This article investigated an eco-friendly technique for the removal of heavy metals using biosorbent derived from cow dung. Heavy metals bearing wastewater were collected from a common effluent treatment plant located at Sangariya, Jodhpur (Rajasthan, India) to evaluate the removal efficiency of synthesized cow dung-activated carbon. The prepared activated carbon materials have a high surface area in the range of 948-1072 m 2 /g and also have significant quantities of micropore and mesopore volumes. Furthermore, pore diameters were in the range of 2.24-2.33 nm. Surface morphology was improved after being treated with NaOH. The adsorbent material was found to be an efficient medium for the removal of Cr(VI) and Cd(II). The results revealed that more than 95.6% of Cr(VI) and 66.88% of Cd(II) were achieved at the optimized condition of pH12.0, initial concentration of heavy metals 10 mg/L, 300 min of contact time, and the dose of 0.2 g/L, whereas only 16.3% removal efficiency was observed for Ni(II). Equilibrium data have been analyzed by Langmuir, Freundlich, Temkin, and Redlich and Peterson (R-P) isotherm models with the help of nonlinear regression analysis. Experimental data were best fitted for Freundlich and R-P isotherms. K E Y W O R D S adsorption, biosorbent, cow dung-activated carbon (CDAC), heavy metal 1 INTRODUCTION Pure water, vital for a healthy environment, is a resource that is adversely affected both quantitatively and qualitatively by man-made activities. Rapid industrialization and urbanization have brought a real water crisis. Industries continue to be a major cause of water pollution due to diverse kinds of waste, especially toxic heavy metal ions released in water bodies, without adequate treatment (Nguyen et al., 2013). Water quality changes significantly with the presence of toxic heavy metals (Ni, Cd, Zn, Hg, Cr, Pb, Cu, and As) when the level exceeds prescribed limits. Thus, it becomes potentially harmful to all kinds of life on this planet. Heavy metals in water streams originate from the effluent of smelters, mines, and various industries such as batteries, tanneries, electroplating, steel, refining ores, paint manufacture, pesticides, fertilizers, pigment manufacture, printing, and photographic sectors (Babalola, 2018). The nature and composition of industrial effluents depend mainly on raw materials, process, and treatment methods. The ingestion of heavy metals via the food chain, in concentrations above the permissible limit, has a detrimental effect on human physiology and other biological systems. Due to their hazardous tendency of accumulation and toxicity, they pose a severe threat to the function of different organs in the human body and aquatic animals (Fu, & Wang, 2011; Rangabhashiyam, Jayabalan, Rajkumar, & Balasubramanian, 2019). Various agencies, viz., the U.S. Environmental Protection Agency (EPA), the Bureau of Indian Standards (BIS), and the Indian Council of Medical Research (ICMR), set regulatory limits for