Forsyth County, Georgia contracted with CH2M HILL to expand the Forsyth County
Water Treatment Plant (WTP) to a rated capacity of 28 million gallon per day (mgd). The new process trains included rapid
mix, clarification (plate settlers), membranes, and disinfection with sodium hypochlorite. The ZeeWeed Ultrafiltration System, manufactured by Zenon Membrane Solutions, of
GE Water & Process Technologies was selected. In order to provide clarified water for the membranes and simplify the proof testing
setup, clarified water was pumped from the existing Superpulsator® effluent to the
pilot membrane unit. However, once operations began, it was quickly determined that
the polymer used by the plant was incompatible with the membranes. This was remedied
by changing approaches and renting a Meurer Research, Inc. (MRI) Pilot Plate Clarifier
to provide clarified water to the membrane pilot unit and to more accurately simulate the
proposed process trains. The MRI clarifier was operated with alum as a coagulant and without the use of
polymers. However, challenges still remained, including: controlling the dissolved aluminum
concentration in the clarifier effluent to prevent additional membrane fouling;
a lack of operational flexibility with the raw water pump
station and, therefore, a lack of control of the raw water flow rate to the plant;
significant peaks and lows of water demand based on outdoor watering
restrictions under Georgia Level 2 drought watering restrictions; and, cycling between operating at or near capacity and then
shutting off during the low demand periods. During periods when the plant was shut off,
there was no raw water to operate the clarifier or membrane pilot units, thus creating poor clarifier performance and yielding incomplete
membrane performance data. This paper discusses the challenges encountered throughout the process, including the
polymer incompatibility, dissolved aluminum concentrations, plant on-off cycle, and
other challenges such as air-entrained rising floc in the clarifier and mechanical
equipment malfunctions. The paper also describes the solutions to these challenges and
the overall pilot process design. Includes reference, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.1 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 31 |
| Published : | 11/01/2008 |
