Radiation induced decontamination of Cr(VI), Cu(II) and phenol in some tannery effluents

Industrialization has led to a number of environmental problems, such as release of toxic metals and other toxic organic and inorganic compounds to the environment. Among all, the rapid expansion of leather related industries in Pakistan have resulted in considerable environmental problems and effluents from processing of both domestic and imported hides and skins have increased pollution to alarming levels. Some tannery effluents of Peshawar area investigated in the present study showed high concentrations of Cr(VI) (2.7-12.6 mg/L), Cu(II) (2.6-11.4 mg/L) and phenol (0.1-4.2 mg/L). These contaminants are very toxic and must be removed from effluents before releasing into water bodies. A new technique of gamma irradiation has been investigated to decrease the load of COD and concentrations of Cr(VI), Cu(II) and phenol associated with tannery effluents to the permitted values. It was observed that concentration of Cr(VI) in the effluents can be brought to the permitted level by applying radiation dose of 3 kGy. A radiation dose of 2.5 kGy was required to remove more than 95% of Cu(II) and 100 % degradation of phenol in tannery effluents could be achieved by only one kGy of radiation dose.