Alkaline steel and cement wastewater to trap millions of tons of CO2

Scientists at Germany’s Helmholtz-Zentrum Hereon have discovered that alkaline wastewater from steel and cement production can be used to capture and store up to 30 million tons of CO2 annually. This approach leverages the natural chemistry principle of neutralization, where carbon dioxide reacts with alkaline wastewater to form bicarbonates, effectively binding CO2 in water and preventing its release back into the atmosphere. Traditionally, such wastewater was neutralized with strong acids, missing the opportunity to utilize its CO2-binding potential. The method is low-cost, energy-efficient, and can be integrated into existing industrial processes without the need for transporting materials, unlike other carbon capture strategies. It offers a scalable and controllable solution to carbon sequestration by mimicking natural rock weathering processes that have regulated atmospheric CO2 for billions of years. This technique aligns with global climate goals, such as those set by the Paris Agreement, by providing a practical way to reduce greenhouse gas emissions from heavy industries. The findings were published in the journal Environmental