The CS6 is a large-scale demonstration for closed-loop water recovery that will be developed at the industrial cluster of Rotterdam Port in the Netherlands. The demonstration involves the chlorine cluster of the area, with the large demo installed at the plant site of NOBIAN/Westlake Epoxy?s in Pernis. In this Industrial Mining case study, the salt wastewater (or brine) from Westlake Epoxy?s plant, is treated with the aim to produce high purity brine which can be a source of salt and water for Nobian?s nearby
Chlor-Alkali plant. The purified brine could partially replace mined salt and freshwater in Chlor-Alkali, reducing the water consumption by 1/3, saving 25 MWh thermic and 6 kilotons of CO2, at full scale. The process is truly circular as the chlorine produced from the waste brine is in turn used by Westlake Epoxy in its epoxy production. In this loop, the chlorine molecule can be considered as a ?chemical lease product.? The demonstration is planned to be set up between June 2022 and June 2023 with a skid-based treatment unit with a capacity of 0.1-2 m3/h, designed by the Austrian firm KVT, which applies high pressure oxidation (HPO) to convert the organic impurities in the waste brine into CO2. Application tests of the treated brine will be performed by Nobian.

Key innovations

Zero Liquid Discharge: Zero Liquid Discharge is a concept that promotes the elimination of pollutants on water related to industrial activities. For this water is kept in a closed loop, recirculating between units or companies in order to be reused as much as possible. Application of Chemical Leasing concept: The Chlorine molecule can be seen as an energy carrier, able to start chemical reactions at the end-user’s plant. If it is not incorporated in the end product, it can be recovered and returned to the supplier in the form of sodium chloride salt, to produce chlorine once again.

Zero Liquid Discharge:
Zero Liquid Discharge is a concept that promotes the elimination of pollutants on water related to industrial activities. For this water is kept in a closed loop, recirculating between units or companies in order to be reused as much as possible.

Application of Chemical Leasing concept:
The Chlorine molecule can be seen as an energy carrier, able to start chemical reactions at the end-user?s plant. If it is not incorporated in the end product, it can be recovered and returned to the supplier in the form of sodium chloride salt, to produce chlorine once again.

Main challenges

1.

Approval of purified industrial brine for Chlor-Alkali electrolysis

2.

Developing and optimizing the treatment train to reduce costs

3.

Business case and business model including logistic or infrastructural solutions for full scale

Outcomes

Reduction in the use of freshwater sources by 70%

Water recovery increase by 40% to reach a value of 0.95 m3 of water re-used per m3 of treated industrial waste water

Energy requirements covered by waste heat recovery from oxidization reaction to more than 40% of total energy needs

Recycling of chlorine/sodium
streams to more than 90% at 110 kg NaCl per m3 of treated industrial wastewater

Expected impact on society

The recirculation of salts would lead to reducing the dependency of mined salts, while ensuring its availability. Although the direct impact of reducing salt mining and the associated environmental impacts at large scale depends on whether recovered brine substitute can complement current mined salt used in epoxy production.

If we consider stricter environmental regulations to be implemented in the future, the recirculation of salts may be a way to deal with challenges to epoxy production and maintain the industrial activity, the jobs and the added value it creates.

Recirculating salts would reduce the amount of wastewater treated in the biotreater and the related resource consumption (e.g. energy, chemicals). It would also improve the quality of water released to the environment.

Business opportunities

As part of the market system analysis, key market actors such as technology and energy suppliers, and institutions were identified.
Concerning business opportunities for the proposed solution, stakeholders and case study owners highlighted the group of industrial salt consumers, the ?chlorine cluster?, consisting of companies located close to the demonstration plant. Potential customers for the produced sodium chloride are foremost.

The case study owners are:

  • Westlake Epoxy
  • Nobian (the largest chlorine producer in the Netherlands)

The case study owners have expressed their interest in the product,produced with the circular economy principles. Other potential users of the cluster include:

  • Huntsman, a global chemicals company
  • Shin-Etsu PVC B.V., a global PVC production company

Expected positive impacts include:

  • reduced waste (brine)
  • less salination of the surface water
  • increased resource efficiency throughout the value chain but the participatory stakeholder consultation

Expected barriers revealed by participatory stakeholder consultation are:

  • lack of economic feasibility
  • mutual dependencies in the market system, which prevents a change in industry cooperation away from the traditional supplier-customer relationship.

On the positive side, stakeholders recommended several actions that could help overcome those barriers.

  • To enhance economic feasibility, investment subsidies via different Dutch schemes were recommended to be further explored and affordable alternatives shall be explored for brine purification.
  • On the other hand, potential partners could support the solution via a third-party investment (DBFO) in return for being paid service fees.
  • To enable changing the traditional supplier-customer relationship, stakeholders suggested among others intensifying the cooperation with industries at the Chlorine Cluster.
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Contact

WESTLAKE EPOXY

Ellen Tuinman

ellen.tuinman@hexion.com

TU Delft

Dimitris Xevgenos

d.xevgenos@tudelft.nl