Start Date: August 2006
Completion Date: December 2006
Client: Consolidated Water Company, Grand Cayman

The Consolidated Water Company (CWCO) operates the North Sound SWRO plant providing municipal water for Grand Cayman. In order to increase capacity at the plant, CWCO selected Aerex® Industries, Inc. to provide an additional 0.8 MGD train.

Throughout the years, Aerex® has continually provided both piping and membrane systems for many of CWCO’s membrane treatment installations. CWCO’s selection of Aerex® was again predicated on Aerex’s® ability to provide this unit to stringent project specifications and an aggressive shipping schedule.

The 0.8 MGD train consists of a 2-pass arrangement that included a Dweer energy recovery system using the spent brine pressure to boost the first pass feed pressure.

The first pass contains 36 seven-element pressure vessels in a multi-ported array. The feed and brine ends connect vertically with manifolds at the center and three 3” ports above and below the manifold in each column. Product water is taken from both the feed and brine end of the first pass. The higher salinity brine end product feeds the second pass.

The second pass contains six seven-element vessels in a 3-2-1 three stage array. Product from the second pass is blended with feed end product from the first pass providing 180 TDS, high quality municipal water. The relatively low salinity reject from the second pass is blended with the first pass feed to reduce the overall salt load on the system.

Aerex® supplied the vessel arrays mounted on a epoxy coated steel frame complete with feed, concentrate and permeate piping, controls and sample panels. Additionally, the SWRO skid houses the Dweer energy recovery system which is mounted below the pressure vessel array with the associated piping and supports. Due to the unusual feed water composition in Grand Cayman, all high pressure piping is 316L stainless steel.

The 22,000 lb. train was fully assembled and shop tested before being shipped to the Cayman Islands. This allowed CWCO to immediately install the train with only minor piping and electrical connections, ultimately saving them considerable time and expense on site.