Desalination & Reuse Handbook - Flipbook - Page 35
FEATURED DESALINATION PLANTS
Featured Desalination Plants
H2OAKS CENTER, TEXAS, USA.
Contracted by the San Antonio Water System (SAWS), the H2Oaks
Center in Southern Bexar County, Texas forms part of a long-term
phased approach to increase access to drinking water by way of
brackish water desalination. The SAWS water management plan
envisages an extra quantity of non-conventional water resource
development by 2050, of which the H2Oaks Center will eventually
provide 30 MGD (113,550 m3/d). The first phase of the project
has a capacity of 12 MGD (45,420 m/3d), with additional stages
scheduled for commissioning in 2021 and 2026.
The facility blends multiple sources of feedwater with its product
water to achieve more efficient groundwater augmentation. The
feedwaters are themselves blended from a combination of wells,
forming two streams with TDS levels of 1,300 ppm and 1,730 ppm.
After treatment at 90% recovery, the resulting permeate water
(TDS 120 ppm) is blended with saline water, creating product
water for injection into the Wilcox aquifer with a TDS of 400 ppm.
The Biwater RO system uses four Biwater Primary RO trains (80%
recovery, 33,3111 m3/d) and two Biwater Concentrator trains (50%
recovery, 4,163 m3/d) to achieve 90% recovery, using DOW BW30400 membranes. The final RO stage operates at a pressure of
200 psi and includes an ERI Advanced Turbo AT-1500 for energy
recovery. The RO system has an energy consumption of 0.5 kWh/
m3.
The project was procured under a Construction Manager at
Risk (CMAR) model, in which a Black & Veatch-led consortium
carried out conceptual design work before the award of the CMAR
contract to a joint venture of Zachry Construction and Parsons
Corporation. This structure differs from the design-bid-build
procurement model, in which a construction project is tendered on
completion of design work, instead bringing in a prime contractor
at an earlier stage of design.
In addition to contracting Biwater to supply the desalination
system, the Zachry-Parsons CMAR team contracted Dynamic
Systems as mechanical contractor. SAWS contracted Black &
Veatch as project manager, which engaged Tetra Tech as process
design engineer.
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