Manganese (Mn) is still a troublesome problem for many water utilities,
and its control and occurrence at the tap are not well understood, especially with regards
to the role of microorganisms. The possible influence of chemical and microbiological
factors on manganese oxidation and reduction in drinking water supply systems has been
studied. Severe manganese contamination was reported in Tegucigalpa, Honduras and for
this reason the city was one of the selected locations for this research. Two water
treatment plants in the southeastern U.S. also perform Mn removal and were selected
locations for this study.
Water samples were collected from locations in the water treatment plant and
distribution system of Tegucigalpa. The results indicated that manganese in particulate
form was easily dislodged from polyvinyl chloride (PVC) compared to iron pipes leading to severe "black
water" problems. To demonstrate the possibility of microbial-catalyzed manganese
cycling, Mn-oxidizing and Mn-reducing bacteria were recovered from biofilm samples
collected from particulates in the sedimentation and filtration basins of the three water
treatment plants studied. Mn -oxidizing and -reducing bacteria were also obtained from
water samples collected in the distribution system of Tegucigalpa. Biofilms from PVC
pipe, iron pipe, and sand filter media from Tegucigalpa were suspended and shown
capable of both Mn-oxidation and reduction. Although Mn-oxidizing bacteria are aerobic
and Mn-reducing bacteria are facultative anaerobic, the obtained results suggest the
possible coexistence of both types of bacteria in the same biofilm. Thus, it is likely that
biofilms formed in the sedimentation basin, filtration basin and distribution system
contribute to manganese release in drinking water.
This study suggests that both chemical and microbiological factors affect
manganese cycling in drinking water distribution systems. Includes 10 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 140 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 6 |
| Published : | 11/01/2007 |
