John
Hello John – It is best to have at 0.2 to 0.8 PPM of peroxide before the carbon. In some of hydrogen peroxide systems for iron we have worked with over the years, no contact tank is used and the peroxide is injected immediately prior to the carbon filter. The oxidation takes place directly on the carbon.
Depending on pH and temperature, generally it takes slightly less than 1 PPM of peroxide to oxidize 1 PPM of iron. With no contact tank, the residual going in to the catalytic carbon filter would be about 4 PPM.
However, one advantage of peroxide is that it also does a great job at killing iron bacteria and
removing odors if there is sufficient contact time. While peroxide is faster acting than chlorine, a retention tank is recommended for disinfection to occur. If you are using a contact tank which can allow several minutes of contact time, a 0.2 to .8 PPM should be present after the contact tank.
