Ecotoxicological risks associated with tannery effluent wastewater

The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K2Cr2O7) and chromium sulfate Cr-2(SO4)(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K2Cr2O7) and trivalent chromium Cr-2(SO4)(3) were obtained for this study. Cytotoxicity assay, anemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K2Cr2O7 and Cr-2(SO4)(3). All the dilutions of TW, K2Cr2O7 and Cr-2(SO4)(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K2Cr2O7 caused significantly more damage (P < 0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K2Cr2O7 treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K2Cr2O7) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.