An algorithm for waste and pollutants reduction in reactor design is presented in this paper. This algorithm use potential environmentalimpact balance (PEI) and PEI rate-law expression to track the generated PEI throughout reaction process within a reactor; and study howreaction conditions (temperature, pressure, concentration, etc.) and various engineering factors (heat and mass transfer, and back-mixing andso on) affect process environmental performance. The form of PEI rate-law expression should be consistent with the method for calculatingthe overall PEI of mixtures of chemicals inside reactors. The algorithm can be used as a tool to aid in designing chemical reactors withenvironmentally friendliness processes. The use of the methodology is illustrated with the reaction system of allyl chloride production.