Statistical analysis and profiling of chromium leaching characteristics in Basic Chrome Sulphate (BCS) sludge dumping at Khanchandpur-Rania, district Kanpur Dehat, Uttar Pradesh (India)

•The leaching of chromium species was significant with increasing depth.•The mean value of TCLP based total Cr, Cr6+, and Cr3+were found beyond the limit.•Results indicated that dumped BCS sludge is hazardousness.•The pH, EC, and TDS significantly increased with increasing depth. The present investigation has been conducted to study the leaching behaviour of chromium species in immobilised hazardous waste containing Basic Chrome Sulphate (BCS) dumped at Khanchandpur-Rania, Kanpur Dehat district of Uttar Pradesh, India. The pH of sludge was found to be basic in nature. The concentration of total and Toxicity Characteristic Leaching Procedure (TCLP) based Cr was observed at 26,208 and 215, 36,102 and 370, and 42,812 and 516 mg kg−1 in the pre-monsoon and 26,194 and 200, 36,237 and 340, and 42,570 and 471 mg kg−1 in the post-monsoon at 0–15, 15–75 and 75–150 cm depth, respectively. The concentration of total and TCLP based Cr6+ was found at 9652 and 107, 243,384 and 151 and 24,936 and 237 mg kg−1 in the pre-monsoon and 9724 and 102, 24,400 and 144, and 24,830 and 228 mg kg−1 in the post-monsoon at 0–15, 15–75, 75–150 cm depth, respectively. Results indicated that the concentration of total and TCLP-based Cr and Cr 6+ increased with depth. A similar trend was also observed in total and TCLP-based Cr 3+, total Fe, total Mn and TDS contents, which strongly justified the leaching characteristic of salts increasing with the increasing depth level of the dumpsite. [Display omitted] I. Generation of basic chrome sulphate sludge. II. Transportation of basic chrome sulphate sludge. III. Dumping of basic chrome sulphate sludge. IV. Overflow of leachate. V. Percolation of chromium species through rain water. VI. Aerobic and anaerobic process of chromium speciation. VII. Movement of hexavalent chromium. VIII. Chromium contamination in groundwater resources. IX. Chromium addition through food chain.