Coagulation pretreatment of highly concentrated acrylonitrile wastewater from petrochemical plants

Acrylonitrile (AN) wastewater is a heavily polluted and a likely hazardous liquid that is generated during the production of AN. Several chemical methods for the pretreatment of AN wastewater are available in laboratory scale. However, the harsh reaction conditions and high operational cost make these methods undesirable. Until now, four-effect evaporation is the only pretreatment method used for AN wastewater in industry despite its huge energy consumption and high cost. It is difficult to find an energy-saving pretreatment technique from the perspective of industrial application. In this study, a safe and low-cost coagulation technique was developed for the pretreatment of AN wastewater. Three types of inorganic coagulant and three types of polymer coagulant were investigated for the coagulation treatment of highly concentrated AN wastewater from petrochemical plants. The effects of coagulant type, dosage, and coagulation conditions on the pretreatment efficiency of AN wastewater were investigated. The results show that a combination of inorganic and polymer coagulants is effective for the pretreatment of AN wastewater.