PRESS RELEASE

Highly profitable evaporation of wastewater

At THALES Nederland B.V. a substantial saving on wastewater -disposal costs has been obtained by a new
system for evaporation which reduces 1000 liter/day of fotoresist-wastewater to 150 -200 liters/day.
The application was subsidised by the Dutch ministry of economical affairs because the system is capable to
evaporate water from heavily fouled wastewaters by using low temperature (waste) caloric energy. At Thales the,
otherwise difficult to treat, resist-waste water is evaporated with energy which is entirely derived from the
surrounding air and compressor cooling air. The unit's own consumption of energy is limited to a (low pressure)
ventilator and a pump. According to Thales the unit works maintenance free ever since the start up 10 months ago.
The evaporation is achieved by saturating a big flow of air with (clean) vapour from the liquid.
The liquid runs down, as thin film shaped flows, over a number of tilted plates having special, louvre shaped,
protruding perforations. Because of this shape the flow of liquid incites (by venturi action) a slightly negative
pressure in the openings of these perforations. This makes it possible to supply and pass through these openings
a big flow of gas having very low positive pressure. Due to the venturi action the gas will have virtually
no positive pressure after it has passed through the openings and is dragged along with the turbulent flow of
liquid as myriads of elongated bubbles. The resulting large contact- area and relatively long contact time leads
to an optimal gas-liquid mass transfer while the plates stay clean because cristals precipitate in the turbulent
flow itself and stay suspended. The modular, virtually sanitary, construction allows fast (water jet) cleaning of
all surfaces during operation. The patented, sturdy, "GALICOS" (Gas-Liquid-Contact-System) modules can be used for
evaporation, condensation, cooling, aeration, stripping and heat exchange of fouled process- or waste water
and cooling, washing, deodorisation of dust loaded gases.