Innovative Salt Recycling: Reducing Water Waste and Preserving Resources in Chemical Production

Imagine turning what is typically treated as waste into a valuable resource that powers key chemical processes. At Covestro’s Krefeld-Uerdingen site in Germany, a groundbreaking project is recovering sodium chloride (NaCl), also known as table salt, from industrial process water streams generated during plastic manufacturing. The goal is to recycle the extracted salt as a raw material for producing chlorine and caustic soda in the chlor-alkali electrolysis process. Additionally, the project seeks to recycle the resulting water, creating a closed-loop system that significantly reduces waste while conserving valuable resources.

Chlorine, for instance, plays a vital role in producing materials like polycarbonate, used in industries such as automotive, electronics, and medical technology. By recovering and reusing sodium chloride, Covestro not only reduces its need for fresh salt but also helps preserve water resources and limit environmental impact.

The recycling of NaCl at Covestro’s Krefeld-Uerdingen site allows the company to save around 19,000 tons of salt and 223,200 tons of demineralized water annually, contributing to a more sustainable production process.

Overcoming Challenges with Advanced Technology

Recycling salt from industrial wastewater presents challenges, particularly due to organic impurities that can interfere with the electrolysis process. Covestro has implemented advanced purification and monitoring techniques, such as activated carbon filtration and special HPLC-MS (High-Performance Liquid Chromatography-Mass Spectrometry) analytical techniques, to remove these impurities and ensure the recovered salt meets the necessary standards for chlor-alkali electrolysis.

This innovative approach not only closes the material loop but also conserves significant amounts of water that would otherwise be lost in traditional wastewater treatment processes.