A high manganese (Mn) concentration in source
water is a common problem faced by water utilities.
Utilities often remove this Mn by oxidation
of the manganous ion (Mn2+) to manganese oxide
(MnO2(s)) using an oxidant, such as chlorine dioxide
(ClO2). Excess MnO2(s) may remain in the water after
treatment, causing brown staining on plumbing fixtures
and laundry. Many water utilities experience Mn
problems from effluent concentrations as low as 20
ug/L, leading some utilities to strive for finished water
Mn2+ concentrations <10 ug/L. Most studies reported
in the literature have not fully explored oxidation of
low initial Mn2+ concentrations (60-200 ug/L) and the
dose requirements of the primary oxidants, ClO2,
potassium permanganate (KMnO4), and ozone (O3).
The overall objective of this study was to evaluate these
oxidants for the oxidation of low initial Mn2+ concentrations
to Mn2+ <10 ug/L. Bench-scale experiments
were performed by applying different doses of each
oxidant to a raw surface water and measuring Mn2+
residuals over time.
The study found that it was more difficult to remove
Mn when the initial concentration was low, regardless of
the oxidant used. ClO2, however, consistently produced
final Mn2+ to <10 ug/L, generally within 60-120 s. All
oxidants produced final Mn2+ <10 ug/L when the initial
Mn2+ concentration was high (1,000 ug/L). The conclusions
indicate that ClO2 may be a viable treatment alternative
for water utilities wishing to reduce Mn concentrations
in finished water to <10 ug/L. Includes 17 references, table, figures.
| Edition : | Vol. 95 - No. 1 |
| File Size : | 1
file
, 260 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 01/01/2003 |
