Opportunities and Challenges for Iron and Steel Industry Water Use, Treatment, and Reuse in the United States: An overview of Current Industry Practices via Case Studies

N. Sharma, P. Lemar
Oak Ridge National Laboratory (UT-Batelle, LLC),
United States

Keywords: iron and steel, water circularity, process water quality, industrial water/wastewater treatment


Iron and steel industry has large water withdrawal (~128 m3 per tonne of steel produced), but a significant portion of it is reused or returned to the source leading to relatively low water consumption ~1.6-3.3 m3 per tonne of steel produced. This industry, including the foundries and supporting metal finishing sectors have process specific water quality needs which require physical and chemical treatment of the influent or reused water. For example, larger sites with steam systems will often require their water used for boiler makeup to be within certain limits of conductivity. Similarly, industrial sites with chiller equipment will require water below certain conductivity limits to ensure their cooling tower heat transfer surfaces are maintained. Industrial sites may also need to monitor and control pH, hardness, and other process limits. Conventional industrial water treatment processes involve chemical additions to improve water quality levels to meet their process or facility needs. While chemical treatment processes have been generally sufficient to maintain process and facility equipment, they are often coupled with volatile chemical supply costs, inconsistent water quality controls, and episodes of ineffective quality control leading to potential process or facility equipment damage. Provided the need to better understand the industrial water quality needs, through this effort we review the water quality needs of key primary metals, foundries and metal finishing processes including boilers and cooling towers where significant volumes of treated water with varying water quality is required. We compare the drawbacks of chemical treatment with costs and benefits of water treatment technology without extensive use of chemicals, focusing on electrically and/or thermally driven options. Additionally, the work characterizes water quality needs and explores where alternative water treatment options may offer an improvement to existing treatment options. The characterization will initially collect information using research on published papers, technical reports, vendor literature, and other data on industrial water needs. This will be supplemented by discussions with industrial facilities, including insights gained by working with the U.S. Department of Energy’s Better Plants Program partners. By involving representative industries, we develop case study information to capture conditions under which more innovative treatment could be demonstrated and collect more information to highlight the effectiveness of alternative approaches under application conditions. The presentation aims to provide an assessment of water quality treatment targets (based on certain water input composition) by process operation, with current water treatment technologies used, challenges associated with current technologies, and areas of potential improvement, in terms of expectations for future targets. Because water is often perceived as a low-cost commodity, discussions with industry partners indicate that water efficiency is often a relatively low priority unless there is an external driver. However, presenting a “true cost of water” provides greater motivation to take initiatives that can improve water efficiency, thereby reducing energy consumption and associated carbon emissions and costs. With this talk we plan to engage both industry and academic audience and bring their attention towards sustainable industrial water use, treatment, and reuse.