Chemical industry wastewater mainly comes from production wastewater discharged from petrochemical industry, coal chemical industry, acid and alkali industry, chemical fertilizer industry, plastic industry, pharmaceutical industry, dye industry, rubber industry, etc. The main measures for prevention and control of chemical waste water pollution are: first of all, the production process and equipment should be reformed to reduce pollutants, prevent waste water from being discharged, and carry out comprehensive utilization and recovery; for waste water that must be discharged, the treatment degree should be selected according to the water quality and requirements. The primary treatment is mainly to separate suspended solids, colloids, floating oil or heavy oil in water. Water quality and quantity regulation, natural sedimentation, floatation and oil separation can be adopted. The secondary treatment is mainly to remove the available biodegradable organic solutes and some colloids, and reduce the biochemical oxygen demand and some chemical oxygen demand in the wastewater, which is usually treated by biological method. After biological treatment, a considerable amount of COD remains in the wastewater, sometimes with high color, smell and taste, or due to the high requirements of environmental health standards, it needs to adopt three-level treatment method for further purification. The third stage treatment is mainly to remove the organic pollutants and dissolved inorganic pollutants which are difficult to be biodegraded in the wastewater. The commonly used methods are activated carbon adsorption and ozonation, as well as ion exchange and membrane separation. All kinds of chemical industrial wastewater can be treated by different methods according to different water quality, quantity and requirements of discharged water quality after treatment