Recycling brine
Covestro AG (Leverkusen, Germany; www.covestro.com) is testing a new process for recycling saline process wastewater that is generated in the production of polycarbonate, a high-performance plastic. A pilot plant for the process, located at the Krefeld-Uerdingen site in Germany, was opened last month.
The current project at Covestro marks the first time in Germany that saline industrial wastewater has been recycled at an industrial pilot plant. Pretreated salt water such as this is usually released into waterways, specifically the Rhine river, which runs directly along the site. Thanks to the new plant, some of this wastewater can now be used in an electrolysis process to manufacture chlorine. Chlorine itself is one of the key raw materials for producing polycarbonate and other plastics.
The new process helps save up to 30,000 metric tons per year (m.t./yr) of salt and 400,000 m.t./yr of fully desalinated water in chlor-alkali electrolysis. The process stops up to 70 m3/h of saline wastewater from being released into the Rhine.
The total cost of investment is around €3.7 million, with €740,000 provided by the German Federal Ministry for the Environment.