Removal of iron and/or manganese from groundwater is a tricky and sometimes difficult thing to accomplish, especially if manganese is the primary element. If the iron level is the only problem, you can use several methods; including: oxidation/reduction/filtration (chlorination or KMnO4 used as the oxidant or in rare cases: aeration), ion exchange (be careful using this process for fear of resin fouling, especially if iron bacteria is also present), and catalyst systems with special filter medias that drive the pH up to high levels allowing easy removal of the iron precipitate. The removal of managanese, however, is much more problematic than iron alone. The key to successful Mn removal is proper maintenance of pH levels, contact time, and Fe/Mn ratio. Manganese has a much higher valence atttraction to the water molecule than iron which creates more difficulty when trying to remove it by itself. For oxidation/reduction systems the pH of the water must be usually kept higher than 8.2, sufficient levels and contact time for the oxidant must be provided and, for best results, the Fe/Mn ratio should be at least 5:1 to 10:1. There are so many variables involved that I cannot begin to list them all, the best advice I can render is this: pH levels are critical, contact time and filtration material and filtration rates must be carefully observed, backwash rates must be adequately high enough with adequate time to lift and expand the media to remove all precipitate and, finally, the presence of iron or manganese bacteria will cause severe problems in most systems. Do a complete water analysis before starting any design work and be cautious of using membrane systems except for final polishing, they have a tendency to foul and plug rapidly with precipitate. Good luck, epbpe.