | 27 (650 m3/day) | 63×86 | 3″ |
Filtering Iron and Manganese from bore water can be a challenging task. Present in dissolved or colloidal state will require the application of different filtration methods.
When deciding the right water treatment for removing Iron and Manganese from water, Watercore can help with a range of water treatment systems that will improve the operational efficiency and final treatment costs.
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REVERSE OSMOSIS DESALINATION
IRON AND MANGANESE FILTERS
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