In some cases, the steel industrial effluents may be treated and not be treated before it discharged into water bodies. The purposes of conducting this study are to characterize the steel industrial effluent from past research as a pollutant source benchmark and evaluate the effectiveness of COD removal for industrial effluent in a treatment train system. Three (3) sets of treatment trains (Set A, Set B & Set C) were set up as cascaded (stepped) system with various plant species planted in the engineered soil media. The best performance between the three (3) different configurations was Set C (Soil with Cordyline Fruiticosa plant). Set C obtained the highest removal rate than the other two (2) sets which was 98.9. To conclude, the bioretention treatment train was very effective to treat steel industrial effluent and it is suggested that further study involve monitoring the performance of the treatment train system for a longer period of time to observe if the quality of effluent degrades over time. © 2024, Institute of Technology PETRONAS Sdn Bhd.