TABLE 2.
Summary of water quality parameters for the biologically treated distribution systems
| Parameter measured | Valuea at the following site:
|
|||
|---|---|---|---|---|
| Raw water reservoir tank | Ozone contactor | Biologically active carbon filter | Free-chlorinated distribution system | |
| Free chlorine residual (mg/liter) | NAb | NA | NA | 1.68 (0.29) |
| Total chlorine residual (mg/liter) | NA | NA | NA | 1.79 (0.28) |
| Ozone residual (mg/liter) | NA | 0.16 (0.04) | NA | NA |
| pHc | 5.76 (0.14) | 6.93 (0.13) | 6.74 (0.22) | 6.82 (0.23) |
| Temp (°C) | 24.0 (1.0) | 20.5 (1.9) | 20.1 (1.8) | 20.2 (1.4) |
| AOC (μg of C/liter)d | 720 (180–1,700) | 384 (114–630) | 39 (12–63) | NA |
| TOCe (mg/liter) | 1.68 (0.32) | 1.73 (0.33) | 1.26 (0.15) | 1.26 (0.12) |
| Turbidity (NTUf | 1.80 (1.03) | 1.97 (0.99) | 0.14 (.03) | 0.88 (2.57) |
| Ammonia (mg/liter) | 0.08 (0.04) | 0.14 (0.07) | 0.05 (0.06) | 0.03 (0.03) |
| Corrosion rate (mils/yr) | NA | NA | NA | 0.73 (0.68) |
| Dissolved oxygen (mg/liter) | 8.17 (1.23) | 8.05 (1.22) | 6.96 (1.02) | 6.41 (1.08) |
a
Chemical parameter measurements are averages from each site, with standard deviations given in parentheses, unless otherwise indicated.
b
NA, not applicable.
c
The system pH was targeted at levels found in previously studied distribution systems (22).
d
AOC levels are reported as geometric means, with ranges given in parentheses.
e
TOC, total organic carbon.
f
NTU, nephelometric turbidity units.