Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/107143
PROJECTS 30,000 m3/d. This will be expanded to 50,000 m3/d in Phase 2. The original specification of the desalination plant was based on conventional pretreatment: DAF, two stage DMF followed by cartridge filtration. Alternative designs based on membrane pretreatment were allowed during the bidding phase. A number of bids were received, based on different pretreatment options: 1. Conventional pretreatment: DAF followed by two-stage media filtration. 2. Single-stage ultrafiltration. 3. DAF followed by ultrafiltration. Based on a thorough tender evaluation, taking into account investment, operational costs, robustness of the process and project capabilities, option number 3 was selected. Compared with case study I, this project is characterized by the following design changes: l Better pretreatment. This project uses DAF as pretreatment prior to the ultrafiltration system. This allows for a higher membrane flux rate and a longer filtration interval. l In-line operation. The UF is operated at elevated pressure. This creates a backpressure on the UF permeate side that allows for feeding directly into the SWRO high-pressure pumps. l Brine backwash. The UF system is backwashed with SWRO concentrate (brine). l All units are backwashed in a sequence. This is a "train backwash": the backwash pump is started, and all units are backwashed one by one with the backwash pump continuously operating. After backwash of the last unit, the pump is stopped and idles until the next backwash is called for. UF design parameters, compared with case study I: l Flux rate: 10% higher l Backwash interval: 60% longer l CEB interval: 100% longer l UF waste water 75% reduction production: The cost implications of the design on this large scale plant are quite considerable: l A higher flux rate means less membrane surface area. This translates to a reduction in number of membrane elements and in number of ultrafiltration units to be installed. l A longer backwash interval decreases the downtime of the ultrafiltration system due to backwashing. This membrane elements and membrane translates to a reduction in membrane units as well. It should be noted that elements and membrane units as well. this plant will be the first worldwide l In-line operation eliminates the need that employs brine backwash on a for intermediate storage tank, transfer full scale dual membrane desalination pump and cartridge filters. This plant. reduces cost and footprint. l The train backwash has two effects: 1. By minimizing the number of start/ l Brine backwash decreases the internal stop cycles on the backwash pump, water consumption of the UF system. Project1 3/4/12 reduction in the wear and tear is minimized. This translates to a 10:24 am Page 1 Ideal for desalination & water reuse plants The World's First Non-Metallic All-FRP Vertical Turbine Pump The patent pending Fybroc® Series 8500 is the first and only pump of its kind PRIMARY ADVANTAGES • NO corrosion • NO harmful leaching of minerals FEATURES • • • • Four pump sizes Capacities to 1700 GPM (386 m3/hr) Heads to 70 feet (21 m) per stage Working pressures to 150 psig (1035 kPA) TYPICAL APPLICATIONS • • • • Seawater intake Brackish water reverse osmosis (RO) Brine Recirculation and transfer 700 Emlen Way, Telford, PA 18969 Phone: +1 215-723-8155 Fax: +1 215-723-2197 E-mail: info@mp-gps.com www.mp-gps.com August-September 2012 | Desalination & Water Reuse | 23 |