Table 4. Mean percentages of viable Cryptosporidium and Giardia for different chlorine exposures at different durations using microscopy.
| 0.5 ppm | ||||||||
|---|---|---|---|---|---|---|---|---|
| DURATION /min |
15 | 30 | 60 | 120 | ||||
| Trials | Cryptosporidium | Giardia | Cryptosporidium | Giardia | Cryptosporidium | Giardia | Cryptosporidium | Giardia |
| 1 | 84 | 67 | 77 | 33 | 53 | 0 | 42 | 0 |
| 2 | 87 | 33 | 74 | 50 | 60 | 0 | 47 | 0 |
| 3 | 84 | 33 | 69 | 33 | 47 | 0 | 42 | 0 |
| 4 | 89 | 100 | 71 | 0 | 58 | 0 | 51 | 0 |
| 5 | 87 | 50 | 59 | 33 | 55 | 0 | 46 | 0 |
| Mean±SD | ||||||||
| Distilled water | 85.5±2.1 | 50.0±24.0 | 75.5±2.1 | 41.5±12.0 | 56.5±4.9 | 0.0±0.0 | 44.5±3.5 | 0.0±0.0 |
| Wastewater | 86.7±2.5 | 61.0±34.8 | 66.3±6.4 | 22.0±19.1 | 53.3±5.7 | 0.0±0.0 | 46.3±4.5 | 0.0±0.0 |
| Syto-9+PI | 85.0±1.7 | 44.3±19.6 | 73.3±4.0 | 38.7±9.8 | 53.3±6.5 | 0.0±0.0 | 43.7±2.9 | 0.0±0.0 |
| DAPI+PI | 88.0±1.4 | 75.0±35.4 | 65.0±8.5 | 16.5±23.3 | 56.5±2.1 | 0.0±0.0 | 48.5±3.5 | 0.0±0.0 |
| 2 ppm | ||||||||
| 1 | 81 | 33 | 66 | 0 | 59 | 0 | 48 | 0 |
| 2 | 79 | 0 | 72 | 0 | 63 | 0 | 54 | 0 |
| 3 | 73 | 0 | 64 | 0 | 54 | 0 | 46 | 0 |
| 4 | 79 | 0 | 71 | 0 | 64 | 0 | 57 | 0 |
| 5 | 87 | 0 | 64 | 0 | 55 | 0 | 46 | 0 |
| Mean±SD | ||||||||
| Distilled water | 80.0±1.4 | 16.5±23.3 | 69.0±4.2 | 0.0±0.0 | 61.0±2.8 | 0.0±0.0 | 51.0±4.2 | 0.0±0.0 |
| Wastewater | 79.7±7.0 | 0.0±0.0 | 66.3±4.0 | 0.0±0.0 | 57.7±5.5 | 0.0±0.0 | 49.7±6.4 | 0.0±0.0 |
| Syto-9+PI | 77.7±4.2 | 11.0±19.1 | 67.3±4.2 | 0.0±0.0 | 58.7±4.5 | 0.0±0.0 | 49.3±4.2 | 0.0±0.0 |
| DAPI+PI | 83.0±5.7 | 0.0±0.0 | 67.5±4.9 | 0.0±0.0 | 59.5±6.4 | 0.0±0.0 | 51.5±7.8 | 0.0±0.0 |
| 5 ppm | ||||||||
| 1 | 42 | 33 | 34 | 0 | 25 | 0 | 15 | 0 |
| 2 | 33 | 0 | 29 | 0 | 21 | 0 | 17 | 0 |
| 3 | 44 | 0 | 34 | 0 | 25 | 0 | 12 | 0 |
| 4 | 39 | 0 | 30 | 0 | 21 | 0 | 14 | 0 |
| 5 | 51 | 0 | 31 | 0 | 25 | 0 | 18 | 0 |
| Mean±SD | ||||||||
| Distilled water | 37.5±6.4 | 16.5±23.3 | 31.5±3.5 | 0.0±0.0 | 23.0±2.8 | 0.0±0.0 | 16.0±1.4 | 0.0±0.0 |
| Wastewater | 44.7±6.0 | 0.0±0.0 | 31.7±2.1 | 0.0±0.0 | 23.7±2.3 | 0.0±0.0 | 14.7±3.1 | 0.0±0.0 |
| Syto-9+PI | 39.7±5.9 | 11.0±19.1 | 32.3±2.9 | 0.0±0.0 | 23.7±2.3 | 0.0±0.0 | 14.7±2.5 | 0.0±0.0 |
| DAPI+PI | 45.0±8.5 | 0.0±0.0 | 30.5±0.7 | 0.0±0.0 | 23.0±2.8 | 0.0±0.0 | 16.0±2.8 | 0.0±0.0 |
Note: Trials 1 to 2: Distilled water. Trials 3 to 5: Wastewater. Trials 1 to 3 were performed using Syto-9+PI stains and Trials 4 to 5 were performed using DAPI+PI stains.