The disposal of membrane concentrate and other residuals from membrane water
treatment plants is becoming increasingly difficult, especially in inland areas. The Cities
of Tipp City and Vandalia, Ohio formed a joint venture to provide nanofiltration
softening for its residents. The disposal of the treatment plant residuals were a
significant driver in the ultimate water process decisions.
The regulations in some states, including Ohio, require that the discharge of dissolved
solids, iron, manganese, dissolved oxygen and other constituents meet a certain standard.
These limits, while not especially stringent, caused a significant change in process design
for this 7.7 mgd nanofiltration membrane water treatment plant.
The process was piloted not only for the typical RO membrane parameters of flux,
recovery, pressures, and permeate water quality, but also for the ability of the concentrate
discharge to be treated before discharge to the Great Miami River, a scenic river in
western Ohio. The original process decision to utilize well water in the anaerobic state
was changed when the difficulty of settling iron and manganese from membrane
concentrate was encountered.
Jar testing of membrane concentrate proved ineffective in the removal of iron and
manganese below the regulatory limits of 1 mg/l. The subsequent decision to oxidize the
iron and manganese upfront was not taken lightly as there are disadvantages with this
approach on the RO process. The ultimate process resulted in three waste streams, two of
which have been permitted for discharge to the Great Miami River. The concentrate
stream, virtually free of iron and manganese, is directly discharged to the river after
aeration along with the decant of the filter backwash holding tank to meet regulatory
limits with a unique blended waste stream.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.5 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 44 |
| Published : | 06/01/2007 |
