Desalination of seawater and brackish water with reverse osmosis and the disc tube module DT

The "open channel" disc tube module type DT can operate effectively and eco nomically at increased turbidity and silt density index levels for reverse osmosis (RO). This module is applied reliably on seawater which has been pr etreated only with normal mechanical filters such as a sand filter and a ca rtridge filter, usually making dosing of disinfectants as well as acid and anti-sealant pretreatment unnecessary. More than 1,800 plants with a permea te production in the range of 2 to 300 m(3)/d have been installed since 198 5 and are operating successfully to secure the water consumption on cruise liners and merchant ships as well as in the navy and on installations offsh ore. The chemical pretreatment, necessary in conventional RO practice in th e field, is avoided using this module type. Therefore, on-shore application s are gaining importance because there is no negative impact on the environ ment that usually is expected because of longterm accumulation effects of t he additives from conventional RO plants that are going back with the conce ntrate to the sea or the raw water source. Due to the low pretreatment requ irements of the module, it can be operated for a wide range of desalination and purification applications. Design details of the DT module and results from practical field work in seawater desalination and treatment of bracki sh water are discussed.