Diatomite Water Filtration Developed for Field Troops

Comparison Studies of Diatomite and Sand Filtration

“…Establishment of the necessary accounting procedures, installation of necessary meters, and completion of training personnel permitted the beginning of routine operations for comparison purposes on Feb. 1,1955. The test period was continued through Jan. 31, 1956.…”

“…Chemicals are fed proportionately to flow of raw water by eductor unit which adds chemicals as a slurry each time a set number of gallons passes through the meter. Pump A has dual function of: [1] providing recirculation through precoat pots and filters to apply an initial coating to the diatomite filters before productive filtration begins; and [2] repumping the gravity overflow from the contact unit when diatomite-filtered pretreated water is to be produced in place of diatomite-filtered raw water.…”

“…In discussing filter aid costs it should be recognized that filter aid is used in two ways: [1] as precoai, in which a definite weight of material is applied to the filtering surface prior to the actual start of production and [2] as body feed, in which a continuous feed of filter aid is maintained proportional to the amount and nature of the suspended solids to be removed. Figure 5 illustrates the effect of these separate filter aid usages.…”

“…At other company locations where diatomite filters are installed, agitated slurry tanks and various types of slurry pumps are used for the injection of the filter aid into the system. Such pumps require considerable maintenance and, more important, are subject to stoppages which in the present abandoned when it was found to have two serious deficiencies: [1] it caused different grades of filter aids to be fed at widely different rates varying by as much as 10: 1, and [2] it seriously damaged the structure of some filter aids, particularly the more permeable ones (which are also the more expensive grades). The next dry feeder tried was of the vibratory type, but it too provided widely variable feed rates for different grades of material and sometimes wide variations within a single grade of material.…”

Diatomite Filters for Municipal Installations

“…To determine what areas of diatomite filtration require further study, the Iowa Engineering Experiment Station conducted a preliminary evaluation of diatomite filters in municipal installations. The study was conducted in two phases: [1] the completion of a questionnaire survey to determine current health department attitudes and experiences with municipal diatomite filters; and, [2] the evaluation of existing municipal installations by means of an inspection visit to obtain plant design and operating data. T H E use of diatomite filters for the filtration of water has greatly increased since their early development by the US Army in World War II (1).…”