Chromium, a heavy metal, is frequently detected in wastewater due to industrial discharges, agricultural runoff, and domestic sewage. This contamination raises concerns due to its adverse effects on both the environment and human health. Upon entering aquatic ecosystems, chromium can disrupt ecological balance, accumulate in the food chain, and harm aquatic organisms. In case of point source pollution, a Permeable Reactive Barrier (PRB) can be employed to effectively extract heavy metals like chromium from the wastewater. In the present investigation, a range of PRBs with varying thicknesses spanning from 1 to 5 cm has been created. Reactive substances, including Zero Valent Iron (ZVI), have the potential to serve as reactive agents for chromium removal. However, it is worth noting that ZVI is both scarce and expensive. Alternatively, activated carbon presents itself as another viable reactive material for adsorbing chromium. This activated carbon can be sourced from agricultural byproducts. In this study, reactive material for PRB has been synthesized from a variety of agricultural residues. Agricultural residues such as rice husk, wheat straw, maize residues have been converted into activated carbon and used as reactive material in PRB. The findings indicated that utilizing activated carbon sourced from maize residue could effectively address chromium contamination, achieving a remediation rate of approximately 60–65%. Additionally, the study observed that as the thickness of activated carbon layer increased, the efficacy of chromium removal also improved. However, it was noted that an increase in thickness led to a decrease in the permeability of the material.