Civil Engineering Reference
In-Depth Information
Fig. 25-5.
Photograph of Reliant (Courtesy of Roberts Water Technologies)
except to ascertain the ability to deal with source specific water quality problems and
identify the best coagulant and optimum dose.'' The systems qualified in California
for approval without further studies are:
Microfloc Trimate and Trident, manufactured by USFilter
•
Pacer II, manufactured by Roberts Filter Group
•
Advent Package Water Treatment System, manufactured by Infilco Degremont
•
The space-saving potential of the equipment is evident because the rise rate through
the adsorption clarifier is generally twice the filtration rate (10 versus 5 gpm / ft
2
). A
contact clarifier therefore requires about one-half of the space of a typical high-rate
filter.
Cleaning of the contact clarifier is accomplished by flushing. A timer initiates the
flush cycle, but the equipment also includes a pressure switch that monitors headloss
across the adsorption media and can automatically initiate a flushing cycle if required.
Figure 25-6 illustrates the operation of a typical contact clarifier flushing cycle. When
a cycle is initiated, the plant effluent valve closes, causing the water level to rise in
the plant as the influent flow continues. When the water level reaches a predetermined
level, a switch causes the influent valve to close. Air in the valve opening is distributed
through perforated laterals beneath the adsorption media. This causes an immediate
expansion in the media, and a vigorous scrubbing action takes place. Influent feed is
opened again and dislodged solids are then hydraulically flushed out of the top of the
contact clarifier to waste. Flushing frequency may vary, depending upon influent water
