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PRETREATMENT SOLUTIONS FOR SEAWATER DESALINATION

IDE offers advanced pretreatment technologies for membrane seawater desalination

The main objective of the pre-treatment step is to provide the quality of feed water to membrane according to the manufacture specification that serve to protect and increase the lifespan of RO membranes. The presence of microorganisms such as bacteria, algae, fungi, and viruses in seawater can lead to significant biological fouling.

Pretreatment is executed by removing particles, debris, microorganisms, suspended solids, and silt from the seawater source before reverse osmosis separation For safe and economic operation. Ideally, the only remaining solids in the seawater after pretreatment would be dissolved minerals. If the seawater system is operated in a way that prevents mineral precipitation on the membrane surface, the SWRO membranes’ lifespan could exceed ten years.

At IDE, we offer a complete range of pre-treatment solutions:

DAF (Dissolved Air Flotation)

DAF technology is an efficient procedure for the separation of suspended matter (turbidity, algae etc.) and SDI from seawater. Dissolved air flotation (DAF) utilizes the property of micro-bubble adherence to suspended solids, increasing the tendency of the particles to float. These micro-bubbles attach themselves to discrete floc particles created in the flocculation process. Thanks to the air bubbles’ velocity under flow with aggregate density decreasing, aggregates will rise to the surface of the water. DAF enables efficient separation of suspended solids, and oil & grease traces, as well as the reduction of organic load.

Lamella Clarifiers

Lamella clarifier serves to remove heavy particle by settling into inclined plates. This separation method requires prior flocculation and coagulation steps. Lamella clarifier is designed to maximize settling efficiency of suspended particles with minimal footprint.

Ultrafiltration (UF)

Ultrafiltration (UF) is a pressure-driven membrane filtration process which uses hydrostatic pressure to force water through a semipermeable membrane. UF is used for a separation of suspended solids, colloids, bacteria and virus. The ultrafiltration membrane, having a pore size of approx. 0,02 μm, creates a barrier and produce water with very high purity and low SDI (silt density index).

Filtration (Multi-media filters)

A multi-media filter (MMF) is used to reduce the level of suspended solids in process water by filtration through the granular media. The filtration degree of a multi-media filter depends heavily on the filter media and flow (velocity) through the filter. The gravity or pressurized filters are used for multi-media filtration depends on feed water quality and intake location. As particles become trapped in the media, the differential pressure across the bed increases. High velocity backwash of the filter media is used to clean and revert the performance.

Granular activated carbon (GAC) is a hybrid mixture of a wide variety of graphite platelets that are interconnected by non-graphitic carbon bonding. The adsorptive capacity of GAC makes it ideal for removing a variety of contaminants from water, air, liquids and gases.