Harn R/O Systems, Inc. was contracted to design and construct a seawater pilot unit permanently installed in a shipping container for mobility. The unit incorporates many features to provide maximum flexibility for studying varying conditions. These features include the ability to draw permeate of one or both ends of the pressure vessels, ability to be modified from single stage to two stage operation, and incorporation of an Energy Recovery, Inc. Pressure Exchanger energy recovery device. A cleaning and flushing system was also provided, and all operation automated through the use of a PLC. The unit was custom-built, tested, and made ready for shipment within an extremely tight time schedule.
Veolia was one of two teams selected to pilot test and prepare proposals for remediating the Tampa Bay Water 25 MGD Desalination Plant. Veolia selected Harn R/O Systems, Inc. to design and build a very specialized seawater test unit that would allow them to test reverse osmosis desalination downstream of two different pre-treatment processes. Due to the tight time schedule for preparing the remediation proposals it was decided to build two independent test units side-by-side to enable the R/O process to be tested on both pre-treatments simultaneously. Due to flow variations in the two different pre-treatment processes, one of the seawater systems would utilize a 4” diameter, 8 element long vessel and the other unit would utilize an 8” diameter, 8 element long vessel. Both units would operate completely independently – separate pumps, instrumentation and controls. The 4” diameter system was designed to be converted to another 8” diameter system for further full-scale testing at higher flows, if desired. A complete cleaning, flush, and permeate drawback system was provided. The unit was assembled in a very short time frame, allowing the Veolia team to obtain as much useful pilot data as possible in the short time allowed.
Subsequent to the completion of the testing at Tampa Bay, Veolia had another application for the pilot unit in another area of the country. They again contracted with Harn R/O Systems, Inc. to pick up the test unit, check it out and test it, and re-assemble it for operation on a large, mobile flat-bed trailer.
Seawater Pilot for Affordable Seawater Collaboration (2004)
The Affordable Seawater Collaboration is a non-profit organization of state agencies, special districts and leading companies in the desalination industry that assembled to demonstrate through pilot testing that seawater desalination is now an affordable, reliable and environmentally responsible source for fresh water. To ensure the success of the demonstration pilot they began a careful and thorough search for a quality company to design and provide the pilot system. Harn responded with the most complete and competitive proposal provided by the six companies invited to submit. Harn also followed up by providing higher quality components than specified and optimizing the initial design to make the test unit a show piece. Many “up-to-the-minute” industry advances were incorporated in the system including, the Energy Recovery, Inc. Pressure Exchanger energy recovery device, and Dow Filmtec Low Energy seawater membranes. The system was delivered on schedule, started-up and immediately began demonstrating a remarkably low water production cost of about $2.00/kWhr. This is already comparable to the cost required to transport surface water long distance in the California region. It is anticipated that the cost can be reduced even more as the test unit operation is optimized.
Harn R/O was contracted in 1997 to design and fabricate six fiberglass seawater R/O skid assemblies for a 3 MGD seawater R/O system to replace steel skid assemblies that had rusted beyond repair. The steel skids were originally designed based on using the minimum dimensions possible. The challenge was to design structural fiberglass skids that would accept the existing membranes, stainless steel piping and valves, maintain the original design and not to exceed the overall dimensions of the original steel skids. In addition each skid had to allow for disassembly in order to pass through the access door for re-assembly and support approximately 30,000 pounds. Harn R/O was able to meet this challenge and meet the short delivery schedule of the project.
In 2003 Harn assisted FKAA in investigating options to replace some and eventually all of the old Dupont permeators that are not made anymore. FKAA was having growing problems with poor water quality, production quantity and pressures. Harn interfaced with Toyobo, a Japanese permeator manufacturer to carefully select a product that would fit dimensionally, operate well on the Keys water quality and produce a good quality permeate at an energy-saving low pressure. Harn installed the first train of Toyobo permeators in 2004 and installed a second train in 2005. FKAA is very happy with the quality and operating pressures. After Hurricane Wilma interrupted water supply from the Florida City plant in October 2005 FKAA ran the seawater plants to provide water for the Keys after more than 20 years in a standby service. Part of the retrofit to Toyobo permeators included replacing the stainless braided hoses that connected the feed and concentrate with Kynar braided convoluted Teflon hose rated for about 1800 psi. These are stronger, will never corrode and makes installation and maintenance more user friendly.
Replacement Fiberglass Frames
Original Corroded Steel Frames
New Kynar Braided Hose Feed/Concentrate Connections
Little Gasparilla Seawater Plant (1986 & 1995)
The Little Gasparilla (Seaside) seawater reverse osmosis plant was the first reverse osmosis plant in the continental United States producing municipal drinking water from seawater. It remained the only municipal seawater-to-drinking water plant in the US until a plant was installed in Santa Barbara, California in the mid-1990’s. The Little Gasparilla plant has been in continuous operation since 1986. Harn R/O Systems expanded the plant from 18,000 gallons per day to 36,00 gallons per day in 1995. The Owner has been very pleased with the smooth operation and ease of maintenance of the plant. Although the manufacturer certainly would not recommend it, the packing glands were not adjusted for several years and the pump worked fine. The Owner has been heard to brag he can balance a nickel on edge on the wetted end of the pump. Even though the system incorporates a triplex positive displacement pump, it operates extremely smoothly due to the proper pump sizing and use of suction and discharge stabilizers.