b. Water Treatment Process. Figure 5-6 illustrates the flow of water through
the WPU, which, in general terms, is as follows:
(1) Raw water is pumped from its source through the aspirators into the
erdlator assembly, which will be discussed in detail in paragraph 5-7. A portion of the
raw water entering the erdlator assembly is diverted through the chemical slurry feeder.
(2) Calcium hypochlorite and ferric chloride solutions, as well as pulverized
limestone slurry (including activated carbon, if required), are added to the erdlator
assembly through separate tubes from the chemical solution and chemical slurry
feeders, respectively, as explained in paragraph 5-6.
Figure 5-6. Flow diagram.
(3) Coagulated water is pumped from the wet weII tank of the erdlator
assembly by means of the filter pump, to the diatomite filter. Initially, during the precoat
operation, filtered water is recirculated from the filter back to the wet well tank. After
precoat is completed and normal filtering begins, the filtered water is pumped directly to
the storage tanks. A small portion of the filtered water is diverted through the diatomite
dilution tank on the side of the chemical slurry feeder tank to the line supplying
coagulated water to the filter pump (see para 5-8).