Author/Authors :
Naim، R نويسنده Department of Environmental Engineering and Biotechnology, Myongji University, Yongin, 449-728, Korea 2 Department of Environmental Sciences, COMSATS Institute of Information Technology Abbottabad, Pakistan , , Kisay، L نويسنده Department of Environmental Engineering and Biotechnology, Myongji University, Yongin, 449-728, Korea , , Park، J نويسنده Department of Environmental Engineering and Biotechnology, Myongji University, Yongin, 449-728, Korea , , Lee، ch نويسنده Department of Environmental Engineering and Biotechnology, Myongji University, Yongin, 449-728, Korea , , 1 Qaisar، M نويسنده Department of Environmental Sciences, COMSATS Institute of Information Technology Abbottabad, Pakistan , , Zulfiqar، A. نويسنده , , Noshin، M نويسنده Department of Environmental Sciences, COMSATS Institute of Information Technology Abbottabad, Pakistan ,
Abstract :
Electroplating industry wastewater (EIW) characterized by high chemical oxygen demand
(COD) is a big source of water and air contamination with heavy metals. The formation of cyanide complex
with heavy metals is responsible for its elevated COD. The concentration of heavy metals in EIW can be
removed by the use of different precipitating agents (sulfide and hydroxide). But the major bottleneck in the
removal of these metals is the presence of cyanide in EIW resulting in chelation with all the metals that are
soluble in water. The present work focused on, the treatment of EIW containing Cr, Ni, Zn and CN and the
optimization of dosage concentration which was reliable for the dissociation of cyanide complex for maximal
removal efficiency. We used hydroxide, sulfide and carbonate precipitation from different precipitating agents
(NaOH, Ca (OH)
2
, CaCO3
Na2
S5H2
O, NaHS and NaHSO3
). Sulfide precipitation was a viable option for the
treatment of EIW as compared to hydroxide and carbonate precipitation. Moreover, COD reduction capacity
of sulfide precipitation was higher than others. It was also found that Ni and Cr made a complex with cyanide
that halted the removal efficiency while there was no evidence for Zn complexation; otherwise fragile complex-
ation was evidenced.
