Integrated tannery wastewater treatment for effluent reuse for irrigation: Encouraging water efficiency and sustainable development in developing countries

Due to the high conductivity and chromium toxicity of tannery effluents, wastewater reuse can be possible only by implementing integrated process of sustainable wastewater treatments. The objective of the present study was to evaluate the suitability of treated tannery effluent for vegetable growth. An integrated treatment technology [ hydrolysis-anaerobic-Sequence Batch Reactor (SBR) integrated with a constructed wetland] was used to treat tannery wastewater. Randomized block design for field and pot experiment was used for vegetable growth. Treated effluent, soil and vegetable samples were analyzed for nutrient, physicochemical, Cr and microbial parameters using standard methods (APHA). The removal efficiency of the innovative integrated treatment system ranges from 82 to 99.9%. The treated effluent concentrations for BOD, COD, TN, NO3-N, and NH3-N were 56 +/- 18, 170 +/- 26, 50 +/- 13, 22.75 +/- 20 and 7.1 +/- 6 mg/L, respectively. Similarly, the concentration of EC, S2-, SO42- and Cl-were 2.23 +/- 0.17 mS/cm, 0.4 +/- 0.4, 88 +/- 42 and 450 +/- 150 mg/L, respectively; with a 99.9% TCF removal. The effluent meets the permissible discharge limits; possibly reuse for irrigation. Cr was found to accumulate the most in all vegetable samples and significantly higher in the field than pot treatments. Cr, Cd, Pb and Ni concentrations in all the pot experiment were found below the FAO/WHO guidelines. The target hazard quotients (THQs) estimation suggests that Cr concentration in all the pot treatment vegetable has no potential health risk.