LANXESS adds low energy elements for reverse osmosis

“The operating pressures of the LE membrane elements are around 20-40% below those of the standard pressure elements in our product portfolio. The pumps in RO plants that use these elements also exhibit corresponding reductions in energy consumption in relation to the volumes of purified water produced and the rate of flow,” explains Alan Sharpe, head of the RO Membrane Project in the Liquid Purification Technologies business unit of LANXESS. LE membranes are particularly beneficial in any applications that demand high flow rates and thus high levels of productivity and where slight compromises in terms of water quality are acceptable. The main area of application for RO elements equipped with LE membranes is the desalination of brackish water. These elements can be used to treat both surface water and groundwater in industrial and municipal sectors, including the treatment of wastewater. LE membranes for reverse osmosis are spiral wound and made from a polyamide composite membrane sheet. The dimensions of the LE modules match those of standard elements, which means they can be easily installed in the standard pressure vessels of RO plants.“Although the new elements have been modified and optimized in a number of ways, their separation mechanism is still based on tried-and-tested polyamide thin-film composite membranes,” explains Sharpe.Three product types are currently available, each with an average salt rejection of 99.5 percent at reference conditions of 10.3 bar (see Table 1).

Table 1: Lewabrane RO product types.
TypeB090 LE 4040B400 LEB440 LE
Average flow rate (m3/day)7.934.838.3
Diameter (inches)  488
Membrane surface area (m2)8.437.240.9

User-friendly, integrated LewaPlus software supports the simulation and design of both reverse osmosis (RO) and ion exchange (IEX) processes for water desalination. This makes it possible to design complex water treatment solutions and draw direct comparisons between calculations for RO and IEX processes. A series of new features and enhancements specifically for calculating RO processes have been incorporated into the latest version of this software (1.4.0).These include:• Energy optimisation of the process and comparison of different RO design configurations to improve energy efficiency.• Cost calculation for capital investment and operational costs to estimate all the relevant factors influencing the total cost of product water.