SPOTVIEW – Sustainable Processes and Optimized Technologies for Industrially Efficient Water Usage in steel, dairy or pulp and paper industry

Initial situation

• Water use in steel industry: 1980 million m³ for production of 169 million tons crude steel divided in 75% cooling applications, 13% gas washing and 12% material conditioning
• Inhibition of water reuse because of salts and hardness (corrosion, scaling), abrasive solids or organic compounds (oil, grease) and cooling water treatment chemicals
• Effect of water components: decreasing salt/hardness removal efficiency of available technologies to an insufficient economic or technical level

Project objectives of the steel case

• Decoupling of production processes from water consumption and reduction of fresh water demand about 20 – 40% or waste waters up to 90%
• 20% energy saving by recovery from cooling water with chemical heat pump

Innovative approaches

• Desalination and softening of waters by capacitive deionization (CDI)
• Use of chemical heat pump for energy recovery
• Direct internal reuse of low or loaded process waters after treatment in different applications (cascade)

Current results (as of 11/2017)

• Determination of suitable streams for applying chemical heat pump and internal multiple use after treatment based on prepared process and waste water overview
• Fulfillment of operational specifications for water composition after treatment of backwash water and river water by means of CDI – chloride and hardness removal: up to 89%, pure water yields: 68 – 79%
• Generation of pure water with conductivities as demineralized water (0 – 50 μS / cm)

Outlook

• Optimization of CDI operating parameters to increase pure water yields and reduce energy demand

Identification of potential disturbing contaminants in the CDI treatment

Chemie Ingenieur Technik, Volume 91, Issue 10, Special Issue:Industrielles Wassermanagement, October 2019 | BFI DE

• capacitive deionisation
• chemical heat pump
• Cooling water
• desalting