The Long Beach Water Department (LBWD), similar to many Southern California
utilities, has been facing the issue of decreased potable water supplies. Because
of its location, the City of Long Beach is ideally situated to take advantage of
desalinated seawater as a source of drinking water and is interested in
incorporating desalinated seawater into its potable water portfolio. However,
before seawater desalination can become a reality, additional advances are
needed to further reduce the cost of desalination. LBWD is currently exploring the
feasibility of using nanofiltration membranes (NF) in a dual-pass configuration to
evaluate the possibility of achieving additional cost reduction as well as meeting
all water quality objectives. Although NF membranes have been previously tested with seawater, the
application focused on using NF as pretreatment for the reverse osmosis
membrane stage rather than using these membranes to produce potable water.
In recent years, however, significant developments of NF membranes have been
made, resulting in products that can achieve high TDS rejections (e 90%) at
lower applied pressures. These advances allow a two-step, permeate-staged NF
treatment process capable of producing potable water with lower overall applied
pressure, and potentially lowering operating energy. To date, this concept does
not appear to have been tested, as evidenced by the lack of literature in this
area.
To provide clear and quantifiable answers to water quality questions related to
the traditional SWRO versus dual-pass nanofiltration process (NF2), LBWD has
formulated an aggressive research program and constructed a 300,000 gallons
per day permeate "Prototype" research facility using full-scale equipment. This
paper presents LBWD's preliminary evaluation of source water quality and its
removal throughout the various processes and initial water comparison of SWRO
and against dual-pass nanofiltration. Includes 13 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 120 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 19 |
| Published : | 11/01/2007 |
