b. Mixing. Mixing is necessary to provide rapid and uniform dispersion of the
chemical throughout the water being treated. The mixing may be done either
mechanically by motor driven propellers or hydraulically by baffled chambers or piping
systems designed to create turbulent flow conditions. The fundamental principle is the
violent agitation of the water and chemical together for a short time.
NOTE: Mixing is a very important step because improper mixing results in the wasting
of chemicals and premature clogging of fiIters.
1. Water jet
7. Agitator shaft
8. Rocker arms
Figure 1-2. Dry-chemicaI feeder.
c. Flocculation. After mixing, flocculation takes place. This process is
accomplished, usually, in a single tank, within a time span of between 15 to 45 minutes.
During this period, the water is gently agitated to make floc particles. Bacteria and