The Central Shoshone County Water District (District) serves potable water in rural
Northern Idaho near the City of Kellogg. The State of Idaho has designated the water
source as groundwater under the direct influence of surface water (GWUDI).
Consequently, the District is implementing a treatment facility to comply with the Long
Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Membrane filtration
was selected as the core treatment process and three suppliers participated in a
competitive procurement pre-qualification pilot study.
Several factors related to the pilot study created a ripple effect that influenced
procurement specification of the membrane system and facility design. Each supplier
started their pilot work at different times resulting in a limited window of data where all
three pilot units were operated at the same time. The pilot study duration was also less
than typical, and repeatability of the efficacy of cleaning cycles could not be verified. An
attempt was made to simulate a high turbidity event during the pilot study similar to the
event that led to state designation of the water source as a GWUDI. The short duration
of the pilot study also limited observation of the impact of seasonal temperature extremes
on membrane performance.
Process definition from the pilot study shaped the design. The backwash, chemically
enhanced backwash or maintenance clean and recovery protocols used in the pilot
study also played a significant role in the design of the facility. The selected site is not
served by a sanitary sewer and the climate, topography and soils are not compatible with
evaporation or percolation beds for wastewater disposal. Consequently, recovery or
disposal of backwash and cleaning wastes were critical design factors. For this reason,
backwash water is recovered to minimize the quantity of residuals requiring
disposal. The broad range of water demands and seasonal water temperatures led to
development of multiple criteria for design flux rates and redundancy requirements. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.7 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 15 |
| Published : | 11/01/2009 |
