Pilot study results from consultant NRS Consulting Engineers have confirmed that seawater desalination on the shore of the Ship Channel in Brownsville, Texas, USA, is technically feasible.
The final Texas Seawater Desalination Demonstration Project pilot study report to the Texas Water Development Board was completed in October 2008 and was published on the NRS website on 30 December 2008.
The report says that, although the ship channel is a challenging water source with extreme variations in quality (especially turbidity, suspended solids, and temperature), a microfiltration pretreatment system followed by reverse osmosis (RO) has adequately treated raw seawater to potable standards. The data and information gained during the pilot study is sufficient to develop a full-scale, 25 MGD (95,000 m³/d desalination plant.
The consultant warns, however, that the plant’s design must be conservative (and therefore expensive) to accommodate the raw water variability and probable environmental events, such as red tides and hurricanes, that were not experienced during piloting but are likely under long-term production.
The Brownsville Public Utilities Board (BPUB) therefore proposes to construct a 2.5 MGD (9,500 m³/d) demonstration-scale plant and research facility at the Port of Brownsville. The proposed demonstration project would provide 9% of the total BPUB demand by 2012, further diversifying its water supply sources.
It would also allow for an evaluation of system performance over several years of operation prior to an investment in full-scale capacity. This data is expected to yield a more efficient overall treatment system design and lower the cost of future expansions as they occur.
Finally, the demonstration facility would include the capability for continued testing of the latest desalination technologies for this and other future seawater desalination facilities along the Texas coast. Such technologies include applications for pretreatment, energy recovery, sustainable energy supply, and larger (potentially more efficient) membranes.
The total estimated cost for the demonstration project is US$ 67,479,000. Approximately half of this amount reflects an investment in full-scale capacity infrastructure, such as the intake and concentrate disposal systems. This investment is expected to significantly reduce the costs of future expansions at the facility.
BPUB proposes to finance a portion of this project using a US$ 20 million loan from the Texas Water Development Board (TWDB). In addition, implementation of the proposed project will also require supplemental funding in the form of a US$ 28.2 million grant from the State and US$ 19.3 million financed under the TWDB State Participation Fund.