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Du Pont de Nemours (Nederland) B.V.Production of demi water from surface water

50-V1200HistoryAt its Baanhoek site in Dordrecht, Evides Industriewaterproduces demineralised water (demi water) for DuPontfrom surface water.DuPont uses this demi water for the productionof polymers (such as Teflon ® and Delrin ® ) and forgeneration of electricity. In 1997, DuPont initiated a survey into the possibilities forhaving the production of demi water handled by interestedexternal parties. Up until that time, DuPont had beenproviding for its own demi water needs (some 1 million m 3annually) by means of an in-house reverse osmosis plant.This plant converted drinking water into demi water.Since the plant had reached the end of its lifespan DuPontfaced substantial new investments in demi water productioncapacity. Under the company’s policy of “back to corebusiness”, the option of outsourcing the water productionwas an obvious one. DuPont chose Evides to be its partnerfor water.BL IXThe first step was taken with the signing of a customcontract between the companies. Besides the technicalterms and conditions (such as output, output variability,water quality, up-time and supply assurance), agreements ofthis type also include other specific conditions (for example,liability, communication between the parties, permits). Incooperation with Vivendi USF Benelux, Evides subsequentlyconstructed, then began the operation of this demi plant.The plant was finished and commissioned in late 1999, withongoing operation being entrusted to Evides Industriewater.At commissioning, the plant’s capacity was 105 m 3 /hour.In mid-2001, at the request of DuPont, the capacity of theplant was raised. To assure continuity of supply, two buffertanks are on permanent standby (total volume: 1,000 m 3 ).

50-V1100 Demi water plantIn the demi water plant, a number of lines - consisting ofserially operated process units - convert river water from theMeuse river (originating from the giant Brabant Biesboschholding basins) into water of demi water quality.The feedwater conductivity is 350-550 µS/cm.All larger suspended matter (up to 100 µm) in the intakeBiesbosch water is first removed with the help of twostrainers. The water is subsequently dosed with Fe(III),which acts as a coagulant. The water is agitated and thenpassed through an ultrafiltration stage (UF; see table 1) toremove particles, suspended matter and microorganisms.This separation takes place in membrane modulesequipped with capillary membranes (dead-end).The UF unit is equipped with eleven pressure tubes.PFD of the demi water plant

Table 1: Description of UF plantNumber of units3 unitsCapacity per unit 80-90 m 3 /hNumber of units in operation 2 of the 3 unitsRecovery 80%Number of pressure tubes11 per unitNumber of membranes / pressure tube 3Supplier & membranesX-Flow UFC M5Flux80-100 l/m 2 h Table 2: Description of RO plantNumber of units3 unitsCapacity per unit 60-70 m 3 /hNumber of units in operation 2 of the 3 unitsRecovery 80%Pressure10-15 barDesign temperature4-25 o CPressure tube configuration (7:4)Number of pressure tubes1st array 7 pcs.2nd array 4 pcs.Number of membranes / pressure tube 6Supplier & membranesDOW – FilmtecFlux20 l/m 2 hSalt retention 99%The UF units are periodically cleaned. This cleaning isnecessary to prevent an excessive pressure differentialacross the membrane due to fouling by organic andinorganic matter on the membrane surface.The water produced is stored in a holding buffer. Besidesholding the feedwater for the subsequent reverse osmosisstage (RO; see table 2), this buffer also supplies the UF unitswith water for flushing. A supply pump delivers the water viaa 5 µm cartridge filter to the three RO lines, one of whichis a standby line. In the RO unit, salts are removed from thewater at a pressure of between 10 and 15 bar.The RO filtration produces a flow of permeate water witha quality of 10 µS/cm, at a yield of 80%In order to protect the membranes from the accumulationand deposition of salts on the membrane surface, the ROfeedwater is dosed with acid and antiscalant.Periodically, the RO unit is chemically cleaned using acidand caustic in order to remove organic and inorganic foulingfrom the membrane surface. The cleaning interval is determinedby the increase in the pressure differential across theunit.Immediately following the RO, CO 2is removed fromthe permeate in a degasser. As a last polishing step in theprocess, the water passes through two mixed bed ionexchange units (see table 3).A feed pump supplies RO permeate from the buffer tankto each mixed bed. In the mixed bed, residual ions inthe RO permeate are exchanged for H + and OH - ions fromthe resins in the bed. This process stage reduces theconductivity of the permeate to the desired target level.Process control of the mixed beds is entirely automatic.The water quality is continuously monitored by means ofconductivity measurement and silica measurement.Once a mixed bed is exhausted, the bed is flushed andregenerated using acid and caustic.Table 3: Description of mixed bed plantNumber of units2 unitsCapacity per unit 140 m 3 /hCation resin 1300 L, type: R&H-Amberjet 1200HAnion resin 2200 L, type: R&H-Amberjet 4200CLNumber of units in operation1 of 2 units

50-V1100 Table 4: Demi water specificationsParameterValueEC:0.2 µS/cmSiO2:0.2 mg/lFe:0.1 mg/lDOC:1.5 mg/lpH: 5.5-7.5ResultEvides Industriewater produces and supplies demineralisedwater to custom specification for DuPont.The outsourcing of its water needs to Evides enablesDuPont to concentrate on its core activities, while ensuringlong-term access to the water of the special quality it needs.After passing through the mixed beds, the demi water isheld in the storage tanks.From the storage tanks, the demi water (see table 4) ispumped to DuPont. Before it reaches DuPont, it passesthrough a cartridge filter in order to remove any residualpotential particle contamination.All process units are controlled and monitored by meansof SCADA systems.To illustrate, the graph below shows the MTC value overtime (MTC: a standard measure for the water permeabilityof the membrane). In addition, the normalised pressuredifferential and salt passage values for the membrane arealso visualised.MTC BWRO

Evides Industriewater:Water chain approach to the benefitof the industry1/06/200Evides Industriewater is a subsidiary of Evides NV which,as a supplier of drinking water in the provinces of Zeelandand Zuid-Holland in of the south-west of The Netherlands,is the second largest drinking water company inThe Netherlands.Evides Industriewater is the biggest supplier of waterservices to the industry in The Netherlands. EvidesIndustriewater is responsible for the production and supplyof process water, demineralised and distilled water to theindustry as well as irrigation water to the agro-business.Total production amounts to approximately 80 million m 3per year. In addition, Evides possesses and managesvarious industrial and domestic waste water treatmentplants.In the district of The Hague, Evides Industriewater is partnerin a joint venture that is responsible for the erection andoperation (DBFO = design, build, finance, operate) of theHarnaschpolder sewerage water treatment plant representing1.3 million population equivalents, and the renovation ofthe Houtrust sewerage water treatment plant. EvidesIndustriewater develops and constructs a waste watertreatment plant in Delfzijl for the chemical industry in thatarea. Evides Industriewater also manages the waste watertreatment plant at the international airport of Amsterdam(Schiphol) as well as the percolation water treatment plantof the landfill site in Vlissingen.All of these plants have been erected by means of DBFO(Design, Build, Finance, Operate) schemes with EvidesIndustriewater being in control throughout all phases.Evides Industriewater uses state-of-the-art technologies(membranes, ion exchange) to convert various surfacewater qualities (sea water, brackish water, river water anddrinking water) into process water, demi water andultra-pure water. In full compliance with ourcommitment to reliability at the serviceof process and customer.Source ofKnowledgeEvides Industriewater BVSchaardijk 150 • 3063 NH ROTTERDAM • P.O.Box 4472 • 3006 AL ROTTERDAMtel. +31 (0)10 293 51 72 • sales@evides.nlwww.evides.nl