Metal Leaching from Surface Dust of an Informal E-Waste Recycling area in New Delhi, India

Recycling and disposal of e-waste by informal sector in developing nations raise concerns due to its environmental consequences and human health hazards. In this study, metal toxicity and leaching behaviour of 13 metals (Ag, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn).  were investigated in surface dust samples (n=20) of informal e-waste recycling area in New Delhi by using Waste Extraction Test (WET) and Toxicity Characteristic Leaching Procedure (TCLP). The WET and TCLP tests were developed by California’s Department of Toxic Substances Control (CDTSC) and the United States Environmental Protection Agency (USEPA) respectively to simulate landfill conditions for metal leaching under laboratory conditions. All metals were leached more in WET compared to TCLP. In WET test, Cd, Cr, Cu, Ni, Pb and Zn exceeded the prescribed threshold limits of CDTSC and failed the test whereas Cd and Pb exceeded the threshold limits of USEPA in TCLP. Though Cu, Ni and Zn are not regulatory metals in TCLP, but their leaching concentrations exceeded the threshold limits of CDTSC. In both the tests, Fe, Mn and Sn were also leached in considerable amounts. In WET, Sn (37.7) leached in maximum percentage followed by Cd (28.7), Zn (27.9), Pb (27.7), Co (21.1), Mn (14.8), Ni (11.4), Fe (8.5), V (7.6), Cu (7.5), Ba (3.5), Cr (2.9) and As (0.4) respectively; whereas in TCLP Co (20.7) leached maximum followed by Cd (17.1), Zn (12.8), Mn (7.1), Ni (6.7), Sn (4.9), Cu (3.1), Pb (2.2), Ba (1.1), Fe (0.4), V (0.3), Cr (0.2) and As (0.1) respectively. The WET test was found to be more aggressive in leaching of metals when compared to TCLP due to citrate ion chelation property. Leaching of metals higher than the threshold limits can cause contamination of soil, surface water and ground water in nearby areas and can affect the human health and environment. Therefore, there is needs to regulate policies and environmentally sound new technologies for e-waste recycling to safeguard the human health and environment.