Salttech Agora 4

Leeuwarden, Netherlands

Salttech Agora 4

Leeuwarden, Netherlands
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Vaudevire E.,PWN Technologies | Koreman E.,PWN Technologies | Galjaard G.,PWN Technologies | Trommel R.,Salttech Agora 4 | Visser M.,Salttech Agora 4
Water Practice and Technology | Year: 2012

In the context of the development of the SIX© Ion exchange process, the Dutch water company (PWN) decided to investigate options for treatment of the brine arising from the regeneration of the resin. Main goals for the brine treatment are volume reduction and product recovery (water {thorn} NaCl). In this regard a biological denitrification (DNF) aiming at total nitrate removal followed by a nanofiltration (NF) aiming at ion separation (monovalent/bivalent) focused on NaCl re-use were implemented on a pilot scale recovering 80% of the total SIX brine (implying 80%recovery of NaCl). Further NF concentrate minimization and Sodium Chloride reclamation would allow a reduction of the disposal fees and chemical uses and therefore largely increase the overall process sustainability. During operation on a pilot scale with a capacity of 250l/h, the Dynamic Vapour Recompression (DVR) technology has proved itself to be capable to reduce the raw regenerate another 6 to 10 times reaching meanwhile the solubility limits of NaCl and other salts making their recovery on a solid stream possible. The condensate that resides after DVR treatment is low contaminated and is therefore suitable for re-injection upstream the SIX pre-treatment process. Laboratory scale evaporation tests showed that salts would precipitate according to the following order: BaSO4.BaCO3.MgSO4. MgCO3.CaCO3.CaSO4.Na2CO3. Na2SO4 and NaCl. A sequenced thickening by DVR treatment leads to selective precipitation of BaSO4, BaCO3, MgCO3, CaCO3 and CaSO4 at concentration factor around 8 but beyond a CF of 10 it leads to a more or less simultaneous precipitation of NaCl, Na2CO3 and Na2SO4 without fouling/clogging problems of the DVR. A reuse of a heterogeneous (co)precipitate solid fraction is difficult; however this problem could be countered by further investigation on a temperature controlled precipitation of Na2CO3 and Na2SO4. Cooling down the DVR brine saturated in dissolved sodium chloride, sulphate and bicarbonate to a temperature of 5 °C increases solubility differences between sodium chloride and its two contaminants, making their separation possible. © IWA Publishing 2012.


Vaudevire E.,PWN Technologies | Koreman E.,PWN Technologies | Galjaard G.,PWN Technologies | Trommel R.,Salttech Agora 4 | Visser M.,Salttech Agora 4
Desalination and Water Treatment | Year: 2013

Nanofiltration (NF) and Reverse osmosis membranes are widely used for diverse applications for their ability to remove natural organic matters, polyvalent cation (softening), etc. However, concentrate streams arising from these technologies often reaches concentrations up to 60 g/L which makes their disposal a major constraint and usually require additional treatments. In the PWN technologies research facility, in the context of the development of the SIX© Ion exchange process, NF is used to recover NaCl from the brine arising from the regeneration of the resin for further reuse in the process. A pilot scale of the technology aiming at ion separation (monovalent/bivalent) focused on NaCl reuse was implemented recovering 80% of the total SIX brine. Further, NF concentrate minimisation and sodium chloride reclamation is, however, desired to allow a reduction of the disposal fees and chemical uses and therefore largely increase the overall process sustainability. Due to high total dissolved solid concentration of the NF concentrate, between 80 and 100 g/L, it was decided to use the dynamic vapour recompression evaporation technique (DVR). During operation on a pilot scale with a capacity of 250 l/h, the DVR technology has proved itself to be capable to reduce the raw regenerate another 6-10 times reaching meanwhile the solubility limits of NaCl and other salts making their recovery on a solid stream possible. The condensate that resides after DVR treatment is low contaminated and is therefore suitable for re-injection upstream the SIX pre-treatment process approaching that way the term of a zero liquid discharge process. © 2013 Copyright Balaban Desalination Publications.

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