The Challenge Planned Brackish Water Reverse Osmosis (BWRO) facility facing significant drop-off in water quality.
The City of North Point, Florida built a new brackish water reverse osmosis (BWRO) facility capable of producing 2.0 MGD of potable water by treating raw water from local wells with a Total Dissolved Solids (TDS) level of about 3,500 mg/L. However, the facility needed a flexible design because the conditions are expected to change over time. Nearby wells are degrading and the City anticipates that the raw water quality will degrade over time; historical data predicts salinity could increase by as much as 370% in the first 10 years of operations. The facility has two reverse osmosis (RO) skids, each capable of producing 1.0 MGD, which are designed to expand to produce 2.5 MGD each as demand for water rises. This wide range of operating conditions presented a significant design challenge.
The Innovation Solution The US’ First Installation of a BWRO PX® Pressure Exchanger®
Energy recovery technologies such as the PX Pressure Exchanger (PX), have previously focused on seawater RO applications due to the rather quick payback. This leaves brackish water RO (BWRO) facilities to turbochargers that yield less efficient transfer of energy than their PX counterparts. Recently, the first municipal BRWO application of a PX energy recovery device was designed for the City of North Port, Florida’s Southwest Water Treatment Plant and will be started up in 2nd quarter 2022.
This will be the first Brackish Water municipal installation of the Brackish pressure exchanger within the U.S. This paper will present and discuss the design considerations and key parameters including impacts to RO system operation and water quality, energy saving considerations, and data from the facility startup in 2nd quarter 2022. Municipalities with brackish-water supplies will be shown the way to reduce operating costs and maintain water quality from their RO treatment facility.
Location: Tortola Island, British Virgin Islands Project: Biwater Tortola
Product Configuration: PX Pressure Exchanger and AquaBold high pressure pump
Capacity: 10,400 m³/ day
The Challenge: British Virgin island dependent on reliable freshwater for GDP growth
Tortola is the largest British Virgin island in the Lesser Antilles with an approximate population of 24,000 residents. 92% of its Gross Domestic Product (GDP) comes from tourism where close to one million people visit the island every year. As with many island nations without natural aquifers, Tortola must produce all of its drinking water and demand is constantly high. Historically the island has supplied fresh water to residents and visitors through seawater reverse osmosis desalination, but current facilities in operation are deteriorating and this is having a deleterious effect on the island’s environment and marine life. In order to meet the island’s growing demand for fresh water supply, Biwater was contracted to design a new, environmentally-sound desalination facility to provide high-quality fresh water to the island alongside wastewater treatment facilities.
The Innovation Solution: The PowerPlay for faster time to market with superior energy savings
Biwater selected Energy Recovery’s PowerPlay integrated solution: PX Pressure Exchanger® 220 and the AquaBold high pressure pump. In island nations such as Tortola where power costs are high, Biwater chose the PX energy recovery device because it has the fastest payback than any other ERD in the market and allows the company to focus on delivering the highest quality water at the lowest price to the end user. In summary, by choosing the PX and AquaBold PowerPlay solution, Biwater is able to streamline the complex process of moving the Tortola plant from concept to operation. By combining the PX and the AquaBold, the Biwater Tortola project will enjoy faster deployment, longer life, and greater uptime.
The Result: Highest quality water for island’s biggest industry
The Biwater Tortola plant will be able to supply residents and tourists with highquality, affordable potable water. When operating at full capacity, the Tortola plant will produce 10,400m3 of treated water per day, and with Energy Recovery’s PowerPlay solution, the energy saved will be an estimated 9 million kWh per year – or the equivalent to taking 1,300 cars off the road. In addition to the new desalination facility, Biwater is also providing wastewater treatment facilities that will help better protect marine life in the vicinity. Once the desalination plant is online, the facility will boast the highest efficiencies possible with the Energy Recovery PowerPlay.