Wastewater reuse and recycling of the steel industry in China: history, current situation, and future perspectives

China is the largest steel producer in the world. Effective methods to alleviate the contradiction between water supply and water demand of the iron and steel industry in China are to implement the recycling of wastewater from the iron and steel industry and develop unconventional water resources. This paper reviews the development of wastewater recycling in the iron and steel industry in China in the past 40 years (1980-2020). During this period, steel output has increased from 36 to 1,053 million tons, freshwater consumption per ton of steel has decreased from 35.9 to 2.45 tons, and water resources reuse has soared from 61.2 to 98.02%. Four typical cases, including the Anyang Steel Group, the Tangshan Steel Group, the Tianjin Steel Group, and the Taihang Steel Group, were analyzed. In addition, a water efficiency research project of iron and steel enterprises in China was carried out in 2019. Statistical analyses on wastewater recycling rate, reuse rate, direct cooling water circulation rate, and other indicators were performed. The recycling of wastewater in the iron and steel industry would be continuously improved by policy drivers, economic drivers, and technical drivers.