Environmental Engineering Reference
In-Depth Information
Recirculation test in a column with pump
10
9
8
7
6
5
4
3
2
1
0
0
Ratio-100
Ratio-200
20
40
60 80
Time (min)
100
120
140
FIGURE 31.12
Effect of media: water ratio.
31.4.4 System Design Approaches
MetaMateria inds that a multichamber approach gives excellent results, especially when
used with recirculation. In this approach, water lows into the irst chamber where 70%-80%
of the total phosphorus can be removed and then into the second chamber, which acts as a
polishing ilter. Once efluent from the second container approaches the desired concentra-
tion (e.g., 1 mg/L), the irst chamber can be taken out of service and phosphorus removed
and media regenerated for reuse. Water can now pass through the second container and
into a third chamber (if available) during regeneration of media in the irst chamber. For
a given concentration and low rate, the amount of media needed can be determined by
desired residence time and the desired time between regenerations. This may require
more than two chambers, especially at lower concentrations. The lux rate through a given
area will depend on the application; however, it is expected to be 75-200 L/min for 1 m
2
of
area, and for some applications it may be higher.
In general, criteria to be considered in designing systems utilizing Meta-PO4 media are
• Concentration of phosphorus, since it affects the average media capacity (g-P/kg-media).
• EBCT determines the time water is in contact with media.
• Initially, a 30 min ECBT is chosen, but this may be lower for some systems.
• F lu x (L/m i n-m
2
) is the amount of water that lows through square meter of media.
• Total lux includes any recirculated water and is typically 75-200 L/min-m
2
but
may be higher.
• Desired regeneration period represents time between regeneration. For lower con-
centrations (<10 mg/L), this may be 30 days or more. For concentrations >50 mg/L,
it may be weekly.
31.4.5 Media Regeneration and Reuse
Media regeneration and reuse is important to the life cycle costs of the media, since the
cost for regeneration will be signiicantly less than that of the initial media. After suficient
