Studies on Diatomaceous Earth Filtration

Progress Toward a Filtrability Index Test

“…Boucher's theory came to the attention of members of the Los Angeles Department of Water and Power in 1948, while they were attempting to find a parameter more reliable than the turbidity of the raw water for the prediction of optimum body feed doses in diatomite filtration (6). His theory was tried by the use of a miniature diatomite filter which contained a single element of 0.18 sq ft of filter surface area.…”

Diatomite Filters for Municipal Installations

“…In the second phase of the preliminary study, the author made an inspection visit to sixteen of the municipal diatomite filtration plants listed in Table 1. The feasibility of municipal diatomite filtration plants was determined by an evaluation of: [1] the purpose of each plant; [2] the source of the water; [3] the installation and its equipment; [4] the adequacy of the operating procedure; [5] the operating results; and [6], the capabilities of the operator.…”

“…Certain recommendations and warnings relating to operations and brought out as a result of the visits, must be given: [1] Plug valves give trouble in maintenance and operating when body feed must pass through the valve; [2] according to the operators, stone elements require more frequent cleaning and replacement than other types of filters should have facilities for removing the heads without the use of overhead cranes or A frames; [7] the filter elements should be independently removable from the tube sheet; [8] the plant layout should be practical and designed for convenience of operation; [9] reciprocating service pumps should not be used with diatomite filters; and elements; [3] the body-feed proportioning pumps do not have sufficient capacity to be effective in periods of high turbidity-with high strength slurries, maintenance becomes a problem and operation becomes erratic; [4] there is a definite need for better flowrate indication and control; [5] the system of pipes should permit backwashing with filtered water; [61 the [10] prechlorination of raw water should be required in municipal filtration plants.…”

“…The records at Cherry Valley most nearly approached the desired minimum records. of view of operation are that: [1] body-feed equipment should be both large and versatile enough to provide continuous body-feed dosage for an 8-hr period at the maximum rate required; [2] body-feed rate should be based on a need of not less than 2-3 ppm of body feed per ppm of turbidity (this is an approximate recommendation as turbidity is a poor indication of body-feed requirements [4,5,9]) ; [3] the operator should anticipate and make body feed adjustments consistent with changes in the water quality; and [4] flash mixers should not be used in Table 6 lists the Cherry Valley average daily use of materials in the operation of its filter.…”

Design requirements of precoat filters for water filtration

“…The first investigations which dealt with the cost of precoat filtration were primarily concerned with the com parison of diatomite filtration to sand filtration. One of the most extensive studies was made in 1951 by Sanchis and Merrell (66) of the Los Angeles Department of Water and Power.…”