Both contactors performed well in terms of lowering the treated Mn concentration to values at or below 0.02 mg/L; only a few observed values exceeded 0.02 mg/L, and even in those instances, the EPA secondary MCL of 0.05 mg/L was achieved. The contactor performance data for Mn removal are summarized in Tables 1 and 2. Both contactor media configurations yielded average effluent Mn concentrations that were below the 0.015 mg/L threshold to protect against aesthetic concerns (Brandhuber et al. 2013).
Summary of contactor performance data for manganese removal
| Media type . | Influent Mn (mg/L) Minimum–Maximum (average) . | Effluent Mn (mg/L) Minimum–Maximum (average) . | Average percent reduction in Mn . |
|---|---|---|---|
| 1.6 mm ES ceramic | 0.007–0.096 (0.044) | 0.004–0.040 (0.010) | 61 |
| 2.0 mm ES anthracite coal | 0.009–0.081 (0.037) | 0.004–0.040 (0.014) | 55 |
| Media type . | Influent Mn (mg/L) Minimum–Maximum (average) . | Effluent Mn (mg/L) Minimum–Maximum (average) . | Average percent reduction in Mn . |
|---|---|---|---|
| 1.6 mm ES ceramic | 0.007–0.096 (0.044) | 0.004–0.040 (0.010) | 61 |
| 2.0 mm ES anthracite coal | 0.009–0.081 (0.037) | 0.004–0.040 (0.014) | 55 |
Impacts of hydraulic loading rate on Mn removal across pilot-scale contactors
| Hydraulic loading rate, m/hr (gpm/ft2) . | Mn removal for 1.6 mm ES ceramic media (%) . | Mn removal for 2.0 mm ES anthracite coal media (%) . |
|---|---|---|
| 29.4 (12) | 61 | 60 |
| 37.8 (15) | 57 | 48 |
| Hydraulic loading rate, m/hr (gpm/ft2) . | Mn removal for 1.6 mm ES ceramic media (%) . | Mn removal for 2.0 mm ES anthracite coal media (%) . |
|---|---|---|
| 29.4 (12) | 61 | 60 |
| 37.8 (15) | 57 | 48 |