AWWA ACE90106

To study the effects of polyphosphates on iron and manganese treatability, this study utilized streaming current detectors, ultrafilters and microfilters. Iron and manganese were effectively stabilized in the presence of polyphosphates and did not precipitate, as indicated by high iron and manganese filterability through microfilters. Streaming current directly correlated with iron treatability, indicating that streaming current detectors potentially could be used by utilities to adjust the sequestrant feed for obtaining good iron treatment. Iron and manganese treatability improved significantly with decreasing pH levels (8.0 to 6.0). In successful experiments, iron was present as a colloid, whereas manganese sequestration did not involve a colloidal mechanism. Polyphosphates inhibited manganese oxidation by hypochlorite leading to the conclusion that this inhibition of manganese oxidation is an important mechanism for the success of this technique in manganese sequestration. The presence of manganese as Mn2+ in successful experiments was consistent with filtration results using 200,000 molecular weight cut-off ultrafiltration membranes.

Product Details

Published:

01/01/1990

ISBN(s):

0898675561

Number of Pages:

28

File Size:

1 file , 760 KB