Environmental concerns are being aggravated with the industrial progress of the country. Untreated wastewater disposal into the aquatic bodies pose a serious environmental threat through heavy metals‘ contamination of food chain, especially the chromium (Cr(VI)). This metal is well known for carcinogenicity and mutagenicity in humans. Inexpensive wastewater treatment technologies with local input of raw materials can be an optimal choice for large scale application for the industries of the developing countries, like Pakistan. Therefore, the major objective of the proposed research was to explore and develop the efficient adsorbents from the locally available biomass resources for Cr(VI) removal from aqueous solution. For this purpose, plenty of waste biomasses were collected, processed and subjected to batch screening for the respective Cr(VI) treatment. All the screened adsorbents, i.e., Eucalyptus camaldulensis sawdust (ECS), Eucalyptus bark, white cedar sawdust and tobacco stem showed maximum Cr(VI) removal efficiency at pH 2. The potential and an abundantly available precursor waste adsorbent, i.e., ECS, was converted to highly efficient (≥ 80% removal) activated carbon (AC-ECS) through two stage phosphoric acid activation (method V). A mesoporous activated carbon, i.e., AC-ECS was developed successfully and it displayed highly efficient Cr(VI) removal of 87% at pH 3. The morphological changes were detected through scanning electron microscopy. An increase in surface area of AC-ECS was noticed i.e., 217 m2 g-1 than its precursor biomass of ECS, i.e., 40 m2 g-1 using Brunauer–Emmett–Teller analysis. The evidence of Cr(VI) ions adsorption was confirmed through shift of wave number of the various surface functional groups and the appearance of crystalline peaks using fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analyses respectively. Cr(VI) adsorption data of AC-ECS exhibited the best fit to Langmuir isotherm (R2 = 0.999) revealing monolayer adsorption than its precursor biomass, i.e., ECS, where Cr(VI) adsorption data displayed best fit to Freundlich isotherm (R2 = 0.992) showing multilayer adsorption. Kinetic studies demonstrated the chemisorption as the rate limiting step. Thermodynamic studies exposed the non-spontaneous nature of reaction in non-activated adsorbents, while only AC-ECS displayed spontaneous reaction on the basis of Gibbs free energy. Fixed bed column studies of both AC-ECS and its precursor ECS showed that the exhaust time reduced with an increase of solution flow rate and contaminant concentration, whereas an inverse trend was observed with increasing bed height. ECS and AC-ECS packed columns indicated the increased breakthrough time from 670-1270 min and 5595-12270 min with respect to bed height (5 to 15 cm), respectively. However the increasing flow rate (5 to 15 mL min-1) and contaminant concentration (50-90 mg L-1) resulted the decrease in breakthrough time from 670-20 min and from 670-90 min for ECS packed column, respectively and from 5595-1330 min and 5595-800 min in case of AC-ECS packed column, respectively. Column study confirmed that AC-ECS packed columns were found more effective for Cr(VI) removal than ECS, as the AC-ECS exhibited the high exhaust and breakthrough times than ECS. Economic feasibility showed that total cost for the preparation of 1 kg non-activated ECS was approximately 4.4 PKR, while the cost of phosphoric acid activated carbon, i.e., AC-ECS prepared in the lab was found to be 4493 PKR. 1 kg of AC-ECS can treat approximately 1562 L of wastewater containing Cr(VI), which is larger than ECS (1388 L). It can be concluded that Eucalyptus camaldulensis sawdust is a good adsorbent for Cr(VI) adsorption among other tested non-activated forms of biomasses, and this is a good lignocellulosic material for the development of highly efficient activated carbon, i.e., phosphoric acid activation. The study recommends to assess the Cr(VI) adsorption performance of both ECS and AC-ECS in multiple solutes mixtures and to uncover the interference of other salts or metal ions through further batch and column studies at pilot scale and ultimately for the launch of these adsorbents for field scale treatment of wastewater.