An evaporative process employing an undulating flexible membrane (4) as an evaporative surface onto which a vaporizing gas (2) such as, but not limited to, air, contacts a liquid solution (1, 5) such as, but not limited to, water, and evaporation occurs. The membrane (4) is supported (3) with sufficient laxity to permit wavelike undulating motion of the membrane brought about primarily by the evaporative airflow (2) itself. The differential flexing and motion of the undulating membrane (4) results in a breaking and peeling away of any normally fouling scaling or plugging solids which have precipitated or accumulated on the membrane surface (4). The undulation of the flexible membrane (4) thereby providing a self cleaning action. The self cleaning action of the membrane (4) assures successful application to evaporative processes with solutions (1, 5) which are prone to scaling, fouling, plugging or solutes buildup. The undulating membrane surfaces (4) can be employed for harvesting of solutes or concentration of solutions (6) in low temperature air (2) induced evaporative processes. Also, the undulating membrane (4) evaporative surface provides exemplary service for evaporative cooling processes by enabling the employment of low quality water (1, 5) as a coolant as well as by reducing or eliminating blow down discharge of concentrated liquid coolant.