Filtration system

Abstract

A filtration system 10B comprises a batch recirculation loop comprising a pressurisation module 20 and a separation module 40, configured to allow liquid to be pressurised using the pressurisation module while recirculating the liquid to the separation module, wherein a feed arrangement 12 feeds liquid into the recirculation loop. The filtration system is configured to operate in an open recirculation mode and in a closed recirculation mode, wherein, in the closed recirculation mode, no feed liquid is supplied into the recirculation loop while the pressurisation module pressurises liquid during recirculation, and wherein, in the open recirculation mode, liquid is supplied using the feed arrangement while the pressurisation module is inactive during recirculation. The pressurisation module may comprise a displaceable actuator, such as a piston 50. The filtration system can be a membrane desalination system. The use of an open recirculation loop and a closed recirculation loop may be coordinated, i.e. used in an alternating manner, to adapt to filtration demands. By providing an operating mode in which the pressurisation module is not necessarily relied upon for pressurisation, the number of recirculation cycles can be effectively increased, or prolonged. [Figure 2]