The bacteriological and physicochemical parameters of water from storage tank with different periods between tank cleaning
| Parameter . | Mean . | SIG. (α = 0.05) . | ||
|---|---|---|---|---|
| Period since last cleaning (months) . | <11 (n = 20) . | 12–23 (n = 20) . | ≥24 (n = 72) . | |
| Bacteriological analysis | ||||
| Faecal coliforms (CFU/100 ml) | 0 | 2 ± 1 | 0 | 0.169 |
| Total coliforms (CFU/100 ml) | 25 ± 6 | 26 ± 5 | 15 ± 3 | 0.013 |
| Heterotrophic bacteria (CFU/100 ml) | 770 ± 132 | 616 ± 132 | 814 ± 154 | 0.178 |
| Physicochemical analysis | ||||
| Free chlorine (mg/L) | 0.01 ± 0.001 | 0.01 ± 0.001 | 0.02 ± 0.001 | 0.979 |
| Colour (Pt Co) | 9.6 ± 1.19 | 14.6 ± 3.08 | 9.89 ± 1.47 | 0.083 |
| SO42− (mg/L) | 5.22 ± 0.47 | 6.34 ± 0.60 | 6.23 ± 0.19 | 0.057 |
| Mn (mg/L) | 0.020 ± 0.001 | 0.020 ± 0.010 | 0.010 ± 0.001 | 0.138 |
| Fe (mg/L) | 0.050 ± 0.001 | 0.100 ± 0.050 | 0.100 ± 0.040 | 0.273 |
| Parameter . | Mean . | SIG. (α = 0.05) . | ||
|---|---|---|---|---|
| Period since last cleaning (months) . | <11 (n = 20) . | 12–23 (n = 20) . | ≥24 (n = 72) . | |
| Bacteriological analysis | ||||
| Faecal coliforms (CFU/100 ml) | 0 | 2 ± 1 | 0 | 0.169 |
| Total coliforms (CFU/100 ml) | 25 ± 6 | 26 ± 5 | 15 ± 3 | 0.013 |
| Heterotrophic bacteria (CFU/100 ml) | 770 ± 132 | 616 ± 132 | 814 ± 154 | 0.178 |
| Physicochemical analysis | ||||
| Free chlorine (mg/L) | 0.01 ± 0.001 | 0.01 ± 0.001 | 0.02 ± 0.001 | 0.979 |
| Colour (Pt Co) | 9.6 ± 1.19 | 14.6 ± 3.08 | 9.89 ± 1.47 | 0.083 |
| SO42− (mg/L) | 5.22 ± 0.47 | 6.34 ± 0.60 | 6.23 ± 0.19 | 0.057 |
| Mn (mg/L) | 0.020 ± 0.001 | 0.020 ± 0.010 | 0.010 ± 0.001 | 0.138 |
| Fe (mg/L) | 0.050 ± 0.001 | 0.100 ± 0.050 | 0.100 ± 0.040 | 0.273 |