Granular Activated Carbon Filter Plant at Culver City, California

Abstract

The filters at Culver City, California were designed to eliminate the tastes and odors, and other ill effects resulting from a heavy infection of iron and sulphur bacteria in the underground water supply. The organisms causing the trouble were of the filamentous group of iron bacteria, identified in the laboratory as crenothrix, leptrothrix and cladothrix, accompanied by the sulphur bacteria beggiatoa. The idea of filtering this otherwise acceptable ground water came reluctantly and only when lesser treatments were found ineffective after many disappointing trials. Activated carbon filters seemed a shorter cut to relief than complete sand filtration as ordinarily practiced. A good strong dose of chlorine could be applied and then the resulting residue of dead organic matter, not oxidized by the chlorine, could be strained out by the filters, with the activated carbon also constituting the dechlorinating agent by reason of its adsorptive powers. All tastes and odors would thus be removed. This was the theory and it was proved to our satisfaction by a small experimental installation at the plant in question. There is nothing new in the idea of carbon filters. Small household ones used to be very common before public supplies were properly treated. Also, carbon in the form of charcoal was used occasionally in public supplies as far back as 1800. It was not very successful, however, because it lacked adsorptive power, and not until the recent war had any way been found to make it more active. Then carbon was used in gas masks, activated so as to be much more adsorptive than natural chars. Activated carbon is now used in many water works plants throughout the country to eliminate tastes and odors. Its use has been confined almost exclusively to the powdered form, the powder being added in the preliminary stages of a more or less elaborate water treatment process and then subsequently removed from the water by sand filters. On the other hand, beverage plants and other industries