Overview of Intake Systems for Seawater Reverse Osmosis Facilities

Abstract

The intake is a critical component of every seawater reverse osmosis facility and controls to a great degree the design and operational cost of downstream treatment processes. Two general classes of intake types occur; surface or open-ocean intakes and subsurface intakes. Globally, most large-capacity SWRO plants use open-ocean intake systems with the actual intake located either onshore (commonly shared with a power plant) or offshore. The most common offshore intake type uses a velocity cap at the top of the invert pipe. Inshore or offshore passive screen intakes are used to reduce the impacts of impingement and entrainment. Subsurface intake systems, either wells or galleries, are being used in hundreds of small to medium capacity SWRO facilities. Because of the greater attention being given to the environmental impacts of impingement and entrainment of marine organisms, subsurface intake systems are being specified for a greater number of facilities with higher capacity.