The supply of water to Dow Chemical in the estuarine delta of the river Schelde in southwest Holland is handled at the DECO watertreatment facilities, owned and operated by Evides Industriewater. The process design is based on sand filtration, ion exchange technology and membrane filtration. Different water qualities are being used as feed water: river water (from huge fresh water basins some 140 km away), locally collected fresh run-off water (rain water), industrial effluent, condensate and – formerly – seawater. Apart from water reduction programs this multi-sourcing strategy of Dow Chemical results in risk mitigation (reduction of its dependability of one single feed water source), sustainability of its production site in Terneuzen and cost savings.

In 2006 a part of the membrane filtration plant at the DECO-plant has been re-engineered in order to replace seawater for municipal effluent as feed source. Since February 2007 a total of 1million m3 of demi-water per year is being produced using the effluent from the clarifiers of the existing municipal waste water treatment of Terneuzen (WWTP De Drie Ambachten). This amount is less than intended, since the existing micro-filtration step (MF) is limited in its capacity and due for full replacement. As a consequence the post-treatment by RO does not produce the quantity of demi-water desired by both Evides Industriewater and Dow Chemical.

In close cooperation with the waterboard and Dow Chemical, Evides Industriewater has decided  to not replace the MF-plant but rathert o increase the quality of the feed of the RO-plant. This will be achieved with the construction of a MBR at the WWTP DDA. The MBR is scheduled to start-up by the end of 2009, so as to ensure that from 2010 the RO-plant produces 2 million m3 of demi-water per year again.