In the process for recovering caprolactam from wastewater using a pulsed-sieve-plate column, benzene, which is used as the extracting solvent, may seriously impact the environment due to its emission during the normal operation of the process. Green design methodology is adopted to redesign the pulsed-sieve-plate column in the recovery process. The quantity of benzene is also optimized by green design methodology to obtain an optimum trade-off between environmental protection and economic profit, and an environmental impact cost is introduced to quantify the impact of benzene emissions on the environment. The results of using green design and traditional design for the recovery process are presented and compared. (C) 2003 Elsevier Ltd. All rights reserved.