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

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