Table 2:
For cement-mortar water infrastructure: Surface concentration of surviving Bacillus globigii spores in cfu cm−2 with decontaminant effectiveness (log reduction) in parenthesis for various decontamination and flushing durations (hr)
| Experimental Phase | Time | Disinfectant with its concentration (mg l−1) and water pH | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Free Chlorine | Chlorine Dioxide | Monochlor-amine | Acidified Nitrite | Ozone | PAA | ||||||
| pH 8, 5 mg l−1 | pH 8, 25 mg l−1 | pH 7, 25 mg l−1 | 5 mg l−1 | 25 mg l−1 | 25 mg l−1 | pH 2, 0.1 mol l−1 | pH 3, 0.1 mol l−1 | 2 mg l−1 | 25 mg l−1 | ||
| Spore Injection | 0 min (initial) | 8.5×104 (0.0) | 4.1×104 (0.0) | 7.9×104 (0.0) | 5.5×104 (0.0) | 5.2×104 (0.0) | 4.4×104 (0.0) | 1.9×104 (0.0) | 1.2×105 (0.0) | 8.0×104 (0.0) | 2.6×104 (1.7) |
| Decontamin-ation with Disinfectant | 1 hr | 7.0×103 (1.1) | 4.6×103 (1.0) | 7.5×102 (2.0) | 5.0×102 (2.0) | 2.5×102 (2.3) | 3.5×104 (0.1) | 2.8×104 (0.0) | 1.1×105 (0.1) | 0.0 (>3.2) | 7.3×103 (0.6) |
| 2 hr | 1.3×104 (0.8) | 2.0×103 (1.3) | 1.5×103 (1.7) | 0.0 (>3.0) | 0.0 (>3.0) | 2.0×104 (0.3) | 2.5×104 (0.0) | 6.1×104 (0.3) | 0.0 (>3.2) | 4.8×103 (0.7) | |
| 3 hr | 7.8×103 (1.0) | 2.5×103 (1.2) | 2.5×102 (2.5) | 0.0 (>3.0) | 0.0 (>3.0) | 1.2×104 (0.6) | 1.8×104 (0.0) | 4.0×104 (0.5) | 0.0 (>3.2) | 3.3×103 (0.9) | |
| 4 hr | 7.0×103 (1.1) | 3.3×103 (1.1) | 1.5×103 (1.7) | 0.0 (>3.0) | 0.0 (>3.0) | 1.1×104 (0.6) | 1.2×104 (0.2) | 5.5×104 (0.3) | 0.0 (>3.2) | 3.3×103 (0.9) | |
| 6 hr | 6.8×103 (1.1) | 1.5×103 (1.4) | 3.3×103 (1.4) | 0.0 (>3.0) | 0.0 (>3.0) | 2.3×103 (1.3) | 1.5×104 (0.1) | 4.6×104 (0.4) | 0.0 (>3.2) | 1.5×103 (1.2) | |
| 18 hr | 2.0×103 (1.6) | 5.0×102 (1.9) | 0.0 (>3.2) | 0.0 (>3.0) | 0.0 (>3.0) | 0.0 (>2.9) | 2.0×103 (1.0) | 4.6×104 (0.4) | 0.0 (>3.2)* | 3.5×103 (0.9) | |
| 22 hr | 1.5×103 (1.8) | 2.5×102 (2.2) | 0.0 (>3.2) | 0.0 (>3.0) | 0.0 (>3.0) | 0.0 (>2.9) | 4.3×103 (0.6) | 7.9×104 (0.2) | No Data | 2.8×103 (1.0) | |
| Flushing 0.3 m sec−1 (1 ft sec−1) | 24 hr | 1.4×103 (1.8) | 5.0×102 (1.9) | 3.8×102 (2.3) | 0.0 (>3.0) | 0.0 (>3.0) | 5.0×101 (2.9) | 0.0 (>2.6) | 6.0×104 (0.3) | 0.0 (>3.2) | 1.9×103 (1.1) |
| 26 hr | 2.5×103 (1.5) | 0.0 (>2.9) | 0.0 (>3.2) | 0.0 (>3.0) | 0.0 (>3.0) | 0.0 (>2.9) | 5.0×102 (1.6) | 3.2×104 (0.6) | 0.0 (>3.2) | 5×102 (1.7) | |
| 44 hr | 5.0×102 (2.2) | 0.0 (>2.9) | 0.0 (>3.2) | 0.0 (>3.0) | 0.0 (>3.0) | 0.0 (>2.9) | 1.5×103 (1.1) | 5.4×103 (1.4) | 0.0 (>3.2) | 5×102 (1.7) | |
*
Data is from 12 hours after the start of ozone treatment