III.
SYSTEM INSTALLATION
Page - 9
Pressure regulator to reduce feed water inlet pressure (if pressure exceeds
100 psi).
Pretreatment equipment including softeners, prefilters and chemical
injection systems. See Section X for further information.
3)
Feed Water Requirements
Each unit design is based on a specific feed water analysis and reverse osmosis
design projection. The flow rates of the system are dependent on these feed
water characteristics. The feed water is defined as either ‘Surface Water Feed’
with a Silt Density Index (SDI) of three to five, or ‘Well Water Feed’ with a
SDI of less than three. Once the exact feed water has been established, with an
accurate feed water analysis, the reverse osmosis design projection is generated
and exact flow rates and operating pressure values are defined. This design
projection will not only calculate flow rates and operating pressures, but also
membrane scaling tendencies and chemical pretreatment requirements.
The raw feed water for the RO system must conform to the EPA specifications
for potable water listed under the Safe Drinking Water Act. See Table 1
below.
Table 1: EPA Safe Drinking Water Act Limits
Contaminant
Limit (mg/L)*
Mercury
0.002
Nitrate (as N)
10.0
pH
6.5 - 8.5
Selenium
0.01
Silver
0.05
Sodium
20.0
Sulfate
250
TDS
500
Zinc
0.09
Contaminant
Limit (mg/L)*
Arsenic
0.05
Barium
1.0
Cadmium
0.01
Chloride
250
Chromium
0.05
Copper
1.0
Fluoride
1.4 - 2.4
Iron
0.3
Lead
0.05
* Concentrations in table measured as ion.
