F-600Iron and Manganese Removal

How it works

1. Why it is dissolved at all — Groundwater sits without oxygen, and in that state iron and manganese are soluble — the water comes out of the borehole clear. Minutes later it is orange in the sink, because contact with air has done what your filter was supposed to do. The whole unit exists to make that happen where you want it, in a vessel, rather than in the customer’s laundry.
2. The limits are aesthetic, and strict — Iron is a problem at 0.3 mg/L and manganese at 0.05 mg/L — neither is a health limit, both are staining and taste. Manganese is the harder of the two by an order of magnitude: a sixth of the concentration, and far slower to oxidise. A plant that meets iron and misses manganese is the usual outcome of a design that treated them as one problem.
3. Oxidise, then filter — Two steps, and the first is the one that fails. Dissolved Fe²⁺ and Mn²⁺ must become Fe(OH)₃ and MnO₂ — solids — before any filter can touch them. Give the reaction somewhere to happen and enough time, or the filter passes the metals straight through and you have built an expensive strainer.
4. pH is the gate — Iron oxidises readily above about pH 7. Manganese does not: with oxygen alone it needs pH 9.5, which is why plain aeration plants so often leave it behind. The catalytic media exist to get around exactly this — an MnO₂ surface drops the manganese threshold by two pH units or more. Drag the pH slider down and watch manganese start to break through while iron carries on unaffected.
5. Manganese greensand — Glauconite grains carrying a manganese dioxide coating, kept active by a continuous trickle of permanganate into the feed. The coating does the oxidising; the permanganate keeps rebuilding it. Its weakness is the coating itself — soft water, low alkalinity or hot water strip it, and once it is gone the bed is just sand.
6. The backwash decides the design — Every gram of metal you remove stays in the bed until you wash it out, and the medium must be fluidised to release it. Density sets that rate: a light medium lifts at 27 m/h, pyrolusite needs about 45. Size the backwash pump and the waste handling for that number, because it is far larger than the service flow and it is what people forget.
7. What governs it — pH decides whether manganese comes out at all; loading rate and contact time decide whether the reaction finishes inside the vessel; density decides what the backwash costs. The cheapest plant is usually the one that corrects pH first and then runs a modest loading on ordinary media.

Design parameters

The panel opposite runs the same correlations as the F-600 design sheet, so the animation and the calculator cannot disagree. Every parameter below is live — drag one and the picture responds.

Open the full F-600 design sheet for the other one inputs, all twenty-two results with their envelopes, the six equations printed beside the numbers they produce, and a calculation record you can export and put in a design file.