工业废水包括生产废水、生产污水及冷却水，是指工业生产过程中产生的废水和废液，其中含有随水流失的工业生产用料、中间产物、副产品以及生产过程中产生的污染物。工业废水种类繁多，成分复杂。例如电解盐工业废水中含有汞，重金属冶炼工业废水含铅、镉等各种金属，电镀工业废水中含氰化物和铬等各种重金属，石油炼制工业废水中含酚，农药制造工业废水中含各种农药等。由于工业废水中常含有多种有毒物质，污染环境对人类健康有很大危害，因此要开发综合利用，化害为利，并根据废水中污染物成分和浓度，采取相应的净化措施进行处置后，才可排放。
Industrial wastewater includes production wastewater, production wastewater and cooling water. It refers to wastewater and waste liquid produced in industrial production process, which contains industrial production materials, intermediate products, by-products and pollutants produced in production process. There are many kinds of industrial wastewater with complex components. For example, the wastewater of electrolytic salt industry contains mercury, the wastewater of heavy metal smelting industry contains lead, cadmium and other metals, the wastewater of electroplating industry contains cyanide and chromium and other heavy metals, the wastewater of petroleum refining industry contains phenols, and the wastewater of pesticide manufacturing industry contains various pesticides. Because industrial wastewater often contains many kinds of toxic substances, polluting the environment is very harmful to human health. Therefore, it is necessary to develop comprehensive utilization and turn harm into benefit. According to the composition and concentration of pollutants in wastewater, appropriate purification measures can be taken to dispose of them before they are discharged.