Because of the uncertainty of water resources in the western U.S., the Long Beach Water
Department (LBWD) is considering seawater desalination as a possible source to augment its
existing water supplies. An AwwaRF-funded project is examining dual-staged nanofiltration
(NF2) for seawater desalination as an alternative to traditional reverse osmosis (RO) membrane
treatment. The primary goal of this research is to determine whether this desalination system can
reduce the operational cost for desalination, as compared to more traditional methods, by
lowering operating pressures while producing potable water.
A secondary objective was to evaluate the effects of blending desalinated seawater into
LBWD's existing water supplies made up of treated groundwater (GW) and purchased surface
water (SW). The existing finished water varies in composition during the year, with 100 percent
of GW in summer, and 100 percent of SW in winter, the latter being provided either as State
Project water (SPW) or Colorado River water (CRW). Based on these conditions, the objective is to
determine the percentage of desalinated water (DW) that can be blended while considering the
issues of DBP formation, disinfectant residual, and corrosivity.
The paper presents water quality characteristics for the various waters to be blended. The
characteristics for DW vary depending on the permeate salinity and pH targets. The two pHs
considered represent one that is similar to the existing pH condition of the water in the
distribution system (8.0), and one that is required if additional boron rejection is required (with
an interstage pH adjustment to pH 9.8). Includes 4 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1000 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 06/17/2005 |
