This paper presents the results of a bench-scale investigation to determine whether phosphate
can be added during rapid mix to reduce the filtered water aluminum concentration in order to
minimize aluminum precipitation in distribution systems. Tests showed that applying
orthophosphate during rapid mix following alum addition was an effective method to reduce
residual aluminum concentration and decrease the potential for aluminum precipitation in the
distribution system. Orthophosphate addition reduced residual aluminum concentrations by as
much as 350 ug/L. Orthophosphate reduced residual aluminum concentration under all test
conditions (pH 7.0 . 8.0, 4 C . 31 C) except at the lowest temperature, where aluminum
concentrations fell below the detection limit, obscuring the effect of the orthophosphate.
Orthophosphate loss to floc particles ranged from 22% to 85% of the applied dose. Adding
orthophosphate before alum addition, rather than after alum addition, resulted in greater
phosphate loss to floc particles, without improving aluminum reduction. Includes 18 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 330 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 11/01/2002 |
