Agenda - 01-20-1998 - 10a - Laserfiche WebLink

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this reason, you may want to connect a softener only to the hot water line leaving cold, unsoftened water for cooking and drinking. In iron and manganese removal, the softener must treat both hot and cold water . - since sinks, laundry, and dishwashing equipment are affected. A separate tap can be installed to provide unsoftened water for cooking and drinking. ~~ AERATION Dissolved iron and manganese aze easily oxidized to a solid form by mixing with air. A pressure aerator mixes air with the water, the air is vented, and then the solid particles are filtered from the water.. This method adds no chemicals to the water and is most effective in-warm climates. The filter must be backwashed frequently to properly maintain the system. To protect the water from contamination by bacteria in the air, the system should be totally enclosed and only biologically safe water should be used. The appropriate pumping capacity must be maintained for adequate air intake. O7GDIZING (CATALYST) F]LTER When the total combined iron and manganese concentration is less than 15 mg/l, an oxidizing filter (natural managanese greensand, manufactured silica gel zeolite coated with manganese dioxide, plastic resin beads, or pumicite), is recommended. Some filters aze coated with a manganese oxide and aze regenerated by using a potassium permanganate solution. An oxidizing filter supplies oxygen to convert ferrous iron into a solid form which can be filtered out of the water. Frequent backwashing and stirring of a manganese greensand bed helps prevent aniron-fouled bed. After several weeks of use, the greensand filter should be backwashed with potassium permanganate to remove solid particles and regenerate (recoat) the greensand to allow absorbation of more dissolved minerals. Synthetic filters, such as zeolite, requires less backwash water and softens the water as it removes the iron and manganese. CHLORINATION AND FILTRATION When the iron and manganese content of the water is extremely high (above 10 ppm), a combination of chemical treatment and filtration is necessary. Small chemical pumps aze used to add chlorine bleach, potassium permanganate, or hydrogen peroxide into the water. After a retention time of at least 20 minutes to-allow for oxidation of ferrous iron into the insoluble ferric form, the solid particles are filtered out. When chlorine is used, the treated water can have an unpleasant taste if a particle filter of calcite, sand, anthrocite, or aluminum silicate is used. Use an activated cazbon filter to remove both excess chlorine and solid iron and manganese particles. Backwash frequently. Some units have an automatic backwash cycle. OTI~R TREATMENTS Complexation is a simple and low cost method for removing iron and manganese up to 3 mg/L. A phosphate compound is added to the water to complex (tie up) the dissolved iron or manganese. However, adding phosphates to water supplies is not allowed by law in North Carolina. ff organic-complexed or colloidal iron/ manganese is present in the untreated water, a longer contact time and higher levels of chemical are necessary for the oxidation reaction to take place. Aluminum sulfate