آب و فاضلاب (Jan 2010)
Heavy Metals Removal from Industrial Wastewater by Sand, Soil and Organic Matter
Abstract
A greenhouse experiment was conducted with a completely randomized design with four treatments and four replicates to investigate the efficiency of sand, soil (calcareous and non-calcareous), and organic matter (rice husk and leaf compost) for the removal of copper, nickel, zinc, and chromium from industrial wastewater by filtration. PVC tubes (columns) 66.5 cm high and 10 cm diameter were chosen and each was filled from bottom to top with coarse gravel, sand, soil, organic matter, and fine gravel, respectively. Then, plating wastewater was added at nine pore volumes to each column. When the filter’s surface was completely dried, a second round of wastewater addition was performed. At the end of the experiment, the columns were cut to collect the adsorptive materials which were then air-dried and transferred to the laboratory for measurement of heavy metal concentrations by atomic absorption spectroscopy. The results showed that putting calcareous and non-calcareous soils under the applied organic matter (rice husk and leaf compost) affected their capacity for adsorbing heavy metals to varying degrees. It was also found that low the cation exchange capacity of soil compared to organic matter did not lead to its reduced adsorption capacity. Analysis of the organic matter revealed that rice husk was the best adsorbent for Cr, while leaf compost was the best for Zn and Ni. In addition, applied sand in this experiment was a good adsorbent for heavy metals in wastewater. Generally, it seems that application of the studied adsorbents was effective and that they could be recommended for the removal of heavy metals from industrial wastewater.
