Compliance needs for the Stage-2 Disinfection Byproducts (DBPs) rule is
prompting many water treatment utilities to explore additional DBP precursor
removal beyond enhanced coagulation. The use of biologically active granular activated carbon (GAC) filters
is now becoming popular as an effective means of lowering DBP levels. To
minimize DBP levels by biologically active GAC filter, many water treatment
facilities are now abandoning the practice of pre-chlorination. Two large water
treatment utilities, one located in Texas and the other located in Arizona, have
implemented or will soon be implementing such practices.
Elimination of pre-chlorination, however, causes iron/manganese (Fe/Mn), if
present in source water, to remain in soluble form (due to non-oxidation) passing
through filtration processes. Upon chlorination of post-filtered water and/or
inadequate mixing during caustic addition have caused dissolved Fe/Mn to
precipitate causing yellow or reddish coloration, staining submerged surfaces
and/or increasing the turbidity in the finished water. To avoid these water
qualities related issues several treatment strategies were investigated in bench
and full-scale settings for these two utilities. Proposed strategies included a
preliminary assessment of the fate and transport of Fe/Mn from raw to finished
water and evaluation of conventional (chlorine, permanganate) and alternative
(chlorine dioxide) oxidants to minimize Fe/Mn related issues for the finished
water. Includes figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 380 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 06/01/2006 |
