Equipment capability

Summary: The membrane distillation (MD) test rig is set up as a plate and frame type module. The set-up includes: the use of a hot water bath, membrane module, pump (different pumps can be used – such as peristaltic pump, rotary pump, centrifugal pump, etc), chilled water tank, and weighing scales and conductivity probe connected to a laptop; in case of using Vacuum Assisted Air Gap MD vacuum pump, condenser trap and ice (to condensate the permeate). Membrane module consists of feed and permeate reservoirs, plastic spacers, a plastic perforated disk, a condensing plate and the membrane.

This system consists of two water loops (one heated and one cooled), and one outlet were permeate is collected. The heated feed water (up to 90 Degrees Celsius) is pumped through silicon tubing to the membrane module is then returned to warm water bath. The feed includes salt solution (water + NaCl) and may also include, dyes, surfactants, or solvents. The second loop is set up so chilled water is used to condense permeated water either in direct contact with the other side of the membrane or indirectly by using a condenser plate inside the module. The temperature gradient drives water vapour from the hot side to the cold side which is then collected as pure distillate. Depending on the configuration of the MD rig this permeate can be collected in different ways: Direct Contact D: Permeate is collected directly in the cold-water loop. AGMD: Once permeate is condensed it start flowing outside the middle-compartment of the module by gravity and then collected through a funnel and a beaker placed below the MD rig. VA-AGMD: Between the two water loops vacuum is applied, which enhance water vapour permeates the membrane from the hot water loop, this vapour is condensed in a trap by means of ice and collected.

Location/partner: University of Manchester