Seawater desalination with memstill technology - a sustainable solution for the industry

Abstract

Membrane Distillation may be applied over several different configurations to carry out seawater desalination. Using a microporous non-selective hydrophobic membrane, a finite air gap, and a cool surface in a particular arrangement, heat transfer may be employed to drive the transport of only water vapour across the membrane. Several limitations in conventional Membrane Distillation platforms dramatically reduce the viability of this water purification technology, namely low transmembrane fluxes, high thermal energy requirements, and low freshwater recovery rates. Keppel Seghers, through the logical application of system integration expertise, has succeeded in systematically removing these limitations during the development of Memstill technology. Memstill technology is a proprietary application of Membrane Distillation in an ideal counter-current flow configuration which allows for highly efficient recovery of heat within the desalination process. The recovery of heat within the Memstill process allows desalination to be driven with a minimal heat input. As such, Memstill desalination may be conducted using waste heat sources that would otherwise be rejected to the atmosphere. In addition, the efficient recovery of heat from the outlet stream of Memstill implies that it may be discharged at significantly lower temperatures than conventional thermal Membrane Distillation platforms. Keppel Seghers has conducted three previous pilot trials of Memstill technology, and is prepared to design, build, own and operate a Memstill demonstration plant with a freshwater production capacity of about 100 m3/day on a petroleum refinery in Singapore. This work will be carried out with the support of PUB.