Bacteriological and physicochemical parameters of water from storage tanks with different hydraulic retention time
| Parameter . | Mean . | SIG. (α = 0.05) . | ||
|---|---|---|---|---|
| Residence time . | ≤1 day (n = 32) . | 2 days (n = 34) . | ≥3 days (n = 46) . | |
| Bacteriological analysis | ||||
| Total coliforms (CFU/100 ml) | 13 ± 4 | 19 ± 4 | 22 ± 4 | 0.344 |
| Faecal coliforms (CFU/100 ml) | 0 | 1 | 1 ± 1 | 0.254 |
| Heterotrophic bacteria (CFU/100 ml) | 687 ± 189 | 585 ± 114 | 967 ± 201 | 0.277 |
| Physicochemical analysis | ||||
| Free chlorine (mg/L) | 0.04 ± 0.03 | 0.00 | 0.010 ± 0.001 | 0.339 |
| Colour (Pt Co) | 7.13 ± 1.00 | 7.97 ± 0.93 | 15.15 ± 2.42 | 0.008 |
| SO42− (mg/L) | 6.37 ± 0.27 | 6.45 ± 0.34 | 5.61 ± 0.32 | 0.072 |
| Mn (mg/L) | 0.010 ± 0.001 | 0.004 ± 0.001 | 0.004 ± 0.001 | 0.458 |
| Fe (mg/L) | 0.040 ± 0.001 | 0.030 ± 0.01 | 0.120 ± 0.001 | 0.085 |
| Parameter . | Mean . | SIG. (α = 0.05) . | ||
|---|---|---|---|---|
| Residence time . | ≤1 day (n = 32) . | 2 days (n = 34) . | ≥3 days (n = 46) . | |
| Bacteriological analysis | ||||
| Total coliforms (CFU/100 ml) | 13 ± 4 | 19 ± 4 | 22 ± 4 | 0.344 |
| Faecal coliforms (CFU/100 ml) | 0 | 1 | 1 ± 1 | 0.254 |
| Heterotrophic bacteria (CFU/100 ml) | 687 ± 189 | 585 ± 114 | 967 ± 201 | 0.277 |
| Physicochemical analysis | ||||
| Free chlorine (mg/L) | 0.04 ± 0.03 | 0.00 | 0.010 ± 0.001 | 0.339 |
| Colour (Pt Co) | 7.13 ± 1.00 | 7.97 ± 0.93 | 15.15 ± 2.42 | 0.008 |
| SO42− (mg/L) | 6.37 ± 0.27 | 6.45 ± 0.34 | 5.61 ± 0.32 | 0.072 |
| Mn (mg/L) | 0.010 ± 0.001 | 0.004 ± 0.001 | 0.004 ± 0.001 | 0.458 |
| Fe (mg/L) | 0.040 ± 0.001 | 0.030 ± 0.01 | 0.120 ± 0.001 | 0.085 |