The Long Beach Water Department (LBWD) is researching a subsurface intake system (under-ocean floor seawater intake) that
collects seawater filtered through engineered sand beds at slow rates. The primary goal of
this project is to determine if the system can deliver a sustained quantity of water. A
secondary goal is to deliver a consistent water quality that can be used as feed water for
desalination membranes. This research also tests concentrate discharge to minimize
localized environmental effects, and evaluates additional potential benefit of reducing
pretreatment processes. The tests are being conducted over 15 months to evaluate differences in influent water
qualities at filtration rates ranging from 0.05 to 0.2 gpm/ft<sup>2</sup>. Two tests have been completed to
date, and show that infiltration rates of 0.05 and 0.1 gpm/ft<sup>2</sup> yield flows that are independent
of the tide level (except in extreme low tidal conditions). Testing is ongoing to ensure the
respective water quality goals of <3.0 SDI<sub>15</sub> and turbidity <0.1 NTU are achieved by cartridge
filtration. These goals are generally accepted guidelines for influent water quality used with
desalting membranes.
The water quality comparisons include chemical analyses (general, physical, selected
inorganic and organic), and specialized indicators of marine life activity (marine heterotrophic
plate count-mHPC, adenosine triphosphate-ATP, assimilable organic carbon-AOC and
dissolved organic carbon-DOC). The comparison will help direct the final stages of testing to
help identify any gaps or validate the current test plan. This paper presents the results of
the side-by-side comparison for the demonstration-scale experiments described above. Includes 5 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 11/01/2009 |
