POLYMERIC SPIRAL WOUND MEMBRANES
Cross flow polymeric membranes are available with different porosities (reverse osmosis, nanofiltration, ultrafiltration, microfiltration) and with different configurations (tubular, hollow fiber, flat sheet and spiral wound).
Each configuration offer advantages and disadvantages.
Spiral wound configuration is normally selected for its efficiency and low cost.
Elements are manufactured with two sheets of membrane rolled on a central permeate tube and separated by a concentrate spacer that create channels for feed flow.
Membrane elements are reinforced with an external fiberglass cage or with a polypropylene cage. On both ends there are supports (ATD) that avoid mechanical deformation of the membrane (telescoping).
A correct choice of construction material and manufacturing process allows to work on low to medium load fluids, at high/low pH and at high temperature, up to 90° C.
Feed solution is pressurized on one side of the element and part of the solution (permeate) can pass through the membrane and is collected in the permeate tube. The other part of the solution flows in concentrate channels and is collected on the other side of the element with all components that cannot go through the membrane.
Spiral wound membranes are finally very tight filters that operate with the following advantages:
- self-cleaning: small solids and solutes are collected in the concentrate stream as turbulent flow keeps them away from membrane surface and mantaint it clean;
- no heating: no product degradation and low energy consumptions;
- submicron filtration: it is possible to operate filtration at macromolecular, molecular and ionic level with concentration, purification and separation of low molecular wight solutes.
SEPRA works jointly with SUEZ (formerly GE) for which is Channel Partner on the Italian market, making available a wide range of standard products for the most common applications. Moreover SEPRA is able to make custom membranes available in special construction for particular processes.