The City of Pflugerville, Texas is embarking on a major project to implement a new water supply to meet
the growing needs of its rapidly increasing population. The new water supply will be surface water from
the Colorado River, which will require complete treatment in accordance with the Rules and Regulations
of the Texas Commission on Environmental Quality (TCEQ). Low-pressure membranes were chosen
over other treatment technologies because they provide a positive barrier for particle and pathogen
removals, they remove higher levels of known microbial contaminants, are relatively easy to operate, and
the costs, both construction and annual, are comparable to most conventional treatment technologies.
Present design standards for low-pressure membrane technology include an extended coagulant contact
time for the removal of organics and turbidity. If the
recommended coagulant contact time prior to the membranes could be reduced to between 15 seconds
and 2 minutes, a substantial savings in initial capital as well as operation costs could be realized.
Reducing the coagulant contact time could make it possible to provide the necessary contact time in the
raw water line between the raw water pump station and the membrane system, thereby saving the costs of
the coagulant contact/flocculation basin and equipment, as well as the separate membrane feedwater
pumps. For this project, an innovative application of membrane filtration with direct coagulation was
pilot tested to determine the feasibility of minimizing coagulant contact time prior to the membranes.
At the present time, membrane technology is classified as an alternative treatment technology under the
federal Surface Water Treatment Rule (SWTR). As a result, the TCEQ requires membrane filtration
systems to provide pilot test data demonstrating that the system will produce water meeting both the
requirements of the drinking water standards governing water quality and the reporting requirements for
public water systems.
Based on this requirement, the City of Pflugerville contracted with Pall Water Processing, Ionics, US
Filter (later disqualified), and Zenon Environmental to provide complete membrane pilot systems. The
Pall and Zenon pilots were skid-mounted units while the Ionics system was a trailer unit. The pilot units
included all pumps, tanks, compressors and other ancillary systems required for full operation during the
study. Each pilot unit included instrumentation necessary to record important operating parameters, such
as flow rate, temperature, turbidity, particle counts, and system pressures. The same membrane and
process conditions proposed for the full-scale plant were used in the pilot plants. The membranes
modules tested during the pilot study were identical to and contain fibers of the same length as those that
will be used in the full-scale plant. The membrane modules supplied with the pilot units were previously
unused and were not replaced during the test program. Includes tables.
| Edition : | Vol. - No. |
| File Size : | 1
file |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 5 |
| Published : | 11/15/2004 |
